# Gear Vendor OD on a Th400, advice on tranny rebuild



## ylwgto (Oct 27, 2009)

My TH400 is a tired tranny last rebuilt in the late early 2000s. Been a great tranny, but recently it's flaring a bit in 3rd and the shifts are just not as neck-jarring at WOT as they used to be...I miss tire chirping. I've been battling with kickdown and short shifting woes for months (may not be the tranny's fault), but nevertheless the TH is the weak link in my car right now.

I've pondered a 5 speed conversion, which I'd love, but my wife likes to drive the car and I like to keep it that way. I've pondered a 700r4 or 200r4, but they both seem to have their drawbacks; the 700 has weird jumps between gears and requires trans tunnel mods and the 200 has to be built up bigtime to survive the torque of a Pontiac. And both have very sensitive and critical TV cable stuff going on.

I'm thinking I may just pull the Th400 and have it rebuilt and instal a GV unit behind it. Pricey, but both those units are pretty damn bulletproof and I could retain my ratchet shifter and not have to buy a new tranny.

My question is on how to have the tranny rebuilt if putting an OD unit behind it? As far as I can recall, I rebuilt it back then with a shift kit, full manual valve body and all the "right stuff" the shop said to do for a street car. Cannot remember the stall on the converter.

Anyone done this? Happy with results? Any advice on 1. th400 rebuild upgrades and 2. good tranny shops in NorCal for the rebuild? 

The car has a strong 400 with all the speed add-ons and a 3.25 posi rear.

Thanks


----------



## Lemans guy (Oct 14, 2014)

I have a TH 350 with a gearvendors behind it and a 12 bolt repository rear. I had the Th350 beefed up with a ratchet diode by Performance Torque Converter, they said it would take 1000 ft lbs of torque nd they never lose them at the track. The TH 400 is beefier than the 350 so that would not be needed.

My Th 350 has a shift kit and a ratchet shifter by B&M. Works like a Hurst dual gate, but ratchets. With the gearvendors, which is wesome you can go to manual on both or auto on both and have many shift combo’s. I can manual up shift to second and then push button the GV from the shift knob for second over which IOC is a 1.13. Nice.

GV splits easchger and you can just leave it in auto and sing along very smooth shifts with RPM’s staying high. You will have to bang up the trans tunnel a small amout, I do recommend the G-Force cross member made specifically for GV on A bodies very strong and gives the added drop needed to mount it all


----------



## roger1 (Jun 25, 2020)

I went with a CPT Art Carr 500HP BOP 200-4R. It's a bolt-in and the stock driveshaft doesn't need to be altered.
By the time you rebuild that TH400 and buy the GV it will cost you just as much and a 200-4R gives you a deeper 1st gear (2.74 vs 2.48) and a taller OD of .67 vs the GV .78.


----------



## armyadarkness (Dec 7, 2020)

You and I have been in the same boat. My TH400 is still a blast... with 336's, it breaks loose in 2nd and chirps 3rd at 80, but I'm tacking 3500 rpms at 80mph and I do 80mph a lot! The gear vendors or a purpose built auto is so much cheaper than the TKX, but I just want my car to be a manual... Not looking forward to the price or doing the job on my back


----------



## roger1 (Jun 25, 2020)

My car isn't on the road yet but I have 3.55 gears, 27" rear tires and with the 200-4R of .67 OD, my calculator tells me that I will be at 2400 rpm at 80mph.


----------



## armyadarkness (Dec 7, 2020)

If I could tach 2500 at 80mph, and put 355 gears in to boot, I'd do that tomorrow.


----------



## Gremlin66 (Oct 11, 2009)

Ylwgto,
Just wondering why you want to go with a gearvendors with a 3.25 gear. I intend to put a GV on my TH400 in the future. Currently my 66 isn’t on the road yet until finished with paint has a 4.10 posi in it. I’ll see how bad it is once driving but I’m thinking the GV will make it more tolerable.


----------



## armyadarkness (Dec 7, 2020)

Gremlin66 said:


> Ylwgto,
> Just wondering why you want to go with a gearvendors with a 3.25 gear.


