BMW brakes conversion Options

[ynotdd]

IF you have done the BMW caliber conversion what do you think of it? Does it make a big difference? I autocross and DE a 2.0 4 and have to redo the brakes just want to know if its a good investment or not? (IMG:style_emoticons/default/spank.gif)

[DNHunt]

I like mine but I don't think it made a huge difference. I think I have more front bias which I prefer. I'd rather see what's in store for me than wonder what I'm gonna go ass end first into.

the only time I've ever had a problem was driving with the PCA in what they call a "spirited drive". To keep up I had to try to brake later and carry more speed through the corners than the tail draggers. It worked fine, I'd get all over the guy in front of me, then he would pull away in the straights. One corner was wet, and I locked up the front for a second. I drove through it but after that the wife said slow down. Next day her right leg was so sore from trying to press the brake pedal she decided to sitout that "spirited drive".

I 'm going to put in a tee the next time I drop the engine. I've got the prop valve full open.

Dave

[McMark]

Brakes work by turning motion into heat.
Brake parts can only retain so much heat before they start to fade.
Generally, calipers make heat, rotors retain and disperse heat.
Think about putting bigger calipers on the same size rotors.

The BMW upgrade works great until the extra heat you're producing creates brake fade. Bigger calipers mean hotter rotors faster.

(IMG:style_emoticons/default/biggrin.gif)

[PatW]

I did the BMW brakes. Yea, the work great but, I feel the money I invested. I could have done better..

Should have listened to Brad and bought a good set of brake pads instead. Save your money.

Pat

[tat2dphreak]

I think good rotors will go farther than the pads really... and good pads are pretty cheap... you could do BMW AND get good pads... I did this when I did my BMW conversion... worked great... but that was for a street car... not auto-x

[1973914]

"Good Pads" run about $150 per end of the car (pagid orange in this example) ...

Good Rotors - hmm not sure what this means. Drilled rotors are more expensive but crack over time - have seen it many times. Slotted rotors vent gasses that are generated during braking but provide minimal returns in terms of additional cooling. The point is you can only go with a certain size rotor and bigger calipers/pads will just sink more heat into the rotors. Rotors are pretty cheap in comparison to pads.

this feels like the thread that never ends.... (IMG:style_emoticons/default/laugh.gif)

OH - and also drilling and slotting remove rotor mass thus creating additional heat sink issues

[tat2dphreak]

I was referring to the cross drilled rotors... I haven't heard of people having issues with them cracking... but again, no auto-x experience...

as far as pads I was referring to "good" in the 50-65$ range... I don't really look at racing pads.... my bad

[RocknRollFrenzy]

i've been trying to decide what to do with my brakes as well. after reading everything i could dig up here, and anywhere else, i've decided that the best way to go is to either keep the stock brakes and make sure they're in good order and well bled, or to go all out and swap both front and rear for something good, modern, and big. the bmw setup just doesn't really seem worth the cost or frustration of trying to get them set up right. i figure i'm better off using what i've got and spending the money on other stuff. or saving it towards a boxter brake swap on all 4 wheels (anyone done this? seems like a cool one, though i'm guessing it might involve a good deal of custom fab work). just my opinion though. there seems to be plenty of people that like their bmw brakes just fine.

[thesey914]

Yeah done this....better but fronts lock up too quickly. I've since removed the prop valve but haven't done any road testing

[banderson]

I’ve done this too and am not too impressed. The bias is all fuct up. Now I want to put the fronts on the rears and add an APV in the console. Does anyone have a good pic of this?

As I see the physics here, There are 2 independent factors; 1) stopping distance 2) heat dissipation and fade resistance.

1)Stopping distance is controlled by getting all four wheels to exert the maximum stopping force without crossing over to skid. BMW brakes put too much force on the fronts and leave the stock rears no where near there potential. This makes some people FEEL safe, but the stock car in front of you can stop faster. This is why I am thinking about putting the stock fronts on the rear and using an APV to dial it in.

2) As said many times before the trick is to get kinetic energy into thermal energy and dump that into the AIR. Its all about AIR FLOW. Vented rotors are like centrifugal fans and blow a lot of air. The other option is ducting. IMHO, increasing thermal mass (larger calipers and rotors) will delay fade, maybe long enough, or maybe not.

YMMV

[Eric_Shea]

Is your motor basically stock?

If so, 1973914 nailed it. Rebuild your stock calipers and use awesome pads. Yup they'll cost you a hoot but it beats mess'n with the current setup. When they work they work better than most any set-up for a stock/semi-stock car. And yes... "all" drilled rotors (cast or drilled) crack. No biggy, they just do.

If you have a high hp motor then by all means look at upgrading your system. I wouldn't consider the BMW's an upgrade, simply more pad without addressing "system" issues. Others have covered what it means to have more heat on the same old rotor, especially in an auto-x situation. "System" means, front, back, p-valve, calipers and rotors.

E.G.: I went up to a six. For me this meant S-calipers, vented rotors all around, t-adapter in place of the p-valve, 911 rear calipers and 911 handbrake. Boatload of work and $!

Short answer: rebuild your stock system with nice pads. You'll have more cash in your pocket and an awesome brake system. (IMG:style_emoticons/default/cool_shades.gif)

[seanery]

they won't cost ya too much.
I ordered some Porterfield R4-S street pads for $58 each axle. Not too bad IMHO.