stock brake booster relocated?

[jalopi]

Yep that's the exact kit.

Used this website to get the following figures:

http://www.jakelatham.com/radical/info/brake_calculators.shtml

Our cars need about 3200 ft/lbs of braking torque to have "good performance" brakes. With the massive kit, stock hydraulics & all you're looking at about 865 ft/lbs with 70lbs of leg input.

3/4" master will bump you up to 1246 ft/lbs.

3/4" + e36 sized brakes will bump you up to 1865 ft/lbs

3/4" + e46 330i sized brakes will get you up to 2524 ft/lbs

5/8" + e46 330i sized brakes will finally net you 3635 ft/lbs of braking torque, though you really need a dual master system for a cylinder that small. Eventually this is what I'd like to do, make my pedal configuration not suck balls and gain an extra 1000 ft/lbs of braking power at the same time



Also, running the lines isn't that hard, I'll take a picture of what I did if it stops raining sometime today.

[The Dark Side of Will]

though you really need a dual master system for a cylinder that small.

You realize that a dual master cuts your line pressure vs. pedal effort in half, right?

[jalopi]

no, running two masters doesn't effect line pressure. dual master systems allow you to run smaller master cylinders (which effects line pressure & pedal effort) because they address the primary weakness of small MC's - not moving enough fluid. that and you gain the safety of having two brake circuits instead of one.

an apples to apples comparison would be that if you had the same size master cylinders in a single and dual setup, lines pressures and pedal efforts would stay the same, but the amount of distance you have to push the pedal for the pads to make full contact with the rotors would be halved. this is the reason most dual setup guys can run 5/8" masters; us single setup guys would have an engagement point that's damn near at the floor, as e30_302 will attest to.

so yeah, previous statement still stands. you should probably do your homework before you call people out in a rude way...

[The Dark Side of Will]

no, running two masters doesn't effect line pressure. dual master systems allow you to run smaller master cylinders (which effects line pressure & pedal effort) because they address the primary weakness of small MC's - not moving enough fluid. that and you gain the safety of having two brake circuits instead of one.

an apples to apples comparison would be that if you had the same size master cylinders in a single and dual setup, lines pressures and pedal efforts would stay the same, but the amount of distance you have to push the pedal for the pads to make full contact with the rotors would be halved. this is the reason most dual setup guys can run 5/8" masters; us single setup guys would have an engagement point that's damn near at the floor, as e30_302 will attest to.

so yeah, previous statement still stands. you should probably do your homework before you call people out in a rude way...

We're talking about dual MC's and a balance bar, right?

If there is 100 lbs of load on the pedal and a 6:1 pedal ratio, there is 600# of force at the MC. On a single MC with 1 sq in of piston area, that makes 600 psi of line pressure. On a dual MC, each with 1 in^2 and the balance bar set 50/50, the same loads are spread across 2 in^2 of piston area and you get 300 psi of line pressure.

Now if you're talking about a production style dual circuit MC, that's something else, but I didn't think that was the case due to the name "Wilwood" being thrown around.

[e30_302]

You wanna try miserable, run a 1" dual bore Wilwood.

[smalcol]

Wait, are some of you guys running a single circuit brake system now? That's a really bad idea. Seriously. There haven't been single circuit brakes in a BMW since what the mid 60's?

[danval]

Has anybody tryed using 2 stock master cylinders and no booster? With their proportioning valves of course

[e30_302]

Wait, are some of you guys running a single circuit brake system now? That's a really bad idea. Seriously. There haven't been single circuit brakes in a BMW since what the mid 60's?

No one said it was a safe idea #YOLO

[jalopi]

[e30_302]

LOL

It isn't smart though, I'm going to look into a dual circuit that's the right size.

[bmk]

Yep that's the exact kit.


Also, running the lines isn't that hard, I'll take a picture of what I did if it stops raining sometime today.

Did you get a chance to snap some pics?

[Stvstr]

Has anyone tried or looked at a step bore m/c that is designed to push a large volume of fluid at the start of the stroke then transition to a smaller bore to build appropriate pressure? 80's Volvos used one that has a 5/8 bore for the secondary.

I bought one to experiment but am having trouble deciding how to route the lines in an e30 so I may have to get a Volvo distribution block. Also I seem to have failed at bench bleeding the m/c as the pedal sinks to the floor even after bleeding all 4 calipers.

[e30_302]

Update: Apparently the Porsche 914 master cylinder (dual circuit) has a 17mm (just slightly larger than 5/8") bore, and a mounting hole spacing close enough to make work. I think I'll have a go at it.

[jalopi]

The ones I found were expensive as fuck though

[e30_302]

Yeah, gonna have to be patient on eBay.