"with 336's, it breaks loose in 2nd and chirps 3rd at 80, but I'm tacking 3500 rpms at 80mph"


----------



## armyadarkness (Dec 7, 2020)

I suspect that 410's you'll be tacking 5k


----------



## roger1 (Jun 25, 2020)

Using 27" tires, a 4.10 rear with a TH400 and GV gives you 3200 rpm at 80 mph. First gear multiplication is 10.47.
Drop down to a 3.70 rear and use a 200-4R and get 2500 rpm at 80 and a first gear multiplication of 10.14.


----------



## Lemans guy (Oct 14, 2014)

I really like that Art Carr built 200R4, a super choice…..


----------



## ylwgto (Oct 27, 2009)

roger1 said:


> I went with a CPT Art Carr 500HP BOP 200-4R. It's a bolt-in and the stock driveshaft doesn't need to be altered.
> By the time you rebuild that TH400 and buy the GV it will cost you just as much and a 200-4R gives you a deeper 1st gear (2.74 vs 2.48) and a taller OD of .67 vs the GV .78.


Looks real slick, as does that tranny crossmember (and your whole project, really)
If I recall correctly, these are upwards of 3K?


----------



## ylwgto (Oct 27, 2009)

Gremlin66 said:


> Ylwgto,
> Just wondering why you want to go with a gearvendors with a 3.25 gear. I intend to put a GV on my TH400 in the future. Currently my 66 isn’t on the road yet until finished with paint has a 4.10 posi in it. I’ll see how bad it is once driving but I’m thinking the GV will make it more tolerable.


Gremlin, I have the 3.25 rear with 275/40/17s on the rear (tire height is 25.6") and am limited to the final drive of my TH400. At 70 I'm clocking over 2900 RPM and I like to drive a LOT faster than that here in CA. my car is LOUD with turndowns, so at 60-65 it is in the 2500-2700 RPM range, which is the loudest part of the RPM band. 

Although roger1 may be leaning me back to the 200r4 again...damn.


----------



## armyadarkness (Dec 7, 2020)

But at 3k, you may teach the wife how to drive the Tremec. I hate dilemmas!


----------



## ylwgto (Oct 27, 2009)

armyadarkness said:


> But at 3k, you may teach the wife how to drive the Tremec. I hate dilemmas!


I know, I know...nothing I want more than a 3rd pedal. but I've made it a "family" car now that it has rear 3 points and can safely carry a car seat. ship has sailed on wife and a manual, so not fighting that fight anymore!


----------



## Lemans guy (Oct 14, 2014)

I kept my Coan TH350 and put the GV behind it because it was set up the way I wanted with the shifter and shift kit and I did not want to deal with the electric shift on the TH350. It has the cable. But of course the GV has an electric shift so it is a wash with the ART Carr.

I did need a new driveshaft. That was easy and under $200. That said I really love the GV the way it shifts the strength of it, just a great unit. So those are a couple of ways. Other guys love the 700R4’s….some choices there!


----------



## roger1 (Jun 25, 2020)

ylwgto said:


> Looks real slick, as does that tranny crossmember (and your whole project, really)
> If I recall correctly, these are upwards of 3K?


Thanks. The 200-4R will work fine with a stock crossmember but I wanted the frame stiffening from this GForce. As you can see, it's really stout and bolts directly to the frame.
Total was $3,643.97 for everything. See this for the receipt:





68 Firebird Convertible 200-4R Install - PY Online Forums - Bringing the Pontiac Hobby Together


68 Firebird Convertible 200-4R Install 67-69 Firebird TECH



forums.maxperformanceinc.com


----------



## ylwgto (Oct 27, 2009)

roger1 said:


> Thanks. The 200-4R will work fine with a stock crossmember but I wanted the frame stiffening from this GForce. As you can see, it's really stout and bolts directly to the frame.
> Total was $3,643.97 for everything. See this for the receipt:
> 
> 
> ...


thanks, very informative. the ease of this swap (barring the TV set up) makes it a very tempting option.

