Commodore’s Garage #35 – Truck Project: The Milwaukee Mishap
January 25th, 2018 by Matt Holden
I knew Milwaukee was going to be a difficult race to get figured out way back when the foundation for this endeavor was laid out. It’s an old track, few series race there anymore, and it rarely gets placed on any of the NASCAR iRacing Schedules meaning there aren’t a lot of people who have Milwaukee on their accounts. It’s also a track that we, as a team, haven’t raced on since 2012 when there was an invitational Late Model league. Many unknowns hit us right in the face last week and, despite finishing 2nd, 3rd, and 4th in the race we ran, The Milwaukee Mile turned out to be the race where we simply “missed” the setup quite severely. It happens, and I’m glad it did, because this is often the point where everyone wonders what to do next with their setup. Do you throw it out and build another one? Do you take a look at it and see what you can fix? The answer might surprise you here, and hopefully you’ll get an idea of where to go whenever this happens in the future.
The Milwaukee setup itself was originally what I ran at California: Left-front bind, low crossweight, big RR spring. Milwaukee’s corners are high speed, relatively smooth, and we can get some speed from making sure the aerodynamic attitude is good while sacrificing mechanical grip. By race time, the springs went unchanged (except for a stiffer left-front for extra travel) and the only things that got swapped out were shocks and weight distribution.
The idea seemed pretty good at first, but it quickly showed its ugly side in the bounce that we simply can’t seem to get rid of in this short track chassis. The same problem that existed at Myrtle Beach and Lucas Oil Raceway returned in force last week and the only thing that alleviated it was some mid-race adjustments, however it did not eliminate the bounce completely.
Unlike Myrtle Beach and Lucas Oil Raceway, where I ran a setup with an un-bound left-front spring (meaning there was something to soak up some of the bounce), I flipped the front end and bound the left-front spring to see if the same thing could be achieved. The short version: Nope. It had great short-run speed but the instability eventually manifested into a severe mid-run falloff that could have resulted in a far worse finish had the field we ran in been much larger.
Ben Welvaert filled the role of third car this week since Jeff doesn’t own Milwaukee, and he ran the exact same setup I ran. Alex went with a front end similar to what we had at Lucas Oil Raceway, and since he was able to gap Ben and me fairly quickly it seems that was the better choice. Still, Ben and I pulled away from the rest of the field over time, so our car wasn’t as disastrous as we initially thought.
The race went caution-free, leaving room for only one pit stop to try to settle down the bounce and make an attempt to get back to Alex on the second set of tires. At one point during the race Nick Ottinger, who was watching me, said the bounce looked “violent” and that was a bit of an understatement. I eventually found a way around the corners that minimized it, primarily staying away from the inside curbing to prevent setting off the oscillation, but the downside was that it was a slower line than what Alex and race-winner Brent Day were able to run.
I’ve mentioned many times the importance of keeping yourself from rebuilding a setup for every race and that statement shined bright when it came time to adjust the car for the pit stop in our race. I knew the adjustments I’d made at Lucas Oil Raceway that cured the bounce completely and, since this setup was an evolution of the LOR setup, I knew the adjustments that should help to do the same thing at Milwaukee:
- Both left-side tires were dropped to 12psi: I started the race on 15psi because of the higher speeds compared to the other flat tracks, but it was pretty clear that this was too much again. I started the left tires at Lucas Oil Raceway with 15psi and dropped them to 12psi and it worked there, it also worked at Milwaukee. This doesn’t really do much for contact patch or anything like that, it’s simply dropping the tire’s spring rate. Since I was coil-binding the left-front, this tire spring rate was the only thing that was soaking up bumps on the track, so dropping the spring rate will help that.
- Wedge bolts to +0.075” LR and -0.050” RR: This is just dropping the crossweight even more to put more preload on the right-rear spring and try to keep the left-front pinned down instead of hopping off the track. These values are different (higher LR adjustment) because the left-rear spring is so much softer than the right-rear spring. Adjusting both by the same amount would alter the overall rear ride height and mess up the aerodynamics.
