Brake pulsing diagnosis - wheel issue?

[metropolis2k]

So I've been trying to solve the pulsing issue on my 1150 and am struggling to work out exactly what the issue is.

I've replaced the discs, the mounting hardware (spring washers and bobbins) and added the 1mm washers behind the disc as the mounting points on the wheel were looking a bit worn.

I'm still getting pulsing through the lever so have been doing more investigating. I've found the point at which the pulsing happens but there's nothing obvious about the discs not being mounted straight which I was expecting to find.

I tested it one side at a time and found that bizarelly the pulsing happens on both sides at the same point (albeit slightly more obvious on one side). Because it's the same each side it makes me think it's not a mounting point issue but perhaps something about the hub or axle. I don't know anyone with another 1150 to start switching parts to test unfortunately.

Anyone got any ideas / experience with this?

 

[ebbo]

Never had a car that could have so many braking problems as my BMW's have

Try this, remove the calipers, mount a clock gauge on the fork leg and check the runout, my old airhead had the mounting bolts shimmed with foil to correct them, once that was done I never had another problem with them

I should add, discs running out of true will wear unevenly, as will discs with one loose mounting bolt... DAMHIK

 

[marfyboy]

check the wheel's running true?

 

[Timolgra]

Adding the 1mm washers won't necessarily cure anything since the lugs won't be evenly worn.
That's where your problem almost certainly lies.

Careful use of a file can sort it.

 

[Greg Masters]

Adding the 1mm washers won't necessarily cure anything since the lugs won't be evenly worn.
That's where your problem almost certainly lies. Carful use of a file can sort it.

+1

Use a dial gauge to check the disc is true.

 

[MikeO]

I eventually had both my wheels replaced by BMW after continual disk 'warpage' from new. Both hubs were warped - never had a problem since (2002 1150 Adv). I'd bet your problem is in the hub, not the disc...

 

[Myke Rocks]

Take wheel to someone who knows how to use a lathe.

I eventually had both my wheels replaced by BMW after continual disk 'warpage' from new. Both hubs were warped - never had a problem since (2002 1150 Adv). I'd bet your problem is in the hub, not the disc...

Turn a centre in the lathe chuck.
With disks off,
Mount wheel between this centre and the headstock centre.
Spin wheel and check truth of disk mounting points.
If out, use something to make wheel rotate with lathe chuck and face them true on each side.
Will take around 30 mins to do everything.
You may have to use a surface grinder to grind washers to bring the disks positions back to where they were, but that is easy.
Myke

 

[metropolis2k]

The washers were to prevent further wear to the lugs as they were a bit worn.

I suspected it would be uneven wear in the lugs and that's why I spent this morning finding out which side had the issue and where. I'm very suspicious both sides have the issue at the same point.

So does anyone know who might be able to sort this for me? Steptoe does my servicing but didn't think he'd be able to help with this one.

 

[Grizzly]

Same Problem

Fitted new discs in the spring to my 2001 1150GS - non abs. Since then I've had the same problem and the MOT tester noticed it a couple of weeks ago and listed it as an advisory!
The original discs had lasted from new ie from 0 miles to 160k and were removed and refitted several times during that time to fit stainless screws plus washers, fit new bobbins etc with no problems and were still working perfectly when removed in March - just worn after 160k.
I got the new discs from Motobins and they are made by Grimeca - I already had a Grimeca on the rear.
Since then then the pulsing has been there in some form or another. It is barely detectable during heavy braking from speed or down alpine passes etc - but sometimes fairly noticeable during gentle braking coming to a junction etc.
It also seems to vary! I usually run BMW/Brembo original pads but when I fitted the new discs I fitted DP HH pads. I've since changed back to originals to see if that helped but although it maybe improved It's still pulsing.
All measurements/checks have shown up nothing so far - next (expensive) test would be to try BMW discs again!
I'm going to do more tests etc as we head into winter! - I'm away in Europe at the moment on another bike. The GS now has 170k on it and ran superbly on two European trips this year - apart from this pulsing!!

Cheers........... Grizzly