Pontiac GTO Forum banner

1 - 5 of 5 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter #1
I'm changing out the backing plates on my 72 lemans rear end and I'm just reading now ...that the rear is kind of a red-headed step child of 10 bolts? I'm not looking to change gears or anything crazy, I just want to pull the axels, put new backing plates on and since its apart new axle shaft bearings too but no one lists the 8.75 ? are the tube end bearing the same for the 10 /12 bolt GM and and the Pontiac oddball?

Also I need (want) a hood, trunk and pass side sport mirror if you have one.
 

Attachments

·
Registered
Joined
·
1,611 Posts
Just looking at your pics, the rearend is an 8.2 Pontiac 10 bolt, not sure where you are coming up with the 8.75 description for that rear. The 8 7/8 MP series rear is another style GM rear (sometimes referred to in chevy service manuals as an 8.75), and there is no version of that style rear that bolts in a '72 or earlier A body. By looking at the shape of the diagonal webbing looking at the center hsg from the rear, along with shape of the rear cover is how I'm ID'ing the rear, and I have half a dozen gray iron versions, along with a few nodular HD Safe-T-Track rears. 8.2 Pontiac rear's were used under all '64-69 Pontiac A body's, and all '70-72 Pontiac A & G bodys except those 70-72's factory equipped with a 455 engine.

On this 8.2 Pontiac rear, you can take a 9/16" socket on an extension and fish it through the access hole in the axle flange. Out on the road, in yards, I usually use a large 1/2 drive flex head socket wrench along with a 3/8" adapter and a 3/8 drive extension to remove the 9/16" headed nuts, then yank each axle out.

If the 8.2 Pontiac 10 bolt rear is out of a '70-72 Pontiac A-body, the axles will have tapered axle bearings with external seals. This style of axle bearing next to never goes bad. My old 4.0 Jeep Cherokee had this exact same axle bearing and seal, and both were in excellent shape at over 280K miles of serious abuse, years and years of heavy loading and towing. The external axle seal is a National 712146, the tapered bearing is an A9. You can slide the axle out and see if there is an external seal jammed up out board of the axle bearing..if so, most likely the axle bearing and seal is fine. Replace if you like, I always do on the bolt-in axle 8.5 A body rears that I build.

On the other hand, if the axle bearing has no external seal, one can shine a flashlight up in the axle tubes a few inches, and one will see an internal seal. The early 8.2 Pontiac A body rear's were used through '69, and they use a sealed axle bearing, the RW507C. this style axle bearing is notorious for seizing and spinning the internal race on the axle and thus chewing up the axle. I've literally pulled multiple hundreds of he early sealed axle bearing axles over the years, an I personally will not build the early gray iron 8.2 rears for performance usage. For high point restorations, it's one thing, will go through them. For strong performance A body's, it's an upgraded 8.5 A-body swap, or an upgraded 12 bolt, have picked up blown parts too many times from 8.2's, they just don't have adequate pinion support.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #3
axle bearings

WOW, I guess you know your axles !

I don't know where I came up with the 8.750 ? I must have confused myself with all the misc info trying to figure out what I had? From what i have read this odd rear is fairly durable but few aftermarket parts are available for it so people take them out and put in 12 bolt or chevy 10 bolt (its how I got it) The guy I got it from had a 71 Lemans and he wanted to swap gears or rears but however or why he went with the Chevy rearend

When he went to swap rears, he kept his good backing plates brakes and axles and slid the others in the axle I have now ...since I have to get at the backing plates I have to get past the bearing, no sense in pressing old bearings in so here we are.

The plates should come off real easy since he just had them off, i'll check for the type and report back ...



thank you so much for your time and help !

Ron
 

·
Registered
Joined
·
1,611 Posts
No problem, glad to be helpful. Once the stamped retainers slide off eachof the 4 t-bolts, the axles will slide out, you can then carefully walk the backing plates off the 4 T-bolts and replace the backing plates. There are three different styles of those t-bolts used in bolt in axle GM A body rears, I try and not lose the t bolts or their matching shouldered nuts, as sometimes will be short on one version or another.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #5
WHOOOPS I feel stupid now :(

Here the whole time I'm thinking the backing plate was trapped in behind the bearing but its not the case at all .....I probably was thinking all non "C" clipped ones were since they made those rust repair backing plates .....


ANYWAYYYYY

I took out the 4 end bolts and tap tap tap with the slide hammer and the axle and bearing slip right out, no problem.

the assembly has the very outer seal with a pretty narrow looking bearing (may 1/2 wide or so ) then a collar (like I see in all the bearing kits) and lots of oil .

I'll run with these bearing and seals, the dust ring/support plate looks dry so the seals are probably fine so if its not broke, then if I leave it won't be either!


The whole reason for this is so I can drop my axle out and cram this one in copleted and ready with all near arms, bushing , brakes and lines so the car isn't blocking up my garage all torn down while I peck at this stuff . I can press the bushing in the axle, have my x-tra set of arms ready, new bolts and knock it out a little fast than my other a body.

thanks for your insight and expertise !!
 
1 - 5 of 5 Posts
Top