Time Attack - Day 65 + 66 - SCCA Time Trial at the Ridge - Full Aero, Full Oversteer, Solid Results!

Another weekend... another Time Trial event at the Ridge! This time with SCCA, which meant I would get to run my Max2 build and go out and compete, which is not something I can say I've run in quite some time. Read on to hear all about how it went.

Leading Up To The Event

Leading up to the event I only had one medum level fix and no major items on my, so I was feeling pretty good about the car. I pulled a few panels to access the rear diff, redid the wiring to the speed sensor, and hey now my ECU knows if I'm in motion or not! This event being SCCA, my car is best classed in the Max 2 category which means I can put my aero back on.

One modification I had done since last taking the car out was I had put in MSI front sway bar relocation blocks. They're pretty slick and I have to admit the revised location is a way way better location! While I was in on the suspension... I decided that since the previous event had gone so good for rear grip I would reduce rear toe since it was likely too much, and I'd even try and give the front a slight bit of toe out to aid the car in rotation. More on this to come...

I washed my car as well... which I wouldn't normally write about, but there's a detail in there possibly for later. The rear bumper was disgusting, likely from imperfect fuel burn staying in the wake of my car and getting on the bumper from there. This only happens with the large spoiler setup I have and not wing. No big deal though, it washed right off for the most part... but I want to mention this because it'll relate to aero conversations later in the article.

With the Corvette not needing much work I pivoted my focus to outfitting my sprinter van. I didn't want too crazy of a build as I wanted to keep weight down, and thus I focused on a very modest couch, a pull out slat style bed, and gettting power for charging various devices and running my cooler. I had also previousl acquired 412ah of lithium iron batteries for cheap... so why not capitalize on them!

The electrical itself all went in under the couch setup I made up, and there's actually a bit of wasted space in there at the moment, though more will be going in there as the build progresses. I did get my starlink 24v connetor in, the general configuration between batteries and the setup along with fuses, battery monitor, bus bars, a fuse panel for all of my circuits, and probably a bunch of other stuff I forgot. It was a bunch of work, but I can say confident with it all complete... it made being in there quite nice! I do have two other big things to wire up, like a modest inverter and a a DC to DC charger... but I've got time for all of that and the setup is likely overkill for a weekend as is.

Traveling To The Event

I don't normally write about traveling to the event as it's rarely eventful, but when you've got a mediocre sprinter you brought back from the dead right at the edge of it's towing capacity... getting to the event can be a bit more eventful.

Sure enough... the van having issues struck again. The van had had some hard start issues for a bit, and I wasn't quite sure what the cause was. I'd heard if you have issues pressurizing the fuel rails it'll hard start, so I had hoped it was that. Given turning the key on and letting the car sit a bit before starting helped, I figured the fuel pump was just tired and the van needed a bit to build up pressure. Everything would surely be fine...

Unfortunately, everything was not fine. About an hour from home the car just suddenly cut out, right as the car made a 4-5 shift... so I was nervous something significant went out. I coasted to the side of the road, and called my wife. She would come help me. The van fortunately after about half an hour started back up and I was able to limp into town. An incorrect address took me away from the autoparts store I wanted to go to, but that worked out since accross the street from my wrong destination was a closed down business with a big parking lot for me to break down in a second time. I pulled the codes for the van, and it would seem the crankshaft position sensor was my issue.

Here is my wonderful, beautiful, amazing, and infinitely patient wife coming to help me! She showed up and I was able to take the truck, get the part I needed from an autoparts store, and reinstalling would hopefully resolve my issue.

Thankfully the van has pretty decent ground clearance, and I was able to scoot my way under the van and gain access to the crankshaft position sensor, which actually seems to go off of the flywheel so it's fairly aft on the motor. I've heard these mercedes Benz motors are a pain, but this particular sensor was quite reasonable to deal with. Now that I know what I know, if I ever have to help somebody out with a T1N sprinter I will recommend they do crankshaft position sensor and camshaft positon sensor at the same time, as I should have done.

The van started right back up, and I was able to head to the track, now about 2 hours behind my planned arrival time. Fortunately a friend had gotten there to do the track day before us and had secured a nice location for us which really helped us out!

Here's the van interior all setup for crashing in at the track. You can see my dog is happily at the foot of the couch, my bed is laid out and just the right size for a singular adult to pass out for the night, and in general the whole thing is WAY better than a tent! Not bad not bad!

