Heat cycles on slicks

[topwelshman]

I'm going to be racing for the 1st time on slicks in a few weeks and need some advice. I'm going to be running 235 620 x 17" Dunlops , how long do they take to scrub in & how many heat cycles do they need before they work at their best. Really don't want to scrub them in in Qualy so might go off for an afternoon and do this beforehand. Any advice on tyre pressures ranges would be helpful too.

[Boro]

If they're sticker tires, you're suppose to scrub em before the race weekend

[topwelshman]

That's the intention, anyone have any advice on heat cycles?

[Tim Falce]

Sorry, but while on the subject of slicks how do you tell the difference if they are worn out ( not worn but don't grip) or the wrong compound (don't get hot or grip). I ran on a set at Lydden last week and they were only reasonably good for about 2 laps after I had done about 3 laps on them. After that they were worse than driving on road tyres with embarrassingly slow lap times. They were Avon formula Zetec tyres on an XR2. After the race after driving into the Lydden paddock they didn't even pick any stones up and didn't feel very warm or sticky.

[topwelshman]

They should have wear indicators on them and when the slick is as low as the indicator they';re shot (I believe). Heat cycles anyone?

[ubrben]

Originally Posted by topwelshman

I'm going to be racing for the 1st time on slicks in a few weeks and need some advice. I'm going to be running 235 620 x 17" Dunlops , how long do they take to scrub in & how many heat cycles do they need before they work at their best. Really don't want to scrub them in in Qualy so might go off for an afternoon and do this beforehand. Any advice on tyre pressures ranges would be helpful too.

Did you check the website?

http://www.dunloptyres.co.uk/ourTyres/motorsport/

If that doesn't cover it I'm sure if you phoned the tech department they'd happily give you some recommendations.

Ben

[graham bahr]

Originally Posted by topwelshman

I'm going to be racing for the 1st time on slicks in a few weeks and need some advice. I'm going to be running 235 620 x 17" Dunlops , how long do they take to scrub in & how many heat cycles do they need before they work at their best. Really don't want to scrub them in in Qualy so might go off for an afternoon and do this beforehand. Any advice on tyre pressures ranges would be helpful too.

personnally i've never had the luxuary of a seperate session to scrub them in, just a few gentle laps early on in qualifying.

re-pressures, a lot depends onthe weight of your car and the rim size, if the rims are a bit on the narrow side for the tyre you'll want highers pressures,

if we are talking a light fwd car i would start out at 24psi, 28 for a rwd car.

biggest piece of advise i can give is watch out for cold slicks they really have very little grip, far less than normal ordinary road tyres, hot well thats another story the grip should be massively higher, generally slicks require stiffer springs and damper settings due the there extra grip and therefore suspension loads

[greenamex2]

graham, any advice on how much stiffer to go on springs?

My one foray onto to slick at Lydden ended up with me stuck in a tyre wall after the suspension bottomed out causing massive understeer.

[marcush.]

heat cycles:very much depends on the tyre make , compounds and abuse.
If you go to hard to early with a compound on the soft side ,the tyres may develop graining ,and if you continue to push they will be destroyed in a few laps...
so it´s a simple question but no easy answer.
Bottoming out can cause understeer ,but it helps actually to bring the tyre temps up....
A really good setup will need the driver to push push push to get the temps up ....
in qualy you could easily scrub your tyres ,starting as eaerly as possible do a warmup lap to bring up the temps slowly increasing your effort and kick loose the rearend by throttle lifting at corner entry (FWD) or hard acceleration, and kick the front loose by turning in too fast ...then one lap at elevated speed but nothing like a qualylap,then a very slow cooldown lap and 5 minutes in the pits.then go out for your qualy attempt.
If you don´t let the tyre cool after the first heatcycle ,it will probably give you a tenth or two extra laptime in qualy,but at the expensense of a faster detoriation .

[graham bahr]

Originally Posted by Denis Bassom

graham, any advice on how much stiffer to go on springs?

My one foray onto to slick at Lydden ended up with me stuck in a tyre wall after the suspension bottomed out causing massive understeer.

compaired to springs for normal list 1A type road tyres about 200%+

[greenamex2]

Eek.

Is that on top of stiffer anti roll bars (stiffer dampers are taken as read)?

[graham bahr]

Originally Posted by Denis Bassom

Eek.

Is that on top of stiffer anti roll bars (stiffer dampers are taken as read)?

yes and no

generally slicks produce so much more grip that they require totally different spring, damper, rollbar rates as well as geometry.

on road cars its preferable to make the roll bars do a lot of the work, so you can use relatively soft springs and therefore get a reasonable ride quality that isn't too rolly polly, for race work its better to have the springs do more of the work, infact particulary fwd cars its often better to soften or even remove the front rollbar altogether.

i dunno what sort of car your running, but all the race spec cars i've had anything to do weigh between 650kg to 1000kg and are running front springs between 400 - 750lb and rears between 250- 600lb

[Alan Cherry]

If you are going testing beforehand, try and beg borrow or ponce a pyrometer. Then get someone to take the temp inner middle and outer on each tyre as soon as you pull in. - you should be able to tell if your'e running the right camber too !
Although I must admit I haven't done it, but the previous owners of my car conciensiously logged tyre pressures in all the races they did at all the major circuits round europe ( they never did Lydden or Stowe though !) so I've taken a rough average of those - as different corners do different amounts of work at different circuits, They logged the working temperatures, and the pressures that they had to inflate each corner to cold - usually every corner was different cold- but i set up each axle with the same pressure as we do short races and it all gets too complicated !

[marcush.]

slicks and tricks......
don´t forget to use the tools you got in hand are for different causes...so you will not be able to cure excessive roll with dampers ,but you can very well control the generation of roll in corner entry (rollacceleration)as well as unwinding the roll at exit.
So to call this stiffer dampers is very very simplified,as the dampers are key to driver confidence ,as they control the transitions from going straight to braking to cornering.
And the lesser mortals profit more than the heros ,rest assured.
the springs may be capable of reducing the rollangle ,but if you happen to have a rather high CG at the front and a very low rollcentre(McPherson,anyone?) you will never ever be able to control this with the springs alone.So a effective means of Front ARB is called for.
As for the geometrie of course the task is to have all four corners on the ground as long as possible during the lap,nomatter what the world is telling you.
As for the springs ,yes of course stiffer but you can easily go overboard there because most dampers are not building up the forces (lowspeed) quick enough,so you need stiffer springs to combat this...

[graham bahr]

Originally Posted by Denis Bassom

Eek.

Is that on top of stiffer anti roll bars (stiffer dampers are taken as read)?

having just realised what car your running from another thread, if on slicks i would be starting out with 600lb front and 300 rear springs

[marcush.]

as for the original question ,the heat cycles for the tyre are something you should really log (just make a marker on the sidewall of tyre before going out )so you have an idea of just how often this set of tyres has gone thru a full temp cycle.
Some tyres are not very sensitive to heat cycles some are degrading abit some have a finite number of cycles.So no genereal rules ,just another variable to be aware of.

[THR]

is anyone on here rich enough to buy slicks when they have x number of heat cycles???
they are sooooooooooooo expensive, surely only the rich can afford to buy tyres when they feel like it.

i know in the ARPF3 no one pits when they put new tyres on.. for at least ten mins, and then its only a quick temp and pressure check. not sure when the quickest lap is put in tho, not checked!

[R59]

Back to Del's question -

I was told that the Formula Saloons guys used to get three meetings out of a set of Dunlops before the time started falling off.

I think it was Ric Wood that said he noticed losing up to 3 seconds a lap if he used the tyres more than 3 meetings. They would be used twice per meeting, 20 minute races usually. With two practice sessions.

Each time they heat and cool, the rubber cures a little harder.

Though saying that, I have a set of 16" Avon's that have never been used, which are probably 7 years old. They are hard as nails.

Del - talk to the guys at HP Tyres in Whittlebury (Silverstone), they'll put you right.
25psi cold is a good starting point.

I too have a lot to learn, going from road tyres, to 18" GT spec rubber in one hit. The last thing I drove on slicks was an old F3 car about 15 years ago. Though actually, they were wets as it p-ed down with rail all through the test.

Rob.

[marcush.]

sorry chaps ,but if you don´t have the money to buy a set of slicks ,you should consider buying a playstation....
Racing is always a budget constraint thing and i would spend more money in buying the best tyres i can get than trying to find a few more horses...
Look at F1 :If you don´t have the best tyre or don´t use your tyre correctly,you cannot win!
AND I have always pushed my Competition cars in paddock instead of waisting expensive runtime of my equipment but I used always the best tyre I could afford.
sometimes this was not the most expensive one

[ubrben]

Originally Posted by marcush.

sorry chaps ,but if you don´t have the money to buy a set of slicks ,you should consider buying a playstation....
Racing is always a budget constraint thing and i would spend more money in buying the best tyres i can get than trying to find a few more horses...
Look at F1 :If you don´t have the best tyre or don´t use your tyre correctly,you cannot win!

Excellent post. The amount of people who spend large amount of money on expensive engine upgrades when they'd go quicker with better setup, better damper, better tyres or some driver coaching always makes me laugh.

When it comes down to it, you are traction limited most of the time, so you should spend most of your budget optimising your traction. Most people don't do this.

Ben

[graham bahr]

[QUOTE=marcush.]sorry chaps ,but if you don´t have the money to buy a set of slicks ,you should consider buying a playstation....
Racing is always a budget constraint thing and i would spend more money in buying the best tyres i can get than trying to find a few more horses...
Look at F1 :If you don´t have the best tyre or don´t use your tyre correctly,you cannot win!
AND I have always pushed my Competition cars in paddock instead of waisting expensive runtime of my equipment but I used always the best tyre I could afford.
sometimes this was not the most expensive one[/QUOTE

THAT REMARK STINKS,

i assume from such a post you can afford to buy the best of everything, well lucky you, 99.9% of racers out there cant, and if all those who went in your lucky position stayed at home you would hardly have a car racing.

why deny someone that chance to race just because they either cant afford to buy some slicks or choose to spent the money elsewhere.

i also assume that you win every time out, if not youd better spend some more money, and if you cant i sugeest you go buy the play station.

yes tyres are very important, but its all a balence, someone just starting out with a mildly tuned car and a set of say fairly sticky yoko 032r's or what ever, may well gain more spending the money elsewhere.

lots of guys race knowing they will never win, they do it because they love racing and building cars, again if only those who could win raced 90% of club motorsport would cease and you would be racing on your own which would probably not be a bad thing if this is how you really think

[graham bahr]

Originally Posted by ubrben

When it comes down to it, you are traction limited most of the time, so you should spend most of your budget optimising your traction. Most people don't do this.

Ben

maybe but a set of slicks still need optium geometry damping etc to work, dont forget most cant afford to do every thing in one hit, and i'd rather not see empty grids whilst everyone saved up!

[R59]

That was the good thing about the now long dead BRSCC Super Road Saloons, it promoted the idea of self development, over and above the mostly standard Road Saloons.

They had full grids, until the rules were meddled with.

We didn't have slicks, but we did have people who developed and learned, sometimes by their own mistakes, but all in all, we enjoyed it.

Going back to the origin of the thread, I remember the days of the Dunlop Rover GTi series, and the front runners would do their fast laps on new sticker tyres in qualifying, then those two fronts would be set aside until the next race, and would be used for the race. The fronts from this race would be put on the rears for the next race, and then consigned to the skip. If I remember it right.

To do that, cost lots and lots of money.

Rob.

[grelley]

If I remember correctly Hoosier recommend with a new set of tyres to do approximately 20 laps on them starting at a slowish pace and gradually working up to a race pace on the last couple of laps, without brake lockup or spins etc. Remove the wheels from the car and store in a cool area for 24 hours. The tyres should then be ready to use. My understanduing with second hand tyres is that if they have been taken to a certain temperature in a race, they will not give proper grip again until that temperature has been exceeded and so on. That is why you can often pick up what appear to be good secondhand tyres that dont work properly and why some FF drivers will replace new tyres after one race.

[COLIN STUBBS]

seen it all before. rich kid wins club races on new slicks. rest of field scrat about on hard/second hand rubber. rich kid goes onto top national championship and despite all daddies dosh, he`s crap.retires at end of season and buys a playstation.and now i know why no matter how hard i try me 216gti wont match the times it did in 1992.on 10 year old slicks. cant decide what to do for next season. free toyos or s/h slicks or a playstation!!