I've got a B&M ratchet shifter I love. Wonder if there is a way to adapt it to the OD 4 speed 200r4 or if I need to factor in a new shifter to the cost of a swap as well.


----------



## armyadarkness (Dec 7, 2020)

ylwgto said:


> thanks, very informative. the ease of this swap (barring the TV set up) makes it a very tempting option.
> 
> I've got a B&M ratchet shifter I love. Wonder if there is a way to adapt it to the OD 4 speed 200r4 or if I need to factor in a new shifter to the cost of a swap as well.


Transmission money requires Kleenex and an alibi for the wife... Shifter money just sneaks across the boarder without detection. I vote Vmatic!


----------



## ylwgto (Oct 27, 2009)

armyadarkness said:


> Shifter money just sneaks across the boarder without detection.


Ha! truth.

In all honesty I wish my TH would just let go already so I "have to" buy a new transmission to drive the car...and also instal a complete EFI system to make it run right


----------



## armyadarkness (Dec 7, 2020)

ylwgto said:


> Ha! truth.
> 
> In all honesty I wish my TH would just let go already so I "have to" buy a new transmission to drive the car...and also instal a complete EFI system to make it run right


Yep, I'm ready for the TKX and EFI, this winter, myself. Can't decide between Sniper and Pro FLo


----------



## armyadarkness (Dec 7, 2020)

ylwgto said:


> Ha! truth.
> 
> In all honesty I wish my TH would just let go already so I "have to" buy a new transmission to drive the car...and also instal a complete EFI system to make it run right


Honey, you're not going to believ this... They finally made the vaccine mandatory. Everyone has to have it by October 1st. Here's the odd part... I read the fine print and it says that all carburetors have to be converted to fuel injection at the same time. Wow! Oh well, its the law.


----------



## ylwgto (Oct 27, 2009)

armyadarkness said:


> Yep, I'm ready for the TKX and EFI, this winter, myself. Can't decide between Sniper and Pro FLo


The pro flo probably makes awesome power with the direct ports, but I don't want fuel rails. I'm also limited by hood clearance b/c I did the functional hood scoop ram air conversion and have to run the super low height antiquated P4B intake.


----------



## armyadarkness (Dec 7, 2020)

ylwgto said:


> The pro flo probably makes awesome power with the direct ports, but I don't want fuel rails. I'm also limited by hood clearance b/c I did the functional hood scoop ram air conversion and have to run the super low height antiquated P4B intake.


Yeah... Hood clearance is an issue for me, too, and here's the thing... Holley/ Summit claim that running the the Sniper on a dual plane intake, like my performer, will yeild poor results. They claim that I either need a .5 open spacer beneath the carb or an open plenum manifold, like a Torker.

So now Im considering a Torker, which will put me in Proflo pricing... DILEMMAs!


----------



## roger1 (Jun 25, 2020)

On my '69 GTO, the ProFlo-4 fits just fine with the Ram Air setup.
My engine is the original 400 bored 40 over. I have the Voodoo 702 cam and RARE Ram Air exhaust manifolds. 
On the dyno, it made 425 HP at 5000 RPM and 480 ft-lbs at 4100 RPM. HP would have been a little higher if he had taken it another 2 or 3 hundred higher in RPM.


----------



## NOS Only (Nov 14, 2017)

200R4's


----------



## ylwgto (Oct 27, 2009)

armyadarkness said:


> Yeah... Hood clearance is an issue for me, too, and here's the thing... Holley/ Summit claim that running the the Sniper on a dual plane intake, like my performer, will yeild poor results. They claim that I either need a .5 open spacer beneath the carb or an open plenum manifold, like a Torker.
> 
> So now Im considering a Torker, which will put me in Proflo pricing... DILEMMAs!


The P4B I'm running is a squarebore dual plane, but on a lot of these a section of the divider is cast "out" to allow for clearance of some crappy smog-era carb or something. I think, conveniently, that would allow enough blending between the 2 planes to overcome the issue Holley brings up (which I've heard as well). At least, that's what I'm telling myself!

