# It's time to Order My Rear Diff, Front Disc Brake Kit, & Suspension Components.



## Sick467 (Oct 29, 2019)

I am hoping to spend some jack in the next month so that when spring/summer hits, I can get after re-doing the rolling chassis and need your help. It's a fair amount for me to wrap my head around and some decisions have to be made...the time has come.

I'm just going to throw out my thoughts and see what sticks...

*1.)* I need a front disc brake conversion kit and am leaning towards the smaller diameter booster for better clearance at the valve covers. I intend on using 15" steelies and am not concerned with originality. I just want better than stock drum braking that discs offer. Ames says you can get the 9" booster upon request. Here's what I'm looking at from Ames...











*Open for discussion...pros/cons with this kit?*

*2.)* Next is the rear end and this one is making my head spin quite a bit. I currently have the stock 10 bolt with the 2.56 gears and want to go with something in the 3's. At first glance, the favorite ratios seem to be in the 3.23 to 3.36 range…BUT I am leaning heavily towards a Gear Vendors overdrive behind my 400TH. Now I’m thinking more like 3.55, *but am open to advice*. I will have maximized the space in the rear wheel wells for the widest treaded radial drags (without cutting the frame and tubbing). My motor build is not set in stone yet, but will land between 400 and 500 HP. I need to prepare for the higher end since “more power” is hard to resist. That leads me to want the 12 bolt or Ford 9”. One thing I could do is buy a Ford 9” without the gear set. *This should allow me to rebuild the rolling chassis and make the gear ratio decision later, Right?*

I want to buy a rear end that accommodates stock/aftermarket replacement suspension parts and bolts in without having to modify anything. I intend to upgrade to tubular suspension and add a rear sway bar that u-bolts to the axle, not the trailing arms (along with frame braces). * I’ll take all recommendations for a company that offers this type of rear end service.*

Another thing on my mind is ordering a custom width rear end to help guarantee that the widest wheel/tire combo can be installed. *Do I need to buy my wheels and tires in order to figure that out?*

I’ll think about drum or disc rear brakes later to keep my head form cracking open. I'm pretty sure I have the suspension parts figured out. Except what rear sway bar to get, but that depends on what rear end I go with, I suppose.


----------



## geeteeohguy (Feb 2, 2008)

I'll play: Have you thought of simply installing '68-'72 A body spindles and front brakes? Did a '65 GTO for a total of $90 years ago, which included all the parts. This was from a sa;avge yarde. Straight bolt on, no brackets to fail or come loose. Won't change front end geometry at all. Franks Pontiac Parts in CA may have the stuff. 
If you are going to bother to upgrade the rear, a Ford 9" is head and shoulders superior to a 12 bolt. NO comparison. And MUCH easier to change gear ratios, since it's a 'drop out' unit. With a GV overdrive, I would run a 3.50 or even better, a 3.89 rear gear, knowing your plans. I would NOT bother with rear disc brakes. They usually have inferior parking/emergency brake capacity compared to the drums, and only do 25% of the stopping. I would only do rear disc brakes if I was going to track the car on a road race course in events that went many laps. Otherwise, total waste of money, and IMO, inferior to stock drum, which don't need failure-prone brackets and spacers and crap to work. 
As for wheels and tires, that is the hardest part, and easy to mess up on. You will need to get your rear end installed and measured and go from there. If I were getting a custom 9" rear, I would likely get one that ran about 2 or 3 inches narrower than the stock 8.2 ten bolt that comes on these cars. I had a set of 11" slicks on my '65 years ago mounted on Chevy rally rims and they fit perfectly. Barely, but they cleared. No air shocks, etc.


----------



## Baaad65 (Aug 29, 2019)

Sick467 said:


> I am hoping to spend some jack in the next month so that when spring/summer hits, I can get after re-doing the rolling chassis and need your help. It's a fair amount for me to wrap my head around and some decisions have to be made...the time has come.
> 
> I'm just going to throw out my thoughts and see what sticks...
> 
> ...


I did an 8" dual booster and can get the cover off easily and have real good brakes, almost 15 inches of vacuum with my cam and 1.6 rockers because of the 114 LSC and I have disc/drum, rear discs aren't necessary unless you want the cool Pro Tour look which if I had to do it over would have gone that way but it's more money. If you're thinking about it do it now because that's why I'm not changing to rear discs I would have to change the P valve, buy new E brake cables and spend a lot more money on the brakes....but you never know with me  I'll have a 12 bolt housing w/Strange axels and maybe brakes available in the narrower '65 width if interested but you might be to far away from Northern IL. You could look at the one I'm getting the Strange Dana S60, it has raised upper arm mounts to help eliminate wheel hop and multi position lower mounts...2600.00 at Summit plus tax and some add ones so about 3K delivered and bullet proof. And don't forget about the drive shaft with 1350's on both ends and the diff yoke.


----------



## Sick467 (Oct 29, 2019)

geeteeohguy said:


> I'll play: Have you thought of simply installing '68-'72 A body spindles and front brakes? Did a '65 GTO for a total of $90 years ago, which included all the parts. This was from a sa;avge yarde. Straight bolt on, no brackets to fail or come loose. Won't change front end geometry at all. Franks Pontiac Parts in CA may have the stuff.
> If you are going to bother to upgrade the rear, a Ford 9" is head and shoulders superior to a 12 bolt. NO comparison. And MUCH easier to change gear ratios, since it's a 'drop out' unit. With a GV overdrive, I would run a 3.50 or even better, a 3.89 rear gear, knowing your plans. I would NOT bother with rear disc brakes. They usually have inferior parking/emergency brake capacity compared to the drums, and only do 25% of the stopping. I would only do rear disc brakes if I was going to track the car on a road race course in events that went many laps. Otherwise, total waste of money, and IMO, inferior to stock drum, which don't need failure-prone brackets and spacers and crap to work.
> As for wheels and tires, that is the hardest part, and easy to mess up on. You will need to get your rear end installed and measured and go from there. If I were getting a custom 9" rear, I would likely get one that ran about 2 or 3 inches narrower than the stock 8.2 ten bolt that comes on these cars. I had a set of 11" slicks on my '65 years ago mounted on Chevy rally rims and they fit perfectly. Barely, but they cleared. No air shocks, etc.


I am hoping for a disc kit. Can the '68-'72 parts be found in a kit of new parts.

