Rear drum sevice

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Zombie Master
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Rear drum sevice

Post by Zombie Master » Fri May 26, 2017 10:45 pm

84 R100

I got nothing in my books on how to remove the shoes on this design.. The shoes are spread by a cam on one end and held together on the other end with a pin that has a retaining head, that can't be loosened because the head is too narrow to get a wrench on. Looks like the only way to get these off is to remove the cam? Can't find a pic on this unit anywhere. Thanx! 8-)
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Rob
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Re: Rear drum sevice

Post by Rob » Sat May 27, 2017 12:20 am

I am pretty sure that you just grab one or the other at the middle point, and pull it toward you, holding the other with your other hand.

I could easily be wrong.
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Re: Rear drum sevice

Post by Zombie Master » Sat May 27, 2017 12:49 am

It's the 17mm head on that pin. You can only move the shoes vertically until you clear the 17mm hex head. It seems the only way to get the clearance would be to remove the brake cam shaft. I want to clean this area up! :ugeek:

The brake cam shaft goes through the rear drive gear case where it connects to the rear brake arm. Is that shaft lubricated by the rear gear oil?
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Airbear
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Re: Rear drum sevice

Post by Airbear » Sat May 27, 2017 1:17 am

You do actually just grab the brake shoes in the middle and pull. You will feel that one of them will fold out towards you with not-much-effort - you can turn the brake arm to stretch the springs a little. Assemble in the same way - with the springs fitted to the shoes.

Here's the link to Duane's page on the final drive - it has info on the brake shoes and cam shaft: http://w6rec.com/duane/bmw/finaldrive/index.htm
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and Brunhilde - 1974 R90/6
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Re: Rear drum sevice

Post by Zombie Master » Sat May 27, 2017 4:27 am

Thanx guys! It worked. Much appreciated. Should I press the brake cam shaft out, for cleaning/lubing?
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Airbear
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Re: Rear drum sevice

Post by Airbear » Sat May 27, 2017 11:35 pm

Won't do any harm. Note the position of the brake arm first.
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Re: Rear drum sevice

Post by Zombie Master » Sun May 28, 2017 12:02 am

Airbear wrote:
Sat May 27, 2017 11:35 pm
Won't do any harm. Note the position of the brake arm first.
Could removing the shaft damage the O ring or gasket ring. I would like to re-lube the brake cam shaft, but if I damage the gasket ring by removing it I'll be waiting for a while for a replacement. Or do they come out and go back in easily?
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Airbear
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Re: Rear drum sevice

Post by Airbear » Sun May 28, 2017 4:13 am

Sorry Neil - the memory is vague. I do recall removing it when I refurbed my FD but can't remember anything special. I think mine had an O-ring and just slipped out. Yours may be different.
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barryh
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Re: Rear drum sevice

Post by barryh » Sun May 28, 2017 5:25 am

Smooth case final drives had no O rings as the brake cam shaft wasn't exposed to the final drive oil.

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.

So on an 84 I wouldn't have thought the shaft should need to be removed to lubricate it.

The smooth case ones definitely do need to come out for a clean and grease as they tend to seize up.
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Re: Rear drum sevice

Post by Zombie Master » Mon May 29, 2017 1:41 am

barryh wrote:
Sun May 28, 2017 5:25 am
Smooth case final drives had no O rings as the brake cam shaft wasn't exposed to the final drive oil.

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.

So on an 84 I wouldn't have thought the shaft should need to be removed to lubricate it.

The smooth case ones definitely do need to come out for a clean and grease as they tend to seize up.
Hmmm that's interesting. Thanx Barry, I will look into this further.
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