forum.jdrace.com

Hi,
Can anyone tell me the steps on how to upgrade a 3.08 gear 8.2 10 Bolt to a 3.55 gear? Also, what all do I need to upgrade it?

Thanks,
Ethan

Hi Ethan, We would need to know the exact 10 bolt rear you are working on.

- 10 bolt chevy c-clip axle retention rear?
- 10 bolt Buick Olds Or Pontiac (BOP) bolt in axle rear?

If it is the 3.08 chevy rear upgrading to a 3.55 is as simple as changing gear ratios. reshimming the pinion depth abit and the carrier shims till the pattern is correct.

IF it is the 8.2 B. O. P. rear you will need to get a 3.36 and up carrier to go with the 3.55 gears. BOP rears have a different carrier cut of ratio then the chevy type rear.

This info includes both posi (limited slip diff) and open type (single wheel peel) rears.

Hi Jim,
Yes, the rear end is out of a 1969 Chevelle Malibu. If you could tell me how to do the switch from the 3.08 to a higher gear ratio would be a big help. My dad and I are going to do probably this summer and wasn't sure how to do it.

Thanks,
Ethan

Well Ethan... It is not just as simple as telling you how to do it. It is one of those deals where you need someone to kind of guide you . Like apprenticeship. etc. Alot is grey area too. wisdom experience.

I can tell you as long as you have the 3.08 carrier and higher your good in a c-clip type chevy rear. Use the original shim to start with. If the original bearing (inner) is still in decent shape use it as your bearing tools.
Hone it out for a slide on fit snug like...this way you can change the pinion shim with out having to press the bearing on and off and end up ruining it.

Go by the pattern as it will tell you where the gear wants to be. Use the pattern chart with the gears you bought or I can send you one if you bought an off brand. it should also show if you need more shim or less shim. Lastly every time you switch the pinion shim you must ALWAY reshim for the backlash too. keep the back lash between .006-.010 NO MORE THAN .010. Backlash is the slap of the ring gear tooth and the pinion tooth. You use a dial indicater and a magnetic base to check it.

If you start up and get in a spot where you need help just ask here on the site. Please do not rush the job. If you are unsure ask or send pictures. Ok? Good luck, Jim - J D Race

Hi Jim,
I thank you very much for the help. I live in Urbana, Ohio, but I don't know if you could help when my dad and I go to do it this summer. You are probably a very busy person.

Thanks again and take care,
Ethan

Yes, but you would be surprised what I can squeeze into a day. Besides where else are you going to get free advise these days...lol. As long as you have digital pictures of the pattern I can let you know how close you are or if it looks like trouble. If not that is cool too. Just trying to help however we can. Jim