Buttonwillow Weekend


After going through many of the initial setup issues on the Seven and giving it a quick shakedown at Laguna Seca, I decided that it was time to take it on my first road trip. I drove it down to Buttonwillow Raceway Park to join a group of other Se7en owners for a track weekend. The fact that there were going to be other owners there made me feel more confident that there would be enough mechanical expertise to solve any mechanical issues that may crop up. Having been to Buttonwillow once before, I knew that the heat would be brutal and was glad to pitch in with the other folks to share a couple of garages with the other folks.

The drive down was uneventful and took me a little over 4 hours to complete. The fact that I was using my cool shirt on the drive down meant that I was extremely comfortable on the drive despite the high temperatures (80+ in Santa Clara to 98 in Buttonwillow). I even got to stop at the San Luis reservoir for a couple of great pictures.

There were 6 different Sevens taking part in the event including a Birkin, a Superstalker and 3 Caterhams (including the only R500 in the country) and we even had another Ultralite owner drop by to to say hi. The coolest car there was this maroon Caterham whose owner had put 70,000 miles on the car over 11 years but still had its looking like new. The even more amazing part was that he drove the car up from LA, completed a 2 hour enduro in it and then packed up and drove it to Lake Tahoe the next morning. 😮

The track action was organized by NCRC and was up to their usual excellent standards. All of us had a blast and got to spend some quality time studying each others cars and talking to fellow Seven fans. As a bonus, Vanhap Photography got some excellent shots of the track action including a couple of staged shots of us together on track.

My favourite part of the weekend was a 4 lap sequence where I was tryng to keep up with the Caterham R500 above. The car has only slightly more power than mine (263 bhp Vs 240 bhp0 than mine but is significantly lighter (1200 lbs Vs 1400 lbs) which makes it much faster in straight line. The video below (watch it in HD) shows the action from my point of view and you can see that every time we get onto a straight he is able to pull away from me. the only reason I was able to keep up at all was because he would have to wait for point-bys from slower cars while I could just stream through the openings he made. Might be a good excuse for me to get that supercharger after all 😉

The car performed very well on track and only had a couple of minor electrical issues. I had no heat issues and the coolsuit helped keep the driver cool as well. The tires performed very well and the only real problem was the too much rear bias in the brakes. Since the Ultralite has equal size brakes front to rear and equal sized master cylinders for each as well, the rear brakes are much too powerfull and will lock up way before the fronts even with the balance bar set all the way to the front. This means that I have to brake very early to prevent locking the rears and unsettling the car. I will likely be getting wither a smaller master cylinder or a smaller rear caliper before the next track day.

After packing up early on Sunday after I headed out early hoping to make it home before dinner. I was just over the half way mark when the car suddenly started producing a loud clunk from the rear when I either accelerated or decelerated. I pulled into the nearest gas station and looked under the rear to find that one of the two bolts holding the differential in place had backed out and that the diff was actually twisting around the remaining bolt and hitting the chassis to make the clunking sound. Unfortunately replacing it will require removing the gas tank which is not the kind of job to be done by the side of the road. Luckily I was less than a hundred miles from home which meant that AAA towed me back home for free

Towed back home

All in all it was a fun trip and I’m surprised at how happy I am despite having being towed back home 🙂 I had a great time at the track and made some great new friends. The car was fast, fun and fairly reliable on the course. I may have broken down at the end but its an obvious problem and should be easy enough to fix in time for the next event. In the mean time you guys can check out the rest of the pictures below:

10 thoughts on “Buttonwillow Weekend

  1. It was great meeting you this weekend. As far as keeping up with Justin… maybe some 15 inch tires will quicken things a bit more without resorting to the supercharger yet;)
    Hey, does that camera come with the speedo, g-force effects built-in? That was kind of neat.

    C ya

  2. Hi Kirk, was great meeting you too.

    I am definitely going to go for a 15″ Kodiak/Hoosier combo but that will likely have to wait till next year as I still have many other things to sort out first.

    The video was recorded using a ContourHD 1080p camera while the data was from a Race Technology DL1 data logger. I merged the two using the Chasecam Dashware software. If you are in the market for something I would suggest trying out the Chasecam PDR100/DIVA which will do everything in one unit and have features like autorecord and continuous loop recording (no HD unfortunately).

  3. Hi Rahul,
    Really glad you had such a god time, even with the breakdown. I was in Fresno for my son’s 40th all weekend and was thinking about you whenever I went out in that valley heat. Wish I could have been there to share the fun and meet some of the other Se7en owners. PS; going to check the bolts on the diff when I get home tonight. I’ll be at T-H with HOD on the 19th doing a track shakedown on my Se7en. Going to trailer it up just in case there is an issue with it being a shaking apart instead of a shake-down track day. LOL

  4. How did the Super Stalker run? Did you get in any laps with that car? Comparo?

    What tires/wheels did the caterham have vs. yours?

    Very nice video w/ the statistics going. Very nice.

    Do you have a URL for your cool suit? Thx.

  5. Stalker ran 2:01 but was in a different run group so I don’t have video. Much of that is down to better driving and brakes. My theoretical best over 2 sessions was a 2:08 and I would definitely get it under 2:05 once I get the brakes sorted out.

    The R500 was doing a few laps on some borrowed Hoosiers while I was on Nitto NT01. To be fair he was pulling me on on his regular Avon CR500s as well.

    Cool suit was from http://www.coolshirt.net/

  6. I had the exact same failure when I took my 2KR out to its first Auto-X. Shortly before the bushings (without the metal liners) were torn by the bolts and the diff was moving around a little. It was enough to brake the weld on the front mount bolt as well.

    Brian sent me a new set of bushings with metal liners that I put in the night before the race. During the install I found the broken mount. I didn’t own a welder so I hauled ass to Lowes and got there a few minutes before they closed. The bolt repaired and new bushings were installed at about 4 AM before the Auto-X at 9 AM. I realized during the install that the bolts were a little short (the metal liners caused the bushings to be longer) but I didn’t have anything else to use and they seemed to hold.

    During my 2nd run I found 1st instead of 3rd in a motivated downshift (this happens to everyone, I think…). I engaged the clutch and got it out of gear before over-reving but it did jostle the drivetrain pretty good. I worked it around the next few corners a lot slower before finishing the course. As I was on the last straight I noticed the clunking in the rear end.

    On inspection I found one of the bolts missing. It took 30 minutes of walking the track (between other driver’s runs) before I found the bolt. I borrowed some thread lock and hoped for the best. It seemed solid through the rest of the day but apparently fell out at the very end of the last run. On leaving I noticed the clunking again but with very gentle driving I kept it from moving too much. I drove the course a few times looking for the bolt but it was gone.

    I later put in longer bolts with thread lock and have never had the issue come up. I believe I stripped some of the mounting threads on the diff plate so I have a new one from Brian if it ever gives me issues in the future.

    Thanks for putting the time into the blog. I’m definitely planning to read through your posts when time allows. BTW, My 2KR is the black one you linked in your discussions about roll cages…

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