I'm totally new to doing rear ends on cars so i come to you all with a stupid question. We have a 87 Iroc with a stock 10bolt rear end. My brother changed the carrier and now the rear end whines like a cat in heat. Could he have put a carrier in thats to big? or would a 9" inch ford carrier for instance fit in anything? Sorry for the dumb questions! New territory for me! Thanks all

 

If it's whining, the gears are not set up properly. You need to set them up for the proper wear pattern and have the correct backlash between the ring and the pinion. Pinion depth is adjusted by changing the shim behind the pinion bearing. It's just about impossible to remove the bearing to change the shim without destroying it. A driveline shop will have a modified bearing that doesn't need to be pressed on so shims can easily be swapped around. Once the proper shim is selected, a new bearing is pressed on. The shims on the side bearings adjust the side to side position of the carrier. They're a tight fit and usually need a case spreader to get them in.

If you have a 10 bolt, it's a 7-1/2" 10 bolt. Around 86, it was upgraded to a 7-5/8" ring gear but nothing else changed. The carrier (posi) for a 7.5" 10 bolt will work with 7.5" or 7.625" gears.

The GM diffs also come in different series. It will either be a 2 or 3 series carrier depending what the gear ratio is. You can't put 3 series gears on a 2 series carrier. Well you can but you'll never get it installed in the diff.

Parts from a 9" or any other diff that's not a 7-1/2" 10 bolt will not fit inside the 10 bolt.

Rebuilding a diff isn't difficult but some knowledge of what needs to be done and how to adjust the gears for the proper pattern is required.

 

Thanks a lot! that answered my questions. Are we looking for disaster by pushing about 450 hp (at the crank) through this rear end?

 

Stop driving the car right now and fix the rear end. If you haven't put many miles on it then there is a chance that you haven't destroyed the gears yet. Your brother obviously didn't get the backlash set right when he swapped the differential. This is a huge problem and must be fixed right now. Read this and fix it. http://www.nastyz28.com/forum/showth...t=install+posi

The 7.5 will not handle 450 HP if it ever gets traction. This rear end is just too small for that kind of power.

 

Thanks for the info!. We stopped driving as soon as we heard that sound actually.. i have the carrier back out.. and the gears are still ok thankfully. Thanks for the link and come to find out my brother didnt check the backlash and such. I think ill just pay someone to do it right ... Thanks all