Improve brake pedal feel? BBK?

[ajw45]

I have an '07 Z4Mc running stock rotors and calipers with PFC 06/08 pads and SRF fluid. The stock set-up is plenty of brake for me and I haven't had any fade at the track with fresh fluid but I'm not getting a lot of feel through the brake pedal. To me, it generally feels soft, a little grabby at the top, and has a longer/lighter travel than I'd like. I've had a few people drive my car and they seemed to think the brakes felt fine so it definitely could be that I'm just used to old cars with heavy pedals. In my e28 M5 we swapped in the master cylinder from an e32 and changed the rear calipers for more rear brake bias and that felt amazing on the track even though the actual braking performance wasn't that much improved or even really all that great by modern standards.

Has anyone done anything to get a stiffer, more progressive, brake pedal feel? For those that have gone to an aftermarket BBK kit, did the feel through the pedal change significantly (for the better)?

TIA!

[Varinn]

From what I've heard, some people say that cycling the ABS pump during bleeding can make a big difference. It's one of my major complaints with the car also, and sadly there don't seem to be any oem sized 4-piston caliper upgrades. The car has heavily boosted brakes, and I always find it hard to jump from my e30 to the z4m. Of course the Z brakes are more powerful and resistant to heat, but the e30 brakes feel worlds ahead in terms of feedback and ease of modulation.

With the cost of the full BBK options that are out there you damn well better know you want them before investing!

[F360C]

Originally Posted by Varinn

From what I've heard, some people say that cycling the ABS pump during bleeding can make a big difference. It's one of my major complaints with the car also, and sadly there don't seem to be any oem sized 4-piston caliper upgrades. The car has heavily boosted brakes, and I always find it hard to jump from my e30 to the z4m. Of course the Z brakes are more powerful and resistant to heat, but the e30 brakes feel worlds ahead in terms of feedback and ease of modulation.

With the cost of the full BBK options that are out there you damn well better know you want them before investing!

You could do a caliper upgrade to 996/Cayman S brembo calipers. By the time you buy pads, fluid, the calipers, brackets etc it would be about $1200-1500 for a 4 wheel caliper upgrade. My brother did it on his M Coupe and the brakes pedal feel and power is night and day compared to my car with PFC pads, brass brake caliper bushing, better fluid.

I am thinking I am going to do it to my car over the winter.

[ajw45]

Originally Posted by F360C

You could do a caliper upgrade to 996/Cayman S brembo calipers. By the time you buy pads, fluid, the calipers, brackets etc it would be about $1200-1500 for a 4 wheel caliper upgrade. My brother did it on his M Coupe and the brakes pedal feel and power is night and day compared to my car with PFC pads, brass brake caliper bushing, better fluid.

I am thinking I am going to do it to my car over the winter.

Awesome, that's great news! Definitely post a thread on your install and experience this winter! I've been so frustrated with the brakes that I started Porsche shopping and suddenly a BBK seemed totally economical

[Varinn]

Originally Posted by F360C

You could do a caliper upgrade to 996/Cayman S brembo calipers. By the time you buy pads, fluid, the calipers, brackets etc it would be about $1200-1500 for a 4 wheel caliper upgrade. My brother did it on his M Coupe and the brakes pedal feel and power is night and day compared to my car with PFC pads, brass brake caliper bushing, better fluid.

I am thinking I am going to do it to my car over the winter.

That is really cool, and despite all my research I had never heard of it before. I'm in need of brakes right now, this might be worth stretching the budget for...

[NickyC]

Originally Posted by Varinn

That is really cool, and despite all my research I had never heard of it before. I'm in need of brakes right now, this might be worth stretching the budget for...

Check out Rallyroad. They make the brackets and the lines which you'll need for the Brembo calipers to fit. Eric is a great guy who will answer all of your questions. You will need the E46 M3 Brembo brackets, and can use the front brake lines from an E46 M3 as well. The rear brake lines on a Z4M are longer than the E46 M3, so you'll need to let Eric know you need the rear Z4M brake lines. He makes them, so no worries there.

http://www.rallyroad.net/

[The HACK]

Originally Posted by Varinn

...and sadly there don't seem to be any oem sized 4-piston caliper upgrades.

RacingBrake makes a 4 piston front, 2 piston rear kit. Although they'll insist on you purchasing a set of RB rotors. They bolt up directly with minimum trimming of the front heat shield (like 2 inches off of the tip). The reason being, the caliper(s) are designed for rotors that are 2mm thicker, so when the pads are fully extended you run the risk of the caliper pistons being too far pushed out.

You can run 1mm shims behind the pads to prevent this issue, but you will have to work with RB to get them to release the kit to you without their rotors.

[UntzUntzUntz]

I did a quick search and found a bunch from the e46 guys have already done it:
http://m3forum.net/m3forum/showthread.php?t=455631

Is this the same process for our M's?

[NickyC]

Originally Posted by UntzUntzUntz

I did a quick search and found a bunch from the e46 guys have already done it:
http://m3forum.net/m3forum/showthread.php?t=455631

Is this the same process for our M's?

Yes, I explained it two posts above.

[Barryb97]

Been having the same issue with my brakes. Stops fine but pedal travel makes it almost impossible to heal-toe. This sounds like an interesting solution.

