Brake failures – F800 with ABS

[Anonymous]

#2200

I'm wanting to know if riders of any other BMW models with ABS have experienced problems that we are experiencing on the F800.I've experienced with my bike failure of the ABS brake system under hard braking when I hit a bump in the surface. This can either be a bumpy corner or even a catseye. In 16000 km's it would have happened no more than 5 times. the problem is being experienced by other F800 riders here in New Zealand and around the world. Additionally its also been experienced by journos testing the bike and writing up magazine reviews. To date BMW has not produced a fix for this.What seems to happen is that the bike is hard on braking and slowing then all of a sudden all brakes are released and the bike shoots forward for what seems like two car lengths before braking reactivates. This gives you the fright of your life and afterwards you wonder if you really experienced it because its uncomprehendable that this could possibly occur. One poster mentions a system that BMW have that releases the front brake if it feels the bike is going to go over the front wheel. others comment on the back wheel getting airbornre and confusing the ABS.My view is that it's not "if" this will cause rider injury but "when".I've had one experience of ending up one lane into a round-a-bout having just missed a car coming through. On the F800 forum, riders report ending up in intersections instead of stopping before them. A rider report on the forum that I saw today saw the rider shoot into the intersection and into the side of a BMW van. He was unaware of the problem. Luckily he's okay but the bike needs repairs (at best).This has been a known problem from early on and here is a list of the forum pages;http://f800riders.org/forum/topic.asp?TOPIC_ID=2872http://f800riders.org/forum/topic.asp?TOPIC_ID=2565http://f800riders.org/forum/topic.asp?TOPIC_ID=1983http://f800riders.org/forum/topic.asp?TOPIC_ID=1425http://f800riders.org/forum/topic.asp?TOPIC_ID=908http://f800riders.org/forum/topic.asp?TOPIC_ID=580So does anyone riding other BMW's with ABS experience this particular problem and has there been a fix for it.I look forward to hearing your thoughts and please also tell any other F800 riders you know of so they become aware of the problem.

[Dave Ross]

#8437

This has been discussed extensively on advrider. I know a guy with a Nissan 4×4 who has the same problem as he comes to a stop. The ABS seems to release. He has a bad sensor. Maybe you can adjust the suspension to soak up the bumps better.

[Anonymous]

#8438

Hi Alex, Thanks I'll jump over to advrider. I also got the comment back that it happens more or less across the BMW range.The F800 has no front suspension adjustment. I did wonder if softening the back would help. So has no one been able to get BMW to fix this flaw in the ABS? I would like to see a fix for this and I don't see it as too much to ask for. Has anyone else found a way around it or a fix. One of the F800 riders has found if he releases the brakes as the bike lets go and then re-apply the brakes then the bike rengages the brakes quicker than waiting for the bike to re-engage.Thanks - Des

[Murray]

#8439

Interesting condundrum Des but, notwithstanding the dire consequences for BMW as a manufacturer if someone does eventually get hurt or killed and it's proved to be due to an ABS systems failure describe in various F800 forums to date, you got to wonder at the logic of tearing up to any intersection and relying on hard braking to kick the ABS in to stop you saftely in the first place. I'm sure BMW has thought about the pros and cons of a system that seems to release the front wheel on purpose to keep the rear wheel on the ground prior to concluding it's to go to market. My understanding is that on the F800 bikes, when the rear wheel is airborne the system will take that as a tip over signal and release both brakes until the two wheels are again rotating at the same speed. Then it starts braking again. I have not ridden one long enough to have this happen to me let alone fully understand where and when it would happen but I've got to say, when we did over 800kms round the Coromandel over three days when the first S & ST arrived we were riding them pretty hard and never once did I feel anything by absolute confidence in the braking system.Personaly, I prefer not to have ABS and can't really be bothered with this tipover detection stuff because in order to provoke a proper tipover, a) you'd kinda think you'd know what you're doing; and b) your natural instinct would be to back off the brakes a bit.Given your concerns though, my advice for what it is worth, is ride it like your not relying on the ABS to stop you and get it to your local dealer smartly for a full checkup on the sensor settings and operation of the ABS. CheersGarryPS If you still don't feel safe on it, I'll swap an XT250 for it  😀

[Anonymous]

#8440

Hi GarryLargely I agree with you. The term hard braking is subjective. I can't recall ever stopping hard enough to activate the ABS in the dry. I have tested it in the wet. I'm just talking about braking. I can brake much harder without bumps and no problems. So for me hard braking means applying the brakes fully to bring the bike to a stop but not agressive braking. I would expect that the way I'm stopping is consistent with many riders.The issue isn't planning to stop dead on the white line at an intersection. Usually you're planning to stop well short but the full release of brakes for a couple of car lengths ends that. So far when its happened except for the round a bout I've still had plenty of road to stop in. This is the only time this has happened in a built up area.I don't ride like I'm wanting the ABS to stop me and agree tearing up to an intersection and planning to stop like that wouldn't be smart. I do expect the brakes to work though. This failure is being triggered by bumps as small as cats eyes.  It's also reported in the bike reviews with a local one being triggered by a cats eye.Maybe the BMW system should not release for so long and secondly perhaps it shouldn't completely release the brakes. You also have to wonder if the incorporation of an electronic gyro chip, which are cheap, would also help stop the problem occurring. This would give an accurate tipover indication that would be 100% reliable.This failure is occurring under what I would consider normal / firm braking not stand the bike on one wheel stopping.I also was interested to find when posting on other forums that it seems to be a common BMW ABS thing that extends across the range and back for a few years. This also concerns me.I have absolute confidence in the brakes outside of this. They haul the bike up pretty quickly and I do practise stopping quickly from time to time and wet or dry the brakes are impressive.Here are some more links on other sites.http://www.advrider.com/forums/showthread.php?t=61479&page=2&highlight=lost+brakes+failhttp://www.advrider.com/forums/showthread.php?t=62933&highlight=lost+brakes+failhttp://bmwsporttouring.com/ubbthreads/showflat.php?Cat=0&Number=791765 http://bmwsporttouring.com/ubbthreads/showflat.php?Cat=0&Number=571045I'll change how I reference the braking in future to be clearer about it. It seems to me that as this is known, riders should know about it and secondly BMW should address this. In the instances where this has happened I would think I was miles away from braking the bike to the tipover point. The bump has just fooled the system and then the system has over reacted.Having read numerous forums and posts now which I hadn't at the start of this thread I'm more convinced that BMW need to fix this problem and that it is serious._______________________If anyone knows of a bumpy bit of road on a quiet straight in Auckland where I can try and activate the problem on purpose to show BMW then I'd like to know and be able to do that. I also wonder if running the bike with a stiffer setup doesn't help things in which case riders can be advised and opt out of the problem more.So can anyone think of a quiet piece of road I can use? If the general view of this being a tipover thing is correct then it seems to me that this can be dramatically improved or fixed. And does anyone know if the bike uses an electronic gyro chip as a sensor? Garry thanks for your comments.Cheers - Des.

[honeybear.2399]

#8441

It's a common feature of BMW's particular iteration of the ABS system. When the rear locks after going over a bump, it releases the front. There is no cure, except that using both pedal and lever seems to lessen the impact.

---

California Superbike School Rider/Coach So it's only a problem on bikes with a linked braking system, is that right?  Phil

[Anonymous]

#8442

Hi Phil,The comment I've seen is the F800 doesn't have linked brakes. But I have no idea if that's right or not.So now that we're aware its a common thing across the brand has anyone tried previously to get BMW to fix it and what does BMW say?Des.

[Author]

Posts