Back on track at last

Well, I finally got he J15 on a race track! I took it to a test day on the Snetterton 300 circuit a couple of days ago.

This is a new layout for Snetterton so it was a new circuit to learn as well as a new car.

I drove up early on the Thursday morning (horrifically early!) and set up near to the garage I’d been allocated. At least this time it looked as though we’d be OK for getting out on track. It was a bit misty, with water in the air, but it wasn’t actually chucking it down.

First up I took the car out for a couple of laps to bed the brakes in. Then, after they’d cooled down I tried to learn the circuit a bit better. The only problem with all this is that Snetterton 300 has now been promoted to the exclusive collection of circuits that make me travel sick. That is, it’s in there along with Cadwell and Oulton. Mind you, it could be because of the early hour I really needed a nice greasy breakfast which I hadn’t had.

After a couple of laps I stopped and checked the chain. As everyone had said it would be, it was really quite slack now. Supposedly this always happens on the first run out. So, I adjusted it up; that was really easy to do with the turnbuckles that I made for doing this, I was quite chuffed about that. Here’s the photo that I put on this site a year ago!

With that done I could try pressing on ever so slightly. That was a mistake as I ended up with a rather lurid spin at the end of what used to be called the Revett straight and is now the Bentley straight. See this video for a unique first view from inside the J15:

As the car was going round I was thinking to myself: “you know, checking the brake bias would perhaps have been sensible”. Luckily nothing was dented and after clearing out the grass cuttings I was on my way again. After that I concentrated on setting up. As is usually the case I really just stiffened things all the time. At first I as getting a slightly alarming high-speed instability. Some of this could well be due to a lack of rear downforce and I want to make a spoiler for my next track outing. However, I did manage to dial out a lot of this by stiffening up the dampers a bit, although I didn’t try adjusting bump and rebound separately, that can come later.

Most importantly, though, the car went well. I suspect I might need a larger oil cooler, or some different sort of duct as the oil temperature got a little high for an outing in a cold March day in Norfolk. However, that’s sortable. The water temperatures were fine and, most importantly, the suspension and transmission system all stayed in one piece.

6 thoughts on “Back on track at last”

  1. Hi Tim

    Good to see the car on a circuit at last! Is it too early to form an comparison with the Fury handling wise? I am building a J15, albeit with a Duratec, having had Furys with a Zetec then an R1. Are you prepared to let me know what spring rates you are using? I appreciate the Duratec engined car will be heavier but that did not seem to make too much difference with Furys and spring rates.

    Regards David

    1. David,

      It’s a bit early at the moment, last week I was really just interested in whether the car was going to fall to bits or not. I’ll dig out the spring rates when I get home and send them to you. I got to the rates I’m using by measuring weights and working out the suspension fundamental frequency.

      I was wondering if the front rate was too high (based on the highly scientific “jumping up and down on the front of the chassis” technique), but I didn’t seem to be getting any significant understeer so perhaps I’m wrong. I’ll be on track again next week, I hope, so if the weather gods are kind I’ll hopefully learn some more.

      Tim

  2. Thanks Tim, I look forward to further progress reports. By the way I suffered from the travel sickness thing at the Bedford(shire?) Autodrome doing a track day a couple of years ago. Too many hairpins that all looked the same!

    Regards David

    1. I suspect that there isn’t really a problem for me with Snetterton as it’s flat(ish) and the problem I usually get is clearly something to do with going up and down, hence Cadwell being bad.

      There are several RGBers who have a problem with Cadwell so it’s not just me.

      I suspect my problem the other day was that I’d just got up too early and not really had a proper breakfast. Next time I’ll have the traditional racers’ breakfast of a bacon roll. That should sort it!

      Tim

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