Event Day 1 - Traffic And Oversteer

Day 1 was a lot to take in. There was a LOT of folks and a LOT of very very nice cars. 53 entries for SCCA, 50+ entries for global time attack, then there was a very busy drift event AND SCCA road racing was in the mix as well for some reason. Those folks took up a TON of space and consumed a lot of track time for what appreared to maybe be 12 people on track.

I pulled to grid and there was no start order... and I went to the back of the pack as there were just tons of very capable cars. I came to regret this choice though, as I hit the track and was instantly in traffic that either had no clue where to go, or no clue what ettiquette was for Time Attack. That made it hard to find my groove. Ultimately I was able to barely click off a 1:49.1, and thank goodness I found the space to do that as I needed it to get towards the top of the grid and out of traffic.

The car was also handling terribly. I was experiencing on entry massive lift off oversteer with the car wanting to fully come around on me at times, and all transitions of weight on the car were terrible. The car was also dragging the splitter all over the place. The oversteer seemed crazy to me considering how composed the car had been out the last time, and a wing SHOULD produce more downforce, right? Well now i'm starting to wonder about the wing versus spoiler situation, although that was a metric ton of spoiler.

Between the practice session and session 1 I decided my toe adjustments had to be off and went to adjust the toe. I jacked the car up and figured I'd just adjust the bump steer at full sag to just add 1-2mm of additional rear toe in. That's when I noticed my rear toe was 4-6mm out. That seemed odd at the moment and had me thinking I had messed up my measurements, but hindsight being 20/20 I am now convinced my rear bump steer (toe change over travel) is way off. That means as I pitched forward and my rear unweighted the rear tires steered outward making the rear of the car want to come around.

I also threw 1 degree of additional wing at the situation to see if that would help, but I was now approaching 8 degrees AOA, so at the threshold where downforce doesn't increase as much as drag increases. I also pulled the front cannards as I clearly didn't need more front downforce.

Day 1 session 2 the car did improve, but it was still problematic. Unfortunately we got out on track and a car immediately broke down, so no hot laps for anybody. Then we got back out and had 1 singular hotlap, which I fortunately was able to turn into a 1:48.1. So I was getting into my usual competitive times, but not fully settled and I still found the car to be a handful.

Between session 2 and 3 I added some front ride height, increased the wing angle further, and reduce rear rebound damping (faster rebound). The plan there was to get the splitter off the ground, since rake was remoed the wing angle would be reduced so adding rear angle probably brought it back to where it was, and the reduced rear damping meat the rear tires would get back to pushing into the ground sooner.

Session 3 and 4 was not actually faster unfortunately. I turned a 1:48.32 and a 1:48.42, which were fine considering temperatures had increased and the track was very dirty from a drift event that had gone out on track.

I settled in for the night, put the car on stands and chatted with some friends about the cars handling. I specifically chatted with Mark over at https://msimotorsports.com/ and he suggested I disconnect the rear sway bar. Given I know a lot of track folks who do this... I figured... maybe there's something to this and I should make this change for myself...

Event Day 2 - Changes, Confidence and a New PB on Vitour P01R's

Day 2 started rather wet, which had me concerned. I fortunately had secured a pretty good result already and felt fine about where I was, but I'd prefer to be driving. I also ahd the car in the air still and wanted to rotate tires, and then try disconnecting the rear sway bar. Since my position was secure, why not see if it yielded improvements? Fortunately the day dried up a ton, and I threw on the front sway bar and got out on track for our first session.

Session 1: The grid unfortunately had changed, and a few less than aware or time attack experienced drivers got in front of me. Another heavy hitting car also had electrical problems on track and we unfortuantely came accross each other at the exact wrong moment for my hot lap and I unfrotuantely had to throw it away.

The GOOD news from that first session though was the car was infinitely more controllable at that point. I can totally see why folks ditch the rear sway bar now, and it did cure a wide variety of chassis configuration sins. While I was only able to put down a 1:48.38, I knew the car had more in it now, and to quote a renowned aero developer "We've never had a car go faster when the car feels worse".

I changed nothing, and prepped myself for session 2.

Session 2 wound up perfect. I was able to get a better grid position, I was able to navigate a flying lap and put down a 1:47.88 on my 25hz GPS. While there was a bit of squirreliness left in the car still, the car felt much much more composed with this setup. I was finally onto someting, and I felt great. Unfortunatey I did drop to sixth despite the improvement, as the fellow in a 2024 C8 Corvette had managed to find a slight improvement in his times and brought down his two day average to .12 seconds faster than me. A bummer, but considering we're in different classes and his car is a 25 year and 3 generation newer Corvette than mine, I shouldn't have been in the same state as him!