The P4B is often poo-pooed in the forums, but Cliff R did some flow testing on one and it did quite well (scroll down to post #12 in the link below):




__





What is a edelbrock P4B intake? - PY Online Forums - Bringing the Pontiac Hobby Together


What is a edelbrock P4B intake? Pontiac - Street



forums.maxperformanceinc.com





As far as seat-of-the-pants feel goes, I love it WAY more than the single plane Street Dominator I had on my car before. Noticeable more torque in the low end.

Maybe a P4B is your solution too!!


----------



## ylwgto (Oct 27, 2009)

NOS Only said:


> 200R4's


so Art Carr is selling snake oil, c'mon....


----------



## ylwgto (Oct 27, 2009)

...but back to the TH400 question. If I go with a GV OD, how should I have the tranny rebuilt?


----------



## roger1 (Jun 25, 2020)

NOS Only said:


> 200R4's


----------



## NOS Only (Nov 14, 2017)

ylwgto said:


> so Art Carr is selling snake oil, c'mon....


There's an ass for every seat and when you sell something, right, wrong or indifferent, you give the people what they want.

Now.…. A question for you.....

How many trucks, Corvettes or any other rough service use vehicle did GM put the 200r4 in?

By the way, while inexperienced people hinge all their preconceived notions on the 200r4 because they were used in the Buick Grand National, keep this in mind..... The most badass Grand National was the GNX and it had a whopping 276 horse that didn't come in at the hit of the throttle.


----------



## NOS Only (Nov 14, 2017)

roger1 said:


>


First off, the guy clearly doesn't even know what he has, he just wrote checks. Every other word is "about this" or "around that". You build a car, you know what you got. This guy's lack of knowledge tells me he doesn't even own the car any longer but he does mention the 200 is in there because of size.

When you build power and quality, size does matter. If you're playing with puny stuff you can have puny parts. Pontiacs have big torque, big enough to laugh at puny parts.


----------



## ylwgto (Oct 27, 2009)

NOS Only said:


> There's an ass for every seat and when you sell something, right, wrong or indifferent, you give the people what they want.
> 
> Now.…. A question for you.....
> 
> ...


My interest in 200r4s as an option is not based on their history as a stock GM transmission (yes, they have obvious shortcomings in stock form), but on the "corrected" versions in which the weak points have been addressed...the models that the aftermarket builders are applying to their high HP cars (like that Vette...I think I remember the Hot Rod article on that very car). If one can be built to withstand a twin turbo 900HP pulling 165 MPH runs, certainly something similar would hold up behind my mild, street dirven 400.

This is a glorified advertisement, but highlights all the weak points that are addressed in "properly" built 200r4:









How to Build a TH200-4R Transmission for Drag Racing


Art Carr shows us how he builds the TH200-4R four-speed OD transmission to handle supercharged big-block power at the drag strip.




www.motortrend.com


----------



## ylwgto (Oct 27, 2009)

That said, and to get off 200r4s, I am still interested in potentially rebuilding my TH400 (a great transmission) and adding a GV.


----------



## Lemans guy (Oct 14, 2014)

Y I like the GV, it is very strong and smooth it has the option for manual shifting or auto and you can turn it on or off from a button on the shift knob. My beefed up Coan Th 350 has a dual gate shifter so you can ratchet shift or go full auto….I like both and with the GV that set up really makes it nice as now I have six forward gears….with the gearvendors splitting each TH 350 gear. True the final drive is not as low as the 200R4 but low enough.

My Coan Torque converter is made for Pontiac street engines 2500 stall. The TH350 has no lockup clutch. But with the GV I do right at 2500 Rpms at 75rihht at the sweet spot of that converter. Sure their are many set ups but the GV behind the TH350 beefed up or the Th400 is good as well.


