M Coupe LTW build

[Michael9218]

Thanks all. I'll keep adding as I go.

Originally Posted by AriuSen

Is the SLR kit any lighter than oem?

According to Sean they are, but I didn't think to weigh them. I was more interested in the performance improvement with the roll center correction.

Originally Posted by AriuSen

I could be wrong but from my experience, your car will be very very twitchy with those spring rates, but please let me know your experience with the z. Maybe with MCS could be different.

Interesting. What rates are you using? I picked these rates as that's what I was running on my E36. Well, actually, I had slightly stiffer rear at 900 lbs and an OEM anti-rollbar. I figured with the shorter wheelbase I would soften it up a bit with 850 lbs and no anti-rollbar.

[Michael9218]

Originally Posted by braindamage

Amazing build! Question regarding the brake cooling. Are the backing plates custom made or off the shelves from E36/E46?

Came off my E36. E86 uses a very similar knuckle. I only had to drill a couple mounting holes since they didn't quite line up. Easy peasy...

[AriuSen]

I have a track journal that you can see the last pages.
Before I put aero, I always struggled with rear grip. My car was fully stripped too, with solid spherical bushings, and similar tires.
I tried those rates you have and with rcomp, I could barely keep my car on the track.
The z4m chassi is very stiff and with a short wheel base, I think the z4m is better with softer Springs. Here you can see all I've done
My track day journal. new update 11/20/2017

http://www.zpost.com/forums/showthread.php?t=1234284

This is the video when I tried 700/850lbs.

Removed them right away
Today with aero I gave 700/650 lbs with front bar in medium and oem rear bar.
Before aero ended up with 500/550 I think.

[Michael9218]

I would say you had a lot more going on there than just a spring rate issue. It looks like you sort of figured that out browsing through your thread. I don't believe I would've turned a second lap if I had a car that badly controlled. I've had corded race tires that had more grip than those squealing street tires.

I did get the car out a couple of weeks ago, but I'll report on that separately (and the car was not twitchy), but then again this isn't my first time to the rodeo...

[dre99gsx]

Amazing work. I'm impressed! You've given me some more ideas for my ongoing project

AriuSen: Regarding spring rates, although I'm not at your level with grip, my power level on corner exit and 'street' tires never kicks out like yours does on the track (or did). I have stock rear 3.0si bar, standard coilovers, but with 504Fr/672Rr springs and no LSD, car was sticking like a mad man on corner-exit full throttle (and 500wtorque from the 2J).

OP: But, at " 700 lb front, 850 lb rear.", I too agree this may be too stiff for the chassis especially if it is now 2800 w/driver. Nothing wrong with trying it, but you'll have some options and experience from a few of us if you run into issues. Just another datapoint...

[Michael9218]

I got the car on track for a shakedown a couple weeks back at Roebling Road. I like this track for chassis setup as it’s a fast smooth track that helps me isolate what the chassis is doing. Although for this first day on track my expectations were more for sorting the car and finding/addressing any issues. Mainly I was going to be content if nothing fell off or blew up…

First session out I ran 3 laps and came in to put the car in the air and check everything. Everything looked good and only a few minor issues surfaced. My VDO gauges were reading erratically (turned out to be a weak ground), I had a bit of oil on the front of the oil pan. I hate leaks…this one was coming from the front main seal. I replaced that damn thing, but it’s very finicky. So now I get to do it again! The third issue was the initial settings recommended to me for the MCS dampers. I had no turn exit grip. Front rebound was far too stiff. I also had some slight tire rub on the front fender liner at the top of the bumper.

For the next session, I dialed back the rebound a few clicks and things improved slightly. But the car was still lacking grip.

For session 3 I dialed out a few more clicks and things improved dramatically. The car was hooking up. I was noticing what I thought was a flat spot on the tune during acceleration. This actually turned out to be the damn DSC being too active. Once I turned it off the car jumped to life. I had hoped this generation of DSC would be better.

