2007 f800 BRAKE FAILURES

I wish to inform you who own 2007 F800st about a problem with some 2007 F800st where the brakes do not operate and in some cases caused crashes, I have spent time reviewing the issues and see a problem with the brake fluid foaming causing poor or no braking with the factory Dot4 fluid. I have in the past used alternative fluids in the brakes in many BMW in the past and have noticed no issues with a product made in Germany which is interesting enough, its called GTLMA 5.1 from castrol, I have performed a complete flush change out on my wifes 2007 f800st and am doing others as well to prevent any failures on these 2007 models. I want to state this is for your information do as you wish (Hope this saves someone from harm)...

Why do you believe the factory DOT 4 fluid foams any more than any other fluid?
Have you done any sort of comparison or do you have a reference for this conclusion?

Primary reason for asking is that I sometimes teach brake system design and maintenance to aspiring track types and have never seen foaming raised as a real world issue previously. Many other imaginable ways of getting air or some gas stuck in brake lines are well known and include things like mc fluid getting too low, entrained air in fluid coming out under heat, boiling brake fluid in calipers for any one of a number of reasons (including improper pad installation). air sucked back into caliper through bleeder screw threads, moisture accumulation in old fluid then subjected to high operating temps, etc.

More info please.
Thanks.

Try here:
http://f800riders.org/forum/showthread.php?t=18225
or here:
http://f800riders.org/forum/showthread.php?t=34179
or here:
http://f800riders.org/forum/showthread.php?t=33349
There are more if you look.

Even the OP's comments look familiar:
http://f800riders.org/forum/showthread.php?t=36803

I'll leave it to you to make up your mind about it; but I think all you may accomplish by changing fluid types is absolving BMW of any liability if you or your significant other can't stop and crashes.

Bob, thanks.

Saw nothing convincing me anything is wrong with BMW DOT 4 fluid. Just normal issues of bike vibration creating bubbles tha can get into line if parts are left out , level gets low, etc plus an apparent ABS design issue on the 800 that can apparently be exacerbated by suspension settings way off.

Nothing wrong with going to a DOT 5.1 but why? Don't need the added heat resistance and I'm not aware that foaming properties are any different. Reservoir design and keping it up to level is the issue there.

Personally, except for racing situations I use manufacturer recommended fluids. For racing, the minor differences in brake fluid VISCOSITY can be used to help (with pad selection) fine tune the precise brake release feel a driver prefers. This can be useful in road course and dirt track racing for cars. don't know about this for bikes.

Having said that re the 800, my 08 RT has a relatively wimpy rear brake and rear ABS kicks in a little earlier than needed in my experience. No behaviors I consider dangerous, just not my preferred balance. I'd like a harder rear pedal that goes all the way to lockup before ABS interferes as I learned threshold braking well a long time ago.

BMW seems extremely paranoid/conservative about avoiding rear wheel lockups under brakes - an opinion that they can probably support with data- but that takes some getting used to for old timers and dirt riders who have often deliberately slid their machines around on a locked rear wheel. (No, I've never owned a Harley). No negatives to the ABS on the front of the RT - the brakes can be used aggressively without any wierdness fom the ABS.

I have changed brake pads on all my Mercedes vehicles because the manufacturers choice makes threshold braking difficult and trips the car into the ABS early by design. NOT a behavior I value on snow and ice where maintaining full steering control on the verge of lockup is important.
Manufacturers tend to make stuff for the untrained....

The only issue I have seen ...

I have owned and ridden my F800ST since 2007. I ride almost daily, summer, winter, spring and fall, here in the NW. I have almost 15K on the bike now, and have only seen one issue with the brakes.

About a year and half, or so ago, I found my rear brakes were not working. I took it to a shop that I frequent (Not a BMW dealer, but the owner is a big BMW fan and is noted in the area for restoration of old bike, many BMW's) where the shop manager is a certified BMW mechanic. He took one look at the bike and determined that the brake reservoir had been over filled by the BMW dealer and this had caused the fluid to over heat and boil under braking. He flushed and refilled the system and I have not had a problem since.

Makes you think, doesn't it.

I took samples from several bmw bike brakes dot 4 and filled them in a small vial then took some used 5.1 gtlma from castrol out of one of my personal bike did the same, used brake fluid one year in the system -- two vials one dot4 and one 5.1 and shook them both, the dot 4 foamed a small layer on top, the 5.1 did not.

Wow; looks like irrefutable scientific evidence to me!

I'm going out and changing all the DOT 4 brake fluid in my 2009/F800ST immediately; after reading the results from this elaborate controlled experiment I think all manufactures of DOT 4 brake fluid should close down their R&D labs right away...

Pray before you ride; Indeed!!!

But really; if you flush and renew your brake fluid, (DOT 4, or other), at least annually, (may be needed more often if you live near the sea), then you shouldn't have a problem. Brake fluid is hygroscopic: (will absorb and retain water under some conditions of humidity and temperature). This will also reduce substantially or eliminate most common brake fluid issues.

Happy Presidents Day !

Yes I work off facts, another note, when I did my wifes f800st brake fluid flush to 5.1 the left front caliper had a significant amount of air in it, I dont know since i purchased it used at 8000 mile if its ever been touched as far as brake bleeding or not, I found this interesting since the bike only has 9500 miles on it,. so from now on any new used bike i get,, im bleeding the brakes just to be safe...matthew