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BMW BMXer
04-26-2004, 12:50 AM
I have been having a problem on and off recently of all 4 of my brakes locking onto the rotors at times when I don't want them to (ie on the highway).

This means that I can be on the highway in 5th gear feet to the floor and cant get past 120km *mumble*

I got new pads and a brake serviced at chucks to see if they could find anything wrong and after it cost me quite a bit 2 days later the problem happened again. None of my cailpers are seized and other than this the brakes are in perfect order.

What could cause this?

Note:
-I dont have to push the brakes for this to happen
-It occurs and stops whenever it wishes
-When it occurs pedal pressure is significantly different (harder pedals higher)
-Smells like shit after driving like this

T.Dot_E30
04-26-2004, 12:56 AM
hmm so all of a sudden it comes on.

Are sure its not when u step on it, it doesn't release fully?

No ABS right? I guess it might be the master cyclinder but i dont see why it would come on all of a sudden.

Maybe a brake fluid flush will help?

BMW BMXer
04-26-2004, 01:30 AM
No abs, or if I have abs it doesnt work.

I might flush the fluid soon thats what I'm thinking may contribute to the problem

Slowered318
04-26-2004, 02:21 AM
seized caliper? make shure your car is cool.. then take it out for a 10 min drive try to avoid hard breaking.. pull off to the side and what ever rim is hot.. should be the one with the problem

Jordan
04-26-2004, 03:39 AM
85 325e does not have ABS.

Sounds like a faulty and failing master cylinder.

BMW BMXer
04-26-2004, 04:42 AM
Originally posted by Slowered318
seized caliper? make shure your car is cool.. then take it out for a 10 min drive try to avoid hard breaking.. pull off to the side and what ever rim is hot.. should be the one with the problem

When it does it ALL the rims are hot.

Jordan you said that before. I was just hoping it was something else since I doubt those are cheap. Is there anyway to no for sure?

Jordan
04-26-2004, 05:24 AM
its VERY easy to swap out a MC. Just get a known good used one. People on R3V are always parting out cars.

FYI make sure to get a non-abs one off a early eta.

BMW BMXer
04-26-2004, 06:16 AM
I just read about replacing it in my Haynes manual. Seems fairly simple, much simplier than swapping springs and struts.

I'll keep an eye out for one.

Thanks

BMW_M52_M20
04-26-2004, 03:00 PM
Master cylinder or brake booster? A customer has the same issue and it was the brake booster because of a vaccum problem with the brakes and the calipers would hold sometimes.
Do you have any scaring or deep lines on the rotors?
Jay

BMW BMXer
04-26-2004, 04:35 PM
Somewhat ya.

BMW BMXer
04-26-2004, 10:01 PM
The rear rotors are def scarred. Front somewhat.

Its getting worse. Foot to the floor in forth gear on derry and I couldn't pass 80km.

e30-323ti
04-26-2004, 11:40 PM
bimmerbushi on bimmerforums had a similar problem, duuno what is was or if he has fixed it, drop him a line.

punnzzells
04-28-2004, 04:26 PM
it sounds like it is a faulty brake booster or master .... when you brake do you get a lot of vibration and shaking in the steering wheel?

I have a similiar problem, but I think that my caliper is sticking.... brakes can be a big pain in the ass!

mike.

BMW BMXer
04-28-2004, 04:35 PM
I got a new master installed.

Ya mime Id would virbate a lot

T.Dot_E30
04-28-2004, 06:31 PM
did it fix the problem?

Mystikal
04-28-2004, 06:36 PM
Good, now you can come out to the E30 meet this Saturday. *th-up*

BMW BMXer
04-28-2004, 10:41 PM
For now its fixed

raffa
04-29-2004, 01:57 AM
If you still have problem with your brakes,check your flex lines.One or more of them may be colapsed internaly.In that case brake fluid will travel to the caliper/wheel cylinder under pressure,but it will take some time for that caliper/wheel cylinder to release due to colapsed flex line.Find out which wheel tends to drag,than check flex line to that wheel.This will most likely solve your problem if master cylinder did not.

raffa
04-29-2004, 04:23 AM
If this brake problem occures right after brake was applyed,your flex lines could be problem.Looks like that is not case with your car.In that case if brakes start braking on they own while you are accelerating,I think you have booster problem.To find out, you can disconect booster(plug vaccum line),drive car on the parking lot and see if same problem occures again(braking will take much more effort without booster).If wheels stop draging,you will know what is your problem.I hope this will help you.

P.S. If your brake pedal is pulsating, and/or steering wheel is shaking, you most likely have warped rotors due to overheated brakes!

BMW BMXer
04-29-2004, 05:49 AM
Originally posted by raffa


P.S. If your brake pedal is pulsating, and/or steering wheel is shaking, you most likely have warped rotors due to overheated brakes!

For sure, I was driving around with the master screwed for too long.