As far as the rear end and wheels and tires go...I'm thinking to stick with standard available back spacings and adjust the rear end width to them. I'm still noodling how to determine the rear width with my car off the frame and on a cart/dolly. 

Thanks for "playing", the game's not over!


----------



## Sick467 (Oct 29, 2019)

Baaad65 said:


> I did an 8" dual booster and can get the cover off easily and have real good brakes, almost 15 inches of vacuum with my cam and 1.6 rockers because of the 114 LSC and I have disc/drum, rear discs aren't necessary unless you want the cool Pro Tour look which if I had to do it over would have gone that way but it's more money. If you're thinking about it do it now because that's why I'm not changing to rear discs I would have to change the P valve, buy new E brake cables and spend a lot more money on the brakes....but you never know with me  I'll have a 12 bolt housing w/Strange axels and maybe brakes available in the narrower '65 width if interested but you might be to far away from Northern IL. You could look at the one I'm getting the Strange Dana S60, it has raised upper arm mounts to help eliminate wheel hop and multi position lower mounts...2600.00 at Summit plus tax and some add ones so about 3K delivered and bullet proof. And don't forget about the drive shaft with 1350's on both ends and the diff yoke.


I will have to do some reading on the Dana S60, your price point seems quite a bit lower than the first, and only, price check I've made on the Ford 9".

What do you mean about the yoke sizes (1350's). I realize that they may have to change styles from original, but I am curious to what you are referring to. At this point, I don't even know what was original to my car.

I'll be happy with drums in the back. My preference in wheels will not show the bling in the background.


----------



## Baaad65 (Aug 29, 2019)

Sick467 said:


> I will have to do some reading on the Dana S60, your price point seems quite a bit lower than the first, and only, price check I've made on the Ford 9".
> 
> What do you mean about the yoke sizes (1350's). I realize that they may have to change styles from original, but I am curious to what you are referring to. At this point, I don't even know what was original to my car.
> 
> I'll be happy with drums in the back. My preference in wheels will not show the bling in the background.


Just make sure the pinion yoke on the 12bolt (if you go that way) is a 1350 with that HP and big tires, the guy that built mine used a 1330 or whatever the next size down is so I changed it out. I also have a 1350 trans yoke. The Dana comes standard with a 1350, also some review the S60 better than a 9-inch, it's 9.750 and takes less power to drive it but the gear changes are easier on the 9 of course but I don’t plan on doing any changing that's why I'm trying to get my gear right for now and in the future.


----------



## GTO Yeah (Dec 6, 2021)

If you go with the Ford 9" rear end, don't forget to make sure your brakes fit with that rear end. Your GTO brakes won't work (or at least might require some different brackets). Ask me how I know.

I went with all UMI suspension parts, but I can't attest to how well they work just yet. The fit and finish was nice enough, though. A lot of people seem to like Global West too. 

As for the axle-mounted sway bar, I've got my eye on either the Spohn or Umi, but that's later down the line for me.


----------



## PontiacJim (Dec 29, 2012)

Sick467 said:


> I will have to do some reading on the Dana S60, your price point seems quite a bit lower than the first, and only, price check I've made on the Ford 9".
> 
> What do you mean about the yoke sizes (1350's). I realize that they may have to change styles from original, but I am curious to what you are referring to. At this point, I don't even know what was original to my car.
> 
> I'll be happy with drums in the back. My preference in wheels will not show the bling in the background.


"1350" is the size associated with the larger U-joints/caps. Pontiac used a large 1330 U-jount while Chevy used a smaller size still, I think 1310.

I have the 9" and got the "large wheel bearings" and the 11" rear drum kit to go along with it. Disc brakes are not really needed with the 11" drums (believe Pontiac was 9"). Get a good "soft" brake lining that will grip well versus a harder "lifetime" lining that won't stop so good.

You will be hard pressed to find a factory '68-72 single piston disc set-up and than all you are doing is installing 50 year old parts which will require rebuilding or replacing of the calipers and at best, turning down the rotors and installing all new bearing/seals - and they won't be cheap. Better to go with an aftermarket disc brake set-up with all new parts.

Some will require different A-arms based on the type of spindles used with the aftermarket kit. 

With disc brakes, it is important to have correct fitting rims that will allow the disc calipers to fit inside and be deep enough so as not to hit the calipers/rotors. Some kits are indeed better than others.

Also want correct proportioning valve to match disc/drums or disc/discs and possibly a metering valve if disc/drums. MC will also need to be spec's as the MC piston bore size is important to brake pedal effort and fluid volume movement. Don't just assume because the advertiser "says" it will fit your car - DO THE RESEARCH.


----------



## Baaad65 (Aug 29, 2019)

Couldn't be more true 👍


----------



## lust4speed (Jul 5, 2019)

I ordered out the rear 11" Ford drums for my Dana 60 in the GTO and they have been perfect. My son's '68 Firebird had the 9" diff and 11" drums and worked great. Then talked two of my friends into the 11" rear drums and they also really like the feel and stopping power. On the other hand, I've had friends in the GTO club that went with rear disc brakes and they have had trouble setting up the rear discs with enough stopping power and couldn't get them adjusted to have the rears do their share.

I've had quite a few vehicles with the single piston front discs and I really prefer the two piston or especially the four piston calipers. Just seems to have better feel and a more aggressive stopping ability. Now the single piston far outshines and out stops the drum brakes, but there is a noticeable improvement when more money is spent. I converted a '67 GTO to single piston setup off a '69 Grand Prix. Got the setup out of pick-a-part and by the time I rebuilt everything I wasn't any money ahead of just going with one of the full kits now available. My blue GTO was ordered with the 4-piston discs and they are massively better than the single piston units that were available in later years. Just a pain finding parts for the early calipers when it does come time to refresh things.

My latest endeavor is the '65 Catalina Safari wagon. That car was truly frightening when I first brought it home and every stop was a life threatening experience. Went with the 13" disc Master Power Brakes and 17" wheels and they really bring the big barge down without a problem. Overkill for a lighter GTO, but bigger proved better for the wagon.










Friend and I made a dual order to save some shipping costs. Here is
the pair of Dana 60's with the 11" drums. We finally decided on the 3.73
ratio because of the 28" tall tires and the 5th gear ratio of the Tremec.


