# Bad news rear end



## denrael (Apr 7, 2018)

The photos below show what I found when I opened up the diff on the '67 that I took delivery of just last week. After hearing a "CLANK" emanating from the rear for about the 3rd time in the 50 or so miles I've driven the car, I thought it might be prudent to do some investigation. Oh man! Between this and the disintegrated RF brake shoe (sticking wheel cylinder), I think it's time I had a talk with the seller... I'm wondering what other disasters are waiting to happen.


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## GTOJUNIOR (Aug 7, 2011)

Holly crap you better check every fastener on the car after finding that mess.
Best of luck.

Cheers


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## Goat Roper (Oct 28, 2014)

Ouch!
I moved your thread and added a descriptor so the rear end guys will see your post.
Good luck, my parts matching turnkey '67 GTO was actually turnkey 3 years after I bought it.


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## PontiacJim (Dec 29, 2012)

A little scary. Right brake worn? I can't tell from the pics if you have posi or not, but if you don't, I would suspect that the previous owner was having a little fun and locking the brakes to keep one side from spinning and smoking the heck out of the other tire.............not that I would ever do something like that. :yesnod:

Hopefully nothing was damaged or gears chipped and it'll be a simple fix and it'll be on the road. :thumbsup:


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## denrael (Apr 7, 2018)

GTOJUNIOR said:


> Holly crap you better check every fastener on the car after finding that mess.
> Best of luck.
> 
> Cheers


You're absolutely correct... hard at it as we speak.


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## denrael (Apr 7, 2018)

Goat Roper said:


> Ouch!
> I moved your thread and added a descriptor so the rear end guys will see your post.
> Good luck, my parts matching turnkey '67 GTO was actually turnkey 3 years after I bought it.


Thanks... I totally missed this sub-forum when I took a quick look. I'll get better as we go along.  

I hear ya on the 3 year thing. If only this car was half as good mechanically as it is cosmetically...


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## denrael (Apr 7, 2018)

PontiacJim said:


> A little scary. Right brake worn? I can't tell from the pics if you have posi or not, but if you don't, I would suspect that the previous owner was having a little fun and locking the brakes to keep one side from spinning and smoking the heck out of the other tire.............not that I would ever do something like that. :yesnod:
> 
> Hopefully nothing was damaged or gears chipped and it'll be a simple fix and it'll be on the road. :thumbsup:


Naah... the brake was a completely unrelated failure. Either the wheel cylinder was sticking or the flex hose was collapsed and trapping pressure. In either case, the RF was intermittently dragging heavily enough that it cooked big chunks of lining off the shoe. I suspect the shoes weren't exactly top notch pieces to start with.

Glad you brought up the posi... yes, it does. But I don't know what type, I'm not that familiar with all the various types of limited-slip units. Here's a photo that shows the cage... anyone care to hazard a guess as to type? I need to know what the recommended lubricant is, before I put it back together. (I'm satisfied I've found all the errant pieces and there is no real damage to the gearset, so it's just clean up the mess and put in new bolts - properly TORQUED!)


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## Goat Roper (Oct 28, 2014)

That was my goat paint and livery done and the good thing was mechanically it was all original and untouched the bad thing was it was all original and untouched.


Make sure you flush that rear end out well and use brake clean on the threads before installing the new bolts and torque them to spec.


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## PontiacJim (Dec 29, 2012)

denrael said:


> Naah... the brake was a completely unrelated failure. Either the wheel cylinder was sticking or the flex hose was collapsed and trapping pressure. In either case, the RF was intermittently dragging heavily enough that it cooked big chunks of lining off the shoe. I suspect the shoes weren't exactly top notch pieces to start with.
> 
> Glad you brought up the posi... yes, it does. But I don't know what type, I'm not that familiar with all the various types of limited-slip units. Here's a photo that shows the cage... anyone care to hazard a guess as to type? I need to know what the recommended lubricant is, before I put it back together. (I'm satisfied I've found all the errant pieces and there is no real damage to the gearset, so it's just clean up the mess and put in new bolts - properly TORQUED!)


Ah, ok on the known wheel problem, and not "burning outs."

I strongly suggest you either send a Personal Message to member *Pinion head* or just wait a bit for him to read your post as he is the expert/rebuilder of Pontiac & other GM rear-end assemblies. He will tell you what to use for oils and ID that posi for you and what to look for. :thumbsup:


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## denrael (Apr 7, 2018)

PontiacJim said:


> Ah, ok on the known wheel problem, and not "burning outs."
> 
> I strongly suggest you either send a Personal Message to member *Pinion head* or just wait a bit for him to read your post as he is the expert/rebuilder of Pontiac & other GM rear-end assemblies. He will tell you what to use for oils and ID that posi for you and what to look for. :thumbsup:


Unfortunately, his message box is full, won't accept any new correspondence.


