Braking Setup Recommendations?

[mimarcos]

The last 2 visits to the track in my 06 Z4MR have resulted in some pretty severe fade, squeal, and vibrations. The fade was far less prominent and the squeals were nonexistent the second time around (I think new pads helped with that), but the vibrations were still pretty prominent. The vibrations kicked in after the first couple hard brakes at Watkins Glen. They went away by the start of each session, but they always came back.

My first thought, particularly after the last time this happened, was deposits on the rotors. But I was doing everything I could to brake properly, wasn't using the parking brake, ran my cooldown laps as expected, blah blah.

So for the spring, I was planning on changing the entire brake system. The one thing I've heard from just about everyone that's done so, is that installing a BBK makes the brakes feel far more linear, less pedal mush in the first 30% of travel. I figured I'd rather spend a little more money and get something new in return, instead of just getting back to stock brakes.

What I've got priced out right now is the RacingBrake 4-piston front and 2 piston rear. I'm not sure which pad I'm going to start with, but the total price tag on all of this is around $4k (might be able to find it for a hair less, but in that ballpark).

My (very longwinded) question to all you braking experts out there is a multi-parter, I guess:

1) Do you have any other recommendation for braking setup that will save me some money? I'm OK with what I've specced out, but if someone thinks there's a better kit, or that I could use OE rears, something like that, I'd be very happy to hear your thoughts.

2) If you have a BBK, do you have different street and track pads? Do you swap them out on the same rotors or do you swap out pads/rotors for an event?

Thanks for any insight!

[Kgolf31]

What track pads are you currently using?

[The HACK]

Originally Posted by mimarcos

2) If you have a BBK, do you have different street and track pads? Do you swap them out on the same rotors or do you swap out pads/rotors for an event?

Thanks for any insight!

Yes. Since I swap wheels/tires out between street and track anyway to prolong the use of my R-comps, when I swap wheels and tires, I swap out for track compound as well. With some power tools, RacingBrake's BBK takes an additional 5-10 minutes overall to swap out the brakes in addition to the time spent swapping out wheels and tires so it was a no-brainer.

I don't touch the rotors.

[mimarcos]

Originally Posted by Kgolf31

What track pads are you currently using?

I just have one pad for both right now. Cool Carbon S/T. From what I've heard they're probably not the best, but they didn't fade pretty much all day (I might not have been braking as hard as my first HPDE, who knows). They certainly didn't glaze over or make the horrible squeal the... don't hate... 7 year old BMW OE pads did my last session. The car has 9k miles on it, they were likely the brakes that came with the car (I bought it at 2.5k, doubt they were swapped before I bought it).

Originally Posted by The HACK

Yes. Since I swap wheels/tires out between street and track anyway to prolong the use of my R-comps, when I swap wheels and tires, I swap out for track compound as well. With some power tools, RacingBrake's BBK takes an additional 5-10 minutes overall to swap out the brakes in addition to the time spent swapping out wheels and tires so it was a no-brainer.

I don't touch the rotors.

Good to know. Do you have them all around? And what pads do you use for the RB BBK, since it kind of looks like that's what I'm going to be going for (unless there are other suggestions).

[Kgolf31]

Using those brake pads it is no surprise why you're getting deposits.

IMO - Instead of fully upgrading run PFC 06/08 pads or similar

[The HACK]

I run RacingBrake ET300 for street, and their RT970 for track. I have RB calipers on all 4 corners.

[Barryb97]

I run the PFC 08 pads and they work great. The only issue I have is a little more pedal travel than I would like. If I could afford a BBK I would, just for the improved feel, less pedal travel, easy pad change and good looks.

[mimarcos]

Originally Posted by Kgolf31

Using those brake pads it is no surprise why you're getting deposits.

IMO - Instead of fully upgrading run PFC 06/08 pads or similar

So out of curiosity, do you think its normal to get deposits and severe vibrations from the OEM pads on a track day? My point being, do you think that the whole vibration thing is due to pad? Because it happened with both the OE and Cool Carbons. So if another set of pads fixes the problem, I think that's something worth trying.

