# Daily Driver Gear Ratio Input



## joesweeting (May 8, 2011)

I’m thinking of running a 3.08 gear ratio in the rear end. This car will be my daily driver and it will be while until I put a 5 speed for it. I’m not sure the current gear ratio, I only had it two days before the crank broke, I will start working on the car the 28th. I have reviewed the gear ratio sticky and 3.08 was on option in 69 per my PHS documents. I’m not sure what work was done to the car before I bought it, It was green with vinyl top, gold interior and hide-a-way head lights. It's currently orange (carousel red) with black interior with hood tach, spoiler with no hide-away headlights. It also had a 73 400 engine in it with a Saginaw 4 speed. However, they went to a lot of trouble to change the color. I had to wait until I got the PHS docs to determine the original paint, even under the door panels where painted. . 

Thanks,

Joe


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## BearGFR (Aug 25, 2008)

The most common ratio the factory put in 69's was 3.23. You said '5-speed' so I'm assuming you're not all that worried about keeping the car "as built" original, so my next question is how do you plan to use the car? For mostly street cruising and only occasional/limited highway driving, something in th 3.50 "ish" range is pretty good. (Ram Air IV car's only came with 3.90's or 4.30's, and no a/c, to let that big cam "work"). If you're going to spend more time on the highway then you might want to go numerically lower - 3.08 or even 2.73. A strongly built Pontiac will still light the tires with those but it won't pull "as hard" on the bottom end, especially if you build one with a somewhat rowdy cam. An overdriven 5th gear like you mentioned would give you the best of both worlds - allowing to you run a strong pulling rear gear and still keep some highway manners. What are your engine plans and anticipated driving conditions?

Bear


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## joesweeting (May 8, 2011)

Bear,

I plan on over half of my driving on the highway. My car was originally 3.55 rear end, I will verify after I install the engine. Tomorrow I will start building a 455 bored .30 over with a COMP Cams Xtreme Energy Cam and Lifter Kits operating range 1,600-5,800 (COMP Cams CL51-223-4) and an Edelbrock Performer RPM Intake Manifolds operating range 1,500-6,500 (Edelbrock 7156). 

Installing a 5 speed is on the bottom of my to-do list. 

Thanks,

Joe


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## geeteeohguy (Feb 2, 2008)

Joe, as you stated in your first post, it will be a while before you convert to an overdrive. If you can find one, you'll love the 3.08. For an overdrive ratio, a 3.36-3.55 would be a great gear with a 455. I changed out the 3.36 gear in my '67 GTO (TH400 car) for a 2.56....and I love it. My mpg increased by over 5, and the car loafs along at 75-80mph...not fast enough to keep up with the local pickup trucks, but pretty close!! Seriously, a 3.08 gear was the "tallest" gear recommended for a 4 speed, and is great in the real world of $3.50 gas. You will notice a big improvement.


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## BearGFR (Aug 25, 2008)

Hey Joe...

That XE268 cam should be a good fit for how you're planning to use the car. It'll have a little attittude but isn't so rowdy that you'll have to worry about sufficient vacuum for power brakes, etc. I agree with what GeeTee said on gear ratio, considering your intended use. You can save some coin by using the factory iron intake, if you have one. It'll make more power than the RPM in the range where you're going to be, especially if you take the time to port/gasket match it. You can preserve that work by cutting the water crossover so that it's separate from the manifold - I did mine that way. The prevents losing all that careful port matching when you tighten up that long skinny bolt that connects the water crossover to the back of the timing cover.

Bear


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## jigaway (Jul 2, 2011)

A question along similar lines here. My 71 (original TH400/400) has, according the the previous owner, 3.31 gears and a shift kit. When starting off, it jumps into 2nd almost immediately, then up to 35-40mph when it jumps in to 3rd. I do not have a tach on it, but it seems like I am screaming at about 60. It has a gorgeous howl at 50! If I let off the gas I get back some back pressure sounds and it slows down quick. 

Is this normal?? You can more or less watch the gas gauge go down! 

I would love to have an overdrive where I "tool along". Anything I can do here?? Or is this the way they ran?

As always, forgive my inexperience and thanks in advance. Love this board..



Dan


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## geeteeohguy (Feb 2, 2008)

3.31 is not a Pontiac ratio. I would verify the ratio....a 3.31-3.36 will cruise 70mph at around 3000 rpm with stock height tires...sounds to me like you have a stiffer gear back there...like a 3.55, 3.73, (chevy ratio) or 3.90.


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## BearGFR (Aug 25, 2008)

:agree I've got 3.50's in the Beast (Ford 9" rear) and at 70 mph indicated the tach is in the vicinity of 3300-3400 rpm. Thinking back to the days of my youth, going on road trips with my Dad driving (usually in an Olds 88 or 98), at 70+ those motors weren't loafing. This was long before the days of commonplace overdrives, so yeah --- things were different then.

I agree with GeeTee though, what you're describing "sounds" like shorter gears than 3.31 to me, subjectively.

Bear


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## jigaway (Jul 2, 2011)

Thanks.. the previous owner is wonderful and tries to help, but I think he is slipping a bit. I need to get a hold of his son, whom will probably give me the true answer as to what gears I have. 

Any way I can tell what gears I have?

Meanwhile Santa bought my Goat some new 15" Vintique Rallye IIs. Currently she has 14s. Hope it helps. 

It's not the end of the world if I don't change it. The car is a monster off the line. I love it. Would be nice to just cruise along at 60 or so.. Don't know if I could go on the highway for very long since Virginia is now a 70 speed limit in a lot of spots.

Dan


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## Rukee (Feb 8, 2007)

Check the stickied gear ratio thread, it tells how to tell your ratio without pulling the cover off.


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