My first Z4M track experience

[Krypptic]

Less than a month with the new ride and I had my first track day at homestead speedway with hooked on driving.



First impressions:

Car handles great. I am riding on h&r sport springs and am very happy with the cars balance.

Traction control on this car is horribly intrusive. I am by no means a track regular and still very much consider myself a beginner, but driving experience was severely hampered by the constant braking from TC, and what felt like a cut in power. I had to ride with an instructor who told me to try a session with it off. What a world of difference. I have no idea why it kept lighting up before because with it off I felt very little slippage that would require even the smallest driver correction. That being said, I wish there was some middle ground as I am not sure I am ready to drive without a safety net.

Braking definitely needs upgraded fluid. I'm not sure if what I experienced was because of how frequent the TC applied brakes during my first session, but on fairly new pads, fade was pretty bad.

Last the engine performed beautifully. Temps were always within norms, and it pulled hard all day. Only thing I noticed was that the power falls off pretty sharp after 7k rpm, and I found myself shifting around there as I felt nothing to gain by redlining. This is pretty different from my experience in an e46 m3.

All in all, had a great day and looking forward to many more.

[MikeCOUPE]

Awesome! Did you get any videos of your laps?

[chickdr]

Power drops off after 7K? The peak is 7900... That makes no sense.

[BMW Maniac]

Originally Posted by chickdr

Power drops off after 7K? The peak is 7900... That makes no sense.

Actually, that feeling of power comes from the torque, which peaks around 4900 rpm.

[ricanbandit]

Sounds like you had fun. I would definitely like to take mine to a track and play a bit.

[kcdedric]

Nice! Glad you enjoyed the track.

I had mine out at the track yesterday and couldn't agree more about the DSC. As long as you are smooth with your inputs, you don't have too much to worry about. Our cars can be a little tail-happy, but it's pretty easy to control if you do find yourself getting in some trouble.

Also, what pads are you running? I used Stoptech Street Performance pads for the first time on the track yesterday and they performed quite well. They didn't fade (on a track with three 100mph+ straights), have a pretty linear feel, and they are relatively cheap ($135 from Tire Rack). I'd definitely recommend them.

[Finnegan]

+1 on the Stoptech Street Performance pads + fresh fluid. Braking technique can affect fade as well.

Odd about 7k RPM vs E46 M3. I feel the power build till redline--did notice a difference though for the better after valve adjustments--it sort of ran out if breath before adjustment.

It's a great time getting to experience the car in this environment! Makes street driving sort of ***yawn*** doesn't it?

[Krypptic]

Thanks for the input guys. No videos yet, but I see a traqmate in my near future.

Definitely gonna upgrade the pads and fluid. Will give the stop tech a try. Maybe while I'm at it, upgrade to stainless lines.

Finnegan, tell me about the valve adjustment? Is it very intensive/expensive? Am I doing damage without having it done? I suspected that the loss in power was due to the difference in exhausts between e86 and e46. From some graphs of headers and exhausts before and after it looks like the header/exhaust fix the power dip at the high rpm.

Nevertheless, if a valve adjustment is in my future, I'd like to know a little more about what it entails? Thanks again.

[chickdr]

Originally Posted by BMW Maniac

Actually, that feeling of power comes from the torque, which peaks around 4900 rpm.

Maybe off the line, but I believe HP is what gives you your top end. My S54 feels strong all the way to 8K.

[Finnegan]

Here's a recent thread on valve adjustment on the S54. Every ~25K miles or so--but some cars can benefit from it more often (tracked cars, cars driven hard). Cost is around 800 from an indie I believe, or you can DIY if you have shims and the right tools. Lots of DIYs on the S54 out there (Google) and right here on the forum too. Shipkiller has this one too, which is good.

BTW, I'm not saying this will "cure" what you're experiencing, just that I did notice a bit of difference at higher RPM before/after. Might be all in my head though--need more data from more people to confirm.

Back on the subject of brakes, my instructor helped me get a lot more out of mine by improving my braking technique.

