Michigan is one of my favorite tracks on the Indy Car schedule, second only to Iowa Speedway. Both tracks require different driving styles, and both tracks are next on the IndyCar schedule. So, expect another article next week. I decided to skip Kentucky because the eight page document that I wrote introducing you to Homestead, should’ve been enough to give you a set for Kentucky. Actually, it is exactly what I used at Kentucky with minimal adjustments. Michigan is different from both of these tracks, but if you had a set that you really liked from Kentucky and Homestead, I would say throw it on and try it at Michigan with some tweaks. The base suspension settings are close enough that it could work.
For starters though, let’s use the setup Brandon Trost kindly shared on the forum and work from there. So, Brandon started from the fixed set and he says that with his edit it can run a .390. About 2 tenths off of his race pace. Last season, people were over a half second off of top pace. You all owe Brandon a big thank you for the help. So, to recap what Brandon has done to the set. He has basically done what we did to our 1.5 mile bases. Lowered the left rear spring significantly, raised the right rear, lowered downforce, shifted ballast back, stiffened front ARB to help corner exit speed, and max WJ. You might be noticing that this is a bit of a trend for these flat out tracks. And to some extent, it is standard operating procedure. After all of this, he ended up with the following:
I am writing this edition assuming that you have read and understood the concepts in the first edition, which lays everything out in a much more simple and organized fashion.
So, thanks Brandon, but we have more to change to get people just a tad closer. Aero, tire pressures, and the front of the car look good to me, but there are some things I definitely want to change. So, I went out and ran a few laps. Not a bad set by any means, but can be better. First off, the place where I had the biggest issue was in Turn One and Two. On center off the car has a bit of a scrub and loses some significant speed. Because this half of the track is pretty close to an intermediate speedway, in that it has a tighter radius than the other half of the track, I would suggest taking a look at the rear toe in values and consult back with what we said for Homestead. Generally, you want the rear of the car to help push you down and hold you on the preferred groove at a full throttle track. Since I felt this while running solo, I’m sure it would be worse at high speed. I would significantly tilt the toe towards the left. Try -9/32 on the left and +8/32 on the right, decreasing the magnitude until you find the lowest value that prevents the car from binding up. So, that’s a bit of a bandaid fix for you.
One huge problem though is the shock rate on the car. Generally, you are going to want your front shocks a lot lower here than you would think. Furthermore, you want to increase the magnitude of the rear shock different that you started. I would drop the front shocks a lot. Then, I would significantly decrease the length of the push rods. This should also bring you closer to bringing that left front up in the air a bit more. After you do all of this, I bet your cross weight will fail. To fix this, I would increase the positive camber on the left rear tire, and decrease the camber on the left front tire. But, the most I would do this is to the point at which the left side of the tire and the middle of the tire read the same temperatures after a run. This isn’t the best solution, but it is one that won’t force you to rebuild the set. I would also lower the caster on both of the front tires a bit. Another change I made is that I significantly lowered the rear ride height by decreasing the right rear spring perch by just a tenth or two. This should increase rake and aero dynamic flow.
If your car is failing in some area of the tech, find a work around. Like I said earlier, cross weight can be sorted by optimizing cambers and also minutely by changing the bump/rebounds (I’ll leave this to you). If you need to fix cross weight you can also play with the ARB preloads as well. One problem I ran into during this 20 minute setup tweak was that the preloads were failing, I just brought these slightly under the point where they fail tech and all seemed fine.
So, in summary:
- Brandon Trost’s base setup
- Front Spring Rates: DRASTICALLY reduced
- Front Spring Perches: DRASTICALLY reduced
- Caster: MEDIUM reductions
- Camber: optimize temperatures, fix some cross weight
– Right rear camber: try and keep it flatter, but passing tech is more important
- Rear Spring Rates: MAXIMUM delta between them
- Rear Spring Perches: Slightly lower the right rear
- Rear toe: MAXIMIZE corner speed, point them left
One may be surprised to find out that in the matter of 20 minutes I managed to find a tenth of a second at Michigan. Well, that is exactly what I found by tweaking just some basic things. As a matter of fact, I might be saving this and running it in the race based on how stable it was. Upon find tuning, and experimentation, it can easily find more time. If you have any more questions, do not hesitate to ask me. There are plans to host a “The Kitchen Sink” session to help drivers with the setup on Thursday or Friday. Info will be in the Dallara sub-forum.