----------



## Baaad65 (Aug 29, 2019)

That's the combo I'm dreaming about, how do you like it on the street? I was going to try and reuse my rear drums as they're only a few years old, Strange said I have to open up the hole on the backing plate for the bigger bolt in axle bearing. Maybe I should check into the cost of the bigger drum brakes.


----------



## Baaad65 (Aug 29, 2019)

The idea I was toying with was to pull my axles then suspended the backing plates without disconnecting the lines, make the holes bigger then pull the axles on the Dana and bolt my plates on. Idk if it's going to work and if the lines will work, my brakes are good and I was hoping to not have to bleed the brakes as I've finally got my master cover to stop leaking but if I have to I do.


----------



## Baaad65 (Aug 29, 2019)

Also sorry Sick467 for veering my rear end into your lane I'll straighten it out and stay in my lane 😉


----------



## lust4speed (Jul 5, 2019)

As far as the price point mentioned above, the 12-bolt was the most expensive, then the 9", and the least expensive was the Dana 60 when we purchased ours. No idea why the 12-bolt was so expensive but it was another $600 over the others when ordered with all the upgrades.

Our original 9" drums are substandard by every measure and you just as well upgrade. The Ford big bearings are the only way to go with whatever rear you choose. I was thinking that the bolt pattern for the Ford backing plate was really different than the 10/12 bolt pattern but never physically checked. Hopefully the 9" drum will fit correctly in both the diameter of the center hole and the axle shaft is properly located to center the drums on the shoes. I was able to use both the emergency brake cables and brake lines with the new rear with the Ford brakes.

We were vacillating between the 3.54 and the 3.73 and I might have went with the 3.54 if I had a milder cam. Makes about a 5 MPH difference in optimum cruising speed with the 3.73's coming in about 78 MPH and 83 MPH for the 3.54's. The main problem is my fairly large cam wouldn't be happy when having to cruise at 65 with the higher ratio. There's always going to be a dead spot with a manual trans where 4th is spinning somewhat and 5th is somewhat low in the RPM range. With the 3.73's the indecision spot between 4th and 5th is between 55 to 60 while the 3.54's would have been 60-65, and there will be many times on the freeway I'd be stuck at or just below 65 in Saturday afternoon traffic. Not that big of deal either way with either gear, but I also prefer the slightly lower first gear final ratio for chugging along when traffic finally drops down to a crawl.

Ford 11" internals. You can see my not-so-pretty emergency brake cables attached.









The extended mounts as mentioned above. This is the standard cover and
is still formidable. The available aluminum covers take things to the next level.
I did spring for the powder coating.










Besides the ring gear being larger in diameter, the tooth width is over a
half inch wider than the 12-bolt or Ford 9". Photo looses some perspective
of the size - that's 3" exhaust in the background.










Last photo just to show we can practice re*neck techniques in SoCal.
The friend on truck is the one that ordered out the other Dana.


----------



## GTO Yeah (Dec 6, 2021)

lust4speed said:


> As far as the price point mentioned above, the 12-bolt was the most expensive, then the 9", and the least expensive was the Dana 60 when we purchased ours. No idea why the 12-bolt was so expensive but it was another $600 over the others when ordered with all the upgrades.
> 
> Our original 9" drums are substandard by every measure and you just as well upgrade. The Ford big bearings are the only way to go with whatever rear you choose. I was thinking that the bolt pattern for the Ford backing plate was really different than the 10/12 bolt pattern but never physically checked. Hopefully the 9" drum will fit correctly in both the diameter of the center hole and the axle shaft is properly located to center the drums on the shoes. I was able to use both the emergency brake cables and brake lines with the new rear with the Ford brakes.
> 
> ...


Wilwood has a great resource for the different bolt patterns here. It's what helped me figure out what I needed to order.


----------



## Baaad65 (Aug 29, 2019)

lust4speed said:


> As far as the price point mentioned above, the 12-bolt was the most expensive, then the 9", and the least expensive was the Dana 60 when we purchased ours. No idea why the 12-bolt was so expensive but it was another $600 over the others when ordered with all the upgrades.
> 
> Our original 9" drums are substandard by every measure and you just as well upgrade. The Ford big bearings are the only way to go with whatever rear you choose. I was thinking that the bolt pattern for the Ford backing plate was really different than the 10/12 bolt pattern but never physically checked. Hopefully the 9" drum will fit correctly in both the diameter of the center hole and the axle shaft is properly located to center the drums on the shoes. I was able to use both the emergency brake cables and brake lines with the new rear with the Ford brakes.
> 
> ...


Good to know and you're the reason I looked into the Dana, like I said if I do the 3.73 I know it's going to be a little rough with my 4spd but I'm talking myself into the TKX maybe in 2024. I have enough to pay off and now a new rear plus our sons wedding in September that we are making a healthy contribution to....could have had a lot of nice car upgrades for that  So I only see two sets of rear drums on the Strange site that say they are Fords, is that what you used because I was going to call them tomorrow, they're also 645.00 so I might stick with mine if possible. I have to get the Detroit Track Lok diff with the helico gears so no clutches as it's the only one available they said, also going with the 1/2" studs and Strange aluminum diff cover, not the pricey one and I think for 83.00 the billet u joint girdle even though they said it's not necessary. This diff also has the adjuster nuts on the caps for adjusting backlash and preload. Summit has it for a 100.00 less than Strange right now and I can pick it up...30 minute from my office


----------



## lust4speed (Jul 5, 2019)

I ordered my Dana three years ago almost to the day. Looked up my invoice and it said "Late B.F. Drum Brake Kit". Also went with the Chromoly 1350 Yoke and the Dana Truetrac with the helical gears. Absolutely love the Truetrac - 100% traction to both wheels as soon as the gas is hit but operates like an open diff when driving normal.

The friend in my last photo has been bitten by the drag racing bug and is in pursuit of better strip times. A couple weeks ago we installed 4.10's in his Dana in place of the 3.73's. It was the first time I played with the threaded preloads and there was somewhat of a learning curve. Was used to the feel of loading shims for preload and was a little worrisome to just crank in preload without having a true reference point. Last time out he was dumping the clutch and bringing the front wheels off the ground about 4" and so far things are all holding up.


