Z3MCJez

That's 'cos you all run 1m behind the guy in front Charles. I'm surprised it hasn't made a difference though ... Jez

You were on 15" rims! My calcs all assumed that experience cars were all on 13s. As you clearly have enough info to do the calc, why not do so and repost here. You'll need to google the profile of the 15" tyres to work out the distance per revolution. You'll need to guess that it's a 3.62 and then find the ratio in 5th. I can tell you that the red line is at 7,200 unless they downgrade it for experience cars. It's only 6,700 in Academy spec for instance. Alternatively tell us where you hit the limiter on Hangar Straight and we'll probably be able to guess +/- 5mph. Actually we can probably do that already - 110mph. Jez Edited by - Z3MCJez on 8 Oct 2013 09:17:31

I think 6th in the 6 speed is equivalent to 4th in the 5 speed. That's a drive of 1.00 which with a 3.92 diff equates to 116mph at 7,200 with 185 AO48s. With 175 CR500s that's more like 110mph. What tyres were you on and were you reaching the limiter in 5th? A 140bhp car won't get to more than about 115, with a decent exit from Beckets and no slipstream. You should have got to 110 ish, even with an average exit, which would equate to the limiter in 6th. I would expect you to be at the limiter in 5th soon after the Hangar Straight bridge. Jez

I should have been a bit more specific. My friend is looking for one with a diagonal across the top. I think this is a 2009-onwards metric Roadsport roll cage. Money waiting ... Jez Previous request: Anyone got one that's come off a straight car? Colour not that important, but should have the racing sticker really. Any Academists looking to convert to road car, or any buyers of Academy cars to change to road variants looking to sell one on? For a friend who had a mishap at the weekend. Jez

Quoting AntonyH: Ah, indeed! I've always understood that aerodynamic lift (up or down) comes at the expense of drag. If you've got lift (or downforce) you've got drag. However, you could design something that has more downforce with less drag than something else. It's what F1 teams invest oodles of money in, and they end up with vanes everywhere. Jez

Ian - still available? Jez

Does anyone know if the Duratec input shaft is the same as the Sigma one? I doubt it but thought I should ask ...

This question is a bit of "How long is a piece of string". In my Academy spec car, I used standard rear brake pads and needed 2 sets to get through the year (which is a shorter year). In my current Supersport Spec car, I have used one set for a full year. They cost 5x the price and last about 2x as long. Jez

In the dry, 16PSI all round cold will lead to imbalances when hot (maybe 18 fronts, 22 rear, depending on circuit and how hard you push it). Tyre pressures should always be set hot for a circuit (it's how you use them). On the road the temp differences (and therefore pressure differences) are much smaller. I missed the always oversteer when you fart on the throttle. I think you need to check rake, or as OBNS suggests, get it properly corner-weighted with a base setting. As a reference, and I run track-only with AO48s, 140bhp and race suspension (Sigmax specification, which is Supersport spec with different tyres) I have: 1) Max castor - all washers are behind the wishbone 2) Neg 3 degrees camber 3) Some toe-out - about 0.5degrees out 4) c. 15mm rake 5) 20PSI hot all round; (23/25 in wet) I change the roll bar settings for every circuit, but would start with something like: 1) Orange front; 2nd softest attachment at the rear (+2), where 0 is disconnected and +4 is stiffest setting 2) Blue front; +3 at rear 3) Wet - no front; 0 or +1 at rear My startpoint will depend on the circuit. At Bedford I'd start stiff, as the track is smooth. At Combe, opposite. In context, when we raced at Cadwell at the weekend I did one race on 1) and one race on 2). Neither was really right, but I didn't get enough time in testing on Friday, 'cos of the rain, to realise this (At that point, I would have left the front on orange, stiffened the rear a little and reduced the rake, by lowering the rear a mm or 2). BUT, TAKE NOTE - I'VE NEVER USED AO21s. And this would be a horrible car to drive on the road (too stiff, too low, would tramline and would constantly want to run me off the road - which is desirable on track, but less so on a country road). Jez

