M50 swap that will blow your mind.

[cdl723]

Well I ended up ordering a clevis from McMaster-Carr that was 20mm longer than the stock e30 clevis and cutting m10x1.5 threads into it. I also remade hard lines from the ABS unit and looped them around to fit. The part number is for the clevis 2448K51. I had to trim it a few mm to fit on the threads as there was not a ton of room to adjust it with a locking nut.

The brakes feel assisted, but firm all the way up until I get close to locking the brakes up. At about 80% of the pedal travel/deceleration the pedal gets really stiff and it takes almost double the force to get the last 20% to lock the brakes up. I am wondering if anyone else has experienced this or if the booster is bad?

[jc1000]

It's a proportioning valve only on those models/that year. I have the same. Some people get rid of theirs. I went through the extra effort to bend the lines and relocate it to underneath the master, positioned horizontally. See my post above, you can baaarely see it hidden under there. I'll try to get a better photo soon.

Hey Chilezen! I am doing the E90 swap now and have ABS and the proportioning valve. Would you recommend keeping the proportioning valve? Why do people get rid of it? It seems easy enough to route the lines from the new master straight to it and hang it below as you did. And keeping it doesn't limit the benefit of the swap, right?

[Chilezen]

Hey Chilezen! I am doing the E90 swap now and have ABS and the proportioning valve. Would you recommend keeping the proportioning valve?

I can't say I've had a point of reference to compare; I mean I don't know how the brakes would feel if I didn't have the proportioning valve. I've kept it the way BMW intended it, but, they designed it to be used with the original master cylinder, sooo... maybe there will be a difference. I don't know exactly how much that valve alters the flow rate of the brake fluid to the rears, and I don't know if the E90 master has that "value" incorporated.

I think in order to get rid of it, you'd have to extend the lines with unions to be able to reach the master.
Getting rid of the valve doesn't reduce the number of connections unless you run entirely new hardlines to the master.

I did have to alter the bends of the existing lines to get the proportioning valve to sit correctly. So either way, you are bending the lines.

I haven't experienced any "unusual" feelings regarding the brake bias with this setup. I have braked hard and felt the ABS engage, and any spirited driving I've done hasn't caused unpredictable trail braking/understeer. So. I'll just say the system works fine as it is.

[jc1000]

I can't say I've had a point of reference to compare; I mean I don't know how the brakes would feel if I didn't have the proportioning valve. I've kept it the way BMW intended it, but, they designed it to be used with the original master cylinder, sooo... maybe there will be a difference. I don't know exactly how much that valve alters the flow rate of the brake fluid to the rears, and I don't know if the E90 master has that "value" incorporated.

I think in order to get rid of it, you'd have to extend the lines with unions to be able to reach the master.
Getting rid of the valve doesn't reduce the number of connections unless you run entirely new hardlines to the master.

I did have to alter the bends of the existing lines to get the proportioning valve to sit correctly. So either way, you are bending the lines.

I haven't experienced any "unusual" feelings regarding the brake bias with this setup. I have braked hard and felt the ABS engage, and any spirited driving I've done hasn't caused unpredictable trail braking/understeer. So. I'll just say the system works fine as it is.

Fair enough, thanks. I think I will give keeping it a try for now.