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R12RT brake vibration


gdouglas

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Just posting here to see if anyone else has experienced a vibrating front end under hard braking on their 1200RT. I had to do a quick stop from 70 the other day and the vibration was very noticeable. Usually in automobiles, this symtom indicates thickness variations in the brake discs. So, out to the garage to get the 0-1 mic and take some measurements. One front rotor has a thickness variation of .002" while the other one is within .001". When applying my back brake only, there is no vibration at all, so I know that one of the front rotors is the culprit. Just for comparission, the rear disc is within .001" on its thickness.

 

The local dealer isn't much help right now since their only BMW mechanic is out on a 2 week vacation. It kind of sucks that correcting this should be under the 3/36 warranty, but I am not going to wait 2 more weeks just so they can finally diagnose the bike and order parts, and then wait another week or two for the parts to come in. So for convenience purposes, I removed both front rotors and I am getting them reground tonight on a rotary surface grinder to true them up. I will post back with some results.

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Yes, I've sometimes noticed a pulsing/vibration, even at moderate levels of brake application. Sometimes it occurs and sometimes not. It's a bit like a warped disc feel, but isn't consistent enough to be that, and it isn't the ABS cutting in. There's currently an upgrade to be carried out (not a recall), which involves replacing the banjo union on the master cylinder. The service manager at my BM dealership, seems to think it's to cusion the sudden application of the front brake. Whether this is related I don't know.

 

On the subject of brakes, have you noticed how over worked the rear brake caliper is, even during moderate braking periods. My rear caliper and disc are nearly always too hot to touch. The caliper has been checked for dragging and put on the BMW brake line diagnostic computer. And before anybody pipes up, I don't ride with my foot anywhere near the brake pedal and have 30 + years riding experience.

IMHO, the servo braking system on BMs is, too complicated and for many reasons, just about the worst brakes to control on any similar motorcycle. Other than that small moan, I still wouldn't swap it.

BTW, don't know how true it is, but the mechanic said that he'd heard that BM were going to move away from their servo braking system.

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Actually I have noticed something similar. It only seems to happen on cornering or light braking. It feels like a drag on the brakes, like the caliper isn't functioning properly...

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I thought that I was experiencing that, and I was getting annoyed about it. Then I realized that the vibration did not change with decelleration.

 

What was it? I realized that when braking I let off the gas and the idle pulsation of the motor was coming through the grips. It is noticeable as during braking your hands are really pressed into the bars. I stopped worrying about it.

 

Go try it out. I suggest that with front braking you are braking harder than with rear so it is more noticeable.

 

Let us know if this is the case.

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Couchrocket

04 RT same problem, warped rotors, get out your wallet -- BMW considers this a "wear item" and not covered under warranty.

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I forgot to mention in my original post that I only have 12,000 miles on the bike. I am wondering if the pad material may have been a contributor to this condition.

 

BTW, if anyone removes the rotors from their bike, the shop manual mentions that the disc bolts are put in with red loctite. You will have to heat the bolts some before you can remove them and make shure you run a tap in the holes before reassembly. I am considering just using blue loctite when I put it back together and seeing what happens.

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There's been quite a few reports of this on the R1200GS, this is the first I think I've heard of it on the R1200RT.

 

As mentioned, the solution is new front rotors. Some dealers are covering it, some are claiming wear item and are not.

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I noticed it about 10k on my '05 RT. I mentioned it to the dealer at my 12k service and he ordered new rotors under warrantee. I'm waiting for the 18k service to have it/them replaced.

 

Hope this helps,

 

Rob Lessen

Arma KS

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This has been mentioned on numerous occasions on previous threads. Whatever your BMW dealer says YOU NEED NEW ROTORS. My dealer couldn't explain what the problem was. They checked the rotors for "run out" and found they were OK, but I still had the vibration. New Rotors were fitted under Warranty - no more vibration. All we can think of is that the material used was irregular and so parts of the rotors were heating and cooling at different intervals causing the pads to slip/grab - who knows. I would strongly suggest they fit new rotors and if the problem goes away, the problem be it BMW's.

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04 RT same problem, warped rotors, get out your wallet -- BMW considers this a "wear item" and not covered under warranty.

Don't be silly. You must have upset your dealership.

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I thought that I was experiencing that, and I was getting annoyed about it. Then I realized that the vibration did not change with decelleration.

 

What was it? I realized that when braking I let off the gas and the idle pulsation of the motor was coming through the grips. It is noticeable as during braking your hands are really pressed into the bars. I stopped worrying about it.

 

Go try it out. I suggest that with front braking you are braking harder than with rear so it is more noticeable.

 

Let us know if this is the case.

I think this is quite possible.

The recall job of replacing the brake union banjo was completed this morning and on the way back home, I felt no difference.

Interestingly, the mechanic was able to download and produce a print out of, the total hours the bikes back brake and front brake had been on, since new.

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Well my RT has 1300 miles and I just made an appt to have the rotors checked. I'm headed down to Fla in 3 weeks and I'd rather not have this problem...

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I got my rotors back on this morning and went for a ride. It feels like a brand new bike now that all of the vibration is gone when braking from highway speeds.

