[mrbiker]

2005 LT with 17,000 miles.

Driving on Saturday night I got the ! symbol in the triangle, usually a brake lamp out.

10 minutes later, after stepping on my rear brake, I get the BRAKE FAILURE flashing, I think once per second. My brakes took at least twice as long to stop.

I was a mile from my girlfriends, so I limped over there. At three stop signs, I turned it off and started it up again. All systems go - for the moment. The problem started up again when I used the back brake, not the front.

As I got closer, I noticed the bike was driving like it had one brake applied all the time - a dragging sensation. After a stop, it was tough to get it rolling, but now I was two blocks away, so I carefully drove into her garage.

When I stopped the bike, I couldn't get it to roll. I went upstairs to get her and see if both of us could push it. By the time she came down (5 minutes), it was rolling a bit freer, but still dragging. We pushed it into a parking space.

I touched the rear rotor. It melted my flesh immediately. It took over an hour to cool.

Last night I popped out the rear pads to see if maybe I was on the backing plates as I didn't check them when I bought the bike. Still, there was over half the pad left. I put everything back together.

This morning, I started it up and rode it around the parking lot at about 15mph and made 4-5 stops. NO PROBLEMS! However, this started as I was exiting the freeway, I was slowing from about 45 mph the first time it happened so a slow speed test might not tell me anything.

LASTLY: I had just finished washing the bike with a high pressure washer. I hit it from every angle to get off the dirt from the last 3 months. I used a blow dryer for 1/2 an hour, toweled the rest of the water spots off, got on my gear and drove away. Is there any reason to suspect water somewhere it shouldn't be?

I called BMW of Hollywood and they won't be able to get it for a couple of days. He said this all sounded very weird - haven't heard anything like this that he could recall. Didn't think water should cause a problem.

What do you all think?

TIA

 

[cfell]

...Mike...
NEVER pressure wash your bike!!! Credit to the "Church Lady"... "It just aint prudent!"

Hard to debug this far away... but here are some 'quick checks'...

Dragging brake.
- binding caliper.. (might have happened when you used the pressure washer) If the caliper was hot when you washed it, there could be a bind as the caliper cooled...
- boiling brake fluid.. if the caliper is dragging, it will overheat... that can "boil" the brake fluid. Boiling fluid, possible too much pressure inside caliper and increasing brake force and increasing heat.
- Which wheel was binding? place bike on the Center stand... which end is binding (check both)
- is the rear wheel spinning freely? Is there play in it.. if so, the rear drive might have overheated and is making it feel like a brake issue....or heating the caliper so much that the brake fluid is boiling up again...

Lots of possibilities...

If you have not flushed brakes since new, there is a possibility of some problems with the ABS unit, etc...

Again, these are all just "guesses"..... really need to have a close look at it before you mess it up worse...

 

[cccpastorjack]

Could it be that some water got behind the piston from the blast of the pressure washer and the water boiled/heated -- expanding and therefore pushing the piston out and tightening up the pads on the disc? Maybe

Sounds like it is related to the washing.

Also, I agree that you need to lift the rear wheel off the ground and spin it to see if the caliper is still stuck. If it is just the pistons sticking, you can usually "bop" them with a plastic hammer and they will free up. If this works...it DOES NOT fix the problem. Calipers will have to be rebuilt.

Just a few suggestions.

 

[mrbiker]

...Mike...
NEVER pressure wash your bike!!! Credit to the "Church Lady"... "It just aint prudent!"

Lesson Learned...

Dragging brake.
- binding caliper.. (might have happened when you used the pressure washer) If the caliper was hot when you washed it, there could be a bind as the caliper cooled...

Bike was stone cold when I washed it. Drove it from inside to outside the garage, shut it off, got out cleaning supplies and went to it.

- boiling brake fluid.. if the caliper is dragging, it will overheat... that can "boil" the brake fluid. Boiling fluid, possible too much pressure inside caliper and increasing brake force and increasing heat.

Maybe it started dragging on the freeway and I didn't notice...

- Which wheel was binding? place bike on the Center stand... which end is binding (check both)

No doubt about it - the rear. Front rotors were cool as cucumbers. OK, one was cool as a cucumber, the other was as cool as the other side of the pillow

- is the rear wheel spinning freely? Is there play in it.. if so, the rear drive might have overheated and is making it feel like a brake issue....or heating the caliper so much that the brake fluid is boiling up again...

Rear wheel was barely spinning at all that night. It felt like the rear wheel (when my girl and I pushed it, the front wheel did what it was supposed to do when turning), and when I touched the rotor, it was so hot it really burned my finger!

The rear drive was also nice and cool. In addition, no freeplay in the wheel at all, although the floating rotor made me nervous until I found out here that is normal. ALSO-now that it's cool and back to normal, the wheel spins nicely again.

If you have not flushed brakes since new, there is a possibility of some problems with the ABS unit, etc...

I bought it used and bought this particular one because all services had been done up to the 12,00 mile one. I now have 17,000 on it. It's 3 years old and my guess the brake fluid hasn't been changed - ALTHOUGH - a couple of hundred miles ago they changed the rear master cylinder due to leaks.

Lastly, at the risk of being redundant, last night the rear wheel was turning fine (the problem was 2 days ago). Then I popped out the disks, and they came out almost by hand - slipped right out.

