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-   -   ring gear spacers, good or bad (http://www.hotrodders.com/forum/ring-gear-spacers-good-bad-231004.html)

actmobmar 03-21-2013 05:36 AM

ring gear spacers, good or bad
 
i picked up a 12 bolt posi w/ 2.73 gears and i'd like to put 3.73's in it, is it ok to use a ring gear spacer or am i asking for problems? thanks!

BigMo 03-21-2013 05:43 AM

In my opinion, BAD....get the right series carrier, I think a 3 series will work with the 3.73's. There is a threshold where you have to go with the #4 carrier, I think its when going to a ratio higher than that....someone chime in here.....I put together many 12-bolts, but never went that high on the gearset, was always into a low ratio (4:10 and lower)

lmsport 03-21-2013 07:14 AM

Spacers are OK for everyday driving, but not in a high performance application.

There are three carriers for both the 12 bolt car and 12 bolt truck.

With a standard gear, 3.73 is used with a three series car carrier or a four series truck carrier.

big gear head 03-21-2013 07:49 AM

I've seen a lot of problems with ring gear spacers. They move the ring gear away from the flange on the differential where there is a machined sholder that centers teh ring gear. This causes the ring gear to float on the differential and only the bolts hold it in place. This causes contact pattern problems. I have seen several 12 bolt rear ends that sheared the ring gear bolts off because of a ring gear spacer. Ring gear spacers are a bad idea and should be avoided.

You can get a 3 series Eaton Posi case and transfer all of the parts from your 2 series Eaton Posi into the 3 series case.

dwwl 03-21-2013 08:09 AM

I think using the spacer is not going to be a good idea. I did that once on a 10 bolt and it didn't go well. It worked fine for regular driving, but i had a very unusual abnormality of having a very large/heavy right foot. I won the race, but spent alot of money replacing the entire rear housing. Was expensive.

BOBCRMAN@aol.com 03-21-2013 08:12 AM

"This causes the ring gear to float on the differential and only the bolts hold it in place. This causes contact pattern problems. I have seen several 12 bolt rear ends that sheared the ring gear bolts off because of a ring gear spacer. Ring gear spacers are a bad idea and should be avoided. "

Yes, these are very old school, but back in the day. Spacers are what we had and I saw a few rears that sheared the bolts off clean.

I had a customer with a 70 Impala with a 427 BBC and 4 spd. Was real hard on drivetrain parts. Sheared the bolts on first drag race..

lmsport 03-21-2013 08:43 AM

I've 12 bolts with all 12 sheared off without using a spacer.
I used to replace them with some super high strength studs, back when some fast cars ran 12 bolts.

Spacers are never the preferred solution, but then again, neither are axle repair bearings or yoke seal Speedi-Sleeves.


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