----------



## Baaad65 (Aug 29, 2019)

lust4speed said:


> I ordered my Dana three years ago almost to the day. Looked up my invoice and it said "Late B.F. Drum Brake Kit". Also went with the Chromoly 1350 Yoke and the Dana Truetrac with the helical gears. Absolutely love the Truetrac - 100% traction to both wheels as soon as the gas is hit but operates like an open diff when driving normal.
> 
> The friend in my last photo has been bitten by the drag racing bug and is in pursuit of better strip times. A couple weeks ago we installed 4.10's in his Dana in place of the 3.73's. It was the first time I played with the threaded preloads and there was somewhat of a learning curve. Was used to the feel of loading shims for preload and was a little worrisome to just crank in preload without having a true reference point. Last time out he was dumping the clutch and bringing the front wheels off the ground about 4" and so far things are all holding up.


Nice, well I guess that's all they offer in drum brakes but they're still expensive. Now it looks like they call the diff with helical gears an S track and I'm also getting the chrome moly yoke 
probably with the heavy duty caps.


----------



## Sick467 (Oct 29, 2019)

Baaad65 said:


> Also sorry Sick467 for veering my rear end into your lane I'll straighten it out and stay in my lane 😉


No worries, I enjoy the conversations and am trying to soak it all up!


----------



## Sick467 (Oct 29, 2019)

I've learned some things from this thread already and have "built" a 9" rear end off the Currie site and have some questions. Not that I am set on Currie...I just started there to get a feel for what's involved. Here's the fictitious build...










*Questions...ignore the ratio for the time being, but I suspect it will be between 3.25 and 3.89.*

1.) Axle spline options are 31 & 35....what's a guy need to know to make the right choice? It makes over $700 difference in the final price plus the case option dollars that follow.

2.) If you choose 35 spline, you have to pick from an nodular iron "race" or aluminum "Pro" case. Picking the 31 spline, the options are the "sportsman" iron or light weight aluminum case. I'd bet this has to do with horsepower and/or weight loss, in general...where do I stand?

3.) What diff style to strongly consider? I here folks bragging about the Detroit and Eaton often enough...pros/cons? Why would anybody build a 9" with and open diff? Here is Currie's options...










4.) The 1350 Yoke comes in Nodular Iron or Chromoly. How to make the $5 difference decision?










5.) These are the drum brakes that come with the kit...looks like they are for the large bearing rear ends. The description is fairly nondescript, anything to question here?...











6.) Wheel stud size options. I'd love to keep the OEM 7/16" size, but should I bump up to the 1/2"? Do the wheels that work on the 7/16" also work on the 1/2"? I guess that's my main concern.


----------



## Baaad65 (Aug 29, 2019)

Nice but pricey, with add ones my Dana should be at 3K with 35 spline axels, Eaton Truetrac, 1/2" studs, chrome moly yoke and heavy duty u joint caps plus powder coated, upgraded cover and oil but no brakes those are 645.00 extra.


----------



## geeteeohguy (Feb 2, 2008)

Lust makes an excellent point if you are running larger camshafts. You don't want your cruise RPM so low you will be 'off the cam' most of the time at cruise, which results in saggy performance and lugging. Have a friend who ran into just this problem and we ended up installing steeper rear gears. His was so bad he couldn't even use OD below 80-85 mph. New vehicles with VVT and all the electronics are happy going down the road at 1500-1800 rpm at 75 mph. A big cammed Pontiac, not so much. 2200-2600 rpm seems to be the sweet spot to be at the beginning of the powerband, get snappy performance at tip-in, and decent fuel economy.


----------



## Sick467 (Oct 29, 2019)

geeteeohguy said:


> Lust makes an excellent point if you are running larger camshafts. You don't want your cruise RPM so low you will be 'off the cam' most of the time at cruise, which results in saggy performance and lugging. Have a friend who ran into just this problem and we ended up installing steeper rear gears. His was so bad he couldn't even use OD below 80-85 mph. New vehicles with VVT and all the electronics are happy going down the road at 1500-1800 rpm at 75 mph. A big cammed Pontiac, not so much. 2200-2600 rpm seems to be the sweet spot to be at the beginning of the powerband, get snappy performance at tip-in, and decent fuel economy.


Right now, I am being advised to not use anything more than a Ram Air IV cam, thereabouts, but the engine build is still a ways off. Not sure how that equates to decent OD conditions? I do know what you mean though...I had a peppy [email protected] motor that lugged quite a bit in OD at 60 minus mph with an AOD transmission and 3.73 gears, but loved the T5 manual transmission. It was all in the control of when OD was used.

Side note: I did a quick 9" rear build on the Moser site and the price for a similar build was considerably lower. than the Currie build It is not comparing apples to apples since the options are not exactly the same, but relatively close. It's never easy. is it? I'll keep at unitl my money's gone!


----------



## GTO Yeah (Dec 6, 2021)

Sick467 said:


> I've learned some things from this thread already and have "built" a 9" rear end off the Currie site and have some questions. Not that I am set on Currie...I just started there to get a feel for what's involved. Here's the fictitious build...
> 
> View attachment 159715
> 
> ...


I wouldn't stress to much about the diff. The great thing about the Ford 9" is you can always change your mind later! This is Currie's video that talks about the differences between their offerings. I went with the Currie TwinTrac for mine.

You can save a bunch if you get the housing and axle package, then buy the third member separately from them rather than a completely built rear end. Of course you'll have to put the axles/third member in yourself, source a brake kit, and paint it yourself. But it's about $1800 cheaper to do it that way.

1/2 studs should work with your wheels. They worked with my Rally II's off a Trans Am.


----------



## Baaad65 (Aug 29, 2019)

Sick467 said:


> Right now, I am being advised to not use anything more than a Ram Air IV cam, thereabouts, but the engine build is still a ways off. Not sure how that equates to decent OD conditions? I do know what you mean though...I had a peppy [email protected] motor that lugged quite a bit in OD at 60 minus mph with an AOD transmission and 3.73 gears, but loved the T5 manual transmission. It was all in the control of when OD was used.
> 
> Side note: I did a quick 9" rear build on the Moser site and the price for a similar build was considerably lower. than the Currie build It is not comparing apples to apples since the options are not exactly the same, but relatively close. It's never easy. is it? I'll keep at unitl my money's gone!


I would ask people here when it's time for a cam choice and also the popular Pontiac engine builders like Butler, Tin Indian, Nightmare and Len Williams...they won't mind a phone call. It sounds like you'll have the drive train done first then I guess you'll have to tailor the motor to that in some degrees?