A few pointers from me. 1) Light hands. In the corners that you are taking without spinning, you have a nearly fixed steering wheel. You're not letting the car feed back to you at all. You can't make aggressive movements in the wet if the car is not under control, but no corner has uniform grip - how are you working out where the grip is? Try holding the wheel with only your fingers. 2) As noted above, most of your spins are too much loud pedal coming out of the corners. That is a feel thing. You need to practice having something other than full throttle. 3) There are some spins that are from removal of drive to the rear wheels. To be quick in the wet, you actually need to use the rear wheels to keep the car stable. The car will drive through the corners much more quickly when you're on the power. It's a bit scary sometimes to get on the power when your running out towards the edge of the circuit (but not too hard!) You can practice this at Bedford! (Note: this is an advanced skill) 4) I think the balance of your car isn't quite right. There are some "half-spins" where the front comes back around. That suggests the front is too stiff. In the wet I would remove the front roll bar. That will make your power spins worse, so more care needed with the loud pedal. How old are the tyres, is the last question. Old tyres can be hidden in the dry, but won't perform well in the wet. You need the edges. I'd also take the pressures way up. At the end of the session, in the wet, I'd be looking for 24psi. In the dry different drivers prefer different pressures. I prefer 20psi, but I know others that I race with would find this too soft. It also means that I'm slow on the first couple of laps as the tyres are still not up to pressure. Although that doesn't explain my woeful starts! Jez

Top end refresh coming then Roger? Jez

Interesting. I will have to test this now too. I wonder if Cadwell is particularly bad for this, as every time you go over the mountain the rear wheels unload and then reload, and if anything is going to move the tyre it's that sort of thing ... Was there any movement on the fronts? That would be braking driven (I would guess). Jez

Can you not drive 5 miles without the clutch? To prove a point, I once drove my old Fiesta for a day without the clutch. It was generally fine apart from having to start it in gear at junctions. Jez

If you're going to repair to make it look as new, it will surely be easier to replace? If the damage is light, you'll probably find a racer to sell the old one to, too (black or yellow only for me!) Jez

Interesting Simon. I have religiously followed the rule on not holding the button for more than 5s (and then giving it a short rest, although that is only 10s or so). I haven't had to try that in anger on a circuit though! That suggests that the reluctance to start is linked to the engine, not that battery. Jez

I've always presumed it's due to the engine being hot, leading to slightly higher compression, but I guess I should pay some attention to whether the battery is warm / hot at the end of a session. I'll check that next time I race - Cadwell, w/e of 7/8 September. Jez

Bringing this back to the top as a friend has just asked what lithium battery he should buy. My thoughts on the RBC400 (used with a Sigma Supersport car with the lightened flywheel): 1) It's very small and light. You can only appreciate this when you see it next to a normal battery. 2) It starts the car fine when the car is cold or warm. It doesn't really like starting the car when the car is hot (I.e. coming off track, stop in parc ferme, it needs some encouragement to re-fire the car). I think it would be better if the car had the normal flywheel as it doesn't have quite the inertia to get over the compression. It sounds like when you start a car with a battery that is dying, but then when the car is cooler, it starts it well. 3) I've had no problems with the battery going flat, but it is always left disconnected by master switch. If I was buying again, I'd be tempted to to buy the RBC600, but at another £200, that's quite an additional cost! Jez

Is that in standard caterham gelcoat yellow? It looks a bit dark, but it might just be the photos. Anyway, if it is the standard yellow, then I'd give you £25 for it and as my sister lives in Hove, I suspect that I can find a way of getting it from you. Jez

Quoting simonpa: AFAIUI, A-frames tend to fail on the nearside in race/ex-race cars due riding the kerbs excessively, or from impacts. They do tend to fail on the nearside - I'd not really thought about why the nearside rather than the offside, given the offside carries more of the driver weight. But fatigue from kerb riding is clearly a big point. Is it possible to ride the kerbs excessively in a race car? 😬 Jez, broken A-frame at Oulton

Good luck with the build. Once you get the top bolts of the suspension in, it all gets easier! Jez

I understand the washer packing point now too. The chance of an A-frame failing on both sides at the same time through fatigue is nil, though. It will go at the weaker point. As that gets even weaker it won't load the over weak point. A bit like pulling a cracker - someone always gets the middle bit. Jez

A-frames snapping there is relatively common on race cars. The longer bolt is likely to have been as a result of the fitment of a side-impact bar on the drivers side, as mentioned above. As Steve said, there shouldn't have been play - just a longer end to the bolt. My guess is that you have an ex-Academy car - so a Roadsport 125 of some vintage? Jez

Nice one MBE. Proper customer care. Jez

If you have only two drivers you can put a bag seat inside the bag seat ... Don't look neat like real seats but made to measure = comfort. Jez

My 2008 bigheads failed. So the manufacturing change if that was the solution to the issue was before then. My bigheads were sourced through RiF. Jez