[inTgr8r]

I ran CC on my OE calipers for a year and had pad deposit issues.
When I changed to my Stoptech BBK I ran a demo set of (improved) CC pads and had the same issue at the track.
With the Stoptech pads that came with the BBK, I had no such issue but they are more of a street pad than track.

I'm currently swapping pads for track days.
Stoptech pads for street;
And for track
Hawk DTC-70 race pads - front
Hawk DTC-60 race pads - rear

[The HACK]

Originally Posted by mimarcos

So out of curiosity, do you think its normal to get deposits and severe vibrations from the OEM pads on a track day? My point being, do you think that the whole vibration thing is due to pad? Because it happened with both the OE and Cool Carbons. So if another set of pads fixes the problem, I think that's something worth trying.

Some pads are worse than others, but there's no guarantee that switching will fix the issue.

Uneven pad deposit comes from a variety of factors. When pads are heated beyond their maximum operating temperature (MOT), it increases the likelihood of uneven deposit because at this point the pads are at or near their melting point. It also comes from operating at or near MOT and activating ABS. It also comes from improper cool-down. It also comes from...get this...UNEVEN ROTOR SURFACE. You got it. The drilled rotors that's on the MZ4 Coupe actually can exacerbate the problem.

Having a set of pads that has extreme high MOT can alleviate the problem, to a certain extent. Having rotors capable of cooling down the pads and maintain it below the MOT can also alleviate the problem. PROPER BRAKING TECHNIQUE can all but eliminate the problem (look up digressive braking). Cooling ducts will manage the temperature better and combined with a high MOT compound would all but eliminate the problem. Cooling ducts, high end rotors, proper pads, proper braking technique will 100% eliminate the problem.

Having said that.

You throw a set of slicks on the car, and all that goes out the window. The R-comps have so much higher capacity for straight line grip, it makes locking up the wheel very difficult even with top end race pads. The end result is it introduces significantly more heat into the system and you're constantly operating at or near the MOT of even the best of race pads. At that point, vibration in the brake pedal is but a fact of life, the only difference is if it's bad, or REAL bad that it will shorten the life of the suspension components (bushings, tie-rods, ball joints etc).

[mimarcos]

Originally Posted by The HACK

Some pads are worse than others, but there's no guarantee that switching will fix the issue.

Uneven pad deposit comes from a variety of factors. When pads are heated beyond their maximum operating temperature (MOT), it increases the likelihood of uneven deposit because at this point the pads are at or near their melting point. It also comes from operating at or near MOT and activating ABS. It also comes from improper cool-down. It also comes from...get this...UNEVEN ROTOR SURFACE. You got it. The drilled rotors that's on the MZ4 Coupe actually can exacerbate the problem.

Having a set of pads that has extreme high MOT can alleviate the problem, to a certain extent. Having rotors capable of cooling down the pads and maintain it below the MOT can also alleviate the problem. PROPER BRAKING TECHNIQUE can all but eliminate the problem (look up digressive braking). Cooling ducts will manage the temperature better and combined with a high MOT compound would all but eliminate the problem. Cooling ducts, high end rotors, proper pads, proper braking technique will 100% eliminate the problem.

Having said that.

You throw a set of slicks on the car, and all that goes out the window. The R-comps have so much higher capacity for straight line grip, it makes locking up the wheel very difficult even with top end race pads. The end result is it introduces significantly more heat into the system and you're constantly operating at or near the MOT of even the best of race pads. At that point, vibration in the brake pedal is but a fact of life, the only difference is if it's bad, or REAL bad that it will shorten the life of the suspension components (bushings, tie-rods, ball joints etc).

Thanks a ton for the writeup. This is all very helpful. I understand how deposits can happen, but the thing that tells me it isn't a pad deposit issue is how quickly they reverted to pretty much fine. Each session started with a much more confident and unshaky braking feeling.

The uneven surface of the rotors is what I feel is the issue, as you mentioned. I'm not sure if it's a function of the cross-drilled rotors or hotspots making the rotors expand/contract at different rates as they heat up and cool down. I hope that doesn't sound like entire gibberish, or completely wrong. What really throws me about what's happening is whether this issue is happening for any other drivers taking a pretty much stock Z4M to the track. If so, maybe it is just the cross-drilled rotors. But it sounds like other people (albeit with different, better, track oriented pads) do not experience the same issue.