----------



## TCone (Jul 4, 2021)

armyadarkness said:


> I suspect that 410's you'll be tacking 5k


yes my 70 has 4.11 that thing is wound up, still have the 14'' stock wheels 3500 stall trans shift as hard as a manual but no high speed driving but launches like no tomorrow


----------



## mikelly2 (Nov 24, 2018)

I just wanted to share that I put a 700r4 in my '68 convertible without modifying the tunnel and I was able to use the stock his and hers shifter. The stock shifter doesn't have enough throw to manually shift into first though. With the shifter all the way back it'll shift once then stay in 2nd until I shift.


----------



## roger1 (Jun 25, 2020)

mikelly2 said:


> I The stock shifter doesn't have enough throw to manually shift into first though. With the shifter all the way back it'll shift once then stay in 2nd until I shift.


Nothing wrong with that at all. I set one up that way in the past. I don't see the need for needing that functionality anyway.


----------



## 2005firstgoat (Jul 2, 2021)

Unless I'm missing something some of you guys are running THM350/400 transmissions with non-lock up converters this a big nono with overdrive units.
Once you engage the OD you are slipping the converters building high heat kind of like driving with the brakes on all the time.


----------



## NOS Only (Nov 14, 2017)

2005firstgoat said:


> Unless I'm missing something some of you guys are running THM350/400 transmissions with non-lock up converters this a big nono with overdrive units.
> Once you engage the OD you are slipping the converters building high heat kind of like driving with the brakes on all the time.


Fake news ^ ^ ^

You don't NEED a lock-up converter. Depending on horsepower and usage a lock-up converter can be a bad idea. Driving "with the brakes on all the time"? Not likely.


----------



## roger1 (Jun 25, 2020)

Seems like using an auxiliary cooler would take care of that issue.


----------



## Lemans guy (Oct 14, 2014)

Click on the gear vendors site and read some of their data on Putting the units behind TH350 and Th400, they have been doing that for many years. Now I know they are trying to sell units of course, that has to be considered but the many years of racing with these units does not appear to have been a problem.

My converter is 2500 stall, at 75 MPH I run 2500 Rpm, the converter does not know if there is a GV or straight TH350 there….It does not lock up like TCC but it is at it’s designed peak efficiency. Don’t think heat is that much of an issue. Maybe it raises the temp a few degrees in imperial testing, but nothing that I have noticed and that the trans cooler lines can’t deal with.


----------



## NOS Only (Nov 14, 2017)

roger1 said:


> Seems like using an auxiliary cooler would take care of that issue.


Ummmm….. Not exactly.

A non-lockup converter will create some heat. Depending on the service duty, a cooler will help but cruising on highways a lock-up is suggested.

I have quite a bit of power in one of my cars and race. A lock-up converter is a big no no. I do drive on highways but it's occasionally and I do have a very large cooler.

Like I said, it depends on usage but only the inexperienced or the Goggle'ers will say a lock-up converter is mandatory.


----------



## armyadarkness (Dec 7, 2020)

fyi, WATCHING hOTROD gARAGE ON aMAZON pRIME LAST NIGHT, THEY HAVE AN EPISODE ABOUT THE gEAR vENDORS


----------



## armyadarkness (Dec 7, 2020)

wOOPS! sORRY FOR THE CAPS LOCK


----------



## pontrc (Mar 18, 2020)

My big like with the 200 4R is the BOP housing. Not a big fan of the adapter plate 700r4


----------



## NOS Only (Nov 14, 2017)

pontrc said:


> My big like with the 200 4R is the BOP housing. Not a big fan of the adapter plate 700r4


Did you happen to catch where the OP doesn't want to hear about 200's?



ylwgto said:


> That said, and to get off 200r4s, I am still interested in potentially rebuilding my TH400 (a great transmission) and adding a GV.


His car and he opted for a good tranny


----------



## 2005firstgoat (Jul 2, 2021)

NOS Only said:


> Ummmm….. Not exactly.
> 
> A non-lockup converter will create some heat. Depending on the service duty, a cooler will help but cruising on highways a lock-up is suggested.
> 
> ...


