Everything you wanted to know about brake boosters and master cylinders

[BigD]

I found an IX booster and MC for around $80 from my buddy bill over at MSR. Call him at 201-675 6658 and see if he can get you one. If he can't I know he can find someone who can. Tell him Jason sent you.

You will also want the 25mm E34 M5/E32 735 MC (or a complete 735 booster/MC assembly, which is the same booster as the iX and same MC as the M5)

[grib]

Stock booster?

I have noticed in reading this forum, AKG and Zionsville that it seems to be common practice to replace the e30 brake booster with an e21 or iX/e32 model booster. Is there any advantage to doing this besides fitment?

I currently have my S52 (without driveline) test mounted up in the engine bay of my 87 325i convertible. With everything (manifold, t-body/boot) in place it would appear that the stock booster might work. I am using e28 M5 mounts with a half inch spacer on the driver side only. There appears to be almost a half inch of clearance between the manifold and the booster. If I shave the bottom portion of some of the manifold fins it would be almost 3/4" of an inch. I will also need to put the hood back on to check the height. I have attached some pictures below, keep in mind that the tranny is not mounted so the pitch angle may not be exact.

My question for those of you already running this swap is - how much does the the engine move around? Does the manifold expand much when it heats up? If a half to 3/4 inch is enough clearance then I would much prefer to keep the stock setup as I am reasonably pleased with my brakes.

Thoughts? :up: :down:

[triggrhaapi]

You will also want the 25mm E34 M5/E32 735 MC (or a complete 735 booster/MC assembly, which is the same booster as the iX and same MC as the M5)

I really don't see why that's necessary, as the ix is an E30 and that setup should stop it just fine. I'm going to run a remote reservoir system to help the intake boot clearance issue. From what I can tell people like the E34 M5 MC because it's bigger and has a firmer pedal feel. I like the way it is now, and I figure with the ix MC it should be about the same. I have Zimmerman rotors and Porterfield semi race pads, so I really don't need major mods to my stops.

[matt]

The 25mm master cylinder won't make your car stop faster... it's just for pedal feel.

Oh, and it shifts the brake bias slightly rearward, which is a good thing, usually.

[triggrhaapi]

I have noticed in reading this forum, AKG and Zionsville that it seems to be common practice to replace the e30 brake booster with an e21 or iX/e32 model booster. Is there any advantage to doing this besides fitment?

I currently have my S52 (without driveline) test mounted up in the engine bay of my 87 325i convertible. With everything (manifold, t-body/boot) in place it would appear that the stock booster might work. I am using e28 M5 mounts with a half inch spacer on the driver side only. There appears to be almost a half inch of clearance between the manifold and the booster. If I shave the bottom portion of some of the manifold fins it would be almost 3/4" of an inch. I will also need to put the hood back on to check the height. I have attached some pictures below, keep in mind that the tranny is not mounted so the pitch angle may not be exact.

My question for those of you already running this swap is - how much does the the engine move around? Does the manifold expand much when it heats up? If a half to 3/4 inch is enough clearance then I would much prefer to keep the stock setup as I am reasonably pleased with my brakes.

Thoughts? :up: :down:

I'm also running E28 mounts. I'm not spacing anything, however, I'm just mounting it in straight, like AKG. I bet that half inch spacer is where you're getting your clearance from...

[matt]

I'm also running E28 mounts. I'm not spacing anything, however, I'm just mounting it in straight, like AKG. I bet that half inch spacer is where you're getting your clearance from...

Clearly.

He will have issues when he goes to mount the downpipe. These motors need a small spacer on the exhaust side of the motor.

[triggrhaapi]

The 25mm master cylinder won't make your car stop faster... it's just for pedal feel.

Oh, and it shifts the brake bias slightly rearward, which is a good thing, usually.

Haha, that's what I said. If I think the pedal feels sloppy I'll definitely change it out, but I don't really like the idea of a more rearward brake bias in a car that is going to have torque up the yin yang and short gearing. I can damn near kill myself as it is with the M20b25 in there. It's not like understeer is an issue, even with the stock suspension on the car. It's a fucking dart man. Point and shoot.

[triggrhaapi]

Clearly.

He will have issues when he goes to mount the downpipe. These motors need a small spacer on the exhaust side of the motor.

How small? I have Supersprint long tubes to fit.

[matt]

I needed about 6mm to fit the stock downpipes. It can vary some though.

[triggrhaapi]

I needed about 6mm to fit the stock downpipes. It can vary some though.

I'll cut some washers to make shims, thanks for the heads up.

[e30_kid89]

right now im getting owned by the sway bar.....but im not running any spacers maybe i should...i just need a couple more mm to clear....

[matt]

When the car is off the ground, the sway bar comes UP toward the exhaust. When the wheels are on the ground, it's better.

For spacers, I used washers from under the headbolts.

[triggrhaapi]

When the car is off the ground, the sway bar comes UP toward the exhaust. When the wheels are on the ground, it's better.

For spacers, I used washers from under the headbolts.

Haha, I was planning on putting the car up on ramps for most of the swap anyway, since I won't need to take off the wheels until it comes time to replace the brake fluid and bleed the brakes, which is after I bleed the MC.

[e30_kid89]

matt - just a question i was wondering did u have to lift up your motor to slip on the downpipes? thats what ive been having to do whenever fitting the downpipe closest to the front of the car.

[matt]

I don't think so... I put a decent dent in the pipe and used a couple of spacer washers on the mount and it works.