Z4 M Coupe mods, the ongoing tale...

Originally Posted by Raff

Wow man, the car is looking good. Are you going to bring that one to the BBQ, would love to check it out some more in person.

-I think I'll be able to. Unless BMS needs it in the shop for mods.

cool can't wait to see it.

Sigh, where to begin? The last week has been CRAZY busy! I guess I'll go through things chronologically. Be warned, it's a loooong post...

As previously stated, we got the new TCK coilovers and camber plates, TMS limiters, and GC control arms on (Mod 25). StopTech took quite a bit more time than we anticipated to get us the 4-wheel BBK kit. In fact, BMS recieved the kit only two days before the Coupe's next track event at Willow! But they got everything installed, alligned and bedded by 6:30pm the night before the event. Props to BMS!

Pics of the BBK install (Mod 26):
The front end, stripped of the stock rotor and caliper:


Carefully hammering the splash guard back for rotor clearance:


Removing a small protrusion in the stock splash guard that could not be hammered back without potentially damaging the tie rod end:


Trimmed splash guard and StopTech caliper bracket in place:


StopTech rotor on:


ST40 caliper on:


Lug stud conversion done (Mod 27):


And the 15mm spacer:


Stock rear brake


StopTech rear brake


On BMS's allignment rack:






Driving out to Willow I noticed a fair amount of road noise that wasn't there before. The tires are the same RA-1s as last time. I guess that the firmer suspension just transmits more noise to the cockpit than the softer BMW suspension. It's not too bad, just a little more rumble. The rear shocks have a slight rattle, but I knew that going in. Something about their design. It doesn't matter as it's slight enough to be unnoticeable over 35mph. The camber plates make a little cluck over bumps, which they shouldn't. BMS will sort this problem out. The ride, to my astonishment, is actually better than stock It's firmer, sure, but the car pitches less and the perceptibly more "planted" feel is much better than stock! The brakes make NO noise, even under braking. I've been trying to figure out how to explain how the new brakes are. The best I can come up with is "I don't know" - the car stops so fast you aren't able to sense anything past the inital Gs - The mph on the speedo just DROPS. It is very, very stable - moreso than stock I think.

At the track the car just ran away from everything else. It's the first time I've ever been at a track event where I didn't get passed by ANYONE all day. The field included several novice drivers to be sure, but also some pretty powerful cars; several Porsche TTs and two cars with more than 600hp. The only car I noticed running about as fast as M Coupe was a older ('80s?) 911 race car that probably weighed a half-ton less than my Coupe and was rolling on Hoosiers. The Coupe with the new suspension just sticks and rotates SO well that it left everything else behind in the turns. Turn 2 at Willow is my benchmark for steady-state cornering. With stock suspension (except for the -1.5 camber in the front) and RA-1s the Coupe could be pushed up to 90mph in 2. With the current setup (and only -1.9 camber at this time) and the same RA-1s I got up to 94mph! That's a hell of a change in a car from suspension alone.

The following picture is the best example of why I love the new suspension. This left edge of this RA-1 was the outside edge on the Coupe's first visit to Willow (stock suspension and BMW "camber mod"). The right edge was the outside edge with the new suspension.


Facts 'n figures:
The suspension mods dropped 6.3lbs, all in the rear. On the street I run +5 all the way around on the bump with 1.5 twists from soft on the front rebound and .75 twists in the rear. At Willow I ran the same rebound but upped the ds front bump to +7, the ps front and ds rear to +6 and the ps rear was left alone.

The BBK dropped only 2.3lbs, IF you count the weight of the spacers I need for my RGRs and the added weight of switching over to studs/nuts instead of lug bolts. However, weight is shifted rearward with the BBK, by 22lbs! That's -14lbs on the front, and +8lbs in the back. Why a weight increase in back? Because both ends use ST40 4-piston calipers, although the rears use a different piston size. Why? Because StopTech says that the larger rear brakes are necessary to provide balanced braking force. Initially I really wanted to lose some weight from the brakes, so gaining more than 1/2 of it back in the rears bothered me. However the car's SO stable under braking now that I don't mind as much.

Pics from the event:






I don't have any pics of my Coupe on track yet...waiting on gbogh6 from m5board to send them to me. If any of you want to go to m5board.com and bug him, feel free


Continued in next post...

...continued from last post (Bimmerfest pic/post restriction)...

Driving back from Willow was pleasant enough. The tires were a little low from being aired-down for the track, so even heated up from the highway they probably weren't over 34psi. It made for a more relaxing ride, especially since I hadn't turned the bump back down to "street" levels on the shocks. I caravan'd back with a 621hp Dinan S3 M5, a 670hp 911TT and two other E39 M5s - good company.

Pics:




Friday I took the Coupe down to BMS for post-track day analysis and to see what could be done about some slight-to-moderate tire rubbing. They were slammed with work on account of the upcoming BMWCCA double-points race at Willow this next weekend, but managed to clear a lift and roll the edges of the fenders in so that I don't have to worry about cutting a tire. Next week we'll get the Coupe on the allignement rack and reset the ride height at all four corners (new springs tend to settle after installation) and add more negative camber to bring the tops of the front tires in a little more.


