Brake booster rod adjustment? 77 530i

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canada karl
Posts: 1064
Joined: Tue Jan 06, 2009 3:50 pm

Brake booster rod adjustment? 77 530i

Post by canada karl »

Most brake boosters have a method of adjusting the push rod but I don't see it here. The reason I want to adjust is because the calipers are locking on.
1976 530i. BMW 59 Triumph TR3A(rolling resto). 67 Triumph TR4A(salvageable). 86 900S Winter car
canada karl
Posts: 1064
Joined: Tue Jan 06, 2009 3:50 pm

Re: Brake booster rod adjustment? 77 530i

Post by canada karl »

Hi Mike I just measured the depth of the rod and it appears to be on spec at 1.92" so My theory that the rod is not adjusted properly is probably wrong. I do hear the air hissing coming from the booster so I believe the booster has failed. Can the booster fail and intermitenly lock the brakes on? My understanding is you can still drive with a dead booster but you have to press harder on the pedal. I can drive sometimes and stop by applying extra pressure on the brake pedal but sometimes the brakes do lock up? Would the brake lock up be normal for a failed booster or is something else going on. Karl
1976 530i. BMW 59 Triumph TR3A(rolling resto). 67 Triumph TR4A(salvageable). 86 900S Winter car
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Mike W.
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Re: Brake booster rod adjustment? 77 530i

Post by Mike W. »

The measurement spec if fine, but what's important is that there's some free play. Not a lot, but some. You can't have any preload on the M/C at all.

I've been seeing some of this on Mye28.com and it seems to be caused by a bad M/C. Not quite sure how, it's not that complicated a device, maybe a plugged port or something in it. They do still seem to be available, but rather expensive. Now being the cheap SOB I am, if it's not out of adjustment I'd buy a kit and rebuild it. Coming from Latvia there's some on ebay for not a whole lot of money. On the other hand, if your M/C is rusted and pitted, a new kit won't last long if at all.

https://www.ebay.com/sch/i.html?_from=R ... 3&_sacat=0

On the booster, correct, a leaky booster will first manifest itself by not having a residual stop or two after the car is shut off, then if bad enough not providing enough or even any boost, but not automatic braking, just lack of boost.
Mike W.



1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
2000 528iit, Vacation mobile/wife's grocery getter
dutch
Posts: 27
Joined: Sat Apr 15, 2023 8:22 am

Re: Brake booster rod adjustment? 77 530i

Post by dutch »

could it be as simple as old brake hoses that won`t allow fluid to flow back...? Or are all brakes locking
canada karl
Posts: 1064
Joined: Tue Jan 06, 2009 3:50 pm

Re: Brake booster rod adjustment? 77 530i

Post by canada karl »

dutch Stainless steel brake hoses. did you ever get your brake booster issue sorted out?
1976 530i. BMW 59 Triumph TR3A(rolling resto). 67 Triumph TR4A(salvageable). 86 900S Winter car
canada karl
Posts: 1064
Joined: Tue Jan 06, 2009 3:50 pm

Re: Brake booster rod adjustment? 77 530i

Post by canada karl »

Mike I do not know how the 0.020" clearance is to be set. The brake booster on the 530i is like a big cavern. I was able to disconnect and pull back the MC enough to see inside without disconnecting the brake lines. I'm new to working on brake boosters but I assume the push rod would have a lock nut that would have to be undone to adjust the clearance.....how a person would access it way back in there beats me? Or the push rod is simply turned in or out by hand, I'm going to put a boroscope in the cave to see what's going on in there. Most of the videos you see on the Internet on how to adjust booster push rods do not have an MC like the 530i that has a 3" metal tube protruding from it. The MC was rebuilt. Best thing I can do is contact the guy I sold my 76 530i parts car to get the booster of it. It seems there was a change in the booster set up from 76 to 77.
1976 530i. BMW 59 Triumph TR3A(rolling resto). 67 Triumph TR4A(salvageable). 86 900S Winter car
dutch
Posts: 27
Joined: Sat Apr 15, 2023 8:22 am

Re: Brake booster rod adjustment? 77 530i

Post by dutch »

I`m not sure about the 530i booster but on my 528 it looks like it can be adjusted by disconnecting the pedal from the rod , loosen the counter nut and turn the fork in or out.
canada karl
Posts: 1064
Joined: Tue Jan 06, 2009 3:50 pm

Re: Brake booster rod adjustment? 77 530i

Post by canada karl »

Thanks for the info. I will have a look
.
1976 530i. BMW 59 Triumph TR3A(rolling resto). 67 Triumph TR4A(salvageable). 86 900S Winter car
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