Track Report – Carolinas Motorsports Park
Spent the day at CMP today with the new JRZ RS1 suspension. Only change from street set up was RE-11 tires and Pagid endurance pads. Weather today was perfect. Low 40s in the am and warming to mid 60s by afternoon with clear blue skies. Couple of notes on unrelated items.
Steering fluid reservoir- As someone who only rarely had problems with the reservoir burping fluid into the engine compartment, I thought it was related to ambient temps. Not on my car. Had recent dealer service and they filled reservoir to full. I always had run on the lower fill mark. Temp today 45F and after the first session had power steering fluid sprayed on the coolant reservoir. Not a large amount but significant. Zip tied a paper towel around the cap and problem solved.
Schroth Mini seat belts – This is the first track where on tech inspection they said “no” to my belts. The reasons given were “they’re so long and they stretch 25% under severe impact and there’s no anti-submarine belt. So back to the regular seat belt for the first time in a long time. Conclusion, the regular seat belts are terrible, after getting used to being locked-down in your seat and only using the steering wheel for steering going back to the stock belt was not fun.
Okay, the part you are waiting for. How is the suspension? When I talked to James at Bimmerworld I told him I wanted something that was 20-30% better than stock. Now most of this review is going to be subjective as I don’t time my laps. I had been at CMP earlier this year with same tires and pads, but stock EDC so that is my comparison.
Turn in- Very good, not that much better than stock with adjustable camber plates and track alignment, but still a slight improvement.
Turn-in to “taking a set” – This I think is a consequence of not being able to play too much with the suspension, but I thought it was a little slow. I’m a one change at a time person, so only tried, initial settings of 12 clicks firm front and back, 14 front and 12 rear and then 14 clicks front and rear. I could have tolerated even more stiffness perhaps 18 clicks might be better. To me the getting to steady state set in the corner was about the same as stock. I think more shock stiffness would have helped.
Mid-corner- Very neutral with very slight tendency toward oversteer, which I think is about optimal. Perhaps a bit easier to steer with the throttle.
Corner Exit- Not sure what to say here, very stable, neutral and though the one thing is that the communication of the vehicle as to what it’s going to do is very easy to feel which allows for minor adjustments without much effort.
Mid corner bumps – CMP has what they call the Kink. It’s not really a turn but more of a bend. If you try to optimize your line through the kink you will hit the bump in the middle of the corner which can really upset your car and sometimes even spin your car if everything is just right and conspiring against you. So here is the only objective finding from stock to RS1. Previously the kink was a 95-100 mph corner and you definitely didn’t want to hit the bump so you generally took more of a sweep to stay wide away from the bump. The kink is now 110 mph for me and it really doesn’t matter where you take the corner. In fact I tried the inside line a few times, right over the biggest part of the bump and you feel the fact that it’s a large bump but the car absorbs it , has minimal loss of stability (no stupid moves allowed at that point) and just plain keeps on honking through. It’s really pretty cool.
Final note. As suspension folks will tell you that suspension is really part of the package and should be “balanced” with your brakes and tires. What I noted today is that my corner exit speeds must have been quite a bit higher as I’ve never had as much brake fade as I had at CMP today and I’m really good at not over-driving the tires but also today I got my rear tires to the point of being really “greasy.” It was so bad that I almost thought I was having a flat, pulled into the pits, everything looked okay, went back out and tires were back to normal.
So in conclusion to address a couple of things. Does it turn the M3 into a GT3 RS? No. Does it turn into a spec miata? No, however it makes a really pretty good car even better. I think it’s fair to say it’s 20-30% better than stock. I have mild street oriented springs and I think if I wanted optimal track performance another 50% more spring rate would be great. However, this is my daily driver and the overall compromise is great. So what is the best suspension (you’ve seen that posted a few times), well it’s whatever is best for your needs. For me the fit is great, enhanced performance on the track, still fully streetable and minimal to almost no downgrade in noise, vibration or hassle. Very tractable, drove home on 14 clicks firm setting and on regular relatively good roads ride is very nice.