k1100 rear hub cap -- Compatible with K100?

[rbm]

Hi, 

I think I made a mistake by purchasing a K1100 rear hub cap for my K100. I'm using a three-spoke K100/K75 3.00" x 17" rear wheel (36312311887) which confused me in my purchase (thought they were K1100 wheel but apparently it is 4.50" x 18").  The hub cap fits the opening including the key slot but the spring clip on the back does not seem to engage anything on the wheel itself.  The hub cap does not remain secured to the wheel.  Can this hub cap be made to work with my wheel or am I SOL? Thanks.

[Rick G]

Rob the K1100 have a fifth bolt in the centre which held a small cup shaped thingy that the spring clip fastened into.

[rbm]

Thanks, Rick, for the reply.  Your information sent me on an investigation.  The K1002V differential I've got has a rubber plug covering an M10 threaded hole in the center of the crown gear.  This has every indication that a threaded rod/bolt should be used here.  I researched some more over on the RealOEM parts diagrams; however, I didn't manage to find any part number for a bolt that would be used in in that location to secure the hub cap.

I'm hoping that the part used on the K1100 will fit the K100 and I just purchase and install.  Does anyone have the part number for that "cup bolt"?  TIA.

[Inge K.]

All five bolts is similar (M12x60x1,5), the center bolt got a cup instead of the conical ring.
The hub cap fits in this cup.................Part # 36 31 2 310 272.

And as you say that the K100 FD got a M10 center thread, I think that you could use a
M10 bolt and washer to mount this cup.

Inge K.

[rbm]

All five bolts is similar (M12x60x1,5), the center bolt got a cup instead of the conical ring.
The hub cap fits in this cup.................Part # 36 31 2 310 272.

Thanks for the part number.  It was not obvious from RealOEM parts diagram that was the cup.  I was wrong about the bolt size; the threaded hole is M12 as I tested the fit of a M12x60 wheel bolt and it fit.  My mistake with the calipers.