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      12-26-2017, 07:46 PM   #1
Michael9218
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M Coupe LTW build

My build is nearing completion, so I thought I would share some of the details of this build since there are few E86 full tilt track builds. My overall objective on this build was to make a no compromise track car build with weight reduction being the primary focus. Adding lightness is the best way to make a car fun and fast on a race track.
By way of introduction, I started tracking sometime in 2006 in my Z3MR. After a couple years I realized I wanted to go racing so I picked up a 1995 M3 and began the long process of building this car, and my skills, to go racing. In 2010 I went racing in IP with BMWCCA. For the next 5 years I raced at tracks in the southeast. It was a great fun, but unfortunately a competitor’s poor judgement took out my car at the end of 2015. The wife declared no more racing (something about bouncing off walls at 100 mph freaked her out…). I was kind of done with racing anyway, but after a year away from the track the bug returned (probably easier to kick a crack habit…). A compromise was reached where I will go back to just tracking a car.
With that agreed, I sought out a car to build. I have had a Z4MC as a weekend car for about 5 years. I always thought this car would make an excellent track car, but this car is a garage queen. I bought it with 3,500 miles at 5 years. A unique color combination of white with red interior and Madeira walnut dash (supposedly 1 of 5). At 10 years this car has all of 18,000 miles. It’s not going to see track time. So I found a 75,000 mile black Z4MC for sale locally. This will be the track car.

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      12-26-2017, 07:49 PM   #2
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With the primary objective being to reduce weight on this car, I knew that I would be stripping the car of everything that isn’t needed to go around a track. The base weight of the car was a hefty 3,200 lbs dry. Heavier than an E36 M3…



The first decision was whether to stay with the factory engine management and ABS or go stand alone. I decided to stay with the factory DME and ABS. As this is my second track car build, I knew that the first step is then to get the DME programmed to ignore systems that will be removed from the car so it stays happy as modules are removed and wires are cut and removed. Otherwise, you will get codes, or worse, a no start situation. Dave Markert at Markert Motor Works in Lawrenceville, GA set me up with an off-the-shelf performance tune and programmed the DME to ignore the following systems: EWS (anti-theft), SRS, TPMS, Audio/video, body control (windows and doors), emissions, climate control. A proper dyno tune will be done later.
With that done, I began to strip the interior of the car. Everything must go.

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      12-26-2017, 08:01 PM   #3
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With the interior panels and carpet removed, the laborious and intimidating process of removing system modules and identifying wires and harnesses to remove begins. This step is not for the faint of heart. You need to have a high comfort level with navigating a wiring schematic and spend time studying every part and wire. I started by unplugging modules one system at a time, starting the motor to check for warning lights after each system. Obviously, you need to disconnect the battery before unplugging modules. In the end about 45 lbs of wire and modules were removed.











I also realized that the bulkhead had to come out. This beast is a pain in the ass to remove. 75 spot welds and stitch welds. Many not easy to get to. But with patience and perseverance, I got the bitch out. 35 lbs! Definitely in the way of a proper cage.





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      12-26-2017, 08:12 PM   #4
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With the interior removed, it was time to remove the drivetrain. I needed to keep the chassis as a roller to get it to the cage builder. So the motor, tranny, and diff were removed. The diff was sent off to Diffs Online for a 4.10 35/60 ramp diff with REM polished gears and bearings. Sorry, no pics of the diff.

I then took the car to Robinson Racing in Cumming, Ga for the cage work. They built the cage in my IP car. They do good work. For this car, I decided to go with what I will call a 2/3 cage. Rear cage with a single diagonal door bar terminating into a forward plinth. This will allow for a forward half of the cage if I decide to add this later. Initially for tracking, I’m comfortable with this set up. Cage designs are very subjective and everyone seems to have an opinion. It’s all about tolerance for risk.

















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      12-26-2017, 08:21 PM   #5
Michael9218
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While the car was at the Robinsons, I put the motor on a stand and did a little motor preventive maintenance. I replaced the rod bearings with BE Bearings and OEM bolts, rebuilt the VANOS with the Beisan kit, replaced the front main seal, vibration damper, and water pump. I also capped off the water lines running to the cabin heater. While the oil pan was off, I had an NPT bung welded on for an oil temp sensor. I also installed Rogue Engineering undrive pulleys. In talking to Ben, he expressed concern that the undriven altenator may not provide enough charge at idle to run the car and with the 10 lb ETX14 battery I will be using. So I opted to use the stock altenator pulley and had to measure for an appropriate belt. A 1520mm belt fit perfectly. As it turns out, the Rogue alternator pulley doesn’t fit the Z4M alternator anyway. Well, it fits, but is out of alignment with the other pulleys. You would need to mill off 1-2mm to get this to work.