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## Pinion head (Jan 3, 2015)

Regret not getting on and seeing this earlier, have been putting in a ton of hours and this type of question, the solution isn't easy to answer on a web forum, very involved. On the clanking noise, most likely, the pinion is loose, and for quite a while there has been next to no drag on the pinion bearings. Vehicle will need to be up on tall jack stands or better yet on a 2 post lift and rear cover pulled, grease drained, then drums & axles pulled. then one can hand rock the ring gear on the pinion and note if really loose. With magnetic dial indicator setup with tip on same plane as ring gear tooth, backlash should not be more than .015. Lot more to determine & repair procedure to follow. I will post back later today, have my help showing up already, got to get after workload before possible severe weather late this afternoon.


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## Pinion head (Jan 3, 2015)

Just looked at the pictures. Was viewing my old (1st gen ) iPad and pictures are slow to load, so went straight to reading and answering the text. The loose pinion "clanging and banging" scenario is very common and was ready to describe that repair. 

On the ring gear bolts coming out, I'd pull the axles, then the carrier and see what damage has been caused to the ring and pinion. Dont mix up the cast spacers or stacks of shims on each side of carrier bearings. The ring gear bolts may have not been previously properly torqued upon installation, or you may have a '70-72 Pontiac 8.2 carrier which was used in a build with the earlier '64-69 Pontiac 8.2 10 bolt or aftermarket gears. The '70-72 8.2 Pontiac 10 bolt carrier has 1/16" diam larger holes in the carrier flange & unfortunately I've prev run across monkeyed up customer driver car rears where rear had early style ring gear bolted to the later style carrier without custom brass bushings installed, and the ring gear bolts eventually worked loose. New ring gear bolts should be installed into solvent cleaned & air dried ring gear with blue loctite. I'd look up axle tubes for other debris & swab out with solvent on rag taped to a broom handle. Easiast way to do do with without proper tool. 

On the axles, might post a few pics of the axle bearings, do they have a green colored ring on the side of them?. The '64-69 8.2 Pontiac 10 bolts, '64-67 Buick 8.2 10 bolts, as well as most of the '67-69 Olds type "O" axles used the sealed axle bearing Rw507CR. Sealed axle bearings are notorious for seizing, chewing up the axle, and then the axle pulling through the steel lock collar. This usually happens around low speed corners, and axle & tire/wheel will walk their way out resulting in damage to the 1/4 panel. I've also examined the results of this happening after a local 442 was taking a corner hard getting on a local expressway at wide open throttle, that was a very expensive repair. Having pulled multiple hundreds of sealed axle bearing axles, the claim rate for unchewed sealed axle bearing axles has not been very good for the last 25 years. 1 out 2 in yard cars, & long time setting parts/project car rears is about as good as it gets. Just went through pulling axles out of more '67-69 8.2 Pontiac rears, and came up with one good used axle after bearings were removed. Thank goodness for GM & Ford waking up and going to tapered bearing axles & housing ends.


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## 67goat (Oct 27, 2006)

Not an uncommon issue, happened to my 8.2 rear, except my engine was pushing 500 lb ft of torque and running a 4.11 ratio. Parked the car after the clunks. Though when I backed up to get the car out of the garage for the tow truck, the ring gear punched a bolt right through the pumpkin.
Likely you will want a new ring and pinion if any teeth were damaged. Definitely replace axle bearings and if the axles are no longer true, get some quality new ones. Not many shops are experienced to properly set up a rear end. Find someone who does and knows GM rear ends very well to properly shim and install the ring and pinion, will be worth every penny to do correctly the first time. While you're at it, if you don't have limited slip, get one. Factory ones are scarce. Auburn makes an aftermarket that is relatively cheap.


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## denrael (Apr 7, 2018)

Thanks guys for the advice and insight. I now have to decide what I'm going to do next. The longer term plan was to get rid of the 3.55 gears anyway, going back to the 2.93 (or taller) gears the car was born with. This may be the opportune moment, regardless of the condition of the current internal pieces. Needless to say, I'm just a little more than pissed to be forced into this decision making process immediately after purchase... this was supposed to be a "driver", not a "fixer-upper".


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## 67King (Sep 18, 2018)

Similar issues, though I bought mine almost 30 years ago. Rear end making noise. My memory is a little foggy, but there were supposed to be shims between the spider gears and carrier. And there weren't. Ended up ruining the carrier, so ended up with a 3.08 open rear in my car :-(

The radiator was a 2 row Dodge radiator. Didn't realize it at the time, but hte bottom of teh core support was cut out. So I had to get a new one of those.

Oh yeah, they had put so much stop leak in the coolant that it clogged up the passages in the heads.


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## geeteeohguy (Feb 2, 2008)

Amazingly, it looks like your gears are ok. And the bolts were too big to get inside the posi unit. Looks like the typical cone type posi that these cars came with....decent units that can be rebuilt if need be. I would get new ring gear bolts, clean it our really well, and use red loktite on the new ring gear bolts, torqued to spec. Also check the torque on the bearing caps while you're in there. Run a non synthetic 75W/90 gear oil with a bottle of limited slip additive and you should be good to go.


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## john23 (Mar 6, 2016)

pinion head, good info...i have a pm for you...would you please clear a spot for it on your message board? thank you, john


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## s27519 (Sep 11, 2018)

I would definitely change the fluid a couple of times after you are all done fixing. Perhaps at 100 miles and then at 500. 

Just my thoughts....

best of luck.


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