Next project! - New brakes but have some questions - The Unofficial BMW M5 Messageboard (m5board.com)

atomic80 · 14th April 2002, 09:22

Now that I've finally gotten the suspension taken care of I've got to spend some time getting used to it. I can't believe I'm already thinking of the next project....new brakes!

I saw a E46 M3 earlier tonight and what struck me as being odd about it was the brakes. He had put Brembo 14" brakes up front and in the rears the discs looked bigger than I'd remembered. When I asked about it, he told me that he had put the front brakes in the back!!! This got me thinking, "would this be possible also with the M5?" "Could I put the front OEM brakes in the back and put new brakes in the front?" What do you guys think? I've got the choices narrowed down to either Brembos or Stoptech. I know that I do NOT want to use spacers. I'd heard that Brembos might have two different types, one that requires spacers and one that doesn't. But from what I understand the Stoptech's come all ready to go right out of the box with no spacers needed. I also know that the brembos come with stainless steel lines but what abou the Stoptech's? Do they also come with SS brake lines too? And lastly, would 14" brakes from either one fit with my stock 18" wheels?

I know that I could have done a search but I wanted to try to get all the answers that I can in one place.

EBMCS03 · 14th April 2002, 09:33

Hehehe Ya ya new Brakes!! Yes yes yes thats good...

Remember this? http://www.bmwm5.com/vbulletin/showt...ghlight=brakes

http://www.bmwm5.com/vbulletin/showt...ghlight=brembo

TCM · 14th April 2002, 15:44

Jason:

The Brembo package makes use of 15mm spacers up front. I beleive the StopTech uses none. So if you are looking for an upgrade without having spacers, go StopTech. Glad to see you are happy with the suspension. Can't wait to see the comparison photos.

Diamond Dave · 16th April 2002, 01:19

Jason,

Since you don't want to use spacers, the Movit kit is out. I'd suggest the Stop Tech's as they look to be a pretty good product.

I'd think that you'd also want to email or PM our resident Brake Expert: Dave Z.

Good luck!

DWP

HaroldC · 16th April 2002, 01:31

Jason,

I would highly recommend the Stoptechs. No fade, awesome braking power, and they will fit under your stock M5 wheels w/out spacers. And they look pretty cool as well.

greg · 16th April 2002, 06:13

Jason - when you brake a bunch of weight is transfered to the front. front traction increases and rear decreases. You probably don't NEED bigger brakes in the rear.

Do you track your car? if you don't, the stock brakes are truly adequate. Braking power is a function of traction, which is a function of surface, tire, and weight transfer. Your brakes already have enough power to overcome the maximum allowable traction unless you've made major changes that would affect traction itself. ON THE TRACK you can overheat the stock setup, and there are indeed ways to overcome that.

Start with this - what do you expect to get out of it?

atomic80 · 16th April 2002, 06:31

Quote:

Originally posted by greg
Jason - when you brake a bunch of weight is transfered to the front. front traction increases and rear decreases. You probably don't NEED bigger brakes in the rear.

Do you track your car? if you don't, the stock brakes are truly adequate. Braking power is a function of traction, which is a function of surface, tire, and weight transfer. Your brakes already have enough power to overcome the maximum allowable traction unless you've made major changes that would affect traction itself. ON THE TRACK you can overheat the stock setup, and there are indeed ways to overcome that.

Start with this - what do you expect to get out of it?

Right now I don't think that getting new brakes is necessarily something that I want to get. What I'm really after is a firmer brake pedal feel. I'm told that I can either change the fluids out to some aftermarket brands with higher boiling points or to change the brake lines to stainless steel ones. Maybe even both would do the trick.

I don't track my car so aftermarket brakes probably isn't something that I need to look into getting.

I also believe that by opening up my brake ducts I was able to partially take care of my brakes overheating.

DaneM · 16th April 2002, 22:02

Quote:

Originally posted by atomic80
What I'm really after is a firmer brake pedal feel.

Stainless braided brake lines and a good DOT4 or 5.1 fluid will do just that. It's a night and day difference.

For brake fluid, the M5ers may have a favorite, but I like Motul 5.1 and AP Racing 5.1. Just don't use DOT5 (silicone) unless your brake system is specifically designed for it. DOT4 and 5.1 are poly glycol based and will work in most applications.

And remember to completely flush the old fluid out when changing to a new brand/rating.

Prometheus NY · 16th April 2002, 23:06

http://www.racetechnologies.com/

These people will retrofit front brakes to fit the rear on the E39 and the E46. I'm going to be moving the fronts to the rear very soon and upgrading the front to 14" rotors and 6 piston calipers.

I'm particular to Brembos, although Stop Tech seems to make an equally good product, and you will definitely have a firmer brake feel. If you want an even firmer feel that you will already achieve by replacing the brakes, then get Yellow Stuff track pads.

Movit might also be another consideration.

greg · 16th April 2002, 23:29

Quote:

Originally posted by atomic80

What I'm really after is a firmer brake pedal feel. I'm told that I can either change the fluids out to some aftermarket brands with higher boiling points or to change the brake lines to stainless steel ones. Maybe even both would do the trick.

That is indeed a reasonable objective - I also think the pedal is too soft. fluid won't help unless your soft feel the result of boiled fluid - and I doubt that. Nothing wrong with going to a fluid with a higher boiling point, but don't expect it to help with the feel.

Good feel is usually described as a control requiring a difference in FORCE, but with very little MOVEMENT. The Porsche brakes are legendary at this - you put the pedal down and it practically feels like you hit a stop when they engage - but from light to full braking the pedal hardly moves - you just press harder. In the M5 under really hard braking sometimes I worry the pedal is going to hit the floor before I am pressing as hard as I can!

Pedal movement comes from the good (actuation of the master cyliner) and the bad (stuff bending/stretching/flexing under pressure that shouldn't be). BOTH of these can be addressed.

You can reduce bending/stretching/flexing by

going to better brake hoses. I think this alone would likely make a very pleasant difference. Anyone done this?
I haven't looked, but I also think the pedal mount itself is yielding some - and perhaps this could be beefed up.
Theoretically the removal of anti-squeal pads helps a little with feel - probably not worth it.
Different/harder pads that provide the same braking with less pressure would also help, since there will be less yielding of everything else with the reduced pressure.

You can ALSO make a huge difference by changing the mechanical advantage of the pedal and the hydraulc system. If you have "Tune to win" go straight to p111 - if you don't I'll summarize: You can get the same line pressure (the hydraulic force acting on the calipers) with less travel if you're willing to press harder with your foot. Says Smith: "A larger cylinder will require more [foot/pedal] pressure per unit of hydraulic pressure generated but will require less pedal travel to exert the same amount of force. My own preference, and that of virtually every driver I've ever worked with, is for a brake pedal with minimum travel and a firmness approaching that of a brick wall."