Session 3 was unfortunately a total throw away. The track was dirty from the drifters, and during one of my fliers I noticed my ABS fault had kicked on. I pitted out, cycled the car off and on again, the ABS fault went away... and by the time I wrapped up my second outlap the checkered was out. Boo to 15 minute sessions, but such is life.

Final Standings

Come the conclusion of the event I found myself sendond in Max2 class, and 6th overall out of a field of 52 entrants. While I had held onto 5th place overall for much of the weekend, a slight boost in Waylon Gobel's time in his 2024 Chevy Corvette just barely bumped me out of fifth by 0.17 seconds. I think had the car oversteer situation been dialed in all weekend I could have fought him off to maintain my spot in fifth, but I was never going to make up the 3.4 second gap between myself and first place.

I feel quite proud of my results. In the top 10 just about every car has 15+ years on me, and the one that doesn't in a C6Z06 with an LS7, a car that should be in a different continent from me time wise. The fact I took a 27 year old 1999 C5 Corvette and put those cars on notice says an awful lot about what I've built and my ability to drive it. Heck, I'm one of only 2 cars from the 90's in the top 25 positions, I feel good about that, especially since I built it for myself and have desgined a lot of the parts and solutions on the car.

Takeaways from the Event

Bump Steer Issues: Right off the bat, I think a lot of details are pointing me right at having my bump steer (toe over travel) being way off. Here's all of my reasonings why I think this is my issue:

1. My cold pit measurement of the toe at full drop being 8mm total out when I know I measured 3mm total in at static ride height leands me to believe as I transfer weight forward, the rear wants to toe out and the car really wants to rotate.
2. When chatting with another C5 owner and telling him all the things I had to do to avoid hitting my coilovers (rear offset toe arm etc) he said "Wouldn't that throw bumpsteer way off?". Yes... it probably did.
3. When I got my adjustable tie rod ends, I couldn't find anybody who would do bumpsteer within an hour of me and I wasn't confident enough to do alignment myself. So I just set it to the default value and sent it... and that seems prone to possibly being way off.
4. When I drive the Dead to Shred C5 which has all factory tie rod components... it's very planted and happy and far easier to control at the limit. I didn't know what to attribute that to, but in hindsight... I'm pretty sure it's bumpsteer related. The coilover and spring rates are a bit different, as are the sway bars, but not so much different I'd expect it to be way off. Even before the wing though the car was far easier to control and work with.

All signs point to bump steer being improper.

Perhaps There's some gains to be had with aftermarket ABS. Currently my setup is using the early C5 ABS setup, and has been good to me for many events, but I've heard they limit your braking potential to about 1G. There might be some improved braking to be had there, along with better trail braking potential to the apex and through the apex. Aftermarket ABS is not a cheap endeavor however... but I'd like to figure out how to add it if possible.

The Ultimate Repacement: DISPLACEMENT! I'm not sure my budget would allow this, but in every class I compete there's headroom on displacement. I could probably pick up 100 horese power and lose torque nowhere and stay within class limits. That would really help me hang with some of these newer cars I'm up against with far far more horsepower than what I have going on!

Things I'll Be Working On Next

Between now and my next event with OnGrid I'll be pulling the aero back off of the car and focusing primarily on alignment and suspension geometry. I know way back when I got the nice tie rod ends and I had to put an offset tierod mount in the rear of my C5 that things weren't going to be perfect... but I got away with it for a long time. Welp... I'm no longer quite getting away with it as my pace has increased, so it's time to really dial in the toe curve of the car and hopefully yield far more predictable handling.

I'll also be swapping over to a new set of the 200tw Vitour Sonic, which will yet again change my cars handling up a bit but also should yield some additional time out there on track and hopefully help me secure another first place finish with OnGrid.

Other minor fixes will include a revamped seal between the trans tunnel and shifter, as that piece having broken is allowing a ton of hot air through and part of the reason I roast so much as a driver. Perhaps I can design something that seals a bit better there? To be determined...

Long Term Upgrade Thoughts... it's a toss up between getting better motorsports grade ABS in the car to improve the braking on the car and building a motor capable of operating at the max potential of the displacement allowed in SCCA Max 2 and OnGrid. I can pick up probably about 100 horsepower switching over to such a setup which I think would yield some notable time improvements. I just hope I don't have to start grabbing 5th on the front straight... but I suppose if I do that's a fair bit of speed and power I'm putting down as well. I doubt I'll get to either of these any time soon. The costs are prohibitive, and I've got to finish the Dead to Shred C5 Corvette next.