Lemons Sonoma Diary: Thursday race prep

In this series of posts I’m chronicling the pre-race prep, practice, inspection, race, and post-race analysis of the 2021 24 Hours of Lemons Arse-Freeze-Apalooza race at Sonoma Raceway.

Goal

Try to win C class. The car is more B class than C, but we have a good theme so hopefully the judges will put us in C.

Shaken

The last race was a success right up until the engine died. We didn’t know why the car was overheating the whole time, but a post-race teardown showed that the head was cracked. In the end, I think what killed the engine was me: I let it run out of water. If we had continually refilled it with water, we might have limped to the end of the race. It wouldn’t change the fact that we needed a new engine though.

In Japan, cars start having biannual vehicle inspections, called shaken, in their 3rd year. Each time they are inspected it becomes increasingly expensive. Therefore, most cars in Japan don’t go through many inspections before they are scrapped. On average, Japanese cars are 7 years old and have about 35k miles on them when they are scrapped. That’s good news for us because we can buy used, low-mileage JDM (Japanese domestic market) engines for a lot less than new.

The 1NZ-FE engine found in the Yaris was in a lot of cars not named Yaris. It was therefore not surprising that some of the parts hanging off the JDM replacement engine didn’t fit in my car. It’s a good thing I didn’t get rid of the old engine. Although it was a pain, I’m glad we (I had help from Tiernan and Mike) did the engine swap in my driveway and didn’t have someone else do it for me. I learned a lot and if I need to do it again it won’t be so intimidating.

Upgrades

We made one upgrade to the car: suspension. The Yaris previously had the TRD kit from Toyota. The springs were really soft and the ride height was only marginally lower than stock. This was the only suspension approved under the SCCA B-Spec rules when I built the car. Later, Bilstein came out with a B14 coil-over kit. I was able to pick up an open box set for half price.

There were two upgrades that were planned that didn’t happen. We didn’t change the final drive ratio and we didn’t install the LSD. I’m hoping that the lower and stiffer suspension means we don’t have inner wheel spin, but we won’t know until the test day (Friday).

Wheels & Tires

Post-race tire inspection from the last race showed that one of the 225/45/15 RS-4s had a flat spot on it. The 15×9 Konig Dekagram rim it was mounted on was also bent. The other tire still has about 1/3 of its life left but the inside lip of the wheel is gouged in places where the splitter smashed into it. Tires and wheels are consumables, but I hate it when they get consumed too early.

Feeling the need to be frugal, I’m not bringing any new tires this race. Instead I flipped some camber-worn tires and we’ll race on those. Here are the 3 pairs of tires/wheels we’re bringing to the race.

• 225/45/15 Hankook RS-4 on 15×8 rims (front)
• 215/40/17 Federal 595 RS-Pro on 17×7 rims (rear)
• 205/50/15 Bridgestone RE-71R on 15×8 rims (maybe front, maybe rear)

Theme

We’re running a variant of the last theme: Toyota Virus. This time, the giant syringe is poking the Yaris in the rear rather than sticking out of the roof. The mounting is better this time, and I’ve put an emergency tether on it so that it won’t go flying off. There are also some social distancing warnings on the back.

I’ve added another wrinkle, just for fun. The original intent of the car was for every kind of racing from rally to sprint. So it has spent much of its life with a passenger seat in it. I decided to put that back in and include a dummy in the seat to look like a rally navigator. From up-close it doesn’t look all that real, but at 60 mph I think it will fool some people.

Next time: test day, tech inspection, and pictures.