[RADRACR]

I find that if I don't wind the S54 up to 8K starting in 1st gear, the subsequent gears suffer noticeably and I'm not getting power in the high RPMs. Moral of the story: wind that sucker up

[jmillet]

If you're running street tires and brake pads and your DSC is consistently intruding then the first thing to look at is the driver not the car. Smooth linear throttle and brake inputs coupled with opening up your steering on trackout will go a long way to giving you fast laps without your DSC coming on. I do a lot of coaching and never let my students turn off their DSC until they can demonstrate linear control inputs and soft steering. Learn to drive fast laps with your DSC on and you'll be even faster and safer when you turn it off.

[3002 tii]

Originally Posted by ricanbandit

Sounds like you had fun. I would definitely like to take mine to a track and play a bit.

What's stopping you? Plenty of us locals go, the more Z's the better! =)

[Krypptic]

That was my understanding too, until I turned the traction control off and the car was not out of control at all. There was no indication why the traction control kept chiming in, if there was no instability. It was my instructors idea, and once we took it off the TC, power delivery and weight transfer become much more predictable. Smoothness wasn't an issue for this track day. Tires never even squealed for a second with TC on. When off, I could hear and feel the tire limits.

On my last car, e93 m3, I would never take TC off. It stepped in as needed rarely. Maybe it was just a more advance system, even without M mode, as other m3's had.

Originally Posted by jmillet

If you're running street tires and brake pads and your DSC is consistently intruding then the first thing to look at is the driver not the car. Smooth linear throttle and brake inputs coupled with opening up your steering on trackout will go a long way to giving you fast laps without your DSC coming on. I do a lot of coaching and never let my students turn off their DSC until they can demonstrate linear control inputs and soft steering. Learn to drive fast laps with your DSC on and you'll be even faster and safer when you turn it off.

[jragan]

Originally Posted by Krypptic

That was my understanding too, until I turned the traction control off and the car was not out of control at all. There was no indication why the traction control kept chiming in, if there was no instability. It was my instructors idea, and once we took it off the TC, power delivery and weight transfer become much more predictable. Smoothness wasn't an issue for this track day. Tires never even squealed for a second with TC on. When off, I could hear and feel the tire limits.

On my last car, e93 m3, I would never take TC off. It stepped in as needed rarely. Maybe it was just a more advance system, even without M mode, as other m3's had.

I generally agree with everything JMillet says but not as it applies to the Z4///M. It was my experience that the TC in the Z4M just could not handle complex situations (off-camber curves, etc) and would start applying brakes when it absolutely shouldn't.

[gcochard]

I do agree that the DSC in the z4m is intrusive, but it comes on when it senses (normally) potential spin/slide scenarios. I do get it from time to time, and I have run autocross with it on and off. I noticed an improvement in my times with it off, but I've also spun twice with it off.

Maybe they made it more intrusive because of the short wheelbase on the e85/6 platform.

[The HACK]

Originally Posted by Krypptic

That was my understanding too, until I turned the traction control off and the car was not out of control at all. There was no indication why the traction control kept chiming in, if there was no instability. It was my instructors idea, and once we took it off the TC, power delivery and weight transfer become much more predictable. Smoothness wasn't an issue for this track day. Tires never even squealed for a second with TC on. When off, I could hear and feel the tire limits.

Stock alignment?

I had the MZ4 Coupe on multiple tracks in bone stock form its first year in 2006. Since it's been 6 years my memory of it was a little hazy, but what I DO remember is that on stock camber it's possible to get the front end to push pretty hard even when you're smooth, especially when you're up to speed and especially at corner exit. The trick, if you don't want to disengage DSC, is to open up the steering wheel slightly/momentarily on exit and re-engage, temporarily feeding more traction back in the front right before the front end starts to push.