I also added stickers from dansdecals.com to cover the rear reflectors. I think it looks better:


Mod 28
Here is the best bang-for-your-buck mods EVER. About $1 in hardware from Home Depot and you no longer have a chaffing mark in your neck from the seatbelts! Why BMW didn't give the Z4 adjustable shoulder belts is beyond me Anyway, I know it's a little ugly, but I'll try to find a cleaner way to accomplish the same task later on. For now, my neck is happy.


Mod 29
Last night I installed two BMW first-aid boxes I recieved from leatherZ.com for more storage. Together they weigh only 1.12lbs, and in my mind it's a no-brainer.


Today my wife and I attended the BBQ in pacoima, organized by some fellow Bimmerfest members. I took some really good pics of the Coupe there, but haven't had time to take them off my camera yet. Look for those later this week.

I'm dropping the Coupe off tomorrow morning at Brea Auto Body to remove a ding I caused by opening my garage door while the Coupe's trunk was open I'm not having them buy a new M badge for the trunk (And pay their markup for no reason). I'm curious to see if I like it without the badge. More than likely, I'll put it back on later - so don't flame me yet.

See you all at Bimmerfest. Look for the Coupe at StopTech's booth.

i finally was able to get rid of all the rear carpeting and installing a pc680. Next I want to run some type of a car in the rear to relocate my racing harness mouting points.

Nice write up Earl. I love your car and yes guys the brakes work very well, got to rid in that rocket on Sunday and that sled is awesome.
Thanks for coming out to the meet.

Here some pics of my Coupe at a Bimmerfest BBQ last Saturday:

Looks great. I have a few questions.

Did you change the front turn bulbs. And do the rear bumper lights show thru the stickers at night?

Great work Earl!
- looks great

Originally Posted by cosmos

Looks great. I have a few questions.

Did you change the front turn bulbs. And do the rear bumper lights show thru the stickers at night?

1) No, all bulbs are stock.

2) I don't know, I never looked. I assume since they were reflectors that they didn't self-illuminate. I'll check.

Coming along nice

So your front still makes clunky noises going over bumps? My TCK coilover did too, as well as a couple of other people I've talked to. The problem is with the struts. TCK knew the struts had problems, but still sold the coilovers to me and a couple of other people. I've sent my struts back to them and they told me they found a solution but they didn't test it on any MZ4 yet (this was 2~3 weeks ago).

Originally Posted by GP20

So your front still makes clunky noises going over bumps? My TCK coilover did too, as well as a couple of other people I've talked to. The problem is with the struts. TCK knew the struts had problems, but still sold the coilovers to me and a couple of other people. I've sent my struts back to them and they told me they found a solution but they didn't test it on any MZ4 yet (this was 2~3 weeks ago).

-I have one of "5" sets that were returned for the clunking problem. According to TC these were hand-rebuilt by Koni NA to fix the problem. I don't know yet if the clunking I hear is due to the struts or the camber plates, but we're suspecting the latter. We'll know more soon. I'll keep you guys posted.

p.s. I got the BMW strut bar on. I chose to leave the nuts bare, I think it looks better than the black plastic covers.

Great write up. Keep it coming.

The Coupe had a great weekend, showing at Bimmerfest and visiting the races at Willow Springs. Because Bimmerfest only allows 25 pics per post, I started a new thread for the weekend here: http://www.m5board.com/vbulletin/sho...55#post1037555

Originally Posted by Palantirion

The Coupe had a great weekend, showing at Bimmerfest and visiting the races at Willow Springs. Because Bimmerfest only allows 25 pics per post, I started a new thread for the weekend here: http://www.m5board.com/vbulletin/sho...55#post1037555

Got a chance to see this at BF and recognized it immediately. Looks just as beautiful in RL as in pictures.

Good work.

Originally Posted by tom @ eas

Got a chance to see this at BF and recognized it immediately. Looks just as beautiful in RL as in pictures.

Good work.

-Thanks

I think it's a little better looking now, as I swapped my CF roundel stickers to brushed aluminum. It definately compliments the interior better, and I like the way it adds yet another shade of silver to the exterior of the car. Pics:
[IMG]http://ebsart.com/images/Net%20Publication/Misc%20Scatha/07,5-08,%20Aluminum%20roundel%20stickers/CIMG2148.JPG[/IMG]






I also used a couple of spares to decorate the stamped roundel in the engine bay:


Then I took it to BMS to raise the ride height a little to elliminate the last potential for tire rubbing. Funny, but I think it actually looks better (moreso in person) now.
Before:


After:


Since an allignment was then necessary anyways, I asked for a little more negative camber. Now I've got -2.2 all around and the car is even more responsive Time will tell if the camber wears out the tires faster. Here's what it looks like from the front:


Then I took it over to K1 for a BMWCCA meeting. Some photos:

Love the roundel mods!! Have you thought about smoking (tinting) your tail-lights? I'm not talking about the ricey-smoke that that looks completely blacked out. I mean the subtle light-smoke that looks transparent and should look very classy. I think that would look hot on your M coupe with the RGR's and your roudels.

