Rear Brake Problem

[jireynolds67]

I have a problem with the rear brake on my 2003 R1150RT-P. The following is an explanation of what has and is happening. I know it is going to be long, sorry about that, but I feel that I need to explain it the best I can.
I had my mechanic install new tires. While doing so, he noticed the rear brake rotor would move a bit. He pointed that out to me and told me the rotor should be replaced. I ordered a new rotor online and went to the local stealer and bought five new mounting bolts. When I received the new rotor, I made arrangements with my mechanic to have the rotor replaced. I took the rotor, new bolts and new brake pads to him and watched him replace the rotor and pads. The mounting holes in the old rotor were worn a bit and were oblong. There were no indicated problems with the new rotor installation. The rear wheel could be spun by hand with the bike on the center stand and the brake caliper was working correctly and I rode away thinking that the rotor would be good for thousands of miles. One day I went for a ride of about 350 miles and on the way back home, I was within three blocks of my mechanics shop and thought I would stop by and say hi. I squeezed the brake lever to slow a bit for a corner and I heard noise from the rear brake. I had not heard that noise from the brakes before. I rode to the shop and when I stopped, I heard the noise again. I went in and told my mechanic and we went out to look at it. He removed the right saddle bag and took a close look. Both brake pads were essentially gone and the rotor was scored on both sides. It had been less than 1000 miles since the new rotor and pads were installed. I caught a ride home with a friend who had just dropped his BMW off to have some work done on it. I still had the old pads at home so I took them back to my mechanic. Later that day, he replaced the pads with the ones I had taken to him. I picked my bike up the following day.
I ordered another new rotor and new pads and again went to the stealer and bought five mounting bolts. I received the new rotor and pads earlier this week and arranged to have them installed. Again, my mechanic changed the rotor and pads and again, everything looked good. With the bike on the center stand, the rear wheel could be spun by hand and the rear caliper was working correctly. The mechanic said he would take it for a ride to check the brake function. He was gone for about a minute and said he probably rode it less than a hundred yards. When he returned, I looked at the rotor and could see it was already showing scoring. I left the bike with my mechanic as I donÔÇÖt want to ride it and have a repeat.
The first time, my mechanic said the pad material must have been bad. I contacted the people whom I bought the pads from. They said that they have sold thousands of them and never had a complaint. I contacted the people that I bought the rotors from and sent pictures of the rotors and the worn out pads. They contacted their distributor by phone and discussed it quite a bit. Yesterday, I had a phone conversation with a person from the company where I bought the rotors and the second brake pads. They sold several of the same rotors between my ordering the two from them. Neither the people I bought the rotors and second pads from, nor their distributor, have had any complaints about the rotors. The distributorÔÇÖs parent company makes and sells thousands of rotors.
My mechanic will not be at his shop again until Monday. I need to find a way to resolve the problem. The distributor has offered to sell me a new rotor and pads at a reduced price but as I see it, that would not help. Something which neither my mechanic nor I have noticed, or been able to find so far, is causing the problem. The original rotor had thousands of miles on it and was not wearing the pads out rapidly and of course the rotor was scored, but not badly. My question is, has anyone ever had the same kind of problem? If so, what was found that was causing it? I would certainly appreciate any good suggestions as to what the problem might be.

 

[chrisz]

If the rear pads are wearing evenly perhaps it's an alignment issue. Other then the alignment, I would suspect that after brake application your calipers are not retreating fully, and hence dragging. How long did the original rear pads last?

 

[racer7]

It seems fairly obvious that for some reason the system begins to drag excssively after normal contact and that drag is reducing life a lot. And that something changed when the new parts were installed.

Typical causes of sticking are a hung pad, hung caliper, or a blocked return. Unlikely but possible causes are pads or rotors of wrong thickness- essentially impossible if you're using correct BMW parts ard awfully rare even in the aftermarket. Also possible is rider error- a fat foot sitting permanently on the pedal.

Were it me, I would start by removing pads from the caliper and reinstall, being careful that placement, mounting, pad fit, caliper movment and mc fluid level are all correct.

If a return is blocked, the drag is happening after riding enough to get a caliper body hot from normal levels of residual friction, not immediately. Have you checked for excessive drag after a ride of 10 miles or more?

Any chance some part of the linkage has been wrongly adjusted or damaged?

Brakes are inherently simple devices and the cause for this is going to be visible if you look at the right stuff. If your regular guy can't find it, get a new set of eyes- failure to find it suggests it may be an error of his that he simply doesn't recognize or that his basic understanding of brakes needs a tuneup - brakes are inherently simple devices but there are a few subtleties...

