Rear end rebuild 1996 7.625

Rear end rebuild 1996 7.625

Postby Astrolife [OP] » May 22nd 2020, 7:07am

Hi all this is my first post, I wanted to document my trials here to share information. I swapped the axle on this thing with junkyard axles 3 times, all were no good. I ordered parts from O'reilly and hadbad luck with parts from them. I ended up rebuilding with a richmond excel ring and pinion, and motive gear bearing set from National Drivetrain. I went from a 3.42 to a 3.73. I used my buddy's shop press, a straight edge, calipers, vise, and various other common tools, and a Bauer electric impact for the yoke nut.
Attachments
Resized_20200520_151300.jpeg
20200520_151224.jpg
IMG_20200511_223103_491.jpg
Tools for the first set up.
20200511_201259.jpg
Pressing on the bearings using the old bearing cones and a stout pipe. Capped with a bearing driver.
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All the measuring tools, dial indicator, inch lb. torque dial, straight edge, and calipers.
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Finished product.
20200517_184716.jpg
Just for fun
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Re: Rear end rebuild 1996 7.625

Postby chevymaher » May 22nd 2020, 11:27am

Looks good. They sing a little when they are new till they break in. So up to 10 thousand miles they actually get a little louder then the wear pattern is broke in. It quiets back down.
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Re: Rear end rebuild 1996 7.625

Postby Astrolife [OP] » May 24th 2020, 3:22am

Thanks for the advice, it's good to know what to expect. Do you mean the richmond excel gears in particular? Or just aftermarket setups?
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Re: Rear end rebuild 1996 7.625

Postby Rod's Trucks » May 24th 2020, 7:24am

Brandon,
I think you will like the 3.73's.
I have that ratio in my '98 AWD, and I just ordered a Torsen rear diff for it.
I did a couple of GM style diffs (Opel race cars) many many years ago, but I have forgotten how much time I spent on them...and we were not worried about diff noise in a race car.
How much time do you think you spent on this regear?
thanks,
Rod
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Re: Rear end rebuild 1996 7.625

Postby Astrolife [OP] » May 24th 2020, 3:37pm

Rod,
Hi yes I have spent countless hours, but honestly mainly because it is my first time getting into a diff and I spent most of that time researching and troubleshooting, ordering parts that were not correct from places that did not have knowledge about the specs.

Actual work, maybe 10 hours. Once I knew what I was doing, I would say I spent about 4 hours on the pinion depth setting, then another 2 or 3 putting it all back together.

Other than that, this will be my fifth time swapping this axle since October so it's hard to tell exactly how much time I have spent LOL! :rolling:
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Re: Rear end rebuild 1996 7.625

Postby chevymaher » May 24th 2020, 8:57pm

Astrolife wrote:Thanks for the advice, it's good to know what to expect. Do you mean the richmond excel gears in particular? Or just aftermarket setups?

I used the same gears you did. No I meant the 7.5 7.625 rear ends. My brothers -04 pontiac GTO sounded just like the van. He took it in and they said it is normal.
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Re: Rear end rebuild 1996 7.625

Postby Astrolife [OP] » May 27th 2020, 12:05am

I have some slop at the yoke, but checked the backlash and that's still good. It seems to be the spider gears, maybe even the internal bore the .middle pin fits into. There seems to be some slop in the floating gears and side gears. The wheel spins maybe a half inch before engaging with the differential while up on stands turning by hand. The thrust washers are pretty well worn also.

My question is: What is the tolerance for movement of the spider gears? Should I just get new ones anyway?
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Re: Rear end rebuild 1996 7.625

Postby MechBob » May 27th 2020, 4:36am

Slop at the yoke is a relative thing. With very little pressure,you will feel the backlash of the ring and pinion, high pressure you will feel all the slop in the diff. different depending on how you are judging it.I am mystified as to why you needed to go through all the trouble of lead paint,paint or whatever you used.Being a retired GM mechanic, you have been able to use a new ring and pinion easily, for years.You could just use the shims off the pinion, swap them to the new pinion, then the only thing you need to measure and change is the side shims on the ring gear.has been that way for 30 years, and even the aftermarket adopted it, because it was made so simple.AS far as the slop in the diff, will get back to you later, perhaps you will figure it out.
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Re: Rear end rebuild 1996 7.625

Postby Astrolife [OP] » May 27th 2020, 10:01pm

MechBob wrote:Slop at the yoke is a relative thing. With very little pressure,you will feel the backlash of the ring and pinion, high pressure you will feel all the slop in the diff. different depending on how you are judging it.I am mystified as to why you needed to go through all the trouble of lead paint,paint or whatever you used.Being a retired GM mechanic, you have been able to use a new ring and pinion easily, for years.You could just use the shims off the pinion, swap them to the new pinion, then the only thing you need to measure and change is the side shims on the ring gear.has been that way for 30 years, and even the aftermarket adopted it, because it was made so simple.AS far as the slop in the diff, will get back to you later, perhaps you will figure it out.

I have heard that is the case with putting new gears in of the same size, but if you switch ratios, you have to reset pinion depth based on the wear pattern using this gear marking compound. It came with the gear set even. The stock shim set the pinion too deep, so did start from scratch. I was getting a pretty strong toe-heel pattern like this:
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Original Poster [OP]
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Van Model Year: 1996
Van Make/Model: Chevrolet Astro
Extra Info: 4.3L RWD 4 Speed


 
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