2001 Rev-3. Purchased used but in incredibly good condition; lots of parts are still factory (i.e. front tire).
Recently I noticed some slop in the front when I squeeze the front brake. At first I thought it was bushings in the forks but then a buddy helped feel around while I activated the brake and pushed up and down on the suspension. Turns out there's rotational slop in the front rotor that transfers to a 'clunk' in the suspension.
My question is, how much of this rotational slop is within acceptable tolerance?
or is it worn rotor bolts?

Floating disk. There are finger washers that keep the rotor under slight spring pressure to keep it from rattling but the rotor moves. Don't make the mistake of trying to tighen the mounting bolts to stop it moving as you'll bung up the hub.

Ok,
So a little slop fore/aft is normal? If so, based on simple wear principles, any two parts that slip and make contact with each other repeatedly will wear under load; so where does the wear occur? Rotor or the bolts?
or is it not enough to worry about?
Thanks for the advice. For a while I thought it was the suspension and was kinda bummed because that's a much bigger issue than floating rotor slop.

Don't worry, is completely normal.

I had this exact issue on a 2012 evo. The rotor is fitted with alloy top hat bushes. They wear over time and cause the effect you describe. They are very cheap to replace and could sort out the excess movement. The rotor should "float" from side to side but shouldn't have much play in the direction of rotation.when you apply the break it should come on smoothly and not with a delay and then a clunk.

Cheers.

Edited August 14, 201412 yr by hoodie2

Just FYI a floating disc comes that way new. I have never replaced the bushings or seen someone else replace them.

Ps, The 2001 was one of the best looking beta`s ever. I had three that year. Have fun with it!

Edited August 15, 201412 yr by lineaway

Yeah a little movement is normal but mine got to the point where if I was turning into a steep decent and applied the front brake I'd get a breif delay then a clunk when the play was taken up. This was bad enough to throw your balance off. Replacing the bushes solved the problem and restored smooth progressive braking. Might be unusual but it can happen. The bushes are also so cheap and the job's easy so it's worth trying if your bike is older and other parts are wearing. When I bought mine it had been well used and most of the bearings needed replacing. I had play in the steering head, swinging arm, shock bushes and linkage......it's an age and stage thing.

Yeah there can be wear. I just thought it important to warn quickly so he doesn't put a wrench to the bolts and crack his hub.

2001 Rev-3. Purchased used but in incredibly good condition; lots of parts are still factory (i.e. front tire).

Recently I noticed some slop in the front when I squeeze the front brake. At first I thought it was bushings in the forks but then a buddy helped feel around while I activated the brake and pushed up and down on the suspension. Turns out there's rotational slop in the front rotor that transfers to a 'clunk' in the suspension.

My question is, how much of this rotational slop is within acceptable tolerance?

or is it worn rotor bolts?

Ok,

So a little slop fore/aft is normal? If so, based on simple wear principles, any two parts that slip and make contact with each other repeatedly will wear under load; so where does the wear occur? Rotor or the bolts?

or is it not enough to worry about?

Thanks for the advice. For a while I thought it was the suspension and was kinda bummed because that's a much bigger issue than floating rotor slop.

If it's still on it's first front tyre, I find it hard to believe the bushes from the brake rotor are worn that bad.

Just screw one of (could be difficult as there could be loctite on the bolts) to inspect and put your mind at ease.

The disc material is pretty hard. It is much more likely that the bolts or bushings would wear first. As Guys said, take one or two of the bolts out and look at the condition of all the pieces. The parts and holes should all be round. If they are worn to an oval shape they should be replaced. AS others have said: some movement is normal, if it is bad enough to affect your riding, fix it.

Uh, why could you not turn them 90 degrees to find out if it made a difference in the wear pattern, just saying?

Uh, why could you not turn them 90 degrees to find out if it made a difference in the wear pattern, just saying?

If the holes have gone oval in the bushes or bolts, you certainly could turn them 90 degrees. Hard to do that to the holes in the disk or the hub.

Bolts and bushes are pretty cheap. Also if the bolts are badly worn, they are also weakened. If I found a problem I might try turning them 90 degrees for testing (or if the event was tomorrow) and order up new parts to replace at a more convenient time.

As someone else pointed out here, with the front tire being new it doesn't make sense that the disk bushings are worn.

I'm thinking you buddy felt the floating front disk move and attributed all of the clunk to the disk. My bet is that your steering stem needs tightening.

Put the bike on a stand or crate with the front wheel in the air. Grab on to the very bottom of the front forks. Pull back and forth. If you feel any movement then this is the culprit. You'll need to remove the top triple clamp to tighten this up.