I am a new owner of an old airhead and am in the process of refreshing a few items. My bike is a 1982 r100rt with a cracked rear rotor. Bmw fiche shows the rotor as 34-11-1-236-566. Looking at the disk itself I see a cast number of 123 1 343. Should the cast number agree with the fiche number? Also, are the front and rear rotors interchangeable? Thanks in advance for the help
The part number on the fiche is not the same as casting numbers on parts.
As for interchangeability, compare the part numbers on the fiche and make a close visual comparison. My guess would be not interchangeable but I have no specific knowledge on this topic.
former Airmarshal, IL.
I do believe the front left rotor and the rear are the same. (The only difference in the 2 fronts is the drilling.) The part number fiche can tell you. Check them out on the Max BMW web site and others.
In your shoes I'd look at buying 2 replacement EBC brand full-floating rotors for the front, then transfer one of the older fronts to the rear. The full-floating action allows the rotor to center up quicker and vastly improves braking ability over the stock unit.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
Thanks wobbly. I never fullly understood the "floating disk" concept until you explained how they center up.
Whereas the BMW discs are riveted solidly to their hub, the EBC discs (like so many newer discs) are attached to the hub with metallic spools which allow some L/R movement. When the brakes are applied, the brake pucks as well as the disc are thereby able to move. The result is more even brake puck wear and better braking effect.
The difference is quite remarkable, even for a casual street rider.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
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