Need Help M50 swap MAJOR STRANGE BRAKE ISSUE

[MaksV]

Basically here are the symptoms:

-extrememly overboosted brakes
-after a while the brake booster activates brakes without me touching them.

Specs:
-NV M50
-Stock 325i brake booster slotted over 1/2"
--worked just fine before swap
-working s50 check valve

What I have tried:
-I thought maybe it wasnt opening all the way to allow vacuum on both sides of diaghram so I shortned the fork by a few turns, but this didnt seem to help. I havnt tried to make it longer, but from my understanding of a brake booster that wont help.

I am out of ideas, and I want my car back. This is literally the last problem from the swap I have yet to solve.

[MaksV]

bump

[Edev]

I don't see why people slot their booster over. I didn't do that to mine. My guess would be something that deals with what you've cut away. But then again, I know a few people who haven't had any issues with theirs that way.

[MaksV]

I don't see why people slot their booster over. I didn't do that to mine. My guess would be something that deals with what you've cut away. But then again, I know a few people who haven't had any issues with theirs that way.

Well the intake just about sits on the booster as is. There is no way to get it in there without moving the booster.

[jlevie]

It sounds to me like the booster pushrod isn't returning all the way, perhaps because you have moved it out of a direct line line with the brake pedal.

I've not done an M50 swap (I find the M20B25 is just fine), but my understanding is that the right way to do this is to use a booster that is smaller in diameter. "Slotting it over" sounds like a bad idea.

[MaksV]

I spoke to several people who said slotting is fine, I mean total distance moved i between 1/4" to 3/8".

How do you properly adjust the brake booster? I screwed in the rod from under the dash to make sure it comes back compltely, is there a lock nut, or something thathas to be adjusted from the front?

[jlevie]

The only adjustment there is on the booster is for the clevis that connects to the pedal. If the cause of the problem isn't from offsetting the booster I'd suspect a bad booster. Though I've not heard of one spontaneously applying the brakes.

[MaksV]

The only adjustment there is on the booster is for the clevis that connects to the pedal. If the cause of the problem isn't from offsetting the booster I'd suspect a bad booster. Though I've not heard of one spontaneously applying the brakes.

it worked fine with my m20. Literally just swapped engines, didnt do anything to booster. It worked fine before.

[jlevie]

Well since the only thing you did to a working brake system was to offset the booster, it would seem like that is the cause of the problem.

[MaksV]

Well since the only thing you did to a working brake system was to offset the booster, it would seem like that is the cause of the problem.

sure but I dont understand why. also it is listed as a common thing and there are plenty of people who have done this with no ill effect. So i wonder if I simply need to make some adjustment.

[Wh33lhop]

Because now you are shearing the rod as well and that is probably binding at the coupling between the clevis and the pedal.

When I thought I was going to relocate the booster like this, I modified my brake pedal by drilling a hole through the pedal stalk, then connecting the clevis to the actual pedal (as opposed to the tab that it normally connects to). That would alleviate a lot of the shearing and likely most of the binding.

[MaksV]

Because now you are shearing the rod as well and that is probably binding at the coupling between the clevis and the pedal.

When I thought I was going to relocate the booster like this, I modified my brake pedal by drilling a hole through the pedal stalk, then connecting the clevis to the actual pedal (as opposed to the tab that it normally connects to). That would alleviate a lot of the shearing and likely most of the binding.

I may have to try that, but it would be hard to get a drill in there.

[nrubenstein]

I may have to try that, but it would be hard to get a drill in there.

Taking the pedal out is easy. Is the clevis mounted to the pedal in stock fashion, or to the side of the pedal? Last I checked, you needed to mount to the side to keep the clevis in a straight line.

[Wh33lhop]

That's why you take the pedal out first. ;)

[MaksV]

how do you take the pedal out? currently mounted in stock position, I would love to just put a bolt through there and have the clevis on the side of the pedal and call it a day,without drilling holes.