New brake disks and play

[georgesgiralt]

Hello !
I finally was able to wear the infamous iron front brake discs and stay alive so I put new BMW sourced (NOS) discs. And brake pads.
Using shims between the disk and the wheel I was able to center the disc in the caliper opening on both sides. Hurray !
But I'm very surprised to see that the rivets holding the disc to the hub are very very close to the fork leg on the left side. And they are so close that at one time they have touched the fork because there is a trace on the leg... As it is not as large than the BMW rivet, I bet it was the iron disc screws that caused this.
I'm very surprised because the gap on the left side is bigger.. And the top hats on the bearings are the correct ones. So the wheel should be perfectly centered on the fork.
What do you think about that ?
I would gladly read your advices and thinking.
TIA !

[Bob_Roller]

The left caliper  should center over the disc without any shims, the right caliper uses flanged spacers to center the caliper over the disc .

Sounds like the shim under the disc, has moved the disc too close to the lower fork stanchion .

This is the first time I've heard of shimming the disc on an R65 at least .

[Sejati]

Does your front wheel able to spin freely and lightly by hand ? Mine can’t spin freely and hard by hand.

[Barry]

Does your front wheel able to spin freely and lightly by hand ? Mine can’t spin freely and hard by hand.

If the brakes are dragging then the caliper pistons need lubricating with brake grease i.e. red rubber grease or silicon based brake grease not copper grease or any other grease with a mineral oil base.  The piston seal should pull the piston back a fraction when the brake lever is released but if the pistons are sticking that won't happen. It's a common problem but it's perfectly possible to get the wheel spinning freely when the pistons are clean and lubricated.

[Tony Smith]

I think that the shimming arrangements for the calipers is another case of BMW solving a non-problem.

The centreing being mildly out has never cause any odd wear issues on the wife's bike, later BMW's such as the oil heads have no such arrangement and the ability to accurately cast and machine components has not changed significantly.

I have never seen a shim fitted under a disc, as opposed to the shim that is supposed to be fitted between the discs and the bolting that holds them to the hub. None of our bikes have this shim either, just washers.

[Sejati]

If the brakes are dragging then the caliper pistons need lubricating with brake grease i.e. red rubber grease or silicon based brake grease not copper grease or any other grease with a mineral oil base.

His grease is applied to the outer piston cylinder right? So with brake pads removed, and brake applied, we can apply it to the exposed piston outer surface ?

[Barry]

His grease is applied to the outer piston cylinder right? So with brake pads removed, and brake applied, we can apply it to the exposed piston outer surface ?

That's right, If the pistons are stiff to move then lubricate the outside of the piston behind the dust seal. Depending how bad they are you might get away with removing the dust seal and pumping the pistons out a little before applying the grease.  The proper way is to apply grease during assembly after overhauling the caliper.