BMW Brakes.., ehhh...aint THAT great.. Options

[914ghost]

So, I gets a set of 320i brake calipers off a wrecked car the other day.
Very good clean condition, pads are like new. They were FREE, so what the heck right?
I got a 70' so ..they bolt right on -- RIGHT?
Not quite, but pretty slick.
Bend the brake line, I had to grind on the outside of the actual caliper body just a smidge (through the part# stamping) because my wheels hit'm - 2 liter fuchs, totally stock. Not sure about that - anyways,
Okay, bolt'em on, bleeed, bleed, bleed...adjusted the proportoning (big word) valve rod all the way in...tried IN and OUT not much diff.
Pedal is still a bit soft, but works. Summary is: No Big deal, maybe I need the big Master cylinder? They work about as good as before.
Pad area is like 40% larger, but it's not much of a difference-
did I forget something?
-Bob O

[banderson]

I did the conversion and was not impressed either. (IMG:style_emoticons/default/barf.gif) Stopping distance feels down, and I still get fade at the track.

As I see it, there are 2 separate issues:

1. STOPPING DISTANCE. This is controlled by BIAS between the front and rear. You want all for wheels to exert there own maximum stopping force on the road. This is best achieved by having a slightly oversized rear caliper and an adjustable proportioning valve. By increasing the front (320I) the rears became less effective, even with a "T".

2. FADE/HEAT BUILDUP. This is controlled by airflow. Vented calipers have squirrel cage fans built into them. This works best. An other good method is ducting. Adding mass or pad area is not a solution. This is what is great about the mythical 4 lug 911 hubs.

YMMV