Author Topic: 12 bolt rear brake drums, a story about "experts"  (Read 1600 times)


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12 bolt rear brake drums, a story about "experts"
« on: April 09, 2016, 12:16:24 AM »
Hi there everyone.

I have had an issue with my rear drums. A brief story:

Went to a brake specialist to have my master cylinder overhauled as I believed it was not returning the rear line pressure causing the rear brakes to partially stay on from time to time which caused the diff oil to overheat and bleed past the seal filling the left side brakes with diff oil.
It turned out to be the flexible line from the body to the diff was blocked with 40 + years of crud.
I had all the lines flushed, everything renewd or repaired and I was told that I had the wrong rear drums.
According to him ( and I have seen the thread regarding drums ) a 12 bolt camaro diff should have the finned drums and I had the plain ones. As he was an "expert" I took his advice and he fitted a pair of finned drums. Excellent I thought.
The car is back in that shop again now after two weeks as I still had the oil leak and was going to replace the seal but found that I couldnt remove the drum. It looked as if the wheel had been a bit loose and had been wobbling about a bit and had mooshed up the centre of the drum into the end of the axle shaft.
They had to destroy the drums to get them off again.
I have a C clip elemination kit on my diff and a set of Moser axles as when I got the car the diff was in a very bad state and it was the only way I cold make it serviceable.
On closer inspection there is a small raised step on the axle where the drum mounts against the hub. The axle is about 0.7mm thicker here, hence the finned drum wont go on the last bit of the axle. Thats a bit odd I thought.
I went to a reputable diff repair shop, this guy is a walking diff encyclopedia, he tells me that all 68 camaros he has ever seen all has the plain rear drums.
He dug out an unmolested 68 camaro original axle and a selection of finned drums from various chevs.
The original axle although it is a bit tapered also had a very hardly noticeable step right in close to the hub. Not as wide as the Moser but there never the less.
Not one of the finned drums would go all the way on. Various plain ones he had did however.
What had happened was the brake guy was either wrong or supplied the wrong finned drum which did not go all the way on.
Even when he tightened it there was still the last bit, about 4mm,  that it was not fitting on to. After driving around for a bit it worked loose enough to mangle itself on to the step and them the wheel was loose as well.
All in all a complete bunch of crap.


Was there really  a correct finned drum fitted to any 68 camaro from the factory?
If so what is the part number?

My feeling is that they were all plain drums and anyone with finned ones probably either doesnt have the correct axles or the drums dont fit correctly and they will end up with my problem.

Any feedback would be greatly appreciated



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Re: 12 bolt rear brake drums, a story about "experts"
« Reply #1 on: April 09, 2016, 12:26:45 AM »
No finned rear drums on any 1st gen Camaro.


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Re: 12 bolt rear brake drums, a story about "experts"
« Reply #2 on: April 09, 2016, 12:50:15 AM »
My father had a May built 1968 Camaro ... finned drums up front smooth in the rear.


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Re: 12 bolt rear brake drums, a story about "experts"
« Reply #3 on: April 09, 2016, 06:31:00 PM »
I agree, I have never seen any finned rear drums on a first generation Camaro.
Bryon / 1968 Camaro SS 396 coupe - now 468 cubic inch BBC/M21
1967 RS/SS 396 coupe L35/M40 - 4 generation family project
Looking for 68 Camaro with body # NOR 181016