2004 R1200GS Front Brake Help NEEDED!!

Afternoon all!

I'll try to write too much but I want to get the whole picture painted as best as I can so I can try and pin point the fault. But in short I have a serious vibration coming from the handle bars when I squeeze the front brake lever anymore than just a few mm.

I had my wheels powder coated a few months back and I'm 99.9% sure the fault wasn't there before this, if it was it would have been VERY minor, so much so that I couldn't notice it. So upon rebuilding my wheels and having them back on the bike I would get a bad vibration coming from the bars when using the front brake only, it would get worse the harder you brake and worse still if carrying a pillion. I took the front wheel off again and noticed I'd put the discs on the wrong way, they have a small lip on both inner edges due to wearing slightly more, so the pads and the discs weren't fitted how they were before paint. I put them back in the correct positions and for a few rides that seemed to do the trick pretty much. There was still a slight vibration but nothing to write home about.

A few rides more it seemed to be creeping back. A few days ago I took a 800mile trip solo, where you really only have the bike and the road to think about, this is where I really noticed how bad it is now. So if using the front brake for anything more that crawling up to traffic lights to a stop it causes a massive vibration on the handle bars. It's hard to tell if it's an up and down motion or side to side, the bike is still controllable, it's not tugging at the bars or anything like that, it's just a massive vibration, similar to what a jack hammer would feel like I imagine. It's always the same amount and that doesn't change and again, it's only from using the front brake.

There's one thing that happened on the trip that makes me think it's a ABS or booster fault opposed to a disc/pad problem. After stopping for fuel the brake failure light and the red warning tringle stayed illuminated, during this period the brake seemed like they weren't quite working as good as normal, maybe, but that may have been in my head. However, no vibration at all, nothing. I was only riding through a town so I wasn't going at any real speed and I turned it off and back on again at some traffic lights. The warning lights went out as normal and then the vibration was back. The scenario with the lights never happened again.

I also tried turning the ABS off briefly to see if that would solve it, brake failure light stayed illuminated but the problem still persisted.

Sorry to be so wordy but i wanted to get as much information out as possible in the hope that someone else has had this issue.

Cheers, Dan

I'd guess that having the wheels powder coated has made the discs run out of true due to an uneven finish on the wheel hub. The same affect as having warped discs.

Possibly the abs fault you mention coinciding with problem disappearing was due to the loss of the servo brakes, and the aptally named "residual" braking, where the brakes barely have the power to stop the bike.
This would cause any disc run out to be barely felt due to massivly reduced power of the brakes.

Now I think about it that does make sense, anything that has a power assist will accentuate any issue when it is fuctioning correctly, so perhaps that brief moment the the vibration stopped was the booster not working correctly. And as I was driving through a town at no more than 30mph I wouldn't have felt the brakes were next to useless without the booster. As I said in the original post I thought they make have had less stopping power but at that speed it was really hard to tell.

When swapping back the discs to the correct orientation I did sand the mount points down slightly on the off chance that was contributing to the issue.

I think it'll be wise for me to buy a DTI gauge and see what the run out is as a first point of call. I'll have a butchers around to see if I can find the run out specification.

dpalmer_2991 said:

Now I think about it that does make sense

Click to expand...

Steptoe always makes sense

No mention of having the wheels rebalanced when tyres fitted?

No you're right, I forgot to mention the front wheel has not been balanced.

I know what an unbalanced wheel feels like though and it's not what I'm experiencing. The vibrations under braking pulse very fast and very aggressive. Plus if it was just a balancing issue it wouldn't really change much like I mentioned in my first post, it would just stay pretty consistent at a certain speed and only change slightly as the tyre wears.

Thanks though!!

I have read in some places about the non floating and floating disc causing brake 'judder' so I was wondering if it could be that, but then I think it's got 70,000 miles on it so I can't see that just springing up now.

I do have a DTI gauge now so I'm going to check run out on Wednesday as well as possibly stripping the front wheel down again, make sure I've got the washers and the ABS ring all in the correct order. More than likely a lot of head scratching too!

what thickness are the discs?

did you clean up surfaces disc meets hub after painting?

do you get pulsing at lever on very slight application of front brake? how about with a little more pressure? (both of these much lighter than proper braking)

If you put bike on centrestand, jack up front of bash plate so front wheel in air, then spin wheel does it spin freely? is sound of pads against disc consistent or does sound vary as wheel turns?

Sounds like your floating discs aren't floating. Or else you have a badly warped disc. Alternatively the surface that the discs bolts are attached to has been damaged.

I had the same problem on another bike which had freshly powder coated wheels - caused the disk to run out of true.

Okay I've got the bike in bits and this is what I've found thus far;

Both discs are slight over 5mm in thickness
Runout on the right side is 0.6mm
Runout on the left side(ABS) is 0.35mm
The inner pads on both sides are worn probably half as much as their outer pads as well

The wheel doesn't spin that freely when the calipers attatched, maybe 2 turns after a good spin so there is a slight brake bind perhaps, but I wouldn't say it's worse than any other bike I've owned from memory, It spins very freely with the calipers removed.

I did clean the mount service up before fitting with sand paper, but I'm going to do that again before refitting today.

