Rear drum sevice

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Zombie Master
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Re: Rear drum sevice

Post by Zombie Master » Mon May 29, 2017 1:47 pm

Barry wrote:
With ribbed case final drives the hole for the brake cam shaft was exposed to the final drive oil presumably to provide lubrication. 2 or more O rings were fitted in an attempt to keep the oil from leaking out.
Has anyone heard about this? I find this facinating :ugeek:
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barryh
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Re: Rear drum sevice

Post by barryh » Mon May 29, 2017 5:03 pm

Not only does the final drive oil lube the brake cam but it does it well enough in some cases to have earned a reputation for leaking out and contaminating the brake shoes. This is why there were changes in the number of O rings in an attempt to keep the oil in. In 1985 BMW gave up and sleeved the hole so the the brake cam reverted to the pre 81 situation where it needed to be greased. They wouldn't have done that without a good reason.

Brake cam.png
Brake cam.png (71.88 KiB) Viewed 344 times
barry
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barryh
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Re: Rear drum sevice

Post by barryh » Mon May 29, 2017 5:10 pm

A service bulletin issued about the leaks.

oil leaks.png
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barry
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Rob
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Re: Rear drum sevice

Post by Rob » Mon May 29, 2017 5:50 pm

barryh 8-)
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Re: Rear drum sevice

Post by Zombie Master » Mon May 29, 2017 7:31 pm

Wow I just installed the brakes and rear wheel. I'm glad I didn't mess with the brake cam shaft as it wasn't leaking. Thanx!
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Airbear
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Re: Rear drum sevice

Post by Airbear » Mon May 29, 2017 7:38 pm

Barryh, thanks for the extra info.

I've learnt something new, so I'm set for the day.
Charlie
and Brunhilde - 1974 R90/6
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