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Topic-icon Parts Advice Needed - Master Cylinder

  • jcrife
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3 weeks 1 day ago - 3 weeks 1 day ago #5690 by jcrife
I have a 1978 R100/7. I need to rebuild my front master cylinder. The rebuild kits I see online are either 14mm or 17mm. How would I determine which I need? Thanks for all advice. Also, I may replace my front wheel bearings and seals (they are original) and the front wheel is squeaking some. Can someone give me a part number and source for this too?
Last edit: 3 weeks 1 day ago by Wobbly. Reason: Changed title to aid future searches

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3 weeks 1 day ago - 3 weeks 1 day ago #5691 by 15908
Replied by 15908 on topic Parts Advice Needed - Master Cylinder
Check fiche at:
shop.maxbmw.com
The best parts locator around.
Russ

shop.maxbmw.com/fiche/PartsFiche.aspx
Last edit: 3 weeks 1 day ago by Wobbly. Reason: Added a web link

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3 weeks 1 day ago - 3 weeks 1 day ago #5692 by Wobbly
Replied by Wobbly on topic Parts Advice Needed - Master Cylinder
Usually that number is molded into the body of the cylinder itself, but it may be hidden from view by the reservoir.



The simple & safe solution: Loosen and disconnect the brake cable from the actuating arm of the master cylinder, pull the arm away, peel off the rubber protective cup, and then you'll be looking directly at the bore of the master cylinder. Measure it with a hand held measuring caliper.

It's either 14 or 17mm. Due to angles of measurement, rust, and other obstructions you'll probably not get an exact number, but one that will allow you to make a very educated guess.


► If there is ANY evidence of leaking (like rust on the frame) then you MUST also inspect the electrical connections directly under the m/c. ESPECIALLY the starter relay.

► If there is ANY doubt about your flexible brake hoses, then read this: airheads.org/forum/technical-discussions...failure-causes-cures

Don't hide 'em, Ride 'em !!
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2 weeks 6 days ago #5694 by jcrife
Replied by jcrife on topic Parts Advice Needed - Master Cylinder
Thanks for this advice. It is a 17mm. The sleeve is quite corroded and probably needs to be resleeved. Has anyone had experience with sending the unit to Apple Hydraulics in NY for cleaning and resleeving? www.applehydraulicsonline.com/collection...?variant=16394000001

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2 weeks 6 days ago #5695 by 14325
Replied by 14325 on topic Parts Advice Needed - Master Cylinder
Not sure where you are located, but we are having a Tech Day in MA this Saturday focused on just this problem, and we have on hand some newly re-sleeved with SS sleeve master cylinders. After the tech day we will likely send out another batch for referb. Let me know if you want to get in on either of these. The cost of a referb unit is $180, no core.

Tim Hille
MA Airmarshal

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2 weeks 6 days ago #5698 by jcrife
Replied by jcrife on topic Parts Advice Needed - Master Cylinder
Thanks Tim. I am in NC so won't be at the tech day but are you saying your group will be selling a referb unit for 180....and what does a referb include? And "no core" meaning you would not need mine? I appreciate your help. John
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