BBK or 5 Lug?

[Fidhle007]

After spending some quality time with a customer's '99 M Coupe today I've decided I want brakes and lots of them! Would I be able to get M Coupe-level stopping power from a UUC or Massive BBK or should I just swap the whole thing to 5 lug and run stock BMW brakes? What's my best bang for the buck stopping power-wise? I know I would have cool wheel choices with a five lug setup but for sake of this question I'm solely interested in sheer stopping power vs. cost.

Thanks!
Brendan

[Jordan]

Get better pads and tires. Much more bang for the buck.

[Van Westervelt]

... and lose the dead weight.

[Fidhle007]

Already done fellas, I'm looking for that dislodge-your-eyeballs-as-soon-as-you-touch-the-pedal feeling that the M has, can that be achieved with kit or would I have to swap the whole thing (aka 5-lug)?

[Jordan]

You could GET BETTER BRAKE PADS AND TIRES.

Again.. much more bang for buck.

You could have 50in rotors and a 2sq.ft. pad surface area with 24 piston calipers. Wouldn't do you a god damn bit of good because your junk ass tires can still only grip the road so much.

[Fidhle007]

And what tires am I running exactly? My tires are fine. Trust me, my Falkens are better than the Sumitomos that our dumbass customer had on the M Coupe in question. I've already done new pads/rotors/lines trying to achieve the kind of braking power I'm talking about but I'm still wonderfully underwhelmed. Jordan, as a fellow BMW tech who gets to drive lots of different vehicles I'm surprised you don't have some more constructive input here. Especially given your E30 modding experience...

[Van Westervelt]

The e36 m3 fronts that I had on for a while werent the greatest pad and rotor, but that eye pulling feeling was present. :)

[jlevie]

The stock brake system in conjunction with good track pads will out perform any tires you can shove under and E30 without mods to the fender wells. For track duty it is essential to have front cooling ducts and you need to use a suitable fluid. But the brakes are fine.

The big difference between the M coupe and an E30 is that the E30 will require more pedal pressure and travel to reach full braking. Either car (with the right pads) can reach full threshold braking for any tire you can fit in un-modified fenders. Note that to achieve try threshold braking you do have to disable the ABS as it will intervene well before you've reach the braking limit.

[asubimmer]

BBK>5 lug

[Fidhle007]

BBK>5 lug

Thank you! I'm not talking in terms of a track car, I'm talking in terms of a spirited street car, which is really what my car is. For track purposes I'm sure I'd be fine with stock brakes and a good pad/rotor/tire combo but it's the pressure issue that was mentioned above that I'd like to address. Perhaps a larger master cylinder would help too?

[asubimmer]

the 25mm master will give you about a 18% shorter throw. It also gives a firmer pedal feel and increases the sensitivity of the brakes.

[jlevie]

While a larger master cylinder would reduce pedal effort, it is possible that other, less invasive, things could help.

A bad brake booster will increase pedal effort as will an intake leak. The brake booster can be tested to see if it has leaks. Intake leaks reduce the amount of vacuum available and thus reduce the effectiveness of the brake booster.

And the choice in pads matters a lot. Since this is a daily driver, you wouldn't want to track pads but a High Performance Street pad will make the brakes more effective.

What pads are you using now?

[asubimmer]

While a larger master cylinder would reduce pedal effort, it is possible that other, less invasive, things could help.

lol you have it backwards. A larger master increases pedal effort and a smaller one decreases effort. A larger caliper piston lowers the effort and a smaller one raises it. :-|

[Van Westervelt]

lol you have it backwards. A larger master increases pedal effort and a smaller one decreases effort. A larger caliper piston lowers the effort and a smaller one raises it. :-|

I was just about to correct him as well. x2

[Massive Lee]

Hi Fiddler

The eye pulling effect on the street will come from a well bled brake system, and proper pads. You will need pads that have a very high coefficient of friction when cold. Race pads don't have to do the same job as street pads. So, a race pad is not necessarely the type you need. Start by bringing your stock brakes to like-new condition.