----------



## Scott06 (May 6, 2020)

Sick467 said:


> I am hoping for a disc kit. Can the '68-'72 parts be found in a kit of new parts.
> 
> As far as the rear end and wheels and tires go...I'm thinking to stick with standard available back spacings and adjust the rear end width to them. I'm still noodling how to determine the rear width with my car off the frame and on a cart/dolly.
> 
> Thanks for "playing", the game's not over!


Not sure if you settled on a disc kit yet, this is a stock type set up i installed on my 65 about 3 years ago. https://www.summitracing.com/parts/sum-bk1501/make/pontiac/model/gto/year/1965

nice kit just needed a few short sections of brake line ( all four drums met a distribution block) and a 9/16 x 3/16 adapter for rear line .. basically stock gm single piston calipers and 11” rotors , pretty basic simple kit for driver quality car


----------



## PontiacJim (Dec 29, 2012)

Sick467 said:


> Right now, I am being advised to not use anything more than a Ram Air IV cam, thereabouts, but the engine build is still a ways off. Not sure how that equates to decent OD conditions? I do know what you mean though...I had a peppy [email protected] motor that lugged quite a bit in OD at 60 minus mph with an AOD transmission and 3.73 gears, but loved the T5 manual transmission. It was all in the control of when OD was used.
> 
> Side note: I did a quick 9" rear build on the Moser site and the price for a similar build was considerably lower. than the Currie build It is not comparing apples to apples since the options are not exactly the same, but relatively close. It's never easy. is it? I'll keep at unitl my money's gone!


35 spline axles is overkill and not needed unless you plan on an engine over 600HP and going to run slicks.

The 11" Ford drums were drilled for the Pontiac bolt pattern - as were the axles.

"Lugging" the engine can depend on the cam if you select a cam that doesn't begin to work until is sees 3,500 RPM's and up and you plan on running 70 MPH at 2,000 RPM's with the OD/rear gear combo. One reason why the RA IV cam used 4.33 gears and 3.90 gears - to keep the RPM's up to make the car more streetable, and even then it was a little balky when driving around town - it was a race engine with a race cam. One thing to look at in a cam is the Overlap. Big overlap means lumpy cam and higher RPM usage. You can get a big cam and still keep the overlap down.

*9" FORD Rear Axle Assembly - 1968 LeMans*

Quick Performance GM A-body 9" housing w/31 spline axles - $745.00
Upgrade to 1/4" heavy walled axle tube rated for 600HP+ - $ 30.00 
Upgrade to new housing center piece & big billet bearing ends - $100.00
11" drum brake kit - fully assembled - $300.00
Shipping - $130.00

Yukon Nodular big-bearing differential case - $354.03
Currie 9-Plus Big bearing pinion support - $114.95
Currie Open carrier case - $105.95
Bolts - Grade 8 for pinion support - $ 7.45
Complete Timken bearing/seal/installation kit - $136.95
Pinion bearing solid spacer kit - $ 16.95
9-Plus big bearing forged driveshaft pinion yoke - $130.55

Power-Trax No-slip locker -$430.00
Shipping -$ 15.65

Motive Gear 3.89 ratio ring & pinion gear set - $189.97

Shop assembly of third member/set-up gears - $128.98

Parts Total -$2,661.80
Shipping Total -$ 145.65
Labor Total -$ 128.98

*TOTAL $2,936.43
*


----------



## lust4speed (Jul 5, 2019)

> ...The great thing about the Ford 9" is you can always change your mind later!


I hear this all the time, but unless you are a race team and need several third members for different track conditions it doesn't make financial sense. The price of a set up third member is about two thirds the price of a complete axle assembly. Currie gets over $1,800 for their cast iron case third member fully set up. A Richmond ring and pinion gearset for the 9" is a little over $350. Most of us will still be changing out the ring and pinion on the 9" third member at the same cost as someone with a 12 bolt or Dana 60.


----------



## GTO Yeah (Dec 6, 2021)

lust4speed said:


> I hear this all the time, but unless you are a race team and need several third members for different track conditions it doesn't make financial sense. The price of a set up third member is about two thirds the price of a complete axle assembly. Currie gets over $1,800 for their cast iron case third member fully set up. A Richmond ring and pinion gearset for the 9" is a little over $350. Most of us will still be changing out the ring and pinion on the 9" third member at the same cost as someone with a 12 bolt or Dana 60.


That's a good point. It's a lot spendier to pick up a fully set up third member. I like it for me because I'm not 100% confident setting the backlash of the ring and pinion just yet. I've never done it and it feels foreign to me. Reading the grease marks is like reading tea leaves in my mind. I'll never be confident I did it right. I like the peace of mind I get just bolting up a completed unit. 

I'm sure someday I'll need to learn to do it. Every car I drive can't have a Ford 9" in it.


----------



## PontiacJim (Dec 29, 2012)

GTO Yeah said:


> That's a good point. It's a lot spendier to pick up a fully set up third member. I like it for me because I'm not 100% confident setting the backlash of the ring and pinion just yet. I've never done it and it feels foreign to me. Reading the grease marks is like reading tea leaves in my mind. I'll never be confident I did it right. I like the peace of mind I get just bolting up a completed unit.
> 
> I'm sure someday I'll need to learn to do it. Every car I drive can't have a Ford 9" in it.


Here is an example of a complete 3rd member. Choose the spline count and your gear ratio and then slap it in. Price is not too bad either -$890.00. Purchase a 9" housing for the A-body and axles and then install the 3rd member, axles, and your brake kit and you are done. Don't like the gears, have another set on hand to use or experiment with.









Ford 9 Inch Posi Differential 3rd Member, 31 Spl, 4.56 Gear Ratio


As featured on Classic Truck’s Week to Wicked. Watch the transformation here! Assembled by Professionals Hand-assembled by trained experts in-house, our Ford 9-inch third members are built from quality components with an exact step-by-step process. We bring this combination of precision assembly...




www.speedwaymotors.com


----------



## Baaad65 (Aug 29, 2019)

PontiacJim said:


> 35 spline axles is overkill and not needed unless you plan on an engine over 600HP and going to run slicks.
> 
> The 11" Ford drums were drilled for the Pontiac bolt pattern - as were the axles.
> 
> ...


So I only have two reasonable gear choices with the Dana and didn't think about pairing it with my cam, how do you think a 3.54 or 3.73 will play with my cam plus 1.65 rockers? and also with my 4 spd or a TKX 2.87/ .68 ?


