Gear ratio swap?
Thread Starter
Instructor
Joined: Jun 2000
Posts: 118
Likes: 0
From: Goose Creek, S.C., U.S.A.
Gear ratio swap?
First I don't know exactly what ratio I have. The housing is stamped for a 3.35 ratio at assembly. The differential was rebuilt by previous owner and I don't know if they used original ring and pinion. The engine turns 3200 R.P.M s @ 70 M.P.H. The tires are 245 x 50 x 16" and measure 26" outside diameter.
I got a 3.08 that I'm thinking of swapping to. How much will this drop my R.P.M.s @ 70? Will I feel a loss of power? If so, how much?
Thanks for the input.
Kerry
I got a 3.08 that I'm thinking of swapping to. How much will this drop my R.P.M.s @ 70? Will I feel a loss of power? If so, how much?
Thanks for the input.
Kerry
Drifting
Joined: Sep 1999
Posts: 1,411
Likes: 1
From: Wylie TX
Re: Gear ratio swap? (waterhead)
According to my calculations, with a 26" tire at 70 a 3.36 rear gear should put you at about 3050 RPM and a 3.08 rear gear would be at about 2800 RPM.
I'd guess that you still have the 3.36 gears. You can verify this by jacking up the rear of your car, marking the tire and turning the drive shaft.
I'd guess that you still have the 3.36 gears. You can verify this by jacking up the rear of your car, marking the tire and turning the drive shaft.
Melting Slicks
Joined: Dec 2000
Posts: 2,635
Likes: 0
From: Union Ontario
Re: Gear ratio swap? (Chris A)
Why would you go 3.36 to 3.08? I'd go to 3.55, it would make it feel like you have more power. If you want to bring the RPM's down I would do an overdrive swap, I think you'd be happier with the results.
Race Director
Joined: Dec 1999
Posts: 11,096
Likes: 990
From: Sierra Foothills CA
Re: Gear ratio swap? (Chris A)
According to my calculations, with a 26" tire at 70 a 3.36 rear gear should put you at about 3050 RPM and a 3.08 rear gear would be at about 2800 RPM.
I'd guess that you still have the 3.36 gears. You can verify this by jacking up the rear of your car, marking the tire and turning the drive shaft.
I'd guess that you still have the 3.36 gears. You can verify this by jacking up the rear of your car, marking the tire and turning the drive shaft.
Burning Brakes
Joined: Apr 2000
Posts: 1,207
Likes: 1
From: Cave Creek AZ
Re: Gear ratio swap? (waterhead)
Kerry
I have the 308's and just did all sorts of motor work, I am going to 373's now. There is no low end power at all. Upstairs is great if you are always cruising at 80+ but for the amount of driving that my car does I want to get the full range of power. From what I have found out the 373 is going to be a good all around gear for what I want to get out of the car.
Just my .02
JoeB
I have the 308's and just did all sorts of motor work, I am going to 373's now. There is no low end power at all. Upstairs is great if you are always cruising at 80+ but for the amount of driving that my car does I want to get the full range of power. From what I have found out the 373 is going to be a good all around gear for what I want to get out of the car.
Just my .02
JoeB
