2002 R1150RT Front "Brake" Vibration

[rxcrider]

Profit disclaimer: I am getting paid to work on the bike I am about to discuss. I know that bugs some of you, so I'm putting out there up front. The owner couldn't stomach the dealer or shop price for the work it needed so he put an ad on craigslist looking for someone to work on his Beemer. At this point, I wish I'd never answered that ad.

First off, I never rode the bike before wrenching on it so how it performed prior to me touching it a bit in question. I performed the following work prior to riding it for the first time:
- New clutch (complete aside from flywheel)
- new clutch slave cylinder (original was scored inside so I couldn't rebuild it and I added a weep hole to the pocket)
- new rear input shaft seal
- oil change
- gear lube change (gearbox & FD)
- Valve Lash adjusted (& rocker end play)
- Throttle synch
- serviced K&N air filter
- spark plugs (Autolite XP3922)
- bled a quart of fluid through the clutch system before it came completely clear.
- electrical work (USB charger and PDM60 added along with general cleanup of stereo spaghetti)
- LH cam chain tensioner update
- JL paralever bushings
- spline lube
- new front tire (Metzeler Z6)
- bled brakes (old fluid wasn't too dark, just overfilled on the front servo reservoir and an air bubble in the rear conrtrol circuit)
- New front brake rotors (ABE from Beemer Boneyard / Spiegler)
- New front brake pads (CL A3+ from Beemer Boneyard / Spiegler) wothj Permatex brake quiet spray on the backs

So last night, I finished the throttle synch and put the bodywork back on as my final two tasks before taking it out for a test ride. For the first 20 miles, with gentle braking, I didn't notice any issues. As I started dialing up the braking force, I experienced vibration during medium to hard braking. It is at its worst around 30 MPH as you are slowing down through that speed. It is definitely tied to front braking and isn't ABS related. I have verified this by shutting off the ignition prior to applying the brake in order to un-link the brakes and eliminate the servo motor and ABS from the equation. Also of interest is that there is no feedback / pulsing through the brake lever, even with the ignition off. So far, I have:
- gone back through every bolt I touched on the front end to verify torque and found no issues
- double checked the front wheel for play and found none.
- Tried the OE rotor hardware as well as the parts supplied with the ABE kit - no change
- partially applied the front brake and rotated the wheel by hand - drag felt consistant
- looked over the wheel and tire for a flaws and didn't see any.
- found a tiny bit of play (with a pry bar, not by hand) in the lower Telelver ball joint along with a torn boot.

At this point, with about 50 miles on it, I feel like the vibration might be decreasing, but it might just be me getting used to it instead.

The next things I'm thinking of doing are kissing the front rotors with some 120 grit, just in case there is a hard spot I don't see or feel and cleaning the brake quiet spray off the back of the pads although I've only had it do good things for me in the past. Beyond that, I'm really feeling like it may be a suspension issue, but it supposedly wan't doing it before I worked on it and I haven't touched the front suspension, so... Have any of you ridden a bike with a worn lower ball joint; will it so this?

If you have thoughts you feel like sharing, I'm all ears. If you just feel like telling me I jumped into someone elses basket case, I should have figured that out 97 hours ago and ran away then. This bike has fought me every step of the way and it doesn't seem ready to concede yet.

 

[dieselyoda]

Just a couple thoughts I'm sure you thought of already;

One or more rotor buttons seized?

Caliper anchors free?

Front tire rotates smoothly right after applying the brakes? Possible caliper piston hanging up?

When you put the front axle in at the tire change, went in smooth? Nut not over-torqued?

Beyond that, I might start at looking at bent rim, possible defective tire, maybe even the ball joint or the steer head bearings giving you grief but I would like to think you covered the simple things first.

 

[BC1100S]

It is definitely tied to front braking and isn't ABS related.

Here's a Wild Ass Guess for you....

Have you checked the trueness of the front rotors using a dial gauge setup? As well, while the disc itself may be true, the surfaces might not be. Check for high and low points on the surface on both sides of both discs.

And how dare you do something for profit . Kidding....

 

[mneblett]

Also of interest is that there is no feedback / pulsing through the brake lever, even with the ignition off.

Not surprising -- the front wheel circuit is hydraulically isolated from the front brake lever circuit (except for a small piston in the ABS unit that allows the front brake lever to apply a small amount of pressure onto the front wheel circuit fluid when the ABS unit is unpowered).

Others have pointed to the obvious things with the brakes (and you sound like you know your way around a wrench).

I know you said you didn't feel any play in the front wheel, but have you removed the wheel and verified the wheel bearings turn smoothly with moderate pressure applied?

The play in the lower ball joint is also of interest. Also, what about the steering head top nut, the fork leg top nuts? Any play in the bearing under the steering head?

 

[pglaves]

I would carefully examine the interface where the disk (carrier) mates with the wheel. You also might try rotating the disk bolt-up to the wheel by 180 degrees.

 

[rxcrider]

2002 R1150RT Front "Brake" Vibration

Only place I found any play was the bottom ball joint. I didn't get anything to move up top. It only has 40k on the clock, but they haven't been the most loving miles. I only found 0.003" or runout in the rotors, but I'm suspicious of high spots around the cross drilled holes. As I sanded the rotors, I was getting more bite around some of the holes like they were a bit proud. I gave the rotors and pads a quick sanding job, hosed everything with brake parts cleaner and put it back together again. I gave it its first bed in run again and then let it cool before the owner took it for the weekend. Hopefully it will smooth out for him. If not, I'm holding onto his old rotors and pads to put back on and verify that the new brakes are really the issue.


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[rxcrider]

Wheel bearings felt good to me and the guy who mounted the new tire.


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