Thread: Rear Diff
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Old 12-23-2020, 04:25 PM
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Quote:
Originally Posted by Stables Auto View Post
I have ERA3001 which is I believe their first 289 street car. It has a 289 w/a Galaxie T10 4-speed and what I think is a 3.xx Jag rear. My issue is that 1st gear is difficult to start out in as it's very high. The first time I drove it I thought I was in 3rd. My question is will installing a 3.5x or lower rear alleviate much of this issue or do I need to look at the gearbox instead? I believe the current ratio is a 3.07 or 3.31.

Any help would be greatly appreciated. Thanks!

If your car is lazy in first gear with a 3.07 or a 3.31 first gear, the problem is not your transmission, the problem is your engine's low speed torque. Something is wrong with the tune or with the build. You should be able to light up the tires at virtually any engine speed above idle with a transmission first gear like either of those — irrespective of your rear end ratio.


Ed


p.s. I don't believe any T-10 had a 3.07 or a 3.31 first gear so I am going to believe you are speaking to a ring and pinion. Commercially available T-10 first gear ratios would look like 3.42, 2.88, 2.64 or 2.43. None of those first gears would have any problem with a 3.07 or a 3.31 rear end gear ratio. This brings me back to tuning and/or build.

There was also a 2.20 (or thereabouts) close ratio gear set. If you managed to get a 2.20 first gear and a 3.07 ring and pinion with an aluminum flywheel you might have difficulty. The short way home is to put in a steel wheel.
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Last edited by eschaider; 12-24-2020 at 03:22 PM.. Reason: Spelling and Grammar
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