 

The machine that I did them on at work reminds me of a flywheel grinding machine, but with a magnetic turntable instead. I ended up having to take about .009" total off each of them to correct for some runout even though the thickness variation was only .002". There is a minimum thickness spec that is stamped into the rotor that states 4mm(.157"). My rotors started out at .175" and I ended up at about .166". Looks like I can do this one more time in the future and they will be at the minimum thickness.

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Mine began to shudder on an 8,000 mile cross country trip. It is most severe when you most want good braking - fast and/or downhill. I am not pleased.

As an aside, after 40+ years of riding "normal" motorcycles, it is difficult to use only the (linked) brake lever to accomplish normal stops, and near impossible when things get interesting. I see this as a major contributer to accelerated rear tire and brake pad wear.

Paul in CA

'05 R1200RT

'98 XR400R

Other vintage

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Gordon K Phillips

I have the vibration also. With hard braking I would liken it to going over rumble strips, it is quite severe. It only occurs with front brake use, not if the foot brake ( rear only ) is used. Thanks foer the info, I am going to check with the dealer. Mine started at about 7000 miles, coincidentely just after New Pilot Roads were installed. They were checked and are not the problem.:(

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All this begs the question - Has anyone identified any after-market rotors that will fit the R1200xx series?

 

If I've got to replace mine, and I do, and they're out of warranty, and they are, I'd rather not install another BMW set that may repeat the issue.

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I've noticed the same thing too but coming off a Harley that was ten times worse I've been tickled just to be able to stop the thing in a distance less than two football fields..I guess all things are relative.. clap.gif

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Thanks for this thread! My '05 RT with 5700 miles has started pulsating when I use the front brake. Its not real bad, but bad enough that my brother noticed it when we traded bikes on a ride recently, and the first thing he said when he got of was " are your front rotors warped, or what??"

I'm getting ready to schedual a 6000 mile service, and will address this with my dealer (Hammersley's in Lynchburg, VA)

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The factory rotors are made by Brembo. I noticed the Brembo logo stamped on my rotors when I had them off. If this early warpage is representative of their quality, then I will stay away from them when replacement time comes. I am not ruling out the pads as being a contributing factor, either. What I plan on doing for now is replacing my front and rear pads as soon as possible with a different compound and seeing how the rotors hold up. EBC offers front pads # FA335HH , and rear pads #FA363HH. They also have OEM replacement rotors for the RT and the GS.

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I think Wunderlich is working on producing wave rotors for the RT. I think they already have them for the GS.

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I think Wunderlich is working on producing wave rotors for the RT. I think they already have them for the GS.
Ah, just looked and you are right. Santa Cruz BMW list them for the R1200GS - at $189.95. Each! Yikes! eek.gifbncry.gif

 

Maybe I will take a big gulp, curse for a minute, then buy another BMW pair after all. tongue.gif

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I thought that I was experiencing that, and I was getting annoyed about it. Then I realized that the vibration did not change with decelleration.

 

What was it? I realized that when braking I let off the gas and the idle pulsation of the motor was coming through the grips. It is noticeable as during braking your hands are really pressed into the bars. I stopped worrying about it.

 

Go try it out. I suggest that with front braking you are braking harder than with rear so it is more noticeable.

 

Let us know if this is the case.

I think this is quite possible.

The recall job of replacing the brake union banjo was completed this morning and on the way back home, I felt no difference.

Interestingly, the mechanic was able to download and produce a print out of, the total hours the bikes back brake and front brake had been on, since new.

 

I'd be curious if a) the new K-bikes had the same rotors and b) if there has been the same problem.

 

Check the runout before changing anything. Max runout is 0.13 mm according to the RepROM manual:

"Front brake disc(s) - lateral runout at circumference max. 0.13 mm"

 

My R1200RT has been laid up with a flat which I just fixed yesterday. I took it out and did some braking runs from about 50 in neutral with and without the engine on. Notable pulsation with the engine on, smooth with the engine off.

 

Now there was obviously no power assist with the engine off but I was able to stop relatively quickly.

 

I'm not saying that the OP's rotors weren't significantly warped, but that there is a sensation of pulsation in the grips even in boxers with in-spec rotors.

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ShovelStrokeEd

Another measurement is called for as well and that is thickness of the rotors. Runout may be in spec but thickness variations around the circumference may still cause the pulsing. On cars, as little as 0.005", which corresponds to that same 0.13 mm can cause pulsing in the brakes. Find and mark both the low and high spots via a dial indicator and measure thickness at those points using a deep throat micrometer.

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I would be interested in a set of wave rotors myself. At $190 each, the price is in line with with what you can get a stock replacement for from Chicago BMW. Retail on a stock replacement is $230.

 

My KTM 450 EXC has wave rotors as stock equipment. No problems with them so far.

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This was a well reported problem with GS owners. There is a bulletin with prescribed fix located here:

 

http://www.ukgser.com/forums/attachment.php?attachmentid=34441

Yup. Already did all that stuff. It did help on the squeal issue, but not the major shudder under hard braking problem.

 

As a matter of fact I have an extra kit (thought you needed a kit for each side), so if anybody needs one let me know.

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