For session 4 I made a couple more damper setting changes and the car felt even better. I was still driving pretty conservatively as the brakes were not feeling fully bedded and I just need confidence in the car. Mid way through the session it threw a “BRAKE” amber light. I wasn’t sure if this was ABS related so I came in. I hooked up my Carly reader and got a steering angle sensor fail. I erroneously thought I had lost ABS and decided caution was the better part of valor and loaded up. I should’ve brought my owner’s manual to the track. Turns out this failure only disabled DSC (which I had off anyway).

Everything else on the car performed flawlessly. The MCS dampers are very responsive to adjustment so I’m looking forward to dialing them in further. The SLR steering design had me worried that it would be too fast, but it felt great. Once I get the car further dialed in, I’ll give a better review of the control arms. The car felt planted and the chassis very communicative (as one would expect with solids and sphericals throughout). The E86 is more lively and fun to drive than the E36. Next track event will be mid January back at Roebling Road.

[Michael9218]

Finished up the hood vent. My plan was to either try to cut the aluminum hood and bend a panel down and figure out a way to hold it in place, or if that didn't work make a CF panel.

Fortunately, plan A worked out quite well. I cut slits from the previous hole I had cut out. Well, actually I started by drilling 1/4" holes at the end of the cuts to prevent stress risers down the road. This meant two slits per side with a 1/4" gap between. As it turned out, this gave me some room to finish up the edges. I then made a bracket to go on the underside and hold the panel down to the top of the cross member. A little trial and error here and I found the correct drop. I then made some carbon fiber 2 layer panels on glass for a nice smooth finish that I then cut to size using cardboard as a template. I taped these in place and then flipped the hood over and laid up some more carbon fiber and epoxy to hold everything in place. Finished it off with three rivets. Easy peasy...

[Beedub]

Originally Posted by Michael9218

Came off my E36. E86 uses a very similar knuckle. I only had to drill a couple mounting holes since they didn't quite line up. Easy peasy...

Can you post up a link for those backing plates!! they are perfect for my needs!

[longress]

That hood looks GT3 awesome! Super impressed with your work.

[Michael9218]

Originally Posted by Beedub

Can you post up a link for those backing plates!! they are perfect for my needs!

I bought them here many years ago:

https://www.harrisonmotorsports.com/...l-1992-99.html

[mattfwalters]

Holy crap, man - nice build. I'm glad you started with interior / front aero, because I had some nagging questions about how I was going to deal with similar issues in my build... and now I don't.

[Shutterspeed]

Impressive work. Very amazing build going on here.

[SaltyNC]

Well done! Congrats. Having just soaked a tie rod locking adjustment nut with PB Blaster, I couldn't help but admire how much your suspension looks like jewelry.

Salty

[M-Cast]

Michael, glad to see that you got this car track ready, hope to see this thing in action at Road Atlanta next month. Did you figure out what you are going to do with the Aero yet? Great Job!

[Azeka1]

Amazing build! Subscribed for more updates.

[angelr]

Any times from Roebling?

[Michael9218]

The car was back in the shop to eliminate lingering bogus codes from the de-wire and to get the dyno tune. The dyno tune found 20 more hp from the off-the-shelf performance tune. There is an odd dip in hp at 7,200 rpm. Tuner thinks this could be some kind of harmonics with the exhaust as he wasn’t able to get rid of this. It’s not noticeable when driving the car. I do like the flat torque curve. I assume this is due to the stepped header design. Absolute values aren’t entirely relevant since different dynos and different days will produce different results. Motor is stock, with Supersprint stepped headers and catless exhaust and underdrive pulleys.

[Michael9218]

This last weekend I took the car back to Roebling Road for another tuning weekend. Rain was in the forecast, so I decided to put in a little softer rear spring. 800 instead of 850. The 850 rate was in anticipation of having a large rear wing.

Saturday morning sessions were in the wet, so I got the opportunity to test out the low compression damper settings on the 3 way MCS dampers. First session out was a wet but drying track, so I went out with slicks and softened the settings. Car handled well. The dampers helped the tires find grip. Next session was raining so I put on full tread Toyo RA1 tires and softened the dampers more. The RA1’s were disappointing! Very slippery. Not sure what to do about this, as these aren’t going to make good rain tires.