BTW, did they sort out the front suspension noises? I talked to TCK yesterday, and they claimed that the 2 people that had the revised struts installed (1 of them is you, the other guy is in FL) never complained about the noises to TCK and they're not aware that the noise still exisits.

Looking Good! What and when on the exhaust mods? Still thinking Custom?

Originally Posted by Palantirion

Since an allignment was then necessary anyways, I asked for a little more negative camber. Now I've got -2.2 all around and the car is even more responsive Time will tell if the camber wears out the tires faster. Here's what it looks like from the front:

Yup, that's some negative camber. Please keep us updated on tire wear and if the car is, um, overly responsive.

Originally Posted by GP20

Love the roundel mods!! Have you thought about smoking (tinting) your tail-lights? I'm not talking about the ricey-smoke that that looks completely blacked out. I mean the subtle light-smoke that looks transparent and should look very classy. I think that would look hot on your M coupe with the RGR's and your roudels.

-Not a bad idea. I've thought about it, just left it on the back-burner for the time being. I guess one reason I haven't cared to do it yet is that the Imola interior, red StopTech calipers and tailights all go together.

Originally Posted by GP20

BTW, did they sort out the front suspension noises? I talked to TCK yesterday, and they claimed that the 2 people that had the revised struts installed (1 of them is you, the other guy is in FL) never complained about the noises to TCK and they're not aware that the noise still exisits.

-I never bothered to call TCK about the front noise, instead I talked to Chris about it. He's pretty sure it's the front shocks making the noise and equally confident that they will always make a little noise because of the shock design. I'm not really bothered by it as the fronts make less noise than the rears - and I knew going in that the rears were going to make some noise. I do agree that it's BS that TCK claimed the fronts would make no noise in order to sell them, and then fall short of what was promised. If he ever comes out with a quiet version I would expect them to offer free replacements to those of us who bought faulty shocks.

Originally Posted by Caddyshk

Looking Good! What and when on the exhaust mods? Still thinking Custom?

-Working on it. I'm thinking custom, but Chris has another idea. Should know more by the end of next week.

Originally Posted by Fast6

Yup, that's some negative camber. Please keep us updated on tire wear and if the car is, um, overly responsive.

-So far it turns in faster, but doesn't overreact. I'll post more after further testing...

Handling update:
I took it out for a quick spin this afternoon. The car feels very, very stable through the turns. If anything, there is a touch of understeer that wasn't there before. This may be due in part to my tire pressures being currently low (around 29psi) because I forgot to air them back up (long story). I'm going to air them up to 32psi and try to get in another drive late tonight.

Mod 30
5-11-07
Attempting to copy my success at turning my wife's 540iT's grill into shadow chrome to match her RGRs, I took Duplicolor's Metalcast to my Z4's grills. I'm pleased with the results, even though the grills had a few tiny rock chips to begin with - it's a track car, I'll get used to rock chips eventually.

Next to an RGR:


Next to a chrome BMW grill:


In the garage (fluorescent light):


At PCH hot dogs in Orange:

Update
I've just signed up for SpeedVentures' Cal Speedway school this Friday and Sunday. If any locals want to come out and get a ton of seat time for the money, I highly recommend Speed Ventures.

Saturday night I hurt my neck driving the car (pulled muscle). I took the car out for a "handling evaluation" after adjusting the tire pressures (31psi). The car is SICK! I actually made myself a little nauseous and after I parked the car at home I discovered that even after a short freeway drive back I was a little bit dizzy. My heart rate was nicely elevated too

Originally Posted by Palantirion

Update
I've just signed up for SpeedVentures' Cal Speedway school this Friday and Sunday. If any locals want to come out and get a ton of seat time for the money, I highly recommend Speed Ventures.

Saturday night I hurt my neck driving the car (pulled muscle). I took the car out for a "handling evaluation" after adjusting the tire pressures (31psi). The car is SICK! I actually made myself a little nauseous and after I parked the car at home I discovered that even after a short freeway drive back I was a little bit dizzy. My heart rate was nicely elevated too

Interesting... Saturday is sold out, but I may try for Friday if I can clear my schedule.

Did you sign up for Infineon?

Originally Posted by PPG4

Interesting... Saturday is sold out, but I may try for Friday if I can clear my schedule.

Did you sign up for Infineon?

-No I didn't. This will be my last track event until the fall, so Chris and the BMS guys can have more uninterrupted time to tear the car apart and work with vendors on some more significant mods. I will probably go to Infineon next year. Ideally, I'd like to hit Infineon, Seca and Thunder Hill all in the same trip.