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Help identifying forks

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Jerry Bushue
(@jabushuegmail-com)
Posts: 3
Active Member
Topic starter
 

All, I could use some help identifying some parts on a current project.   I have a titled 1985 R80RT frame (purchased at auction) that I’m trying to clobber together enough parts to create a cafe bike.  Can someone help me identify these forks so that I can source a front brake caliper which is missing from the bike?  Fork sliders are marked with Part Numbers “1 452 315” (assume full PN is 31 42 1 452 315) and “1 452 316”.  Single rotor is marked “1 454 179” (assume full PN is 34 11 1 454 179).    I looked for these part numbers on Max BMW parts fisch without luck.  

 
Posted : 07/06/2025 13:44
Larry A. Chabira
(@2659)
Posts: 17
Active Member
 

those are standard Mono shock forks, if you have a non drilled disc, thats from a R65, drilled dual disc set ups are on R80 , R80RT,  R100RS and R100RT . 1985 to 1995,  specific BREMBO calipers are used. they must be the 85 to 95 type.   don't assume numbers you see on parts are actually the part numbers, many times they are just CASTING numbers.  

 
Posted : 07/06/2025 14:12
Jerry Bushue
(@jabushuegmail-com)
Posts: 3
Active Member
Topic starter
 

@2659 Thank you.  If I understand correctly, I need to look for a caliper off a R65?  Does it matter which year?  Trying to keep the cost down as much as possible.  Would like to put this back on the road for someone to enjoy rather than scrapping a perfectly good frame.

 
Posted : 07/06/2025 14:24
Richard W
(@wobbly)
Posts: 2662
Member
 

Agreed.

Furthermore, on the hydraulic side.... BMW's plumbing layout was expensive and tended to not be self-bleeding. (That is, by design it needlessly trapped air inside the system.) I'd buy a single, all-flexible hose to run from the M/C on the bars, all the way down to the RH caliper. (As opposed to BMW's standard plumbing to the LH side.) Then use the standard Airhead non-flexing U-tube to jump between the 2 calipers. 

Such a unique flexible brake hose can be ordered from Fragola Performance Systems (click name for link). Also note that 1. all Airhead brake fittings are M10 x 1.0 thread, and 2. that Fragola, JEGS, & Summit all consider the 3/8" banjo the same as 10mm.

Here's my Fragola-plumbed brake hose. My only mistake was taking it to the LH caliper, instead of the simpler RH caliper route. 

This post was modified 3 weeks ago 2 times by Richard W

Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.

 
Posted : 07/07/2025 07:37

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