rear diff dissaembly question
Thread Starter
Pro
Joined: Nov 2004
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From: Nice Lake Ontario
more rear diff disasembly questions
My 69 diff is at the shop gettin rebuilt, they tell me my new GM 370s won't fit 
.
I'm also told I need a "rear diff spreader" to pull the crown out? Is that true or can a backyard mechanic do it?? I have availabile to me a complete diff with 3.55s in it, can I use the new parts from my rebuilt diff with 4.10s in it??
.I'm also told I need a "rear diff spreader" to pull the crown out? Is that true or can a backyard mechanic do it?? I have availabile to me a complete diff with 3.55s in it, can I use the new parts from my rebuilt diff with 4.10s in it??
Last edited by sxr6; Jun 2, 2005 at 07:17 AM.
Safety Car
Joined: Aug 2000
Posts: 3,711
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From: San Antonio TX
What the hell is a crown (other than royalty, and I'm assuming there's no queen in your rear ;-)?
The spreader moves the housing apart which allow for easy removal and installation of the case. You otherwise may have to pound the shims in. Not that it can't be done this way (believe me, that's how it was done in the old days) but a professional rear shop, like VanSteele, would probably use a spreader to put tension on the housing.
Did they tell you why the 3.70 won't fit? I know the case breaks at 3.90 and up which means that you can't put a 3.55 gear on a 4.10 case and vice-versa.
The spreader moves the housing apart which allow for easy removal and installation of the case. You otherwise may have to pound the shims in. Not that it can't be done this way (believe me, that's how it was done in the old days) but a professional rear shop, like VanSteele, would probably use a spreader to put tension on the housing.
Did they tell you why the 3.70 won't fit? I know the case breaks at 3.90 and up which means that you can't put a 3.55 gear on a 4.10 case and vice-versa.
Race Director
Joined: Dec 1999
Posts: 19,610
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From: Forked River NJ
The 3.70s will fit on a 3 series carrier. If your previous gears were a 3 series they will fit. I just put in new gears this winter and did it without a spreader. If Iwas doing multiple rears I would use a spreader. I set up the carrier so it was a snug fit. I had to push it in. Once I had the pattern correct I put in an extra .005 on each side so it would be tight. I had to tap, not hammer the shims in. I rechecked the pattern and everything was fine. It is quiet and working fine this way.
I just reread your post. If you have a 4.10 gear and 4 series carrier you will need to get a 3 series carrier. All the internals will fit in both carriers.
I just reread your post. If you have a 4.10 gear and 4 series carrier you will need to get a 3 series carrier. All the internals will fit in both carriers.
Tech Contributor
Joined: Aug 1999
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From: Connecticut, USA
If they have the correct corvette ring and pinion set(crown) it should fit. It's a 10 bolt - 8.2" ring gear.They are corvette specific.
A spreader bar will stretch the cast iron housing enough to release the carrier bearing pre-load to remove the carrier. I borrowed one for the first differential I did and never used it but once. You can remove the carrier by using a 9/16 box wrench on a ring gear bolt and turning the pinion yoke to walk out the carrier.
If your shop couldn't get past this point I would have another shop do the job or send it to me to do. Did they stamp the bearing caps before removing them? What was the problem you were experiencing?
Spending money on another used differential may put you right back where you are now. If yours isn't cracked or broken it should be rebuildable.
'69 differentials used 10-18 spider gears and solid clutches in the posi. Positraction was still an option then so be sure you have one. Some were sold as cheap as can be - no posi, 3 speed manual, no Power, etc.
As Gordon said see if it's a 3 series carrier, what gears are in there now?
Good luck,
Gary
A spreader bar will stretch the cast iron housing enough to release the carrier bearing pre-load to remove the carrier. I borrowed one for the first differential I did and never used it but once. You can remove the carrier by using a 9/16 box wrench on a ring gear bolt and turning the pinion yoke to walk out the carrier.
If your shop couldn't get past this point I would have another shop do the job or send it to me to do. Did they stamp the bearing caps before removing them? What was the problem you were experiencing?
Spending money on another used differential may put you right back where you are now. If yours isn't cracked or broken it should be rebuildable.
'69 differentials used 10-18 spider gears and solid clutches in the posi. Positraction was still an option then so be sure you have one. Some were sold as cheap as can be - no posi, 3 speed manual, no Power, etc.
As Gordon said see if it's a 3 series carrier, what gears are in there now?
Good luck,
Gary
Last edited by gtr1999; Jun 1, 2005 at 04:55 PM.
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From: Nice Lake Ontario
gears
"The 3.70s will fit on a 3 series carrier. "
Ok how do I know if it's a 3 series carrier?
Gerry; "Did they tell you why the 3.70 won't fit? I know the case breaks at 3.90 and up which means that you can't put a 3.55 gear on a 4.10 case and vice-versa."
What do you mean the "case breaks at 3.90"?
I should have made note of the stampings before I sent it in
but I do remember it has a 68 with some letters after. I assumed it was a 1968 carrier.
Will a 79 rear diff fit?? I have the BB drive axle yokes, will they fit into that diff?
Ok how do I know if it's a 3 series carrier?
Gerry; "Did they tell you why the 3.70 won't fit? I know the case breaks at 3.90 and up which means that you can't put a 3.55 gear on a 4.10 case and vice-versa."
What do you mean the "case breaks at 3.90"?
I should have made note of the stampings before I sent it in
but I do remember it has a 68 with some letters after. I assumed it was a 1968 carrier.Will a 79 rear diff fit?? I have the BB drive axle yokes, will they fit into that diff?
Last edited by sxr6; Jun 2, 2005 at 07:20 AM.