 

[MotorradMike]

Most everything I've read about bad rotors has been that they've warped.
I've never read anything about bad pads anywhere.
So my guess is that you don't have defective parts.

The rear brake MUST be dragging to wear that fast. You can verify that by checking the rotor every time you stop. It will be VERY hot so put your hand close but not touching!
At least you should be able to figure out what makes it drag, then repeat it for the mechanic.

 

[sbartz1]

I think the flexable break line is ruptured inside my triumph did the samething.what it does is bulge inside the hose and does not release so you end up with pressure on the caliper that is not releasing and will bleed down after a bit.hope this helps

 

[jireynolds67]

When I bought the BMW last year, the mileage on it was 56,336. I do not know when the brake pads and rotor were changed prior to that so have no way of knowing how long they were lasting. The pads which were on it with the old rotor looked good and still had quite a bit of material left on them. I had an inspection performed at 60,300 miles and the brake fluid was completely replaced by flushing and bleeding all systems with new DOT4 fluid. My mechanic has been a BMW mechanic for over 23 years and has his own shop. I have been there and watched him perform all the work on my bike. He did not notice anything wrong with the caliper and it appears to be working like it should. We did not check the pedal linkage so can take a look at that. I do not ride with my foot on the brake pedal and actually use the brake lever most of the time because of the integrated system. After having the problem with the first replacement rotor, I didnÔÇÖt want to ride it with the second replacement rotor, after seeing the scoring when it was ridden such a short distance. The first replacement rotor had not changed color so apparently the pads were not dragging enough to cause a lot of heat, but certainly something was wrong enough to cause then to wear out in less than 1,000 miles. My mechanic will be in his shop on Monday and I will be there too. Hopefully one of us will come up with a fix for the problem. I had hoped someone else had experienced the same or a similar problem and could tell me what was found to be causing it.

 

[ALIENHITCHHIKER]

my mechanic said the pad material must have been bad.

I know you said your mechanic has 23 years of wrenching experience with BMWs - but, assuming that the pads were supplied by any of the major manufacturers, I'm very surprised he suggested that was the likely cause of the premature wear.

Some ideas:

1) Inadequate amount of free play in the rear brake lever linkage.
2) Master cylinder (could be either of them with a linked system) is gunked up and not permitting full release of pressure from the calipers.
3) Calipers are gunked up and the pistonns are not retracting.
4) Enough water is mixed into the brake fluid that its volume expands as things heat up and this causes the rear brakes to be partially applied. (This is not such a far fetched thing - especially if the brake fluid came from a previously opened container or there is a crack in the fluid reservoir or its cap.)

I've not had first hand experience with the 1150's linked brake system, but there is probably a proportioning valve where the front & rear brake line systems are linked. This too could be a place things are gunked up and not allowing the calipers to retract.

If it were my bike I'd start by changing the fluid again, and this time I would vigorously back flush all circuits in the system. If that doesn't do it I'd start with the master cylinders & calipers.

BTW - are these whizzy brakes (power assisted)? Not sure what part they could potentially play in this sort of problem - just curious.

Good luck on Monday. Let us all know the outcome.

 

[NESBOCAJ]

New Pads and a new rotor may displace more brake fluid, remove some fluid from the rear reservoir.

 

[ALIENHITCHHIKER]

New Pads and a new rotor may displace more brake fluid, remove some fluid from the rear reservoir.

Duh - that's so simple !!!

(I've heard it said that it often takes a great mind to recognize the obvious )

 

[jireynolds67]

My mechanic and I discussed the problem. We decided to rebuild the rear caliper. When he took it apart, the seals or "O" rings were hard and brittle. He installed new ones and now the rear brake is working fine. I have not ridden very far since then but will be doing some fairly long interstate rides now that the weather has cooled down a bit. I will keep a close watch on the rear brake rotor and pads for the next few thousand miles, just to make sure there is no longer a problem.

 

[69zeff65]

Replace the lines

If you have any rubber flexible brake lines I would replace them with either new or stainless from Spiegler. The rubber gets old, just like you caliper O-rings and it expands and brakes down. Just a matter of time before you get exterior leals in your lines

 

[RSSSSSSS]

Also, make sure the pins that hold the pads are nice and clean and lubed with a bit of neverseize. They have a habit of getting corroded and not letting the rear pads fully disengage. I had this problem but not to the extent you did. A bit of sandpapering the pins and some lube and they are fine for awhile.