My reason for going to a BBK is two-fold.

First, it will hopefully help with this problem (as the rotors will be slotted instead of drilled, the rotors will be made of a more heat resistant material). I think if there's a problem with the rotors, replacing all the rotors and getting better pads will help alleviate this too.

Second, it will improve the braking performance, in fading, pedal feel, modulation, all that jazz. Something I think is worth spending more on. I've always thought the pedal feel was too weak and mushy for the car they're on.

[The HACK]

What you're experiencing, is either the rotors or the pads operating at, near, or past its maximum operating temperature, and it is likely an issue with the pad (because the MZ4 rotor is excellent). The pads work just fine when it's cool or warm, but once they're hot, they start "skipping" across the surface of the rotor. What exacerbates the problem, is the drilled rotors on the MZ4 Coupe makes that skipping effect worse.

I'll bet, if you take your pads off the car, you'll see the surface of the pad CHEWED UP. Bad. While you may not necessarily be experiencing "pad fade," the problem with pads that are designed to be aggressive street pads used for the track, is that they disguise their high temp behavior. The end result is, while they don't technically drop off the cliff like street pads do at high temps, that "skipping" effect at or near MOT causes that vibration like sensation. The only way to solve that, is through what I suggested above. Keep the temperature of the system well below MOT (by altering braking, or ducting, or move the MOT up).

So to circle back. What others suggest will likely help. True, high-end track pads can sustain operating temps in excess of 1,200ºF, moving your MOT way up compared to the pads you currently run. Cooling ducts will help. Digressive braking, which allows more time cooling the rotors and pads while giving you near threshold level brakes, will help. BBK calipers will help in that the braking force is spread out across multiple pistons and will alleviate the "skipping" effect.

What you propose to do, by going to large, fixed caliper brakes, will likely fix your issues. But I would heed the other poster's suggestions and use a dedicated, track only pad, not a dual purpose street/performance pad for your track use.

[mimarcos]

Originally Posted by The HACK

What you're experiencing, is either the rotors or the pads operating at, near, or past its maximum operating temperature, and it is likely an issue with the pad (because the MZ4 rotor is excellent). The pads work just fine when it's cool or warm, but once they're hot, they start "skipping" across the surface of the rotor. What exacerbates the problem, is the drilled rotors on the MZ4 Coupe makes that skipping effect worse.

I'll bet, if you take your pads off the car, you'll see the surface of the pad CHEWED UP. Bad. While you may not necessarily be experiencing "pad fade," the problem with pads that are designed to be aggressive street pads used for the track, is that they disguise their high temp behavior. The end result is, while they don't technically drop off the cliff like street pads do at high temps, that "skipping" effect at or near MOT causes that vibration like sensation. The only way to solve that, is through what I suggested above. Keep the temperature of the system well below MOT (by altering braking, or ducting, or move the MOT up).

So to circle back. What others suggest will likely help. True, high-end track pads can sustain operating temps in excess of 1,200ºF, moving your MOT way up compared to the pads you currently run. Cooling ducts will help. Digressive braking, which allows more time cooling the rotors and pads while giving you near threshold level brakes, will help. BBK calipers will help in that the braking force is spread out across multiple pistons and will alleviate the "skipping" effect.

What you propose to do, by going to large, fixed caliper brakes, will likely fix your issues. But I would heed the other poster's suggestions and use a dedicated, track only pad, not a dual purpose street/performance pad for your track use.

Hack, thanks again. I'm definitely going to wind up with two different pads for the different applications. After going for a BBK, it seems like it'd be a very foolish choice to compromise on pads.

I can't check the pads right now, but I can definitely confirm that the OE pads were torn up something bad after the last event I ran. They have loads of little pock marks all over them.

This was my second HPDE event, so I'm still learning a ton. The brakes on the M are really fantastic, even with these Cool Carbon pads.

Hack, I have two more questions for you - do you have the 6 or 4 piston fronts? I was looking at the 4 since they'd accomplish both items on my wish list, but do you think I'd see a big difference in the 4 and 6? Also, as far as durability, have you had to replace the rotors? Do they last a good amount of time?

