Stuck brakes M535i
Stuck brakes M535i
Hello friends,
I have a problem with my 86er M535i. After driving the car for +- 15 minutes, I notice that there is a "free play" on my brake pedal, and that my brakes (I think all 4?" are getting stuck. I have reserved the calipers all with new gaskets, and guide bushes. I did not replace the brake pistons because they looked neat. I have the impression that the brakes also get stuck when the car idles for a long time for 10-15 minutes. So it has to do with "heat" All brake hoses have already been renewed, this did not help either. Who has experience with this, and does anyone have an idea where this problem comes from? Thanks in advance!
Yours sincerely,
M535i
I have a problem with my 86er M535i. After driving the car for +- 15 minutes, I notice that there is a "free play" on my brake pedal, and that my brakes (I think all 4?" are getting stuck. I have reserved the calipers all with new gaskets, and guide bushes. I did not replace the brake pistons because they looked neat. I have the impression that the brakes also get stuck when the car idles for a long time for 10-15 minutes. So it has to do with "heat" All brake hoses have already been renewed, this did not help either. Who has experience with this, and does anyone have an idea where this problem comes from? Thanks in advance!
Yours sincerely,
M535i
Re: Stuck brakes M535i
Did this happen after your brake rebuilding, or was it happening before and that's why you were rebuilding the calipers?
Re: Stuck brakes M535i
This probably won't be much help, but on my US spec 535i I ran into a problem where if I was sitting, foot on the brake pedal for a long time, 10-15 minutes??? they would lock up. Actually I think it was fronts only, but I'm not positive. It could idle for a long time just fine, but if I had my foot on the pedal, not hard, but on it, they could lock up. Solution was to push on the pedal hard, then they would free up and all was well.
I figured out if I was going to be sitting for 10 minutes or more I could just put it in neutral and put on the parking brake to avoid problems. Never actually fixed it, just did a work around.
I figured out if I was going to be sitting for 10 minutes or more I could just put it in neutral and put on the parking brake to avoid problems. Never actually fixed it, just did a work around.
Re: Stuck brakes M535i
Interesting too.. but I have another problemMike W. wrote: ↑May 19, 2023 1:55 AM This probably won't be much help, but on my US spec 535i I ran into a problem where if I was sitting, foot on the brake pedal for a long time, 10-15 minutes??? they would lock up. Actually I think it was fronts only, but I'm not positive. It could idle for a long time just fine, but if I had my foot on the pedal, not hard, but on it, they could lock up. Solution was to push on the pedal hard, then they would free up and all was well.
I figured out if I was going to be sitting for 10 minutes or more I could just put it in neutral and put on the parking brake to avoid problems. Never actually fixed it, just did a work around.
Re: Stuck brakes M535i
Same problem in my 525i when I bought the car.....the problem (solved) was a bad Brake Master Cylinder, this unit get stuck when press the pedal.
Re: Stuck brakes M535i
I once experienced brakes that would lock up when hot because of an internal leak in the booster cylinder.
You could test this by getting the lock up condition, stopping the engine and pumping the brakes to discharge the accumulator. If the car then rolls (engine off), it probably is the booster.
You could test this by getting the lock up condition, stopping the engine and pumping the brakes to discharge the accumulator. If the car then rolls (engine off), it probably is the booster.
Re: Stuck brakes M535i
I don't think I understand that last part. As far as I know, the car should (after pumping on the pedal) just roll. Surely the brakes shouldn't get stuck when you pump the pedal? Or do I misunderstand you?Federico wrote: ↑May 19, 2023 10:04 AM I once experienced brakes that would lock up when hot because of an internal leak in the booster cylinder.
You could test this by getting the lock up condition, stopping the engine and pumping the brakes to discharge the accumulator. If the car then rolls (engine off), it probably is the booster.
Re: Stuck brakes M535i
The idea is to discharge the brake bomb/accumulator so that there is no pressure left in the system. If there is a leak inside the booster cylinder, it could push your brakes slightly, as if you were riding the pedal. It cannot do that if there is no pressure in the steering/booster circuit.Alberto89 wrote: ↑May 19, 2023 8:26 PMI don't think I understand that last part. As far as I know, the car should (after pumping on the pedal) just roll. Surely the brakes shouldn't get stuck when you pump the pedal? Or do I misunderstand you?Federico wrote: ↑May 19, 2023 10:04 AM I once experienced brakes that would lock up when hot because of an internal leak in the booster cylinder.
You could test this by getting the lock up condition, stopping the engine and pumping the brakes to discharge the accumulator. If the car then rolls (engine off), it probably is the booster.
So:
Warm it up until the brakes drag
Stop the engine
Pump the pedal until hard/no boost
Check if the car rolls easier now.
Re: Stuck brakes M535i
I'll give it a try. Do I have to do something about the brake bomb before I perform this action?
Re: Stuck brakes M535i
Yes, I changed the BMC myself, it's not difficult and just requires some tools and patience. In a photo to the left you can see the original unit (more than 30 years old) where you can see that the cylinder was stuck inside. When driving, the brake would stick after hitting the brake once or twice...after a while it would slowly release. First I thought about the Booster, but when I disassembled I realized that the problem was the BMC and that solved all the stuck brakes problem.
