68' rear noise, metal shavings

[greggome]

Just pulled right rear wheel off and noticed fine metal flecks on inside of wheel and along trailing arm etc. have been noticing a rubbing ,scraping sound coming from the rear of car lately. Bearing problem? any other possibilities?

Assuming its a wheel bearing is it a difficult do it yourself repair job?

 

[Mac]

Is it do-able? Sure. That being said, many guys choose to have trailing arms rebuilt rather than tackle the bearing... and, often as not, it's better to do them as a pair rather than just doing one. After all, if one is ready to fail, the other isn't likely far behind.

Mac

ps: I'm not pushing VTech or any other company. I just like how he shows the parts, including the cut away.

 

[Antz81]

Assuming its a wheel bearing is it a difficult do it yourself repair job?

Unless you have access to a large press (20+ton) and have reasonable mechanical knowledge then I wouldn't attempt it.
send it off with the other one as Mac suggested and have the whole trailing arm rebuilt.

 

[greggome]

Looks like the trailing arm is a bit tricky to get off. Anyone ever tried this?

 

[Hib Halverson]

(snip)

Assuming its a wheel bearing is it a difficult do it yourself repair job?

For a DIY, C2/C3 rear bearing service is difficult, if not impossible.

Unless you have experience with axle bearing service, a 20-ton hydraulic press and the equipment to set-up the bearing clearance, either have a service shop which does C2/C3 rear arm work do the job or buy a remanufactured rear bearing assembly from CAC sponsor Zip Products.

If you want more info on rear bearing work, see:

Corvette Action Center | Tech Center | Hib Halverson's Big Block From Hell Series - Part 12

 

[Mac]

Tons of good info in your article, Hib.

Here's a pair of videos from the same guy I linked earlier on how to remove trailing arms. He shows a couple of neat tricks like using a wooden block & a c-clamp to prevent the jack from sliding up the spring... and he offers several tips on things that can go wrong...

Part 1 - Video Instructions to Remove Trailing Arms from your C2 or C3 Corvette - YouTube

Part 2 - Video Instructions to Remove Trailing Arms from C2 and C3 Corvettes - YouTube

Mac

 

[greggome]

Well it turned out to be an upper PB spring that dropped down to the bottom of the PB area rubbing not a wheel bearing as was thought. While I'm undertaking the PB repair I have a clear view of the rear diff. plug. The car has never had a fluid change. Wondering if its a good time to drain and put new fluid in BUT "if it aint broke dont fix it" comes to mind. Any thoughts on this. Also i understand you need to do figure 8's after a change for the posi unit. cant think of anywhere local that i have enough space to pull that off.

Tons of good info in your article, Hib.

Here's a pair of videos from the same guy I linked earlier on how to remove trailing arms. He shows a couple of neat tricks like using a wooden block & a c-clamp to prevent the jack from sliding up the spring... and he offers several tips on things that can go wrong...

Part 1 - Video Instructions to Remove Trailing Arms from your C2 or C3 Corvette - YouTube

Part 2 - Video Instructions to Remove Trailing Arms from C2 and C3 Corvettes - YouTube

Mac

 

[Midnight 99]

Definitely change the differential fluid. Glad to hear your bearings were not the problem. I replaced mine when I was doing the ground up on my 69. The trailing arms can be a bear to remove and the bearings are a major job for anyone but an experienced mechanic with the proper equipment.

 

[Mac]

Well it turned out to be an upper PB spring that dropped down to the bottom of the PB area rubbing not a wheel bearing as was thought. While I'm undertaking the PB repair I have a clear view of the rear diff. plug. The car has never had a fluid change. Wondering if its a good time to drain and put new fluid in BUT "if it aint broke dont fix it" comes to mind. Any thoughts on this. Also i understand you need to do figure 8's after a change for the posi unit. cant think of anywhere local that i have enough space to pull that off.

I don't think the expression "If it ain't broke, don't fix it" applies to fluids...

Mac

 

[greggome]

GM Lube

Okay, I' m planning on using GM Lube and posi additive in my 68'. I have seen numerous versions and part # for these products. For the Diff lube theres AC Delco 80W-90W 10-451 GL-5, AC Delco "speacial formula"75W-90W 10-4061, Genuine GM Fluid 80W-90W GL-5 89021669, or AC Delco 80W-90W GL-4 89021671.