Thanks!

[The HACK]

4x2. My first set of rotors lasted me 6 years and about 50 track days.

[Finnegan]

Take a look at pad cost on 4 vs. 6 piston set-ups. There can be a significant difference when shopping track pads with various 4/6 piston set-ups.

I gained a lot of knowledge and help from this post. Good classroom knowledge and good to share discuss with an instructor. Also, some of this can be practiced in day to day driving that helps teach habits/techniques. http://www.zpost.com/forums/showpost...7&postcount=27

[mimarcos]

Originally Posted by Finnegan

Take a look at pad cost on 4 vs. 6 piston set-ups. There can be a significant difference when shopping track pads with various 4/6 piston set-ups.

I gained a lot of knowledge and help from this post. Good classroom knowledge and good to share discuss with an instructor. Also, some of this can be practiced in day to day driving that helps teach habits/techniques. http://www.zpost.com/forums/showpost...7&postcount=27

Haha, I was actually reading that earlier today. Apparently hack knows what he's talking about (though I knew that from lurking all these years).

Glad to hear it, Hack. I'm feeling more and more confident about RB now, thanks.

[Kgolf31]

Originally Posted by mimarcos

Hack, thanks again. I'm definitely going to wind up with two different pads for the different applications. After going for a BBK, it seems like it'd be a very foolish choice to compromise on pads.

I can't check the pads right now, but I can definitely confirm that the OE pads were torn up something bad after the last event I ran. They have loads of little pock marks all over them.

This was my second HPDE event, so I'm still learning a ton. The brakes on the M are really fantastic, even with these Cool Carbon pads.

Hack, I have two more questions for you - do you have the 6 or 4 piston fronts? I was looking at the 4 since they'd accomplish both items on my wish list, but do you think I'd see a big difference in the 4 and 6? Also, as far as durability, have you had to replace the rotors? Do they last a good amount of time?

Thanks!

Personally, IMO. Since it is only your second event I think you'll be fine with upgrading to full blown track pads on OE calipers and rotors and still be okay.

There is probably still room in there for some improvement in braking technique as well. It is the nature with starting out

[The HACK]

Originally Posted by Kgolf31

Personally, IMO. Since it is only your second event I think you'll be fine with upgrading to full blown track pads on OE calipers and rotors and still be okay.

There is probably still room in there for some improvement in braking technique as well. It is the nature with starting out

I concur.

Although, I ain't going to lie, I like RacingBrake products and having had a hand in developing their rotors and calipers for the MZ4 Coupe, I wasn't going to try and dissuade the OP from putting RB products on all 4 corners.

[dschultz]

I had much the same issues as OP. Was running Pagid S Sport pads (their S/T pad). I was burning through pads in 3-4 track days and getting tons of buildup on the rotors. I ended up warping my rotors. I *think* the pad deposits contributed to uneven rotor wear, though I may be blowing smoke. My cheapo runout gauge said .008".

Switched to PFC08's and new rotors. No problems and while I don't have enough data yet to say for sure, pad wear looks good. Only downside is that they tend to squeal around town at low speed. But I rarely DD the car so I can live with that.

[Kgolf31]

Originally Posted by The HACK

I concur.

Although, I ain't going to lie, I like RacingBrake products and having had a hand in developing their rotors and calipers for the MZ4 Coupe, I wasn't going to try and dissuade the OP from putting RB products on all 4 corners.

Give me a set for my 128i and I'll edit my post.

[mimarcos]

Originally Posted by Kgolf31

Personally, IMO. Since it is only your second event I think you'll be fine with upgrading to full blown track pads on OE calipers and rotors and still be okay.

There is probably still room in there for some improvement in braking technique as well. It is the nature with starting out

It sounds like you're right, but I think if I were to go this route I'd want to at least get new rotors installed as well. I'm not saying the cost difference is small, but going for a BBK seems to make more sense now, if I am going to wind up replacing the rotors anyway. It's something I've been considering since I first brought the car home.

Anyway, thanks for the info everyone.

[3002 tii]

Go BBK with brake cooling! =D