- Tape from 46% to 50%: The engine was running cool. Not anything exciting going on here.
The tire data basically confirmed that I’d made the right adjustments but whenever there’s a problem as huge as the bouncing in my car, handling and tire data is not particularly important. I was more concerned with getting all four tires to stay in contact with the track than I was getting everything balanced properly. The only thing that is interesting is the right-rear tire being the coolest on the car, which can be addressed very easily in the future.
So the setup was junk and, had the field been full-sized, would have likely finished very poorly. Do we throw out the setup and start over or do we adjust the problems out of it? This is a common question in sim-racing, and most people will just start over at the next track. This setup, however, will be unloaded at Iowa instead of thrown in the trash bin, and the California setup will go to Michigan and Rockingham. It’s easy to take a bad setup like this one and just throw it out, but starting over erases everything we’ve learned so far. More likely than not, any setup that gets built in its place is going to be built in the same way and the problems will likely still exist because nothing was learned that could overcome the problems.
But let’s say that I rebuild the setup and the problems do go away. I’ve gotten rid of the bouncy problem, but how did I get rid of it? With this way of thinking, there’s nothing that explains what was causing the bounce or what went into killing off the problem, so I have no way to fix it in the future. It will simply return in the future and then I’ll have no information on what to do outside of just starting over on a vicious cycle. I’ll be the first to admit that it’s very difficult to take a setup that was utter trash and keep working on it, but had we not done just that at Gale Force Racing, Alex Scribner would never have won the Class B Championship in 2016, and I wouldn’t have been fighting for wins in the same series in 2017. Both of us had races where we would have been perfectly happy to take cars and put them in tree-chippers, but we didn’t. We took the problem setup to the next track and worked until the problem was gone. Then when the problem came back a month or so later, it was a matter of minutes until the problem was gone. Eventually we knew how to work on our cars to the point where weekly practices took 30-45 minutes and we were rolling on cars capable of winning races. Had we restarted every time we ran into a problem, we’d go back to square one every single time.
Options to cure the Bounce
There are a few options available for getting rid of this irritating issue that’s plagued all our setups at short, flat tracks this season. Luckily, running California’s setup at Milwaukee unveiled something very interesting in the way the Truck works: This bounce is only present in the Short Track version of the car. I basically ran the same car at both tracks, and only one had a bounce. Sure, California results in a lot more speed and downforce, but the hallmark signs of the death-bounce were not present in that chassis. It was smooth as butter.
With only three races left, only Iowa will run on what we call the Short Track chassis, and this track is configured in a way that allows multiple setup options to exist. We can flip it back to the LOR configuration by binding the RF corner and opening the LF spring up. We can run a fully conventional setup with some bigger springs and high-rebound shocks. Or, we can run the same thing and go up on the left-front rate even further to try to get the spring to open up and absorb the bouncing. There are many options, but all center around one thing: Get the left-front suspension to work better. Simply understanding what needs to be done is a huge step towards fixing it because it places a target to aim for. We already know from LOR and Myrtle Beach that running a larger left-front spring and un-binding it will reduce the bounce considerably, but it’s now a case of figuring out which method will work best for each driver.
If we were going to another flat track again, such as New Hampshire, there is one change that can be made immediately to help the car. I mentioned the right-rear tire being cold relative to the other tires, and that’s a pretty simple fix: Soften the right-rear spring. It’s really not necessary to run such a stiff right-rear spring at a flat track like Milwaukee or New Hampshire since the vertical load is so low. Softening the spring would put some heat into the right-rear tire and possibly even help to subdue the bounce on the left-front when it was transferring over to the right-rear.
It looks like a tall order to try and cure a problem that’s plagued every short-track car I’ve put on the track this season, but this was the point of the Truck Project in the first place: Demonstrate how to work through problems without having to rebuild setups each and every week and eventually wind up with a setup that works well everywhere and does what the driver wants. While it may look like we’ve gone nowhere in 4 weeks, the truth is that we really have a lot of information we can work from to get the truck working properly. It’s not an overnight success story and it never will be, but it looks like the sun’s starting to rise and we’re headed in the direction we want to go.
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