I don't really get pulsing in the lever I don't think, it's all on the bars mainly. If I use VERY light pressure on the lever I don't get any vibration, much more that that then I will, all the way through to heavy braking.

I can't see how the discs could have warped so quickly if they have, I don't ride this bike hard enough to get that much heat into the discs to cause warping.



If someone can tell me how to upload pictures I can pop some up of the condition of everything.

Thanks again everyone for your help!

Runout should be less than 0.15mm. Seems to be your problem!

fwiw you should check condition of wheel bearings too. esp nearside

Every time I have ridden a bike with warped discs i feel it first with pulsing at the lever under soft appliation. others can correct me

What condition are calipers in? pad wear pattern you describe suggests something going on there. do all pistons move freely?

Okay, update...

Wheel bearings are perfectly fine as they're new and turn nice a smooth, no play. Calipers seem to be in good condition, I can push all the pistons back by hand with a bit of force.

After giving everything a bit of a sand (discs, pads, disc mount points) and a clean, the problem seems much better so far! I popped it all back together and took it up and down my street and the vibration is still there, but much much less violent and it's only barely noticeable now. So I'm starting to think it is the powder coating, perhaps the discs are 'sinking' into the coating over time as powder coating is quite a soft finish and giving the effect of a warped disc?

As for runout, I'd take it with a pinch of salt to be honest, as you can only really measure the very tip of the disc, maybe the last 3mm of the edge due to all the drillings in the disc. So it's likely to have slight build up there ect as the pads don't really contact that tiny part of the disc.

I'm yet to take it for a proper run as I'm now in the process of fixing the drivers heated grip!


Can anyone give me some tips to upload pictures?

Thanks again!

There shouldn’t be any powder coating between the disk and the wheel. It should be metal to metal contact so I’m not sure how the disk can sink into the powder coating.
Hopefully your powder coater masked these off, along with the bearing locations.

E.g.

imgbb

ShakeyBMW said:

There shouldn’t be any powder coating between the disk and the wheel. It should be metal to metal contact so I’m not sure how the disk can sink into the powder coating.
Hopefully your powder coater masked these off, along with the bearing locations.

E.g.

Click to expand...

As i said in post 2 of the thread, but everyones been dicking about looking for other problems........ As you've pointed out, and kindly posted a picture, they shouldn't be powder coated.
Clean up the hubs where the disc mounts, and then see what happens.

Diagnoses.... One thing at a time, then check the result. Then to the next thing on the checklist if no change.

Okay, took the wheels and discs apart again last night, because when I actually took the bike for a longer run, the problem was still noticeable and annoying!

This time however I didn't just sand the mating surfaces a little, I filed them all very carefully back to bare metal as per the photo that shakey as uploaded (I'm still unsure how to upload my own photos). After this I've only tested up and down my street again, maybe to 20/30mph and it genuinely seems better. I think the first time I was kidding myself. I'm off on a high mileage trip on Wednesday so we'll see how she fairs.

But yeah, unfortunately my powder coater only masked off the bearing location. Lesson learned for next time around! So I'm thinking the problem got better and worse over the short space of time because the disc was in fact sinking in to the coating, thus in effect, warping the disc. Well, giving the same fault as a warped disc anyway.

Thanks again for all the help and I'll report back in a few days!

Dan

dpalmer_2991 said:

my powder coater only masked off the bearing location.

Click to expand...

Simples

Also, good lesson in why one should take responsibility for these tasks oneself

NicD - Are you saying I should have masked them off before handing them over or?

Turns out the problem is still exactly the same. So it looks like it wasn't the powder coating after all anyway! I did 1300 miles over a few days last week and the problem still persists. I think what I may do is take the none abs side disc off, put a piece of wood in to that caliper and then run the bike gently to see what happens. At least then I can hopefully try to isolate which side is causing the vibration, or maybe see if it's both side.

I really don't want to fork out for new discs just yet before I've exhausted every avenue, for the simple fact that they're not cheap and mine don't need changing yet (thickness wise)

Yes. If there is a problem then it is you who has to pick up the pieces. At least you should verify with the guy exactly what needs to be done - a quick google and you can normally get key parameters . I normally find people amenable to others taking an interest and valuing what they do, so checking details isn't a problem, but some take offence and it is possible to annoy people if you handle it badly. But ultimately if an error is your problem, then it's your responsibility.

It may still have been the coating. Others may know the answer as I don't, but presumably the discs may have warped during the period they were mounted on top of the powder coat?

I've still not come up with a solution to my problem, although I did come across something yesterday which may not be helping the matter.

I wanted to see how easily the pistons moved in the calipers, on both, they don't move that much without the ignition (booster) on. With the ignition on and all the pistons pushed back, 1 out of 4 on each caliper moves out really quick. If i put a chock of wood in for the pads to grip on then all the other pistons catch up and apply pressure, all be it the inners move out more than the outer pistons, again, on both calipers. So I'm wondering if the calipers are applying slightly uneven pressure onto the disc. I can push the pistons back relatively easy with a little force.

Would people suggest a through clean, or a strip down and replace the seals?

Cheers