Brake Problem

[BMW BMXer]

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

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]

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]

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]

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]

85 325e does not have ABS.

Sounds like a faulty and failing master cylinder.

[BMW BMXer]

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]

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]

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]

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]

Somewhat ya.

[BMW BMXer]

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]

bimmerbushi on bimmerforums had a similar problem, duuno what is was or if he has fixed it, drop him a line.

[punnzzells]

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]

I got a new master installed.

Ya mime Id would virbate a lot

[T.Dot_E30]

did it fix the problem?