Was definitely time for new bearings.






With the transmission out, it made sense to use the ZF 5 speed I had in the shop. I also had the Bimmerworld strapless clutch kit from the S52 that will mate the S54 to the ZF tranny. The ZF is 20 lbs lighter than the Getrag 6 speed. Mounting the shorter ZF is pretty easy. Order yourself a transmission mount from a 2.5 Z4 that came with this transmission and it then bolts right up. The driveshaft did have to be lengthened 100mm by a local driveshaft shop. I also had to have a custom length DSSR fabricated for the gear selector.





I also took advantage of Turners Christmas deals last year and picked up a set of the Supersprint full stepped headers and section one. I had them ceramic coated to keep underhood temps down.

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      12-26-2017, 08:35 PM   #6
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With the car back from cage, it was time for chassis work. Now, the underside of the car was stripped. Subframes came out. On the front subframe, I welded on the motor mount reinforcements. On the rear, all bushings were replaced with aluminum or spherical bearings. NVH, who cares?







Rear suspension bits:



For the front, I went with SLR roll center correcting control arms.







I reinforced the front swaybar mounts using the epoxy method. I roughed the mating surfaces for better epoxy grip.







For suspension, I chose MCS 3 way adjustable with remote reservoirs, Ground Control camber plates, GC front sway bar, and GC rear articulating adjustable spring perches. 5” tall 2.25” springs, 700 lb front, 850 lb rear. The 5” springs in front will allow more tire clearance.

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      12-26-2017, 08:38 PM   #7
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For brakes, I was thinking of going with enhanced OEM brakes. On the E36, they were adequate, though in the end I did have Alcon front brakes with PFC rotors and pads and did like the pedal modulation. Once I removed the Z4 OEM calipers, I realized they were very heavy. So WTF, time for brakes… After some research, I decided to go with Stoptech Trophy brakes. 355mm ST40 4 wheel kit. Brake parts are consumables. PFC makes nice brakes as well, but pads and rotors are not as easy to source. Stoptech rotors and ST40 pads are available everywhere. Even Summit Racing carries them. Plus having the same rotors and pads front and rear makes inventorying parts easier. The 355mm ST40 kit also fits inside 17” wheels. Yep, I plan to run 17” wheels. Apex ARC8 17x9.5 et 35. Fits with 275/40/17 Hankook Z214 tires. The fronts do require a 5mm spacer to clear the spokes. I’m also running a 10mm spacer in the rear for wider stance.



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      12-26-2017, 08:57 PM   #8
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Well shucks.
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      12-26-2017, 09:09 PM   #9
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With the motor and trans back in the car, now for some custom plumbing work…

First up was the leak prone OEM power steering. I had converted the system on my E36 to AN and did the same for the E86. Braze welded the male AN fittings on the metal pipes and use braided line for the hose. For the high pressure side, I used triple braid rated for 2,200 psi.





For the radiator, I opted for the OE fitment CSF 3055 radiator. At $250 it was a steal for an all aluminum 42mm radiator. More capacity than stock and aluminum reliability. I did want to modify the mounting location and go with a custom setup to take advantage of a vented hood. Meaning, change the direction of the air flow post radiator to go up and out the hood rather than down and under the chassis. To accomplish this, I needed to move the radiator down and lean it forward as far as I could. The stock location puts the radiator at a 5 degree backward lean. I ended up tilting the radiator 15 degrees forward. This made room for a nice air box on the backside of the radiator in front of the front bulkhead. I also shaved the top of the bulkhead to make a flat, or straight, top to allow better hood venting. One nice thing about the E86 is that the front clip can be removed and you can work on all of the plumbing (water, oil, PS) on a workbench. This made fabricating the required shrouding much easier!

Repositioned the lower radiator mounts:












For oil cooling, I decided to go with an aftermarket universal cooler. A 19 row Setrab cooler. These coolers are more efficient than the wide fat under radiator coolers (and considerably less expensive). The only drawback is finding captive air for the oil cooler. If you’re going to stack your coolers, you need to shroud the front and the back of the oil cooler to allow the low pressure on the backside of the water cooler (radiator) to draw air through the oil cooler. This should still be significantly better airflow than the OEM oil cooler.





For the power steering cooling, I decided to keep the aluminum loop. Not a very effective cooler, but I’m not sure how much it needs. I’ll monitor the PS fluid and change this if needed. I’m double under driving the PS pump, so it may not be a problem. For now, I braze welded AN fittings on the aluminum tubing and moved the cooling loop to the backside of the radiator. It should get considerably more airflow than the stock set up in front of the AC exchanger and radiator stack. I mounted the loop to the Spal 14” fan in the radiator air box.





