Monday, June 23, 2014

Mission Report: Corvettes of MN

After MOWOG 3, I had a few things to think about, and a few adjustments to make.

I installed the data logger setup, as well as the SpeedoDRD as mentioned in earlier posts, but I still had concerns about the cause of that spin in the back. The current thought was that I bottomed out that strut, and it threw the car.

In order to remedy that, I jacked the back end back up, and took about another half inch out of the overall length of the shocks. This time, I make sure to add the needed zip tie to measure just how much travel was actually being used. When I checked the zip tie on the other side it was all the way at the top. This is the side that has the extra inch of travel, so I doubted that it was bottoming out. I figured the ziptie was too loose, and had carried momentum from a quick hit past the point of shock travel. I reinstalled new ziptie that was tighter.

Overall length wise, this is about as much as I can take out of the rear shocks before I fully compress the tender springs. Further than that, and I may begin to adjust the static ride height by compressing the springs with the shocks which would demand a re-alignment.

All these tasks completed, the car went back on the ground and for a test drive. No significant changes to the handling.. maybe a little bit smoother. it would have to wait until the event to see if the desired results had been achieved.

Unfortunately, the mid week weather reports didn't hold out. A storm was definitely brewing. The Good news was that STU was running first.. but in the COM ways, they're breaking the heat into three sub groups. By where you stood. I made sure I was standing in the 1A group as I really wanted some dry runs to see if the issue in the back had been sorted out. Also, hey.. what autocrosser hasn't seen the "one dry run was the fast one" situation play out a few dozen times?

I landed in 1A, much to the chagrin of most of the other STU drivers who landed in B and C. Whatever, I'm not really fast enough to be a threat right now anyways.

Antsy as all hell, the car was running and ready to rock when they called for the first group. Right down to the starting line I drove. First car off.

I was a bit tentative, but still laid down a good time... if I hadn't hit two cones. I just can't get my damn head around how wide this car is.

Time for the second run, I'm gentler around that first cone I hit, but otherwise I've bumped up the intensity. it's starting to step out more. I make it to the top of the hill... and... damn. Spun again. Not a comfortable place to spin either, but I followed the rules. No wheels off, no cones hit, and didn't even DNF. At least I don't have to go home early.

As I pulled back into line the rain started. Shit. So much for useable data. And I began to think about my two spins so far. both times when loading up the right rear. In the conditions presented, I should have had enough grip for how fast I felt I was going, but the car just let go.

This last run of the morning, I tried a little more in the slalom. it definitely felt like any time that right rear loaded up, the car wanted to step out, where the left rear felt planted. I'm still not entirely sure if this is just me being hyper-aware of something that I think is a problem, or something that actually is a problem, but I'm going to look into it as a problem.

Upon returning to grid I checked my zip ties. there was about an inch of available travel left in the right rear, and almost 1.5-2 inches left in the left rear. I wasn't bottoming out the struts.

The rest of the day wasn't great. the rain continued for awhile, but letup for when I had to work. and then started again just in time to put me in the wet for all of my afternoon runs. I tried a little more to loose time, but my confidence in the car was shaken after that spin, so I kept finding myself pussyfooting on the gas and braking gently.

Up until the last heat, I had actually been standing in second on the power of my first run, despite the cones as everyone else had to deal with wet runs. But, fortune smiled on a few of them as it stopped raining quickly in 1A, and began drying for B and C where they were able to catch up.

So, now I'm playing through things in my head, trying to figure out what's wrong with my right rear. First one is that the toe bolt may have slipped. here's hoping that's a simple one. Next up is a ride height issue. When the car was at Jeff's I remember there being a height difference between the rear wheels. The margin escapes me and which direction, but we wrote it off as insignificant at the time. Now, I'm starting to think otherwise. And the car was not corner balanced in it's initial alignment.

The good news is that both of these issues can be fixed with another appointment to Jeff, with an order for a full corner weight and alignment. I'm also going to re-assess ride heights a little, and this time focus on keeping the factory height stagger of 3/4" higher in the rear before corner weighting.

I'm really hoping to slide into Jeff sometime this week for that work, but I'm pressed for time and so is he. and my error in over filling the gas tank makes getting a good corner balance a more difficult thing as I need to run it down before that.

If that doesn't rectify the issue, then it's on to bigger problems. That is the corner with the screwed up strut, so a replacement set of Koni somethings for the rear may have to be ordered.. otherwise it's also possible for it to be a shot bushing or ball joint providing too much play.

Fingers crossed it's something that can be fixed with adjustments though, because i'm feeling kinda tapped out at the moment.

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