----------



## Sick467 (Oct 29, 2019)

Baaad65 said:


> So I only have two reasonable gear choices with the Dana and didn't think about pairing it with my cam, how do you think a 3.54 or 3.73 will play with my cam plus 1.65 rockers? and also with my 4 spd or a TKX 2.87/ .68 ?


It's my new understanding that the rpms at which you will be going into OD, or maintaining in OD, is the key. Your engine RPM's, in OD, should be in the power band of the cam. For example, pretty radical cams may not have a power band that starts below 3000 RPM's...if your car will be cruising in OD at less than that...you risk lugging the engine. 

Do you have the power band info for that cam? I do not see it on Bulter's site...



https://butlerperformance.com/i-29361022-butler-comp-sp-street-performance-billet-roller-cam-hr-282-288-230-236-510-521-114-ls-std-firing-order-std-journals.html?ref=category:1272239



They say it has a broader power curve, but they don't give the range.


----------



## Sick467 (Oct 29, 2019)

Scott06 said:


> Not sure if you settled on a disc kit yet, this is a stock type set up i installed on my 65 about 3 years ago. https://www.summitracing.com/parts/sum-bk1501/make/pontiac/model/gto/year/1965
> 
> nice kit just needed a few short sections of brake line ( all four drums met a distribution block) and a 9/16 x 3/16 adapter for rear line .. basically stock gm single piston calipers and 11” rotors , pretty basic simple kit for driver quality car


Thanks for the recommendation Scott! What diameter was the booster? And, do you know where it was made? I am assuming overseas for the most part, but I have got in the habit of asking on just about anything I buy.


----------



## Baaad65 (Aug 29, 2019)

Sick467 said:


> It's my new understanding that the rpms at which you will be going into OD, or maintaining in OD, is the key. Your engine RPM's, in OD, should be in the power band of the cam. For example, pretty radical cams may not have a power band that starts below 3000 RPM's...if your car will be cruising in OD at less than that...you risk lugging the engine.
> 
> Do you have the power band info for that cam? I do not see it on Bulter's site...
> 
> ...


Ok, I just thought when you're in overdrive you are not concerned about power that it's for cruising at a higher speed but I can see where you don't want it lugging and if a hill comes up I would just down shift into fourth. Here's the only other description other than this I would have to call them. And so if we're worried about lugging all the more reason to use the 3.73 gear correct ?


----------



## PontiacJim (Dec 29, 2012)

Baaad65 said:


> So I only have two reasonable gear choices with the Dana and didn't think about pairing it with my cam, how do you think a 3.54 or 3.73 will play with my cam plus 1.65 rockers? and also with my 4 spd or a TKX 2.87/ .68 ?
> View attachment 159737


Should be fine with either gear. Using a cam overlap calculator and the advertised duration numbers, it comes up as 58 degrees - pretty mild. The 114 LSA is a plus.

The factory RA IV cam has 87 degrees of overlap. The popular "068" Pontiac cam has 63 degrees of overlap and often with the 4-speed had 3.55 gears - so no issues there.

Here is a reference I have showing the RPM range of a cam based on the cam's duration @ .050". Look at the 221 to 230 specs - power band is 2,000 - 5,500 RPM's. You are probably OK in general with this as long as your figure you want your engine spinning near the 2,000 RPM range while highway cruising at 70 MPH. Above 2K would be better, but once you get below this, the car might seem a little labored - like putting the car in 4th gear at 30 MPH. An automatic with its converter might be a little more forgiving.

Many factors will also come into play such as size of the engine, type of intake/carb, compression, timing. So this is just a generalization. The air/fuel velocity could play a role in this where a smaller sized induction set-up generates faster and more responsive port velocity versus a larger induction set-up aimed at more mid-to-upper RPM power to match the cam - so you might get away with a bigger cam due in part to the increased port velocity of the smaller induction set-up. As the head CFM increases, it can mean a lazy and less responsive engine at the lower RPM's but really turns on in the mid-to-upper RPM's - as does a big cam with lots of overlap. So it is a balancing act and why ALL parts from the engine to the rear end gearing should be matched as a complete package.

Moving down the rows, you can see how the RPM band moves up. You might not be happy with an engine spinning 2K @ 70 MPH and a cam that begins its power band at 3,000 RPM's - unless you had an automatic with a high stall converter that allowed the converter to slip to keep the RPM's up in the 3,000 RPM range while cruising @ 70 MPH - but then your gas mileage would suck and you would be generating a lot of heat into the trans/converter.

BUT, you will have those who go big and with a correctly set-up car, can cruise at the lower RPM's @ 70 MPH, but my guess is that works OK on flat roads and light peddle pressure, not mountains or big long hills.


----------



## Baaad65 (Aug 29, 2019)

PontiacJim said:


> Should be fine with either gear. Using a cam overlap calculator and the advertised duration numbers, it comes up as 58 degrees - pretty mild. The 114 LSA is a plus.
> 
> The factory RA IV cam has 87 degrees of overlap. The popular "068" Pontiac cam has 63 degrees of overlap and often with the 4-speed had 3.55 gears - so no issues there.
> 
> ...


Great info, so my cam is 230/236 but I forget how much do 1.65 rockers add? according to my chart with the .68 OD that would put me at 2029 @ 70 mph with the 3.54 and 2132 @ 70 mph with a 3.73 so right in the sweet spot correct? Of course if I'm cruising only at 60 or 65 it drops below 2000 especially with 3.54's like 1739/1884 then I guess I put in fourth.


----------



## lust4speed (Jul 5, 2019)

Cam is similar to the "Stump Puller" designed and sold by Dave Bisschop at SD Performance. We have six cars in our GTO club with that cam. It idles just a little better than the RAIV, much more power, and doesn't burn your eyes when you walk behind the car like the RAIV cam does. It's a good Choice.

I agree that either ratio will be fine. My suggestion is if you have 28" tall tires you go with the 3.73. The 3.55 ratio would work with stock tires around 26-1/2".


----------



## geeteeohguy (Feb 2, 2008)

lust4speed said:


> Cam is similar to the "Stump Puller" designed and sold by Dave Bisschop at SD Performance. We have six cars in our GTO club with that cam. It idles just a little better than the RAIV, much more power, and doesn't burn your eyes when you walk behind the car like the RAIV cam does. It's a good Choice.
> 
> I agree that either ratio will be fine. My suggestion is if you have 28" tall tires you go with the 3.73. The 3.55 ratio would work with stock tires around 26-1/2".


