Z4 M Coupe mods, the ongoing tale...

On a more technical note, Saturday was the second time I'd tracked the new Michelin Super Sports on pavement. I had tracked them for 3 laps on concrete at El Toro with OCRC, then with BMWCCA at Auto Club Speedway's infield course, and now at Willow. I noticed no wear from OCRC, but the wear in the pic below surprised me. This is from one day at Auto Club:


I've worn out plenty of tires in my day, but never seen chunking like this without corresponding "gummy" sections from over heating the tire. This was running the same suspension and tire pressures as I did at OCRC. The tires felt great at OCRC, but didn't feel particularly good at Auto Club - more squirmy. I suspected that perhaps I was running too much bump and that this was putting too much energy into the front tires. So as a quick experiment I added 2psi to each front tire (to stiffen them) and added a 1/4 turn of rear rebound (to slightly reduce longitudinal load transfer to the front). This had a marked improvement on front grip and contact patch predictability. But there were no more sessions left to try other suspension changes.

At Willow I noticed more significant chunking, but also a fair amount of heat and conventional wear. Here are the fronts at the end of the day (after being swapped left-to-right 1/2 way through the day).




I also reduced the bump 2 clicks, added an additional 1/4 turn of rear rebound and let 2psi out of the front tires. The car handled much better, and the wear seemed to then cover more of the tires' face instead of just wearing the middle. Still, this is a lot of wear for just two track days - particularly on a street tire designed specifically to be durable on the track.

The rears show very little wear, even though they were seeing more extreme pressure and heat cycles than the fronts. They were consistently getting hotter than the fronts and would lose grip slowly and predictably throughout a session whereas the fronts' grip remained pretty much constant:

Damn, I just missed you. I was there on Sunday.

I managed a 1:37 with my stock setup on street tires but was running consistent 38's and 39's later in the day. Definitely was a perfect weekend at WSIR though - great weather and very light traffic.

Shame the stars didn't line up just a bit better to be able to run with you.

Originally Posted by imager993

Damn, I just missed you. I was there on Sunday.

I managed a 1:37 with my stock setup on street tires but was running consistent 38's and 39's later in the day. Definite was a perfect weekend at WSIR though - great weather and very light traffic.

Shame the stars didn't line up just a bit better to be able to run with you.

-Yeah, damn! Would have been great to be there with you.

Originally Posted by Palantirion

I've worn out plenty of tires in my day, but never seen chunking like this without corresponding "gummy" sections from over heating the tire. This was running the same suspension and tire pressures as I did at OCRC. The tires felt great at OCRC, but didn't feel particularly good at Auto Club - more squirmy.

What was the tread depth are your tires? I shave the street tires that I also autocross in, to make them last longer (6/32). The squirm means your tread blocks are moving which generates heat -> chunking.

http://www.tirerack.com/tires/tirete....jsp?techid=67

Originally Posted by klin

What was the tread depth are your tires? I shave the street tires that I also autocross in, to make them last longer (6/32). The squirm means your tread blocks are moving which generates heat -> chunking.

http://www.tirerack.com/tires/tirete....jsp?techid=67

-I am familiar with shaving tires. In this case it would have defeated the purpose of tracking the street tires. As mentioned above, I would have thought that there would have been more visual evidence of overheating in conjunction with the chucking. Particularly in the pre-Willow garage pic it looks like the tires chunked without significant heat buildup.

Originally Posted by Palantirion

-Ron, got any tips or suggestions on what I will need to do to convert from non-heated to heated seats?

From Z4POST:

http://wds.spaghetticoder.org/

wow!

Wow that's awesome
How did you get a "4" micro antenna? it is pretty cute. Could you advice me how can I buy it?

Originally Posted by ahrdyrxkd

Wow that's awesome
How did you get a "4" micro antenna? it is pretty cute. Could you advice me how can I buy it?

-Check Scatha's website: www.mymcoupe.com (exterior section)

Has anyone successful done a heated seat refit?

Originally Posted by STIHLBOLTS

Has anyone successful done a heated seat refit?

Dunno. Perhaps I'll be the first?

A more recent development for my Z4 has been treating the paint. After testing a 540 fender (that I painted with acrylic) at Meguiar's I decided to treat the paint on the Z4 using what I learned from that night. The acrylic clearcoat is much more resilient than I expected.

The process I used was red pad with Ultimate Compound, usually two (heavy) applications, followed by black pad with #7 glaze, followed by Tech Wax applied and removed by hand with a rough microfiber applicator (closer to terrycloth) and microfiber buffing cloth.

The interesting thing about this paint is that it requires a long tooth on any towel to really get into all the texture of the paint. Conversely, the paint is so elastic that it's very hard to scratch. So this is a rare circumstance in which a terrycloth rag is better than microfiber.

