Got into a Z4M; a few questions...

[lucid]

Hi All,

Got into a CPOed '07 Z4M coupe recently. It's been really cold out here, so I haven't been too hard on the car, but so far great ride. I get the feeling BMW will not produce a car like this one again any time soon unfortunately--simple and focused. Anyway, a few questions:

1. What is up with the brake pedal? Why is it so hyper-sensitive? Almost binary at low speed. I assume it's not as much of an issue at the track under heavier braking loads, but hello, modulation?

2. Will 245/35/19 up front rub with good offset choice at the track under heavy compression on stock suspension? I have some cup tires that have 2-3 more days in them, and would like to use them up on this car if I can. I searched it sounds like this would work, but I want to make sure before I buy rims.

3. How much of a stagger are folks maintaining at the track? 30mm stock seems like a lot given the car does not have a ton of power, but I don't know how the suspension behaves close to the limit. Factory sets up cars for understeer, but this seems like a lot at a first glance. I'm thinking 245/265, but 255/275 in the long run would be nice if it fits (under heavy compression).

4. Camber settings for more neutral handling (and even tire wear) at the track? Is it necessary to go beyond -2? How much will stock suspension allow for without plates?

Thanks.

[blender]

The brake sensitivity is definitely the factory brake pads. They have very high initial bite and iffy sustain. Get some good aftermarket pads and it's light years better.

I don't know enough to even guess on the tire size questions, sorry.

On Camber: You can get nearly -2 out of the fronts by pulling the pins and maxing it out. There are also inexpensive E36M3 washer kits for the front knuckles that subtract another 0.5 degree, so you can achieve in the neighborhood of -2.4 without plates. I've not needed more than that for 'spirited' canyon driving. Search the suspension forms here and at bimmerforums for your best answers.

Lastly, if you still have the Continentals, burn them up and go for some better rubber; that also makes a huge difference.

good luck,

RC.

[lucid]

Thanks. Good to hear you can get -2 out of the stock setup. That should be good enough for occasional track driving. The car came with brand new SportContact3s. Honestly, for street use, I'm not that sensitive about the tires. A new set of Direzzas would run $750+, so I'll wait until I'll go through what's on the car. Cheers.

[ianbiz]

nice pickup.
big aggressive brakes + small car = win
not sure about the rest.

[imom]

I was told by someone who tracked their Z4MC that MOTUL brake fluid and stainless steel brake lines will help with that brake problem. I had my fluids changed by the dealer and they did a crappy job...lots of bubbles. I had it flushed and put new oil in and I thought about putting in the stop tech brake lines, but my mechanic advised against it because it may void the brake warranty. I have a set for sale in a different thread...but you've been warned about CPO warranty issues with upgrading parts. I wanted to replace the pads because of the brake dust, but they say it will void the rotors and pads...so I opted not to do it.

[lucid]

The hypersensitivity could be related to the pads as mentioned above or it might have something to do with how the booster is set up/controlled. It can't be related to fluid although flushing with better fluid and using SS will help with with limiting pedal travel/improving pedal feel on the track. Most dealers don't make a big deal out of SS lines. Fluid can be a little more tricky as they say some fluids cause build up/degradation in the calipers or something to that effect, but I haven't had any problems. I think it is fair to expect BMW to give you 2 sets of new rotors in 4 years, and in my experience, as long as you don't try to push it beyond that, they are fine with it even if you've used non-OEM pads.

[jragan]

Originally Posted by rcleme05

There are also inexpensive E46M3 washer kits for the front knuckles that subtract another 0.5 degree, so you can achieve in the neighborhood of -2.4 without plates.

Most of the kits are actually labeled for E36M3, not E46: Turner-http://www.turnermotorsport.com/html/detail.asp?PRODUCT_ID=TSU3690036 (they claim it doesn't work on the E85/E86 ///M but it does as the car shares the same front suspension as the E36M3).

More Negative Camber up front plus stickier tires put me much more close to neutral.