You can take this to the bank. What Jim said as well.
I like my Pontiacs to put out torque over HP, which means low rpm grunt and easy driving with less broken stuff. 
I almost never drive my '65 GTO with its high-strung 11:1 389, rowdy Sig Erson cam, and steeper gears. If I changed the rear gearing I'd have to change the cam, etc. Maybe in my retirement I'll spring for aluminum heads so I can drive the darn thing in pump gas. Sigh....


----------



## Baaad65 (Aug 29, 2019)

Well most signs are pointing to the 3.73 and it will just have to be a dump truck next summer


----------



## PontiacJim (Dec 29, 2012)

geeteeohguy said:


> You can take this to the bank. What Jim said as well.
> I like my Pontiacs to put out torque over HP, which means low rpm grunt and easy driving with less broken stuff.
> I almost never drive my '65 GTO with its high-strung 11:1 389, rowdy Sig Erson cam, and steeper gears. If I changed the rear gearing I'd have to change the cam, etc. Maybe in my retirement I'll spring for aluminum heads so I can drive the darn thing in pump gas. Sigh....


Yep, going red-neck with my long hair/pony tail and biker beard. BUT, I could be trolling.........for NJ hookers.

Look at Speedmaster aluminum heads. Cheaper than E-heads and on Black Friday, they drop way down plus free shipping. Got a bare set for the Pontiac last year and just got* a complete pair* ready to run for my Fury 360 build - $875.00 delivered.

Get them directly from Speedmaster or off Ebay where they also have a selling site.


----------



## ylwgto (Oct 27, 2009)

Sick467 said:


> I am hoping to spend some jack in the next month so that when spring/summer hits, I can get after re-doing the rolling chassis and need your help. It's a fair amount for me to wrap my head around and some decisions have to be made...the time has come.
> 
> I'm just going to throw out my thoughts and see what sticks...
> 
> ...



Did exactly this conversion (including the 9" rear) in 2020 on my '66. Happy to share my parts list. it all went together VERY smoothly and the end result is nothing short of car-changing.


----------



## Sick467 (Oct 29, 2019)

ylwgto said:


> Did exactly this conversion (including the 9" rear) in 2020 on my '66. Happy to share my parts list. it all went together VERY smoothly and the end result is nothing short of car-changing.


Yeah! I'd love to see your parts list and the places you had good luck buying them from.

How's the noise level of the 9" Ford? I have heard that they put out more sound than the 12 bolt.


----------



## ylwgto (Oct 27, 2009)

Sick467 said:


> Yeah! I'd love to see your parts list and the places you had good luck buying them from.
> 
> How's the noise level of the 9" Ford? I have heard that they put out more sound than the 12 bolt.


I'll dig it up and post it here when I get back to CA next week...just recently shared the front end details with another forum member as well, but that did not include the details about the 9" and rear suspension/brakes etc.

9" rear seems silent, but my exhaust (turndowns before axle) is so loud it's all I can hear!


----------



## Sick467 (Oct 29, 2019)

Rear Diff newby question:

With the 9" Ford, Do you center the input yoke with the body/tunnel or the pumpkin?


----------



## ylwgto (Oct 27, 2009)

Sick467 said:


> Rear Diff newby question:
> 
> With the 9" Ford, Do you center the input yoke with the body/tunnel or the pumpkin?
> 
> View attachment 159769


That's a good question to ask Strange or Currie or another that builds these. I'm not sure if the axle tube lengths (and axles) are different on each side in the 9" rears they modify to fit GM A bodies.


----------



## Baaad65 (Aug 29, 2019)

Sick467 said:


> Rear Diff newby question:
> 
> With the 9" Ford, Do you center the input yoke with the body/tunnel or the pumpkin?
> 
> View attachment 159769


Sooo does this mean you're ready to order the 9 ?


----------



## ylwgto (Oct 27, 2009)

here are a few pics of mine before I put it in. Can provide details late next week (full details from the build sheet if helpful) with measueres and stuff...I think.

There are some important particulars about axle tube ends, bearing style and flange type that will impact your brake selection. This is ESPECIALLY important if you are doing a 4 wheel disc conversion (I did Wilwood).


----------



## Sick467 (Oct 29, 2019)

Baaad65 said:


> Sooo does this mean you're ready to order the 9 ?


Nope, not just yet...just collecting information. I am leaning towards the 9", but I have not gotten to the dollars part yet. My "guy" who built my last diff says the 9"s are noisier than the 12 bolt, but that may just help influence the decision on cut-outs later on in the build. 

Can anybody put some relativity to the sound levels?


----------



## Baaad65 (Aug 29, 2019)

Sick467 said:


> Nope, not just yet...just collecting information. I am leaning towards the 9", but I have not gotten to the dollars part yet. My "guy" who built my last diff says the 9"s are noisier than the 12 bolt, but that may just help influence the decision on cut-outs later on in the build.
> 
> Can anybody put some relativity to the sound levels?


Don't know about sound levels but have read that a 9 takes more power and I'm pretty sure it's the most expensive compared to the Dana and 12 bolt. The only advantage I see with the 9 is if you're going to be doing gear changes, like I mentioned the Dana S60 is available at Summit starting at 2600.00, mines going to end up about 3K but I get raised upper arm mounts and multi position lower mounts that I don't think the 12 bolt or 9 have.


----------



## Sick467 (Oct 29, 2019)

Baaad65 said:


> Don't know about sound levels but have read that a 9 takes more power and I'm pretty sure it's the most expensive compared to the Dana and 12 bolt. The only advantage I see with the 9 is if you're going to be doing gear changes, like I mentioned the Dana S60 is available at Summit starting at 2600.00, mines going to end up about 3K but I get raised upper arm mounts and multi position lower mounts that I don't think the 12 bolt or 9 have.


I've seen where the 9" can come with adjustable lower arm mounts, not sure about the raised uppers, however. Not even sure what that would do for my car? I believe I have heard you say that the adjustable lowers help dial out wheel hop. Right now, I am considering the three diffs nearly equal for what they would do for my build and merely leaning towards the 9" due to popularity...AND, if I try to undersatnd all the diffs at the same time...I get corn-fused and mixed-nutted-up...one thing at a time for me.  

From what I have read, the 9" consumes 2-3 horsepower more due to, generally speaking, the size of the rotating parts, but that the size is what gives it a bit more strength.