The afternoon finally brought a dry track and I got in two good sessions at speed. Making adjustments between sessions. The car is very predictable and neutral in it’s handling. Not at all twitchy or exhibiting snap oversteer. It's a blast to drive! I was looking forward to making more adjustments and turning up the heat on Sunday, but the event got canceled due to an unfortunate incident late Saturday. So, next time…

Here is a sort video of a couple laps turning 1:22/1:21 laps. Still lots of potential in the car. These laps are at pace, but a bit leisurely. Still not pushing the car.

https://photos.smugmug.com/BMW-Z4-Tr....10.18-640.mp4

[angelr]

Originally Posted by Michael9218

This last weekend I took the car back to Roebling Road for another tuning weekend. Rain was in the forecast, so I decided to put in a little softer rear spring. 800 instead of 850. The 850 rate was in anticipation of having a large rear wing.

Saturday morning sessions were in the wet, so I got the opportunity to test out the low compression damper settings on the 3 way MCS dampers. First session out was a wet but drying track, so I went out with slicks and softened the settings. Car handled well. The dampers helped the tires find grip. Next session was raining so I put on full tread Toyo RA1 tires and softened the dampers more. The RA1’s were disappointing! Very slippery. Not sure what to do about this, as these aren’t going to make good rain tires.

The afternoon finally brought a dry track and I got in two good sessions at speed. Making adjustments between sessions. The car is very predictable and neutral in it’s handling. Not at all twitchy or exhibiting snap oversteer. It's a blast to drive! I was looking forward to making more adjustments and turning up the heat on Sunday, but the event got canceled due to an unfortunate incident late Saturday. So, next time…

Here is a sort video of a couple laps turning 1:22/1:21 laps. Still lots of potential in the car. These laps are at pace, but a bit leisurely. Still not pushing the car.

https://photos.smugmug.com/BMW-Z4-Tr....10.18-640.mp4

Very cool man! I'm sure once you get it all dialed in it'll be doing 1:16's. I have a video of a few laps in an Audi TTS in Roebling in the wet and they were in a similar range as yours....it's fun to play around a little under those conditions.

[FD3S]

Originally Posted by Michael9218

There is an odd dip in hp at 7,200 rpm. Tuner thinks this could be some kind of harmonics with the exhaust as he wasn’t able to get rid of this. It’s not noticeable when driving the car. I do like the flat torque curve. I assume this is due to the stepped header design. Absolute values aren’t entirely relevant since different dynos and different days will produce different results. Motor is stock, with Supersprint stepped headers and catless exhaust and underdrive pulleys.

Nice build!

I have the same problem with my tuned car but with a completely different setup. After the 7200 rpm I have a dip that nobody can explain. My tuner told me that this maybe was a heatsoak. I would be glad if you solve that problem to share how you did it.
By the way, which tuner do you have?

For my numbers you can check here:
https://z4-forum.com/forum/viewtopic.php?f=9&t=100283

[M-Cast]

Have you ever looked at Turner's IAT Relocation Kit? They say it handles that issue, but I have never seen anyone use it. When I get my engine back, I will check to see if I run into the same issue when we get it back on the dyno.

https://www.turnermotorsport.com/p-3...rness/?pdk=AgM

Originally Posted by FD3S

Nice build!

I have the same problem with my tuned car but with a completely different setup. After the 7200 rpm I have a dip that nobody can explain. My tuner told me that this maybe was a heatsoak. I would be glad if you solve that problem to share how you did it.
By the way, which tuner do you have?

For my numbers you can check here:
https://z4-forum.com/forum/viewtopic.php?f=9&t=100283

[FD3S]

Originally Posted by M-Cast

Have you ever looked at Turner's IAT Relocation Kit? They say it handles that issue, but I have never seen anyone use it. When I get my engine back, I will check to see if I run into the same issue when we get it back on the dyno.

https://www.turnermotorsport.com/p-3...rness/?pdk=AgM

It can be a possibility. Due to the fact that I have a CSL airbox and the IAT is relocated I give it a small chance. However I have to research it with all the other possibilities eg. better airflow for the airbox, valve adjustment.

Please keep me updated after your dyno.