HOWEVER, you may be on to something. Maybe I had the back brake dragging for some reason and it heated up the brake fluid which expanded and caused the rear caliper to squeeze shut on the rotor! This would explain why letting the bike cool for a few minutes got the bike rolling again.

 

[mrbiker]

Could it be that some water got behind the piston from the blast of the pressure washer and the water boiled/heated -- expanding and therefore pushing the piston out and tightening up the pads on the disc? Maybe

Sounds like it is related to the washing.

Also, I agree that you need to lift the rear wheel off the ground and spin it to see if the caliper is still stuck. If it is just the pistons sticking, you can usually "bop" them with a plastic hammer and they will free up. If this works...it DOES NOT fix the problem. Calipers will have to be rebuilt.

Just a few suggestions.

I'm starting to think the water started the problems.

As mentioned, the caliper wasn't stuck after the bike cooled. And again, everything worked as advertised this morning.

I'm going to drive it on an empty street tonight and see what's doing. If it's normal, I'll bring it to the dealer and get the fluid changed. If it's not normal (if it happens again), I'll have it towed to the dealer and have 'em fix it. Of course, the warranty just expired. I tired to buy an extended warranty just before it did but everyone talked me out of it - that includes 2 BMW dealers!

If it happens again, it will leave me stranded as the bike is almost unmanageable except to pull over and stop.

 

[waynelt]

My '96 RS did almost exactly what you experienced a couple years ago. My buddy tightened the rear brake play for me and the rear must have been dragging a bit. I was rolling along about 55mph and it was like I put the brakes on, bike stopped dead in the middle of a bridge and wouldn't budge. I also burned my fingers on the rotor (doh). After loosening the adjuster I managed the 200 mile ride home, then had the brake fluid changed. I believe there was in fact moisture in the fluid which caused the lockup given the heating of the caliper.

I'd find it hard to believe however that you could manage to get water inside the brake line with a pressure washer, unless you blasting were the hell out of the caliper seals directly.

 

[mrbiker]

I'd find it hard to believe however that you could manage to get water inside the brake line with a pressure washer, unless you blasting were the hell out of the caliper seals directly.

I may have. I was blasting everything as it's been sitting in a dusty area for a couple of months. I really went to town with the soap, water and hose.

 

[mrbiker]

Another Theory...

Here's something I discovered.

After some suggested brake fluid expanding from heat caused the problem, I gave it some thought.

Recently, I installed Suburban peg lowering mounts and an Ilium brake pedal.

I adjusted the brake pedal height bolt (the bolt and nut you can see on the brake pedal) so it tripped the brake light immediately. About 1 mm of travel sets it off. This also sets off the brake servo.

The night this happened, I was on a very busy freeway here in Los Angeles. I usually drive with my foot over the brake pedal in these situations. I'm thinking that my very large motorcycle boot may have touched the brake enough to keep this on.

I adjusted the nut for about 5mm of free play today and drove it to work (only because it gave me 10 minutes warning before big problems occurred the other night). The brakes worked as normal, but it's only a 20 minute drive to work on surface streets and the problem occurred after 30 minutes on the freeway.

Any more ideas?

 

[mtrevelino]

Here's something I discovered.

I adjusted the brake pedal height bolt (the bolt and nut you can see on the brake pedal) so it tripped the brake light immediately. About 1 mm of travel sets it off. This also sets off the brake servo.

I think that you found the problem.

 

[Lee510]

B-i-n-g-o, B-i-n-g-o

and lowering the pedal caused the problem-O!

While reading through the messages, I thought the brake problem sounded just like the one I had shortly after getting my LT last June. I decided the pedal was too high and thought it would be a great idea to lower it using the bolt and lock nut. Long story short, I developed a parking brake within two miles. Look behind the brake lever mount. If you lower the pedal, you have to adjust the assembly there too. I don't know how to do it. My pedal is back where it was. Got the info from the great bunch of folks here. Someone will be able to tell you exactly how to adjust it.

 

[stevie1]

Mr Biker

I had a similar problem a couple of years ago, one of my front brakes bound on.
Bike slowed right up & disc was hot, let it cool off & everything ok!, i had just left a motorway, & had done some heavy braking.
I took caliper off the wheel, removed the brake pads, then packed the pistons, so that only one would extend at a time, i then pumped the brake lever, carefully extended the individual pistons, & using brake cleaner & a nylon dish scourer, cleaned the crud from each piston, i then lubricated the pistons with silicone spray, this cured the problem, i repeat this about once a year.
There are no weather seals on the individual pistons, so the crud will build up, this can cause a bind to occur, probably not under normal use, but if you are a gentle rider & suddenly use your brakes heavily!!.
I find the water in the system from a pressure washer a bit hard to believe.
Regards
Stevie
PS its an easy job to do, & even if its not the cause??, at least you have eased the wear on the caliper piston seals.

 

[cfell]

yup... gotta check that rear pedal....

 

[mkiesel]

I remember a similar post a couple of years ago. Only this guy's paralever boot actually caught on fire. I remember he said that he couldn't even move the bike at all unless he turned the key turned off. He discovered that he had the same problem (as mentioned in a previous post) with the incorrect brake pedal adjustment that caused the break servo and pump to apply the rear brake whenever the key was turned on. He could actually push the bike fine with the key off, but was not able to budge it even with the engine with the key on.