$3,2500 seems to be about where a 9" would land with several upgrades. Some of the upgrades are a bit overkill for a 500 HP build. I'm still trying to figure out some of the upgrades.


----------



## Greek64GTO (Dec 13, 2015)

I have used many a 9 inch in my Shelby or Ford arsenal. I don't think I would worry about 2+ horsepower when you have over 400+ ft. lbs. of torque. As for the noise.............that is one place you don't want to buy cheap gear sets. It is tempting as we all know. Cheap gear sets are noisy and I have experienced this. Slap in some good quality OEM gears from Ford, Ford Motorsport, or a reputable manufacturer of U.S.A. made gear sets and all smooths out!


----------



## Baaad65 (Aug 29, 2019)

Sick467 said:


> I've seen where the 9" can come with adjustable lower arm mounts, not sure about the raised uppers, however. Not even sure what that would do for my car? I believe I have heard you say that the adjustable lowers help dial out wheel hop. Right now, I am considering the three diffs nearly equal for what they would do for my build and merely leaning towards the 9" due to popularity...AND, if I try to undersatnd all the diffs at the same time...I get corn-fused and mixed-nutted-up...one thing at a time for me.
> 
> From what I have read, the 9" consumes 2-3 horsepower more due to, generally speaking, the size of the rotating parts, but that the size is what gives it a bit more strength.
> 
> $3,2500 seems to be about where a 9" would land with several upgrades. Some of the upgrades are a bit overkill for a 500 HP build. I'm still trying to figure out some of the upgrades.


The raised upper mounts help wheel hop like putting no hop bars on, the adjustable lowers changes your lift point of the car from way out in front to more in the front end of the car therefor putting more weight to plant the tires. Your not going to break any of these diffs, mine broke because it was just a normal Yukon posi and the combo of big sticky tires, sticky track, 530 lbs of torque and clutch launches at 5000 rpms did it in. I forget are you running an auto or manual? It's your dime your dance floor so do what you like, maybe I have a hang up of having an F word part in my car 😉


----------



## Sick467 (Oct 29, 2019)

Baaad65 said:


> The raised upper mounts help wheel hop like putting no hop bars on, the adjustable lowers changes your lift point of the car from way out in front to more in the front end of the car therefor putting more weight to plant the tires. Your not going to break any of these diffs, mine broke because it was just a normal Yukon posi and the combo of big sticky tires, sticky track, 530 lbs of torque and clutch launches at 5000 rpms did it in. I forget are you running an auto or manual? It's your dime your dance floor so do what you like, maybe I have a hang up of having an F word part in my car 😉


Yeah, I'm running an auto (400TH) and, I too, feel odd about the "F" word. My 67 [email protected] has Cadi parts, my 72 C10 has a Pontiac engine, and I'd bet my GTO gets cross bred a little...it already has patch panels made from a 76 Cheby. My decision is far from made, I just started learning the 9" first.

I did see where the 9" could come with the raised upper mount locations.


----------



## 67ventwindow (Mar 3, 2020)

There is always this. They say it lessen the pinion angle change during suspension travel. Stronger mount point and adjustability. 









64-67 A-Body Adjustable Upper control arm mount


Our GM A-BOX Adjustable Upper Control Arm mount with custom trailing arms, 10 holes of instant center adjustment for the perfect hook.



wildridesracecars.com


----------



## Baaad65 (Aug 29, 2019)

Sick467 said:


> Yeah, I'm running an auto (400TH) and, I too, feel odd about the "F" word. My 67 [email protected] has Cadi parts, my 72 C10 has a Pontiac engine, and I'd bet my GTO gets cross bred a little...it already has patch panels made from a 76 Cheby. My decision is far from made, I just started learning the 9" first.
> 
> I did see where the 9" could come with the raised upper mount locations.


I have the "Hook and Launch" book and there's a lot of good information in it 👍


----------



## DustyOldGTO (Jun 26, 2019)

Noise and efficiency - it's a basic design difference:
"The Ford 9-inch pinion is mounted lower in the carrier and has the greatest hypoid offset, which causes it to consume more power to drive it than the Dana 60 or GM 12-bolt."
Link to the article:








Dana 60 vs. GM 12-Bolt vs. Ford 9”: The Pros & Cons of Popular Rear End Assemblies - OnAllCylinders


You’d think selecting a rear end for a project car would be easy. It’s not. Browse Summit Racing’s website or catalog and you’ll discover there are almost too many choices. …




www.onallcylinders.com




.

wait, I should add something funny/rude...
"remember to consider the hypoid offset when selecting NJ hookers or the TTOF gals at the all-you-can-eat-buffet...."
you're welcome. ;o)


----------



## Sick467 (Oct 29, 2019)

Well,

My rear end search has taken a turn. I have found that the Ford 9" can be built to my needs from $3200.oo to over $5000 (that range is ready to go, including disc brakes, 35 spline axles, 1/4" tube walls, etc...good for 600+ HP...more than I need). The lower end is from state local "I build them in the shop out back" to the premium racing sites on the web delivered to my shop. 

Here's my turn, a buddy has offered me a 12 bolt housing, flange to flange, that came from a late 60's Chevelle and was once in a late 60's GTO. It has the C-clip elimination mod and comes with the axles, rear aluminum cover, but no gears. The offer is free if it saves me money.

Now I have to research the 12 bolt and see if the savings is there to go to a rebuild scenario compared to all new. 

Any advice on the 12 bolt direction would be great!

Do these photos show adjustable lower trailing arm brackets? The owner and his son are big into drag racing Pontiacs. I'm not sure what I am looking at here other than there are South Side Machine lower trailing arms on it that look pretty beefy...



















Here's a photo of the inside of the pumpkin in case someone sees something worth discussing. BYW, the diff cover has jack bolts built into it that firm up against the caps to help keep them tight (the caps with the yellow paint on them).










I am open to the group's thoughts on this direction since I have been leaning towards a Ford 9", but now may have an edge to stay with the general. My HP ambitions are to be around 500 HP.


----------



## Baaad65 (Aug 29, 2019)

I'll guess you'll have to blast it then see if any cracks show up, what's the history was it raced? Also those don't look like my SSM brackets, now yes figure everything that has to go into it. Are you planning big sticky tires and racing it...remember I shattered a 12-bolt Yukon posi with 500hp just saying 😉


----------