[F360C]

Originally Posted by NickyC

Check out Rallyroad. They make the brackets and the lines which you'll need for the Brembo calipers to fit. Eric is a great guy who will answer all of your questions. You will need the E46 M3 Brembo brackets, and can use the front brake lines from an E46 M3 as well. The rear brake lines on a Z4M are longer than the E46 M3, so you'll need to let Eric know you need the rear Z4M brake lines. He makes them, so no worries there.

http://www.rallyroad.net/

I would suggest not using RallyRoad for the rear brackets. The RallyRoad brackets have 2 issues:

1. The pad does not sweep the entire surface of the rotor which leaves a visable rust ring on the rotor. This is well documented if you search "RallyRoad rust ring." A member of M3Forum "p0lar" went through alot of trouble to design a new bracket that eliminates this issue. If you contact him he will sell you the brackets.

2. The RallyRoad bracket contacts the upper bolt on the control arm. Again well documented on M3forum. The "p0lar" bracket fixes this on the M3 but it does not fix it on the Z4M. The p0lar bracket still contacts the bolt on our cars so alittle grinding if the bracket is needed. I just used a dremel tool and was able to make clearence.

Although both brackets have an issue with contacting the upper control arm bolt and will need grinding the p0lar bracket does eliminate the issue of the pad not doing a full sweep of the rotor surface.

p0lar being the genius he is also did alot of calcuations on pad size, pad shape and piston size on the 996/cayman s calipers to determine brake bias. With 996/cayman S pads being used on our cars it shifts some of the brake bias forwards not unlike the brembo BBKs for our cars. He was able to find a different pad combination that moves the bias a bit rear wards which is close to the stock CSL brakes/ AP Racing BBK brake bias. I found this helped alot under hard braking at the track as it makes the car a bit less skiddish under heavy late braking. I am not sure of the exact pad shapes we ordered but I am sure a PM to p0lar and he will be able to let you know. Or I can look at the part number on the pad boxes when I get home.

In the end my brother set up is as follows..

Front:
996/Cayman S caliper (5mm of the mounting boss must be machined off, Rally offers this service or any machine shop can do it.)
Rally Road Bracket
Rally Road Brake Lines
Stock CSL/ZCP Rotor

Rear:
996/Cayman S rear caliper
p0lar Bracket
Rally road brake line
Stock CSL/ZCP rotor


*****Now looing at the Rally Road site they state to have redesigned their caliper bracket to eliminte the issues mentioned above.

[sipman]

Originally Posted by Barryb97

Been having the same issue with my brakes. Stops fine but pedal travel makes it almost impossible to heal-toe. This sounds like an interesting solution.

If pedal travel is your only issue, I can solve that for you. for $35 you can buy a new brake pedal arm from BMW. Cut the metal pedal pad off the arm. Drill 4 holes in each corner, and then drill 4 matching holes in the pedal pad on the brake pedal in your car (Do this after you remove the pedal pad cover).

Insert 4 long bolts into the new pedal pad and use washers to raise the height of your brake pedal to an acceptable height. Put the bolts through the original pedal pad and install nuts and tighten. Then install the Pedal Pad Cover onto the new pedal pad and you will suddenly have a brake pedal who's height will match that of your gas pedal so you can roll the outside of your right foot onto the accelerator pedal for heel/toe rev matching. And no one but you will know that you modded it.

Of course, then send me all the money you saved on not having to purchase a big brake kit to me as thanks!

[Vanne]

I had issues with pedal feel aswell, but my brakes had 200K on them, after i swapped to Stoptechs steel braided brake lines and pads, and a brake rebuild, its a complete other story. love the feel.

Crap, disregard if the issue isn't feel...

[ajw45]

Going for shorter travel, firmer pedal, and more progressive brake actuation. Otherwise, this would be even cheaper...

[Barryb97]

All joking aside. I'm still dealing with this issue. Unfortunately, I haven't driven much because of the weather. I ordered a new master cylinder just to feel like I'm doing something. As the weather gets a little better maybe I can get it out and try to actually diagnose what is going on. If you have any suggestions on some technics let me know.

[Beedub]

i need to get back behind the wheel of my ///M because i can't exactly remember what the modulation of the brakes of the AP bbk is like .... what i do remember is braking is much stronger and the pedal feel is better, but when they are cold they feel pretty shit imo.... This may be a characteristic of large brakes with multi piston setup from cold?? or my race Pads.

Once warmed up, they feel, and brake better than anything I've driven, the warmer they are, the better all the reference points mentioned feel.

[inTgr8r]

^ it's your race pads, they require some heating up to work properly.
I swap mine out with street pads in between track days. (Another benefit of having top load BBK fixed calipers)

[ajw45]

I actually like running race pads (running pfc06/08) on the street - the lack of bite when cold makes the brakes feel less grabby
I'm driving ceramics on the cayman and they are also grabbier than I would like but at least the pedal is heavier and has more feel. Fwiw, my e28 M5 had small oem 4 piston fixed calipers on the front and sliding upgraded single pistons at the rear, not as feelsome as the Porsche but way firmer and half the pedal travel which was awesome for heel toeing. I'm thinking maybe the only option is to go with a bbk for some fixed calipers...