Here are a couple before/after pic sets that show the effect of this work. Note that the goal is not to eliminate the brush marks, but to bring a more even gloss to the paint.

Before:

After:


The trunk half the blue area has been treated, the roof's half has not:


Before:

After:


Before:

After:


Overall the paint colors are more vivid and the finish is more glass-like. To describe using Home Depot's interior finish chart I would say it's gone from a 3 (satin) to a solid 4 (semi gloss).

Earl - Looking at the wear on your Pilot Super Sports, it makes me wonder if that is a combination of 2 "new" features of this tire. The first is that Michelin have reduced the "dry" compound on the outer tread to 20% of the total tread face from 50% on the PS2s (the remaining inner is more geared towards wet/lower temps) - this makes be believe that now a larger portion of the tread will not withstand higher temps seen under dry conditions compared to PS2s. This will most likely be exacerbated by the Twaron liner on the Super Sport that is designed to keep more of the tread on the ground at all times.

I did 300 miles at Road Atlanta this past weekend on PS2s (my first time on these tires) and was pleasantly surprised at the grip levels, communication and breakaway character of these. I will take some pics of the tread after the Turkey Day coma tonight to see how they look for wear - I most definitely heated them a lot on some sessions where I had to back off for a couple of laps to let them cool down and come back to initial grip levels.

Happy Turkey Day 'festers!

Originally Posted by pal

Earl - Looking at the wear on your Pilot Super Sports, it makes me wonder if that is a combination of 2 "new" features of this tire. The first is that Michelin have reduced the "dry" compound on the outer tread to 20% of the total tread face from 50% on the PS2s (the remaining inner is more geared towards wet/lower temps) - this makes be believe that now a larger portion of the tread will not withstand higher temps seen under dry conditions compared to PS2s. This will most likely be exacerbated by the Twaron liner on the Super Sport that is designed to keep more of the tread on the ground at all times.

I did 300 miles at Road Atlanta this past weekend on PS2s (my first time on these tires) and was pleasantly surprised at the grip levels, communication and breakaway character of these. I will take some pics of the tread after the Turkey Day coma tonight to see how they look for wear - I most definitely heated them a lot on some sessions where I had to back off for a couple of laps to let them cool down and come back to initial grip levels.

Happy Turkey Day 'festers!

-What you say makes sense, but is counter to the purpose of the SS as a tire that is supposed to have better track durability than the PS2.

It's been a quiet pre-holiday season for Scatha. We'll be at Buttonwillow on 12-19 with Speed Ventures. Should be a fun day with very low car counts and too much track time! Zach's article about Scatha for Total BMW should be coming out any time now...

Originally Posted by Palantirion

It's been a quiet pre-holiday season for Scatha. We'll be at Buttonwillow on 12-19 with Speed Ventures. Should be a fun day with very low car counts and too much track time! Zach's article about Scatha for Total BMW should be coming out any time now...

My Total BMW arrived today!!!!,

Originally Posted by 03BeastCharmer

My Total BMW arrived today!!!!,

...AND? I haven't seen it on shelves yet

It's a nice three page article that goes over the different modifications, and the inspiration for the two themes in the paint. They have a picture looking into the car through the drivers door which I don't think is a good photo. Also a nice small picture on the cover.

Originally Posted by 03BeastCharmer

It's a nice three page article that goes over the different modifications, and the inspiration for the two themes in the paint. They have a picture looking into the car through the drivers door which I don't think is a good photo. Also a nice small picture on the cover.

-I'm still trying to get some copies, no bookstores around here carry Total and more. How did you like the article?

Check your e-mail. Let me know if you want my copy of the magazine.

Originally Posted by 03BeastCharmer

Check your e-mail. Let me know if you want my copy of the magazine.

-Checked. Thank you!

Originally Posted by Palantirion

Dunno. Perhaps I'll be the first?

Maybe...

Here's a link to the "installation of power seats" thread. Posts #15 and #16 go a long way towards understanding the "heat" circuitry. Have fun!

http://www.zpost.com/forums/showthread.php?t=521977

You'll make a lot of new friends if you post a good "step-by-step" of your adventure. I suspect the seat swapping will increase in frequency as our cars age and seat mods become more common.

Cheers.

Thanks for the link EenyBear.

I've just finished updating the MyArtCar gallery if you want to see new pics from the track and other local events.

A new post on Scatha's Art Car thread, showing paint repair: http://www.bimmerfest.com/forums/sho...38#post6808038

Scatha at Bimmerfest 2012: http://www.bimmerfest.com/forums/sho...39#post6850839

I posted it on the Art Car thread instead on this mod thread. But in case you fear that this thread is running aground be assured that there are several "real" mods planned for 2012 that will appear with the usual documentation.

Scatha v1.1
http://www.bimmerfest.com/forums/sho...=1#post6870828