Finally rebuilding my 7.5

[pontiacgp]

Klaird, while it would seem possible to just change out the outer bearing and seal, what condition is the inside bearing? There are two you know, and both probably should be replaced. That said, the factory manual states that ANY part replacement requires rechecking everything to specs and using a new crush collar. But I would bet that you could get away with changing out BOTH bearings as well as the the races, reuse the stock inner bearing pinion shim (unless it's chewed up), a new crush collar, and reset the pre-load to "new bearing" specs. BUT, changing the bearing races is impossible without the pinion gear coming out, which requires the ring gear carrier to come out, which involves re-installing the stock cast carrier spacers (fragile- do not hammer them in) or a new carrier shim set. Ain't rears fun? But the original idea of just changing the outer bearing seems like the easy way out, but are you comfortable using a new bearing in an old race? Of course you could also just leave the bearings alone, tighten up the pinion nut to "used bearing" specs, add a new seal, and pray all will be well. Pinion pre-load is the inch pounds of torque needed to turn the pinion flange with NO brakes dragging. As you tighten the pinion nut to achieve pre-load, the collar crushes and too much ruins it, you can't loosen and try again, gotta replace it and start over. Do ya feel lucky?

you forgot to put the axles have to come out to remove the carrier...

but you are right, if the bearing in front needs to be replace the inner bearing would most likely be damaged as well since that one takes the direct force of the pinion trying to walk away from the crown.

 

[Bonnewagon]

I thought his axles were out because of the bearing/c-clip issue? He hasn't buttoned it up yet?

 

[pontiacgp]

you got me there... 8)

 

[klaird]

Bonnewagon/PonticacGP, yes the axles are currently out of the housing. I am going to take the plunge and attempt to rebuild the rear. I am going to replace the pinion bearings (both) as recommended. How do I know if the carrier bearings need replacing? Is there a tolerance spec? I might transfer everything over to a better (less rotted/pitted) rearend housing which is going to take some time to prep....Can you confirm that a 7.625 inch ring gear will fit into a 7.5 inch rear housing?

 

[klaird]

Is #5 in the diagram synonomous with Crush Collar? In reviewing what my Haynes manual has to say about bearing pre-load, it states: "between 15 and 30 lb-in with new bearings..." My question is why is there such a wide range in bearing pre-load spec? Should I err toward 15 or err toward 30? Or try to hit a happy medium at say 23? What is the significance of this relating to bearing life?

 

[pontiacgp]

that is it but here'a picture that might make it clearer for you..

 

[Bonnewagon]

From the '86 Pontiac manual- pinion (only) bearing pre-load (measured at pinion flange nut): New bearings-20-25 lbs in. Reused bearings-10-15 lbs in. Total assembly (pinion and carrier) pre-load: New bearings-35-40 lbs in. Reused bearings- 20-25 lbs in. Ring gear: .006"-008" backlash. OK, now, if the rear was quiet, no growling or hum, probably the carrier bearings are fine. If you feel the need to replace them, or swap the carrier to another rear, EVERYTHING must be reset. This is because the bearings, races, and shims you have now, are correct for that particular rear ONLY! Theoretically, if you had a new set of carrier bearings and shims, and they miked up at the exact same thickness as your old bearings, they could go in with no other changes, but that's unlikely.The pinion bearings aren't as complicated as the ring gear, although technically pinion depth should have been verified as new bearings may affect that spec. However, the cast carrier shims are just for that rear, with that carrier, and those bearings. Any changes require re-setting the carrier to it's pre-load. This is done by shimming the carrier to .000" preload (that means you cannot measure even .001" clearance between the bearings and carrier) while checking the tooth contact pattern and backlash. When satisfied, you then add .004" to both sides, thus totaling .008" pre-load. So for example if the left shim pack was .214, then the final thickness would need to be .218. By adding .004" to both sides, the ring gear position stays static.The factory determines the shim pack thickness, then installs that exact thickness cast iron shim. My whole point is, changing anything, or putting it all in another rear, requires a lot of work with special tools. Some may claim you should just "slap them in there", but I like my rears to last 100,000 miles and stay quiet. Just remember, the pre-load holds the gears in suspension, so that the driveline torque does not cause any deviation in their position that would cause the gears teeth contact to vary. For a guaranteed headache, please read a factory manual about this.

 

[onebadasscutlass]

Ok I know it took some time since my last post so here is the update! I finally got to work on building the rear end. I did how ever get in contact with richmond about there gear and that went no where. I dont know how you can market the same exact gear as a sportsman gear and a excel gear and charge two different prices for the same gear. but thats the last time I deal with them. So I finally got extra time to assemble the rear end. It took all day sunday. All because the mock up bearing we were using was smaller than the new bearing. After that situation was resolved. We put the rest of the odds and ends on. I broke that clip that holds in the wheel cylinder so I have to either figure out where I brought I from and exchange it or buy a whole new one. That clip design sucks and should have never been used imo. And I found out that shiming sucks and will drive you crazy after awhile lol
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[Bonnewagon]

"shimming sucks" ha ha ha. Massive headache! And why shadetree types say to "just slam em' in". I'm sure that retainer clip is a HELP! item, if not RockAuto has a rebuild kit for a buck and includes the clip. "RAYBESTOS Part # WK886 {#35886} Professional Grade One of our most popular parts
Rear $1.06"

 

[pontiacgp]

if you had kept the original shims and put them back in the way they came out you might not have to play with the shims and if you did it would have been very close. If you have a micrometer to measure the shims so you know what you have on each side it's easier working it out to adjust the shims