Re: Stuck brakes M535i
Had the same problem when the car had fully warmed up - it was caused by the bush at the end of the master which deteriorates over time and swells when hot, gripping the rod and not letting it return, When the car cools down the problem disappears.
There's an excellent writeup on an E24 site - remove master, strip cylinder, slightly ease bush and reassemble, but removing the retaining circlip then extracting the rod and seals takes care - try to find the E24 post. Apologies I don't have the link still. Cost is entirely in your time plus fluids - might be worth emptying the steering/servo fluid first - mine drained itself onto the garage floor.
There's an excellent writeup on an E24 site - remove master, strip cylinder, slightly ease bush and reassemble, but removing the retaining circlip then extracting the rod and seals takes care - try to find the E24 post. Apologies I don't have the link still. Cost is entirely in your time plus fluids - might be worth emptying the steering/servo fluid first - mine drained itself onto the garage floor.
Re: Stuck brakes M535i
Thank you for sharing your experience. How did you bleed the brakes?Aldo525 wrote: ↑May 20, 2023 11:25 AMYes, I changed the BMC myself, it's not difficult and just requires some tools and patience. In a photo to the left you can see the original unit (more than 30 years old) where you can see that the cylinder was stuck inside. When driving, the brake would stick after hitting the brake once or twice...after a while it would slowly release. First I thought about the Booster, but when I disassembled I realized that the problem was the BMC and that solved all the stuck brakes problem.
Re: Stuck brakes M535i
Thank you. I'm going to look for the post from the E24 forum!Maaaate wrote: ↑May 25, 2023 7:53 AM Had the same problem when the car had fully warmed up - it was caused by the bush at the end of the master which deteriorates over time and swells when hot, gripping the rod and not letting it return, When the car cools down the problem disappears.
There's an excellent writeup on an E24 site - remove master, strip cylinder, slightly ease bush and reassemble, but removing the retaining circlip then extracting the rod and seals takes care - try to find the E24 post. Apologies I don't have the link still. Cost is entirely in your time plus fluids - might be worth emptying the steering/servo fluid first - mine drained itself onto the garage floor.
Re: Stuck brakes M535i
How??....the old fashion way: My son pumping the brake pedal and I opening every brake bleeding screw until no more dirty fluid or bubbles (starting from Rear Right....then Rear Left.....then Front Right.....finally Front Left). Take care on the fluid level at reservoir. First remove all the fluid you can extract from the reservoir using some device like a suction pump, add new fluid to top and check and refill accordingly the reservoir going empty during the bleeding.
Re: Stuck brakes M535i
I cannot find the link. Might have been on a UK forum. It's over five years since I did this.
Key points are:
-the snap ring which holds the internals in place is made so you can't easily get it out. Drill a fine hole through the side of the cylinder to the snap ring, near the end whose overlap will allow you to push it inwards using for instance the blank end of a drill bit one size down, to get purchase and lever the ring out.
-to get the shaft, bush and internals out, you need to pull the shaft. Put something - a 1/4 drive socket - inside the shaft so that when you grip it, with protective wrapping, in a vise, you don't crush it. With the shaft held in the vise, carefully tap the brake cylinder around its periphery - not the lugs as they break off, until the bush and internals come out.
-relieve the bore of the bush, and maybe the outside, a very small amount. I think I used some abrasive sheet.
-assembly is of course the reverse. I considered finding an internal circlip to replace the snap ring, but the nearest store is a 40mi round trip. But replace the circlip so it lines up correctly with the hole you drilled.
The link I can't find describes this really well with photos.
Key points are:
-the snap ring which holds the internals in place is made so you can't easily get it out. Drill a fine hole through the side of the cylinder to the snap ring, near the end whose overlap will allow you to push it inwards using for instance the blank end of a drill bit one size down, to get purchase and lever the ring out.
-to get the shaft, bush and internals out, you need to pull the shaft. Put something - a 1/4 drive socket - inside the shaft so that when you grip it, with protective wrapping, in a vise, you don't crush it. With the shaft held in the vise, carefully tap the brake cylinder around its periphery - not the lugs as they break off, until the bush and internals come out.
-relieve the bore of the bush, and maybe the outside, a very small amount. I think I used some abrasive sheet.
-assembly is of course the reverse. I considered finding an internal circlip to replace the snap ring, but the nearest store is a 40mi round trip. But replace the circlip so it lines up correctly with the hole you drilled.
The link I can't find describes this really well with photos.
Re: Stuck brakes M535i
Binding brakes/faulty master cylinder; mystery solved???
https://bigcoupe.com/phpBB2/viewtopic.p ... 18c9c65d9f
https://bigcoupe.com/phpBB2/viewtopic.p ... 18c9c65d9f
Re: Stuck brakes M535i
Hey guys, I'm just now seeing this post. Will I no longer be notified of new messages? Thank you all for your answers. I appreciate it. @maaate, thanks for your detailed information. I can't follow it well because my English / American is not good. I installed a new master brake cylinder today. Fill and bleed brake fluid tomorrow. Am curious! I'll keep you informed.