Which gear ratio is best for street? - Third Generation F-Body Message Boards

camaro87-alex · 08-17-2009, 01:09 PM

What kind of gear ratio are you guys running on your street cars?

I have a plan changing gears on my 87 Camaro. I am building my 305TPI engine so it should have about 250HP or something like that.
Headers, cam, high flow cat and catback system.

I am using my car most on the street. Driving for the most in speeds about 40-60MPH and slower...I like acceleration and that the car moves fast up to speeds about 100MPH but not to keep 100MPH. Only to get a little kick, if you know what i mean...

3.43 or 3.73???...

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Atilla the Fun · 08-17-2009, 02:22 PM

3.42:1, definitely. Yes, you could drive 3.73s just as well, but really, for stock TPI plus cam and headers, they're a bit much.

camaro87-alex · 08-17-2009, 04:30 PM

Quote:

Originally Posted by Atilla the Fun

3.42:1, definitely. Yes, you could drive 3.73s just as well, but really, for stock TPI plus cam and headers, they're a bit much.

Okay..Thanks for answering so fast

...Highly appreciated

..
Then I would probably go for the 3.42:1 gears...I guess I will notice a little bit difference when it comes to acceleration here

...
What kind of speedo gears do I need for correcting the speedometer?

Atilla the Fun · 08-17-2009, 05:04 PM

can't figure speedometer gears without knowing what size rear tires you'll be using.

camaro87-alex · 08-18-2009, 11:24 AM

Quote:

Originally Posted by Atilla the Fun

can't figure speedometer gears without knowing what size rear tires you'll be using.

Ok...My rear wheels are 255/45/R18..

subroc · 08-18-2009, 06:36 PM

Just another option..i didnt notice too much (if any) decrease in off the line grunt going from a 3.42 to a 3.27 rear ratio. The benifit of the 3.27 is i do drive on the highway and it a nicer gear for that. It lowered my cruising rpm down about 200.

PURPLEFORMULA · 08-19-2009, 05:50 PM

Since you are running 255/45/18's, they are taller than the stock 245/50/16, so with a taller tire, I would go with 3.70 or 3.73 in what ever axle you have, that will give you a good highway speed and still give you good power off the line.

Eric

camaro87-alex · 08-19-2009, 05:53 PM

Quote:

Originally Posted by PURPLEFORMULA

Since you are running 255/45/18's, they are taller than the stock 245/50/16, so with a taller tire, I would go with 3.70 or 3.73 in what ever axle you have, that will give you a good highway speed and still give you good power off the line.

Eric

Wellwell..I have ordered parts for $2500 now so I would stick with those.
As for the differential and the rear axle I bought a Eaton kit. Brand new kit with 3.42 gears and a mega install kit..Almost a $1000 with shipping and taxes to Norway

...

ojfox · 08-20-2009, 08:27 PM

eaton is a good brand so it should be almost bullet proof.....how well does the gear work out with your set up

InfernalVortex · 08-20-2009, 10:49 PM

Quote:

Originally Posted by camaro87-alex

Wellwell..I have ordered parts for $2500 now so I would stick with those.
As for the differential and the rear axle I bought a Eaton kit. Brand new kit with 3.42 gears and a mega install kit..Almost a $1000 with shipping and taxes to Norway

...

Eaton? This isn't the gov-loc (aka grenade-loc) is it?

Pro Built Automatics · 08-21-2009, 01:25 AM

A torque converter change will much more than a rear end gear ratio change, in terms of ET. If you are interested in acceleration only, do both, 3.73's or 4.11's, and a minimum 2,400rpm stall. The stall will depend on what is done to the motor, camshaft specs at .050" lift, head work, etc. And how do you drive? conservative, moderate, moderately aggressive, or aggressive? You will find if you do this right, you will have traction problems, now for stickier tires. The 10 or 9 bolt rear end will hold up fine with the right torque converter and Shift kit, and it eats very little in terms of horsepower. Dana