trying to replace the fried auburn in my 72 gs,got some #`s of the ring but don`t really know if it`s a 8.2 or a 8.5.It`s a 10 bolt with bolt in axles and 28 spline and it`s a 3:42 ratio.I got several part #`s off the ring, one being 1234670.Anybody give up some help? thanks, joe
Here's a web site with a lot of good info to help you determine your rearend: http://firstgenfirebird.org/firebird/FAQ/wheel_brake_axle/axles.html A surefire way I was told to know if it's an 8.5 or not is to look at the center section housing where the axle tubes come into it. If it's smooth, it's an 8.2. If it's got four "bumps" around it, it's an 8.5. Another, but not 100% of the time, is to look for the ears on the bottom of the center section at the 5 and 7 o'clock locations. An 8.2 rearend center section will be just round, but most 8.5's have the ears on the bottom. But the four bumps around the axle tube area is the best way to tell, except for measuring the ring of course.
Joe, It sounds like you have the original 8.5 A-body rear with original Warner-Motive cone type posi. The Warner-Motive posi case bolts together & only uses two spider gears. Have never been a fan of the Warner -Motives, usually pitch them when worn out & go back with a rebuilt clutch type carrier or a new Eaton. One of the easiast ways to quickly ID the rear in a car as '71-72 8.5 A-body rear, is to look at the pinion flange. U bolts & nuts holding the u-joint, & a side cutout 10 bolt rear cover, it's a bolt-in axle 8.2 of some form. Stamped steel straps & 7/16" headed bolts attaching the u-joint, the original rear is an 8.5 A-body. Problem with going looking at bumps (am assuming the two plug welds per side), is there are 2 different center housings used on '71-72 8.5 A-body rears. The most common housing will only accept the side cutout style rear cover, & when looking at the housing from the rear cover side, will have two plug welds per axle tube. This common style housing will also have the big square lugs on bottom @ 8 & 4 o'clock. Other '71-72 8.5 A-body center housing had only one plug weld per side, used a round cover, & had no big square lugs on the bottom. Got Posi? :3gears: Roger
unfortunatly the cover is back on and the car is home, we did this at a friends last nite w/ a lift and i`m getting mixed reviews back on this.I know the posi is an auburn and what i really need to do is to tear it all apart again and measure the ring or someone told me to count the splines on the pinion,but i can`t get the use of the lift for a while, thanks, joe
Unless an Auburn 8.5 carrier has been added at some time, the '72 rear didn't originally come with one. The Warner-Motives were a similiar cone-type carrier that were used a lot in '71, & some may have ran over into '72 production. The "S" spring type 8.5 clutch type carriers started showing up in '72 The 8.5 pinion flange with straps, vs u-bolts comparison is the best way to quickly ck. The 8.5 pinion flanges are quite a bit longer than all the various 8.2's flanges, making the 3R style 8.5 flanges really easy to spot. Got Posi? :3gears: Roger
