e34 remote brake booster install

[noid]

Whos car is that? I think thats the guy with the hydroboost setup right?


Would be cool to have a DIY guide on the linkages, or for him to produce/sell them.

[Jean]

I don't know if you guys have seen this, what are your thoughts on doing something like this?

[JGood]

Made some good progress today. Ditched the clutch master cylinder spacer idea and built a separate bracket to space it away from the pedal box, so that I have full clearance for the linkage. I had to cut and grind in a LOT of places to make this all work. I now have full pedal travel, only limited by the e34 linkage parts themselves, so I will have the same travel a stock e34 would have. I was able to connect the linkage at the same height on the brake pedal as stock, so my pedal effort shouldn't change either.

[Jean]

I will take a look at the 540i and 525i MC's and see what they show.

I don't believe they were all 25mm....

[JGood]

My config is the same as well, no abs in this car, MC with 3 lines vs 2.

Are you answering me, or asking the same question as me? Lol.



Did some searching on realoem, looks like all V8 e34 MC's produced after 9/93 come with a third output, and it's plugged from the factory. On the pre 9/93, that hole is not there.

I'll have to look at mine again, I forget if mine is from an e34 or e32, and have no idea what year it is. I'm assuming that second hole could be used for non-abs cars?


It's the hole with with the bolt in as a plug:





Does anyone know what the MC size is? I know the 25mm MC was a huge upgrade on my e30 track car, the pedal is much firmer, and I'd be fine with the travel this setup is giving me, as the pedal barely moves.

[Jean]

My config is the same as well, no abs in this car, MC with 3 lines vs 2.

[JGood]

While we're on the braking topic...

My car is non-ABS, so the stock MC has 3 outputs, 1 for each front wheel and one for the rear wheels.

Will I be OK running a 'T' for the front wheels, since there is only 2 outputs on the e34 MC? Or does that drop the overall front pressure, requiring more travel, and reducing the front/rear bias?

[JGood]

Garey - Would you be able to check the linkage motion distance on your e34? I'm getting a total of 3-1/8" of rod travel (the long rod that connects the firewall bracket with the booster bracket). It seems like it would be JUST enough when looking at the amount the pedal is moving. But, when I operate just the e34 linkage stuff itself, not connected to the pedal, it only has ~4" of travel before it starts binding up on itself. And I'm sure BMW didn't design it to bottom out at just over the usable motion range. So that tells me I might be good with what I have.

Here's a video I made showing where some of the binding spots are, and my usable travel. The clevis doesn't fit down in between the M/C and pedal bracket when depressed, due to the length of the pin and bulkiness of the c-clip, etc... But- the arc of the pedal is such that it won't allow the linkage to depress any further even if there was clearance, it's at too much of an angle, it binds up on the hole in the firewall pivot bracket due to the angle, and in addition the clevis actually binds on the pivot itself due to the angle. So all of these things are happening at once.. which is actually kind of good I guess, because hopefully the pedal never has to go down that far...

[JGood]

Lol, I do now. Now I'm going to have to watch that tomorrow instead of work on the car!

[bmwmech1]

Says the guy who started his build before I was born...

Thanks... I just spit my milk all over the coffee table... jerk, lol!

Garey

EDIT: Did you get the Caddyshack reference?

[JGood]

Says the guy who started his build before I was born...

[bmwmech1]

Yeah, I would just hate to run into a situation where a brake master cylinder went bad or something, and I needed the additional travel, but was limited by binding of the linkage. I think it rests at the fully extended position, or very close to it. The brake light switch and bracket seem to be the 'stop' for that.

I have another idea instead of those spacers, which would give me all the clearance I need for the clevis, and provide a more solid mount for the clutch master cylinder.

Will report back tomorrow :)

Well... we're waiting...

Garey

[JGood]

Yeah, I would just hate to run into a situation where a brake master cylinder went bad or something, and I needed the additional travel, but was limited by binding of the linkage. I think it rests at the fully extended position, or very close to it. The brake light switch and bracket seem to be the 'stop' for that.

I have another idea instead of those spacers, which would give me all the clearance I need for the clevis, and provide a more solid mount for the clutch master cylinder.

Will report back tomorrow :)

[bmwmech1]

The one thing to keep in mind here is that the pedal arm, unless something catastrophic happens, will never be fully extended or fully depressed. Actual effective travel is minimized to a much smaller arc. What you need to figure out is how much actual pedal travel is needed to effect maximum rod travel at the booster. That will give you the real travel arc of the pedal arm...;-)

Garey

[JGood]

Cool, thanks Garey. Looks like I'll be good to go!


I got some proper hardware to mount the MC today. I'm going to try to find some stainless spacers for the final version, I got the brass pieces so I could easily cut/grind them for fitment. It's very sturdy, doesn't flex at all. Not sure if that will change when there's actually hydraulic pressure...

I need to work on the movement of the arm that reaches in to the pedal. Right now, it can fully extend and retract, but not in the arc that it will be moving in when attached to the pedal, it would bind up on one of the MC mounting bolts. So, I either need to have a pivoting attachment point on the pedal to allow the arm to move along it's own path, or move the pivot point on the firewall bracket to allow for more movement of the arm. I also need to trim down the pedal bracket, as the pedal and clevis get seperated by it when fully depressed. I'm sure none of this makes sense to anybody, unless you have this exact setup right in front of you. haha

On to the pics. New hardware:






Pedal and arm fully extended:






Pedal and arm fully depressed: