Hi folks Have a mk 2 16v car for track use. Don't want to spend any money on it at the moment but was hoping to improve the understeer it has. Lowered 30mm, front upper strut brace, half cage in rear. On advice from others at the track (non VWs) I've upped the front pressures to 40 but haven't noticed any difference. Anybody any experience on this? Will try varying rear pressures next time.
safe practise states, equal pressures, or higher on the front to promote understeer as its easier to control than oversteer. higher rear pressures will give you snap oversteer on lift mid corner. experimentation is the way to find your best set-up, although pressures alone will probably not help you cure understeer by much.
Cheers Saul Realise the effect will be limited but any advice is useful. Experimentation takes so bloomin long doesn't it
Tried mine on sunday. 30 fr 27 back nice, but a bit skittish in the long corners (while drifting) 25fr 25 back, grip was there but I could feel the tyre walls flexing quite a bit, didn`t really get on with them this low, althoug a lot people use these pressures (or lower!) I`m starting at 28 27 on the next one and go from there. O would have thought 40 in the fron`ts would just make the car skip a lot and give massive understeer?
Colin, I take it you're checking the pressures hot? (ie after a session) I've done a lot of experimenting with tyre pressures and run around 23-25 psi (cold) all round on dry tracks - the pressures only increase a couple of psi after a 20 min session, on Sunday I ran 28 front and 25 rear in the wet, this stopped a lot of the oversteer I find with the tyres harder than this (cold) the grip soon goes off near the end of the session, on my car, with me driving the lower pressures seem to make the grip consistent, as Keith says you can feel the sidewalls flex for the first lap or so, but when they get some heat in, I find them ok. A cheap thing you can do that kills a lot of understeer is to run more than the VW specified 40 mins of negative camber on the front, a set of poly-sport bushes (30ish) in the rear beam also helps. So does left foot braking, but that's another story. Just to add, what works for me on my car, may not work for others. I forgot the most important thing, brake harder , go into the corner slower, don't scrub the speed off with your tyres Edited by: G_V_K
Hi G_V_K Thanks for the info. Will try lowering the pressures next time. Take your point about braking. I do approach the corner where the car understeers worst of all a bit fast and go into it faster than I would like. It's at Knockhill and there's a series of 3 corners (starting at Duffus) close to each other. Feel I have to accelerate round the first 2 to keep pointing in the right direction and that leaves some heavy braking for the third. Why would left foot braking help? Is it easy to learn? BTW, great video
I'm no expert at left-foot braking but I've had a go. it's easy to get your feet tangled up Theory behind it is, whilst your right foot is on the throttle as hard as you like,you transfer weight onto the front of the car with the brakes through the corner, reduces understeer especially in the wet Problem with it is, your left foot is used to pressing the clutch hard, so it's not as sensitive as your right foot on the brake pedal. Expect to headbutt the windscreen a few times I'm gradually getting out of the bad habit of not braking enough on track, ChrisP commented about it when we went to the Ring, he said "you should be either braking or accelerating, no inbetween fannying about" what's that old adage? "slow in fast out?" look out for more vids on the site Edited by: G_V_K
ok i'm running a semi slick tyre and drop mine down to about 15psi cold front - at this pressure when hot coming of track i have seen over 40psi in the tyre !!! i've yet to find out which is best, using my mini cams i have seen the sidewall disappear thro the craner curves (diff day diff pressures) It's possible that the 205's dont like a 7j wheel tho ...
Personally I think what you say above is true - I was looking into A032R semi slick pressures with the Yoko agent, and he said that they only recommend a 6.5J on a 195 section tyre. As to the other points, I would like to add that different makes and models of tyre will behave better at different temperatures. The driver will also prefer the feel of different things from a tyre. I like GVK like to go out on a soft tyre from cold, but when they have some heat into them (nothing like a bit of gooning to sort that out eh G ) I find them excellent. We were both running A539 Yoko's at that point In reference to left foot braking, try practising on quiet roads - you will need a lot of attempts to get anywhere near decent! And it will be a different story on the track also. It has taken me a lot of practise to get to a half decent level, but it feels great to do it well on the road or track. After a while you will also need to think about the concept of changing gear whilst left foot braking - its damn complicated believe me - try watching modern WRC drivers, they are experts at 'dancing' on the pedals
left foot braking hey...just requires practice until you have the 'feel' in your left foot. i can do it now (did have a few sletchy moments at first), you have to be a lot gentler than your foot wants to be...so concentrate on that. also, helps you when you go karting!!!