Then the limited slip fluid GM 88900330 or AC Delco 10-4003.

Any ideas on the correct fluids? I have seen all advertised for use in my car in different corvette parts mags and on line. Whats the correct ones for my 68'? (none are synthetic).

Also I have seen using 2 4 oz. containers of limited slip some say 4 oz. is enough other say six ounces.

 

[frank_nesta]

AC Delco 10-4052 (88900330). 4oz work perfectly for 38 years running.

 

[Tom Bryant]

I had to go out and look at what I use. I have GM 1050081 Special Formula Multi Purpose Rear Gear lubricant. Granted I have had this on the shelf for a number of years and it may have changed numbers but this one product came out in replacement of the old standard rear gear oil and the Positraction gear oil for over the counter sales at the GM parts departments. It was supposed to already contain the posi additive but I always added 4oz of the GM 88900330 with it. The GM and Delco are the same stuff as I remember. It just depends on where you buy it.

Tom

 

[greggome]

tried to get diff. square head plug out with 12 point socket no go. six point socket doesn't fit either. No room for an open end wrench. Suggestions on what to use to get this plug out? heard somewhere to use a 5/8" crowsfoot wrench?

 

[GDaina]

Crescent wrench works very well

 

[Midnight 99]

Ditto on the crescent wrench.

 

[greggome]

no room for a crescent but the crows foot did the trick.

 

[Antz81]

Glad you got it sorted. Another option would have been a gator grip socket.

 

[greggome]

okay , changed out my rear lube with delco brand 80w-90w plus the limited slip fluid 6 oz. worth. thought that might help the rear as it was noisy but it almost seems noisier (no chatters or high pitched noises but like a rubbing sound almost like the sound of tire scrubbing on a tight turn. It gets more pronounced as speed increases). Also, even prior to the oil change I have noticed on shifts when letting clutch out that some times I get a clunk and once in awhile I'll hear a metallic ping from the rear. Which brings me back to wheel bearing vs rear differential problem. None of which sounds good.

 

[GTR1999]

Greg
If you have an original '68 diff with posi then it has the 1st design Eaton posi and those were very prone to cracking and as time goes by will break. I had Jack Panzica in here a few weeks ago with the '68 diff out of his '66 and that is what happened. The posi cracked and finally split in half locking up the diff and wrecking everything inside it. About the only warning you will get is a clicking sound from the diff, once you hear that I would stop and pull the diff before the case spreads and jams the posi spiders.

If the rear bearings are bad you are going to be able to feel them when checking the wheel off the ground. Check your u-joints for signs or rust or play in them. If your car has not been touched in many a year it could be all.

Posi chatter is from tight spider setup in conjunction with the 4 springs. Once the diff is hot the posi may chatter or hammer around corners, either turning or typically starting up. The additive chemistry has changed over the years and has been very good but I have seen a tuned posi chatter when using only one bottle of the current GM additive so I suspect it has changed again. I now use 2 bottles in a rebuilt diff and posi.

Good luck, if you need any advice let me know.

Gary

 

[frank_nesta]

Greg
If you have an original '68 diff with posi then it has the 1st design Eaton posi and those were very prone to cracking and as time goes by will break. I had Jack Panzica in here a few weeks ago with the '68 diff out of his '66 and that is what happened. The posi cracked and finally split in half locking up the diff and wrecking everything inside it. About the only warning you will get is a clicking sound from the diff, once you hear that I would stop and pull the diff before the case spreads and jams the posi spiders.

If the rear bearings are bad you are going to be able to feel them when checking the wheel off the ground. Check your u-joints for signs or rust or play in them. If your car has not been touched in many a year it could be all.

Posi chatter is from tight spider setup in conjunction with the 4 springs. Once the diff is hot the posi may chatter or hammer around corners, either turning or typically starting up. The additive chemistry has changed over the years and has been very good but I have seen a tuned posi chatter when using only one bottle of the current GM additive so I suspect it has changed again. I now use 2 bottles in a rebuilt diff and posi.

Good luck, if you need any advice let me know.

Gary

Hi Gary,
I have a couple of questions. Why do they replace stub axles when they rebuild rearends? And do you use new or re-manufactured / rebuilt stub axles?