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R65 Brake Question

tlangman4

Member
Hi All-

Just picked up an ‘81 R65 with relatively low miles but needs a lot of work. The bike has twin front rotors, something I thought wasn’t available on the R65, but rather on the LS. So perhaps that is the modification as it appears to be stock equipment complete with Brembo gear. The master cylinder is shot, so trying to source a new one. Would anyone be able to tell me the size of m/c needed per mm’s? Also, suggestion on where to source this part?

Thank you!
Tom
 
If I'm reading this RealOEM page right for an '81 R65:

http://www.realoem.com/bmw/enUS/showparts?id=0364-USA-01-1981-248-BMW-R65&diagId=34_0598

it seems to suggest that the single ATE or Brembo master cylinder was 16mm. I checked a '81 R65LS and the parts fiche says 16mm as well...although I'm not so sure I'm reading things correctly. I know on my under-tank master cylinder, the size is actually stamped into the body of the part...maybe on yours??

I suspect a dealer can still get a master cylinder. There are used part places in the link in my signature line. Plus, there are a couple of links there that indicate places that do resleeving.
 
Mine had a 16mm, 15 is available and will give better leverage.
The twin discs were an option, I had the same setup. But!
Those ATE pistons are plated steel and are going to be pitted, the seals are also costly.
82ish on used a brembo which has anodized aluminum pistons, that'd be the simplest swap/upgrade and probably the most economical.

I adapted some Japanese discs and calipers but that is not a simple upgrade and is only economical if you make your own parts.
 
Changed my R65 ATE calipers to Brembo F08 which replaced the ATE with no issue and gives better braking. $113 from mgcycle.com.
 
Mine had a 16mm, 15 is available and will give better leverage.
The twin discs were an option, I had the same setup. But!
Those ATE pistons are plated steel and are going to be pitted, the seals are also costly.
82ish on used a brembo which has anodized aluminum pistons, that'd be the simplest swap/upgrade and probably the most economical.

I adapted some Japanese discs and calipers but that is not a simple upgrade and is only economical if you make your own parts.

Thanks for the information. I would rather go a different direction than the ATE, good to know Brembo will work.
 
Changed my R65 ATE calipers to Brembo F08 which replaced the ATE with no issue and gives better braking. $113 from mgcycle.com.

This is great news! So the F08 will bolt on straightnaway without shims, etc.? Did you also purchase a new m/c as well?

Tom
 
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