So here's the thing. On the MZ4 Coupe, if your front end pushes slightly the DSC will either brake one of the wheels up front or cut back throttle slightly to bring the car back in line. Since on stock alignment it pushes rather easily, when you turn off DSC it will feel like the car "handles" better. The truth is, the car is set up with such a stiff chassis and thick front anti-roll bar that if you turn DSC off, it'll let the front end slide a little bit and as you continue to feed throttle it will eventually overwhelm the rear tires to return back to neutral state (sliding all 4), and that trick LSD in the rear prevents the rear from stepping out TOO far if you're driving it right.

BUT.

The tricky part about the MZ4 Coupe is, that the transition from understeer to oversteer in corner exit comes really quickly (not abruptly, like an older Porsche, but the transition time is short, unlike E46 M3s or any 3 series variant*) and if you're not ahead of that transition, it will catch you by surprise and loop the car. Between 2006 and 2007 I attended 20+ days in the MZ4 Coupe, and I've found that you can drive it super smooth and super fast and DSC will never complain if you know how to maximize traction. There are times where I was out driving at 9/10th my capabilities on various tracks and had completely forgotten that I didn't turn off DSC and didn't realize until I get to the straights and check my gauges and didn't see the familiar DSC off symbol.

Also, what I've found is that the DSC on the MZ4 Coupe is closer to the Dynamic M mode on the E46 M3 equipped with ZCP, in that it WILL allow you to hang the tail end out far enough but not far enough to get in trouble. There are multiple instances where I had forgotten to turn off DSC, and on an off-camber slow turn the tail will wag far enough but tuck right back in (since my first instinct is to counter steer as soon as the rear steps out of line). Full E46 M3 DSC on won't allow you to do that.

Summary: Again, if you get nothing out of my usual dissertation. The DSC in the MZ4 Coupe is tuned to mimic the E46 M3 M Dynamic mode. It's actually quite forgiving. I don't know if the M engineers got lazy and just ported the E46 M3's M Dynamic mode over without actually accounting for the idiosyncrasies of the MZ4 Coupe chassis, that's something else entirely above my pay-grade, but what I've found is, the DSC on the MZ4 Coupe is unforgiving on understeer but very forgiving on oversteers. It'll intrude and interact on the first sign of understeer but give you the leeway to hang the tail out a little.

The end result? If you're on stock alignment and street-ish tires (mostly stock alignment, actually), DSC will go crazy trying to reign in understeer on corner exit. Two ways to cure this is to either 1) turn off DSC or 2) learn to maximize your front end traction through the use of minute hand movement or to late apex the turn and use throttle to force the car to rotate.

Or increase front camber.

p.s.: * Not that anyone cares, since this isn't exactly the forum to discuss non-Z4 BMW chassi, but your typical 3 series (non M versions) won't aways transition from understeer to oversteer at corner exit like the M3s and our MZ4 Coupe. Them being equipped mostly with an open diff, means that at corner exit understeer if you feed it more throttle, it'll just lazily send all the power to the wheel that has no grip, slow the car down, and naturally go from understeer to neutral (since the car naturally slows down if you tried to apply MOAR throttle) to understeer again to neutral, depending on how long the corner is. Same thing will happen to non-M Z4s, except the chassis is much shorter and the transition time from understeer to neutral at corner exit due to slowing down is not as "long."

Observed this when a friend of mine was complaining about his inability to keep up with certain cars in slow turns despite the same weight to power ratio and basically a very similar chassis (E36 M3 vs. supercharged E46 325i) and experience level. We surmised that it was an issue of the open diff basically slowing him down in the slow turns and sure enough, after he swapped in an entire rear subframe and diff from an E46 M3, he was able to keep up and even pass those same E36 M3s.

On a slight tangent here, but whatever.

[Krypptic]

Wow Hack, that was a lot of helpful info. Thanks for taking the time. From the looks of it, there are a lot of opinions on how or why TC/dsc kicks in. I do want to try and increase camber to max allowable amount on stock form.

That and new pads and brake fluid and I should be ready for my next track day. Will post what I find out.

Thanks everyone.