Front wheel Vibrating during braking

[katsim]

Hello to all,
Recently I bought a second hand adv wheels with fitted disks for my BMW r1150 gs with new tr91 tyres!
As soon as I hit the road I noticed a vibration during braking and only in 50km/h coming from the wheel!
I was told that the problem occur since I didn't fit new brake pads for the used disks...
Now after 600km the problem still exists! It seems from the photos that the pads don't use all the surface of the disk!!
Any ideas please??

 

[Ian J Hartley]

I don't know whether this is relevant or not, because you haven't given enough information, particularly about the year of your R1150GS, but those wheels look like they are post sep 2002 when evo brakes were introduced.

There were a lot of design changes with evo brakes, wheel hubs, discs, abs ring, brake calipers, and I think even the forks are different.

Just hope you haven't created some incompatibility for yourself.

 

[katsim]

Mine is 10/2001
It didn't cross my mind that would not be compatible with mine!
Except from the abs ring that I will remove, I don't see any other change! Thanks for the advice though!!
I will try to exchange the disks from my old wheels with the new ones to see if anything change!

 

[Ian J Hartley]

I was just making the observation.

I don't know whether pre and post EVO brakes wheels are interchangeable, for that matter whether any of the brake components are interchangeable.

I understand that the different ABS rings do cause problems with the ABS sensing a fault, but it sounds like you don't have ABS fitted on your bike, so not an issue.

The ABS ring on post sep/2002 fits under the disc. Where as previous models the ABS ring sat on it's own mountings.

 

[warmshed]

Difficult to see from the photo but one possibility would be discs that are not true, you can spin the wheel and watch the disc through the pad gap and you should be able to see any warp on the discs.

The fact that it seems you only have part pad contact on the disc is not good, this will reduce the maximum braking efficiency, as they have now been used on the later discs you will not have full contact if you use your old discs.

The other fact is the speed you notice the vibration, this could be tyre induced.

 

[DrAlf]

Judging by the rust in the those photos I'd say grooved or warped discs. I'd definitely be changing the discs over to the originals and take it from there. Tip: the bobbin threads are long and held with loctite - crack the loctite by hand, unwind then use a cordless drill to undo - otherwise you'll be there for days. + it feels like you're a member of an F1 pit crew.

 

[Ian J Hartley]

I don't know whether this technical write up is of any use to you. It mainly deals with fitting cast wheels, but does cover the variations between the BMW wheels and brakes.

http://www.largiader.com/parts/wheels.html.



From what he says the brake rotors (discs) are interchangeable between pre and post evo brakes on the wire spoked wheels.

 

[DrFarkoff]

USE HEAT to soften the threadlock or you "may" damage the threads!

Heat gun or butane torch or even boiling water (as a last resort) trickled over a bolt at a time will soften the threadlock

BMW use a particularly nasty pink stuff that is on new bolts when you buy them, clean the originals and the holes and you can re use them with the correct threadlock and torque setting

Judging by the rust in the those photos I'd say grooved or warped discs. I'd definitely be changing the discs over to the originals and take it from there. Tip: the bobbin threads are long and held with loctite - crack the loctite by hand, unwind then use a cordless drill to undo - otherwise you'll be there for days. + it feels like you're a member of an F1 pit crew.

 

[katsim]

Thank you all for your help,
I will try to exchange the discs during the weekend to see if anythings changes!
Btw do you know the torque setting?

 

[Ian J Hartley]

Thank you all for your help,
I will try to exchange the discs during the weekend to see if anythings changes!
Btw do you know the torque setting?

Front Brake disc to wheel

24 Nm with loctite 243.

Rear brake disc to wheel

21 Nm with loctite 243

 

[MattW]

As Ian J says - be sure to use loctite - the torque settings take account of the lubricating properties of the thread locker and they will be under torqued without.

 

[MikeO]

There are two different types of front disk - the 'skinny' disks fitted to bikes with Servo ABS and Tokico (sp?) calipers and the standard ones fitted to all the others, generally fitted with Brembo calipers (and branded BMW).

You can't fit a wheel with one type of disk to a bike with the other type of caliper. If this is the problem, then comparison of discs fitted to the two wheels should point it out...

Mike

 

[Firefox]

simple solution??

It is just possible there may be a simple solution and it's certainly worth a try.

I had a pulsing vibration from the brakes on an 1150gs. I checked the discs for warping and couldn't find any. For various reasons, I had the calipers rebuilt with new seals and pistons and it was a significant improvement but there was still a slight problem.

The Clymer manual recommends that if you change brands of pad, you should clean the disc with emery paper!! So I did and it seems to have resolved the problem.

So my advice is: check the discs for warping and if there is none, give them a damn good clean with emery or even a wire brush. Its a cheap option and might just cure the problem.

 

[Steptoe]

There are two different types of front disk - the 'skinny' disks fitted to bikes with Servo ABS and Tokico (sp?) calipers and the standard ones fitted to all the others, generally fitted with Brembo calipers (and branded BMW).

You can't fit a wheel with one type of disk to a bike with the other type of caliper. If this is the problem, then comparison of discs fitted to the two wheels should point it out...

Mike

Correctamundo.

The O/P has the bigger discs, which require ferodo 2125 pads. Same discs as the 1200 used up until 2008, and the same pads all 1200 bikes use until the LC arrived .
The "skinner" discs use 2124 pads, they look identical but are a couple of mm difference in size and aren't as deep.

 

[katsim]

You were right!
I changed the brake discs and the problem got solved!
I also did a good cleaning to the calibers and the braking feels much better!

Thank you all for the help!