Do I need a new wheel?

[ElevenFifty]

04 1150 RT 136K miles

 

Problem ... slight persistent judder in front brakes when braking agressively.

 

Dial indicator reading on the disk surface just above the screw that holds the disk to the wheel AND on the inside working edge of the disk are consistent

 

1 = 0.000

2 = 0.000

3 = 0.000

4 = 0.003

5 = 0.005

 

Questions:

Is 5 thousands out enough to cause judder or should I look elsewhere?

Can the wheel be fixed?

 

I don't notice any increased vibration when at speed so IF it is the wheel the only noticeable symptom (to me at least) is the judder. Is it possible to just mill down (file) the two high bolt receivers to true up the disks? (Comments about cheap BMW owners are appropriate)

 

I realize that I need to take the disk off and measure again directly on the wheel but believe that I will find the same readings. The judder is enough to seriously impact both pleasure and safety.

 

Thanks

 

DH

[realshelby]

I don't think you need to be worrying about the wheel. The bobbins would allow for any slight variation in the wheel. I suspect your rotors are out of spec or have an issue with the surface causing the pads to grip better on portions of the pad under hard braking.

[dirtrider]

Afternoon DH

 

.005" RO is WAY too much if it happens in 10° of wheel rotation. It isn't enough to worry about if it happens over 180° of rotation.

 

With semi floating rotors & 4 piston calipers brake disk run-out is very seldom the cause of brake judder.

 

More importantly would be rotor thickness variation especially if it changes thickness in a very short section.

 

Most (pretty well almost all) brake judder is due to either rotor staining as that causes a big difference in rotor friction at the stained area. Or due to uneven brake pad disposition on the rotor surface. That can cause either rotor thickness variation or friction differences. Even a pad disposition on the rotor of as little as .0005" can cause brake judder in some instances.

 

Is your brake lever pulsating in tune to the judder? If so then look for rotor thickness variation issues.

 

If you get the judder but mostly a quiet hand lever then look for rotor staining or uneven pad build up.

 

[ElevenFifty]

Thanks Dirtrider ... I have replaced disks (relief but it doesn't last) and cleaned disks with some temporary relief. I have begun to wonder if the pad material may be the issue. I seem to get LOTS of brake dust on the front wheel. I have used Carbone Lorraine and EBC but have not used stock BMW sintered type pads.

 

The only other 'anomoly' that I can identify is that the spacing of the ABS sensor is lots more than .2mm ... close to 1 mm. ABS seems to function normally but since their is NO way to close that gap EXCEPT to shim the sensor wheel (and, consequently the rotor) I wonder if that might be the issue.

 

The parts fiche shows a spacer 34 11 7 670 217 that is referenced as a 'stop disk' that looks to be a spacer between the wheel and the ABS sensor ring (the fiche also shows the sensor ring mounted outboard of the rotor which is obviously wrong.) I do not have any of those 'stop disks' but wonder if that might be part of the problem.

 

If not, I intend to aggressively clean the rotor and replace the pads. What would you do?

 

Thanks

 

D

[dirtrider]

 

If not, I intend to aggressively clean the rotor and replace the pads. What would you do?

 

 

Afternoon DH

 

I seriously doubt the sensor gap has anything to do with your problem.

 

More than likely either rotor staining from wet bake pads sitting on the rotors for a few days (never wash a bike then park it for a long time without riding it far enough to dry the brake pads).

 

Or, brake pad transfer to the rotor while sitting stopped after a hard stop (like exiting the freeway then sitting with the brakes clamped onto the hot rotors). Some of the more aggressive brake pads a prone to doing this.

 

If a pad transfer or staining problem sometimes just cleaning or lightly sanding won't be enough. I have seen them so bad I have had to actually remove the rotors & blast them in my glass bead machine ( I run very aggressive pads one of my Ducati's & that bike has a bad pad transfer problem after making a rear wheel lifting stop from 150 mph.

 

What would I do?-- probably REALLY clean the rotors, sand the heck out of them, scotch pad the heck out of them. Then try a different brake pad from a different manufacturer.

 

If still bad, probably remove the rotors, mask the non- braking surface off then lightly glass bead them using well worn glass beads.

 

 

[g_frey]

one of the first signs I noticed about fork seal problems was a slight shuddering noise in the front. The fork oil had contaminated the disk and pads.