It helps at Karting until you get a b0ll0cking off the marshals It burns out the centrifugal clutch on the little put-put 'arrive and crash' karts. I'll have to find the footage of ChrisP demonstrating left foot braking at Alconbury last year, the speed he was carrying through the chicane was incredible Just hoping I haven't recorded over it with other stuff [:^(] Edited by: G_V_K
I check my tyre pressures at every track after qualifying and make a note of them. Once they've cooled down I then reset all the pressures so they would have been 40 when hot. That means different pressures right and left, never mind front and rear. I've never used left foot braking for a quick lap round a circuit, I'm not sure if any of my competitors do either. Its more important to get a smooth gear change and be back on the power at the right time. To dial out understeer you can fit a much stiffer rear ARB and modify the front struts and run about 3 degrees of negative camber. I can get the back to drift out on my Mk1 quite easily.
I would've mentioned a stiffer rear ARB but ColinT said "I don't want to spend any money on it at the moment" I'm struggling to understand what you mean about the tyre presssures, can you give me an example of the cold pressure, hot pressure and the pressure you set it to? 3 degrees negative is all well and good on a race car, but on a daily driven road car it'll kill tyres and you've got to be careful with drive shaft lengths as well. Edited by: G_V_K
err no but that is from stone cold ie the day befroe kinda thing like i said if i run em soft the sidewalls disappear or to hard then they slide.... i have yet to find a happy medium - although at donny on a 28psi cold pressure (and like a dumb as5 i didnt check them during the day) they were fine in the wet and ok in the drying line - with hindsight i should have kept an eye on them but just plain forgot about it !!!
I go out onto the track (preferably testing pre-race day rather than qualifying) with the pressures approximately correct from last time and blast round for 20 mins. Then I pull into the pit lane and get a mate to take all the tyre pressures accurately with a decent gauge. What we then get depends on track temperature conditions plus the actual track itself - but might be something like 47-43 LF-RF and 38-41 LB-RB We then take out 7 psi from the LF, 3 from RF, add 2 to LB and let one out of RB. When the tyres cool down the pressures will seem all over the place, but the idea is that when you've finished the green flag lap (without excessive weaving of course) they're all pretty much at exactly 40 degrees for the race start. This is of course always with only me in the car - and the car is always exactly 800kgs at the start of the race with the same amount of petrol in. In a track car these might be more variable if for instance you have a lardy passenger. A stiffer rear ARB is a fairly simple mod and very worthwhile but yes, it'll cost money. And yes - I wouldn't put any -ve camber on a car unless it was primarily for track use. If its just driven to and from a circuit and not an everyday car then 1.5 to 2 degrees would be a great benefit, yoo could always keep swapping the tyres round to even out wear.
Ahh, understand now - what tyres do you run? I run the mk2 on 2 degs negative with 0 toe, the tyres do wear pretty evenly all the way across.
I have to run Dunlop Formula R D84's, they are quite sticky but nothing special. With 3 degrees of camber they get wrecked on the outside edges very quickly. Nice web site by the way, I think I might try Stealth for my pre-season rolling road tune next year, see if they can drag another BHP or two out of my rebuilt engine. Oh - toe. I was running 1 degree toe IN most of this year until Dave Walker put the car on his rolling road. He couldn't believe how easy it was to keep on the rollers and said that I should be running at least 1 degree toe out for a sharper turn in. Tried this for the last round but unfortunately only managed a lap so can't really comment on the difference - however people have since told me that its worth up to 1 sec a lap. Basically keeping setting the toe out until its too hard to drive in a straight line anymore then back it off slightly. Again maybe not so practical for a road car....
I was told also to run 2mm toe out on my car - I tried it, and the tyres had no inner edges after a fortnight of road use Turn in was razor sharp mind you. Thanks for the comments on the site, It's my first attempt.