Well since I'm neither "inexperienced or a Goggle'er" maybe you can enlighten me and the others. Why did all the major auto mfgr's put lockup converters in front of their O/D transmissions and also why a lockup would be a no no with a high performance car?
After all it would be a considerable cost reduction for them to run open converters! I guess if you limit your driving to 1/8-1/4 mile runs and tow it on a trailer there is no reason for the added cost of a lockup converter.
Not trying to start a pissing contest here just pointing out some of the pitfalls of only doing half a job, installing an O/D transmission with an open converter. After all you are installing an O/D to reduce the engine speed while cruising aren't you?


----------



## BearGFR (Aug 25, 2008)

Something to also keep in mind, as if you didn't have enough to think about already, is the converter. If you have a "loose" (aka. "stall") converter already and subsequently go to some sort of overdrive setup, there's a good chance the converter will still be slipping significantly at highway speeds. That will put a lot of extra heat into the transmission fluid, transmission, etc. for an extended period of time. 

Bear


----------



## NOS Only (Nov 14, 2017)

2005firstgoat said:


> Well since I'm neither "inexperienced or a Goggle'er" maybe you can enlighten me and the others. Why did all the major auto mfgr's put lockup converters in front of their O/D transmissions and also why a lockup would be a no no with a high performance car?
> After all it would be a considerable cost reduction for them to run open converters! I guess if you limit your driving to 1/8-1/4 mile runs and tow it on a trailer there is no reason for the added cost of a lockup converter.
> Not trying to start a pissing contest here just pointing out some of the pitfalls of only doing half a job, installing an O/D transmission with an open converter. After all you are installing an O/D to reduce the engine speed while cruising aren't you?


Sure

When you can explain why everybody pushes 1 wire alternators when not 1 auto manufacturer uses it.

Here's a hint..... Because people on the interweb say so.


----------



## NOS Only (Nov 14, 2017)

BearGFR said:


> Something to also keep in mind, as if you didn't have enough to think about already, is the converter. If you have a "loose" (aka. "stall") converter already and subsequently go to some sort of overdrive setup, there's a good chance the converter will still be slipping significantly at highway speeds. That will put a lot of extra heat into the transmission fluid, transmission, etc. for an extended period of time.
> 
> Bear


Bear.…. This has an Art Carr 700R4, 3800 stall converter (non-lockup), quite a bit of highway miles, quite a bit of local street miles, quite a bit of 1/4 mile passes and it has been in the car since 2010


----------



## ylwgto (Oct 27, 2009)

BearGFR said:


> Something to also keep in mind, as if you didn't have enough to think about already, is the converter. If you have a "loose" (aka. "stall") converter already and subsequently go to some sort of overdrive setup, there's a good chance the converter will still be slipping significantly at highway speeds. That will put a lot of extra heat into the transmission fluid, transmission, etc. for an extended period of time.
> 
> Bear


good point. i seem to recall even mild pontiacs like 2200-2500 stall, which always seemed high to me, but no idea how that should change with an OD set up. 

but I assume a GV behind a TH400 wouldn't impact stall, or is my thinking off on this?


----------



## ylwgto (Oct 27, 2009)

What specific *BUILD* questions would you all ask of a seller with a "street/strip" TH400 for sale?

Got a local guy with one he says was behind a Bruce Fulper built 455 (660HP) in this project car:





*I've read all about Fulper's reputation, so no need to turn the post into a history lesson on his exploits*

No data tag on the case and the only info provided is "Short shaft , large drum, full manual valve body". The rest of the description is soft-info like "super hi performance. $ 2800 to build. Only the best products were used to build the car. This transmission is built to take over 700 hp..." etc etc etc

Supposedly 1000 mi on the tranny, no drag runs. Comes with a 2800 stall converter.

I should probably keep walking from a used tranny with no documented history, but thought I'd ask...

What would it be worth in your opinion even as a gamble?


----------



## armyadarkness (Dec 7, 2020)

Personally, I wouldnt spend more money than I could afford to lose on a used trans or engine. Just too much at risk... and how do you trust a stranger, anymore?

However, if it was a local guy, I'd be inclined to make him a half-now offer, and that after the unit was installed and the car driving down the road, Id pay him in full.


----------

