BMW e90 M3 LSL - Willow Springs
Finally finding some track time as the weekends get a little less busy, or as I merely put off projects. The car is fairly well sorted with some recent updates to the suspension and tires. Bimmerworld lower control arm and trailing arm sphericals installed. Updated front and rear Swift springs for slightly stiffer rates at 10kgf/16kgf. Car has been re-aligned, balanced. Michelin Sport Cup 2 (240) Connected tires were fitted to the Titan7 T-R10 wheels along with the little temp/pressure sensors. I have the Motion Control 2way shocks set up nicely as well.
These Michelin are interesting in that they are a Sport Cup 2 tire but in 240 tread wear. The tires are quite soft still, similar to a regular Sport Cup 2. Hoping for some longevity out of these, as I get some new wheels sorted for track use. The Michelins are also the new “Connected Tire” which means they have a small pocket on the inside for a sensor that measures pressure and temp. The sensor comes with a separate 500$ package that is 4 sensors, receiver and a phone mount. The idea is that the sensors are paired to the Michelin Track Connect mobile app, giving you real time temp and pressure data. The data is collected while you are on track with real-time feedback as to state of tires relative to their sweet spot. The app is much like a lap timer, giving you lap times (GPS based) and a course map review of what your tires did and where. Its interesting seeing the temps go up as you run the session. The lap timer is nice but more importantly - you just get a quick readout for temps and pressures.
One of the track events was the Shift-Sector half mile event. This is not the car for it but still fun to stretch it out some. With poor start traction and relatively low effort on my part it ran 135mph or so in the half. To put things into perspective, the McLaren 675LT we bought out ran 187mph at 1000whp and our Porsche GT2 flagship runs 205-208mph consistently at just over 1400whp (6speed to boot)
Two weekends ago got to Streets of Willow at Willow Springs Raceway with SpeedDistrict and the shop, which was sort of the first time the car was set up right. Good tires, shocks tuned with the stiffer springs and etc. This was my first time being at Streets and was a great time learning the track and getting a handle on it. Managed to just dip into 1.29s - lots of work left. It was quite cool and the track took a bit to warm up - this is where that Michelin app came in handy - you could see how the tires were taking a bit to get up to temp. Looking forward to the coming weekend at Big Willow and more California track (I’ve been in SoCal 3 years and its time to get out and drive)
The Brembo GT-S holding up great, though Im nearing the end of the Ts-20 pads. Shocks are always there and the car just deliveres. 167k Miles and counting!
Overall the car handles great. I need to look at mitigating body roll somewhat and setting up with a track-only set of wheels and tires so I dont kill the street tires. Keep tuning the dampers and just get more seat time. Really want a set of seats and harnesses, but maybe just harnesses. Getting flung about is tiring.
Images by CaliPhotoVideo for SpeedDistrict
BMW e90 M3 LSL - Suspension
One hundred and thirty thousand miles on OEM shocks, bushings. Some of that with lowering springs installed by a previous owner. Time for a change.
The factory shocks with the lowering springs feel bouncy, with too much rebound or shot compression or just too much wear. The car crashes and rolls and just soft all around. To solve those problems the vehicle needs better bushings, better shocks and springs and better sub frame mounting.
With a wide variety of systems available I chose to work with MCS. Their shocks performed extremely well on some other builds with being very responsive, tunable and of high build quality. The valving works great and each adjustment has a significant change, impacting the overall feel. I did not want to deal with external reservoirs as the car would not see racing conditions to justify the components. Keeping in mind the goal of the vehicle and the LSL mentality - the setup had to be similar closer to what an OEM might come up with for a special model.
MCS offers the 2WNR shocks - which are 2 way adjustable (rebound and compression). The adjustment mechanism is quite unique in that the same little knob will do both, depending on position. You can click the knob down for one adjustment and release it upward for another. Easy.
The shocks are paired with Swift springs with front at 504lbs, with 168lbs helper and rear at 784lbs. This should provide enough compliance for roads and rougher tracks but also support the chassis well. Ground Control Race camber plates will secure the assembly along with their pivoting rear spring perches. The rear perches will pivot as the suspension travels, keeping the spring more square and not skewing the rate.
With better chassis control - need to ensure that there is minimal flexibility. Bimmerworld has a very comprehensive catalog of components to eliminate rubber and create a more direct chassis.
The rear subframe gets solid alum bushings along with the differential. Also eliminating the subframe side camber arm bushings in favor of nice sealed monoballs. The trailing arm bushings get replaced with a similar bushing. Also updating the front control arm rubber bushing to a monoball setup.
Bimmerworld uses nice sealed OEM like monoballs which will go a long way with reducing noise and increasing longevity. Monoballs are reliable and strong but most of the time they are exposed to the elements and wear prematurely - its not as relevant in motorsport due to increased service interval and more controlled conditions. BMW already uses monoballs on some suspension arms and I am merely finishing their job. A Porsche GT2RS (or 3RS ) does not have a single rubber bushing in the suspension, running the same sealed monoballs everywhere.
Im also adding adjustable drop links to aid in corner balancing the car (and the OE units are long dead) along with toe links. Ill address the bushings in the rear control arms at a later time if they prove to be too flexible.
One helpful note before installing coilovers is to measure the current ride height. This helps when resetting the car up, as you end up back in the ballpark of the alignment. This gives you the ability to use the car and have it drive more or less straight if you need to take it somewhere.
Getting new parts is fantastic, but installing them can be a “ride”. The rear subframe bushings are a real challenge. I decided to yank the subframe out with a friend, which was relatively easy. Using a press along with a lot of adapters and cylinders I got the bushings out, installed the Bimmerworld solid units. By the time that was done, we just wanted to get the thing back into the car.
I opted to do the rear monoballs, toe arms and diff mounts another time - for I could do those myself. Instead, we threw in the coilovers and set the car to previous ride height and camber. The trunk lining prevents easy access to the rear shock tower and over the tower itself was a rubber cover. I punched a hole in the trunk lining with a holesaw and re-used the rubber cap for a clean install. Easy access and looks intentional. The rear Ground Control spring adjusters are quite useful. Ride height tweaking is a breeze with easy tool access and a very effective design as the area is already so tight withouth easy tool access. No need to remove the wheels!.
Once the rear suspension upgrades are done, I will then corner balance the car and do a full alignment.
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