Author Topic: Make brakes firmer by swapping booster? (Read 3720 times)

josephb983 · « **on:** March 21, 2008, 12:09:10 PM »

I notice my brakes are not as firm on my BMW as on my other cars. It feels like the booster just doesn't push as hard (not a hydraulic leak). What other brake boosters will work on the M42 E30? I've heard of swapping in boosters from a 7 series, but I don't know which will work.

tjts1 · « **Reply #1 on:** March 21, 2008, 02:15:57 PM »

Change the brake fluid and front brake pads. New thick brake pads reduce the total volume of the brake system circuit compared to think worn out pads. Brake fluid should be replaced every 2 years.

Wise Old Dog · « **Reply #2 on:** March 21, 2008, 02:37:15 PM »

The e30 m3 has a larger bore piston that will reduce your brake pedal travel. IIRC there are also upgrades available from bimmerworld. That's the route I went. Big difference in the feel.

quinn11m20 · « **Reply #3 on:** March 21, 2008, 05:35:19 PM »

Stainless steel brake lines work, as well. Also from bavarian autosport there is a little bronze bushing they have that installs on the caliper that gives a firmer pedal feel. http://www.bavauto.com

magnum2066 · « **Reply #4 on:** March 22, 2008, 02:30:23 PM »

Quote from: tjts1

Change the brake fluid and front brake pads. New thick brake pads reduce the total volume of the brake system circuit compared to think worn out pads. Brake fluid should be replaced every 2 years.

Quote from: quinn11m20;45224

Stainless steel brake lines work, as well. Also from bavarian autosport there is a little bronze bushing they have that installs on the caliper that gives a firmer pedal feel. http://www.bavauto.com

+2

D. Clay · « **Reply #5 on:** March 22, 2008, 11:27:19 PM »

The calipers do wear in the guide pins and this adds a bit of soft pedal. I replaced my 16 year old rubber lines and it helped a lot. I'm a big fan of a pedal the goes down about an inch and gets very firm. Solid calipers, either 2 or 4 piston also are firmer than the single piston floating type. A worn wheel bearing will also introduce play into the system. The wobble from the bearing or a warped rotor will make the piston retract further. I don't think the booster would be the solution to a soft pedal.

josephb983 · « **Reply #6 on:** March 23, 2008, 01:08:23 AM »

Quote from: D. Clay;45277

I don't think the booster would be the solution to a soft pedal.

Yeah, I went and re-read the original post about the 7 series, and they said to put a new master cylinder from a 735i, and an ix booster to go with it, to make brakes firmer (during an M50 swap). I had miss-remembered the post. Sorry about that.

josephb983 · « **Reply #7 on:** March 23, 2008, 01:14:39 AM »

Quote from: D. Clay;45277

I replaced my 16 year old rubber lines and it helped a lot.

What kind did you put in as replacements? New oem? Or the steel ones?

josephb983 · « **Reply #8 on:** March 23, 2008, 01:18:20 AM »

This topic has yielded very helpful info. Thanks for your posts.

Looks like the trick is to get a bigger bore master cylinder, so less travel.

I don't feel spongyness in the brakes, so I don't think my brake fluid is bad (I've experienced this on another car). I have thick/almost new pads, so not much fluid in the lines. Now I understand why warn pads means less braking power though, thanks!

I'll have to check out the bronze bushing. I know older toyota corollas have very hard core braking, very very responsive. I've also driven new mazdas and they have very firm responsive brakes. I hope to make my E30 just as firm and responsive if possible.

josephb983 · « **Reply #9 on:** March 23, 2008, 01:22:58 AM »

Quote from: quinn11m20;45224

Also from bavarian autosport there is a little bronze bushing they have that installs on the caliper that gives a firmer pedal feel. http://www.bavauto.com

I was not able to find this bushing on bavauto.com

EDIT: I found it, searching "caliper bushing". Thanks.
http://www.bavauto.com/assets/imglib500/CBUK.jpg