brake problems

[mike944]

HI

I am having 2 braking problems with my '94 325i. I don't think they are related, but who knows.

1. the ABS kicks on very often whenever i hit a bump while braking. I don't have to be braking very hard for it to happen, but it's really annoying. I know how the ABS works, it looks for differences in wheel speed to come on, which is happening when i hit a bump, but it should be so minor as to not engage the ABS. It seems like the ABS computer is overly sensitive. anyone else have this problem? i've never had this problem on any other car i have ever drove before.

2. when it's raining, and i get on the highway, and drive for at least 1/2 hour without touching the brakes, when i do step on the pedal, light to moderate pressure, the brakes don't do anything for at least a 2-4 seconds. that scared the SH_T out of me the first time that happened. in order to get the brakes to work immedietly, i have to push pretty hard. It almost seems like the pads get water-logged, and they don't work for a few seconds until the friction heat dries them out. once they start working, they work fine. BTW, i have the slotted rotors (ATE, i think) does this sound like something wrong with the brake pads? i have no idea what brand of pads are on the car, i just bought the car not too long ago.

Mike

[Wayne 962]

Hi there. What do you mean by slotted rotors? Are these aftermarket? Or do you mean vented rotors?

It sounds like the two problems indeed might be related. I'm not sure, but a lack of fluid/pressure might cause both to occur. Is the fluid level ok? Did you have any brake work done in the past? I would take a guess that maybe the brakes weren't bled properly.

I have a similar problem with my truck when it's sitting for a long time (2nd problem). It takes a few pumps to get the brakes going.

There is supposed to be a shield over the brakes and the ABS sensor. If this shield is missing (sometimes people who do bearing replacement accidentally cut it off, it may cause excess water, or the ABS sensor to become caked with dirt...

???

-Wayne

[canyonlands]

ABS is something I don't mess with so if it were me I'd call a specialist. The one I use is actually so nice that if it's an easy fix he'll tell me what to do and save me the trip to his shop. I realize shops like that are going to be rare but you can call a few and see if they have any advice.

As far as the ABS light goes, I'm pretty sure the light only comes on if the system has failed, not when the system is activated. That might help you out some. Could be a short being broken by the jarring on rough roads.

Pulling the wheel and checking the pads for extensive wear is pretty easy. I take it you aren't getting a "Brake Linings" warning though. You didn't mention it anyway.
Order a Bentley manual from BMA or Bavarian Auto. The Bentley manual is the best, far better than Haynes or Chilton. Cost is about $45-$55. I'll look through mine when I get the chance to see what it says about ABS warnings.

Good luck,

Ron

[canyonlands]

[QUOTE]Originally posted by Wayne at Pelican Parts
[B]Hi there. What do you mean by slotted rotors? Are these aftermarket? Or do you mean vented rotors?

snip...

Slotted rotors have gas slots cut into the face of the braking surface. It is similar in concept to drilled rotors but slotted rotors are usually a little more long lived. They don't look as cool though so you don't see them as often. I think he would be talking about ATE (German) "Power Discs" which are vented and slotted and through BMA parts they only cost $48 each!!!!!!! What a deal. (and no, I don't work there)

Cheers,

Ron

[mike944]

the slotted rotors are ATE "Power Discs" I did not buy them, they were on the car when i got it.

The fluid level is ok, and the brakes don't feel spongy, but i'll re-bleed them anyway. I did not have any brake work done yet, since the brakes were in good condition when i bought the car.

the ABS light does NOT come on, they just act funny.

i'll definetly look for missing shields over the ABS sensors

the second problem has no relation to how long it has been sitting, even when they are already wet, i have to drive at least 1/2 hour without touching them to cause the problem.

thanks for the quick response.

Mike

[Wayne 962]

How about when dry and driving on the highway for about 30 minutes? Similar problem? Or is it a similar problem, that is just made worse by the rain?

Hosing down the brakes on the street and then driving? Would that generate the same problem?

-Wayne

[mike944]

works fine in the dry, no problems.

i'll have to try hosing them down, to see if it causes the problem

Mike

[Dave at Pelican Parts]

BTW, Pelican also carries the Bentley manuals for the 3-series. I just recently got one for my folks' new-to-them 98 328.

--DDD

[Wayne 962]

Yes we do!

-Wayne

[watchroadahead]

Canyonlands senior member , wrote power discs at bma.. what brake pads for normal driving would go with those..i am in the process of doing a first time brake job. and gaining confidence by listening to comments on the forum.. 1st i'm going to read the bentley thoroughly.. and then access the situation when i get the wheels off. and of course not knowing what i'm looking at ..suseptible to most anyones assessment ? hmm i hope the bentley book addresses rotors /pads guidepin bushings,shield over the brakes/abs, and procedure.. i was pleasantly rewarded after sifting thru the info on at transmission change.. i did myself with assurance from avid bmw drivers that it was first a good thing to do. and second that it was doable. i appreciate the help... and like my mechanic buddy.. lack of money creates a way to do it yourself.. he didn't mention the satisfaction as a by product... well it took awhile to get here but glad i made it. i need to work on brevity..

[Jeron]

You've dredged up a very old thread and your post seems rambling. Create a new thread and try to be more concise about your question.

[watchroadahead]

well i appreciate the unsolicited comments.. i'll create a new thread but what are you doing there if it's a very old thread... some think advice i timeless...i'll create a new thread when i have a better question.