With the front clip on the workbench, I also made modifications to the front bumper for brake ducts and blanks for the stock brake vent holes (I don’t think I would call them brake ducts…) and the headlights, oh, and also removed the headlight washers. I don’t plan to run headlights. 20 lbs of unnecessary weight! So I fabricated some brake hole blanks and headlight blanks with some wet layup carbon fiber. For the brake holes, I made blanks out of aluminum and then laid up the carbon fiber over that as a mold. The headlights were a bit trickier. The headlights are actually undersized for the cutout to allow for adjustment. I wanted the blanks to be a tighter fit. So I used modeling clay to fill the gaps on the headlights and then used the headlights for the molds.







Bumper loosely installed:



With the airflow through the radiator now routed up, I needed to vent my hood. I looked at all the options that were available, including the recent trend for heater vent looking louvres. In the end I decided to give it go to make my own vent panel out of carbon fiber. For now, though, I’ve run out of time and am anxious to get the car on track to begin sorting the suspension, so a preliminary hole was cut on the hood. More to follow on this modification…

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      12-26-2017, 09:26 PM   #10
Michael9218
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With the interior stripped, I carved up the dashboard to eliminate the duct work on the underside. With no heater box, I won’t be needing the ducts. For air flow, I did realize that the E86 pulls cabin air aft of the firewall but in front of the windshield. So I fabricated a panel to plug the hole and sourced a couple 2” hose mounts from Aircraft Spruce. I found some 2” flex tubing that I can route to push air to my feet and one shooting at my chest. Should feel good when the temps rise.



I also needed a dash panel for my auxiliary gauges to monitor oil pressure, oil temp, water temp, and volts. I used the OEM dash panel to make a mold for a little carbon fiber layup. This dash panel will also provide a mount for the switches for the seat vent, cool suit, camera, and radiator fan.





For my seat I went with a Racetech 4009 HSR vented seat. I had this seat in my other car and really liked the fit, and the forced air vent. Since I won’t be needing a passenger seat, I moved the battery to the floor in the passenger area. I fabricated a rack to mount the battery and my cool suit.







Since I won’t be needing the door windows, I cut out the door panels and fabricated a new interior door handle mount.



I also fabricated a floor panel and dead pedal.



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      12-26-2017, 09:29 PM   #11
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2007 EuroSpec Z4///MC DIY Arial. Carma FF race exhaust. Cust. D///MK 6 Speed ultra SSK. CDV X. CSL 19" Rims. Apex 75mm kit. Stoptech brake lines. APR Aero. CSL intake. Epic Alpha-N. KW CS. SS sec1. 288/280. ECS power pulleys. Tillet B6Fxl. Sabelt.Varis. Brembo GT. ME STB. JB/Sachs Race SMFW .
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      12-26-2017, 09:33 PM   #12
Michael9218
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M Coupe LTW

At this point the car is ready to go play on the track, sans aero. But first, suspension tuning and adjustment. I’ll go with the recommended initial damper setting provided by Wyatt at MCS and adjust from there. I set the ride height and then using my Longacre camber gauge set the camber. For toe, I made up a string box and used this method to get the desired toe front and rear. Once that was done I corner balanced the car with my Longacre scales.

Oh, and 600 lbs has been removed from the car. The weight below is with half a tank, driver weight and coolsuit water weight. Empty weight is now @ 2,625 lbs.



Ready for the track and the first shakedown.

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      12-27-2017, 12:11 AM   #13
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total off the hook build! You sir have mad skill and deserve much respect.
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      12-27-2017, 12:40 AM   #14
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Wow. Bespoke carbon fiber pieced, endless fab.
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      12-27-2017, 01:09 AM   #15
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incredible
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      12-27-2017, 01:24 AM   #16
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Superb work!
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      12-27-2017, 01:43 AM   #17
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Proper build and documentation. Well done!
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      12-27-2017, 03:57 AM   #18
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wow, just wow....
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      12-27-2017, 04:43 AM   #19
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Mama Mia

Amazing build!

Is the SLR kit any lighter than oem?

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.
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      12-27-2017, 05:27 AM   #20
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Also interested in a review of the SLR arms. Looking for a set myself. Sweet build. Can't wait to see what you do next.
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      12-27-2017, 08:23 AM   #21
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in.sa.ne.


Well you came out of no where and blew shit up!! Well done man.

LOVE the standard of your work!
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      12-27-2017, 02:19 PM   #22
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Amazing build! Question regarding the brake cooling. Are the backing plates custom made or off the shelves from E36/E46?
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