77 replies to this topic

[Sputnik]

So,

We still have three things to get clarity on: 1. Suspension setup 2 .Tyre pressure and 3. Driving style/skills. Althought no 1 and 2 seems to be a personal preference, that I can understand, no 3 is also up to the individual driver. Does the below look right ??

[Cooperman]

So that you feel better about it (well, maybe) my son works as a consultant design engineer with one of the leading F1 teams, can't say which. They are currently working hard to sort out a problem whereby in very high speed corners they are getting a bit too much understeer, but in slower corners they are getting too much oversteer. They are playing with computer simulation programs with different aero-d set-ups, different ballast and suspension adjustments, but it still ain't right.
So you are not the only one.
I asked my son, who has a lot of Mini experience what TP's he would start off with on a Mini on a race track and he said he would begin at about 46 psi front and 42 psi rear and do comparative lap times at different pressures and different fuel loads.

[Wil_h]

So that you feel better about it (well, maybe) my son works as a consultant design engineer with one of the leading F1 teams, can't say which. They are currently working hard to sort out a problem whereby in very high speed corners they are getting a bit too much understeer, but in slower corners they are getting too much oversteer. They are playing with computer simulation programs with different aero-d set-ups, different ballast and suspension adjustments, but it still ain't right.
So you are not the only one.
I asked my son, who has a lot of Mini experience what TP's he would start off with on a Mini on a race track and he said he would begin at about 46 psi front and 42 psi rear and do comparative lap times at different pressures and different fuel loads.

This is all very interesting, but F1 tyres are a world away from what we are talking about, in construction and materials.

If you want a real answer, ask the manufacturers, which you have done and they have given you an answer. I think at 46psi you'll have a massively balooned tyre offering less grip, but less roll. I doubt it will make the car quicker.

As a side, I run crossplys and have 18psi in the front and 14 in the rears. Again, different construction to the tyres being discussed, but this is correct for my car and tyre (it must be I hold 3 national hill records).

Edited by Wil_h, 26 October 2012 - 09:35 AM.

[Cooperman]

So that you feel better about it (well, maybe) my son works as a consultant design engineer with one of the leading F1 teams, can't say which. They are currently working hard to sort out a problem whereby in very high speed corners they are getting a bit too much understeer, but in slower corners they are getting too much oversteer. They are playing with computer simulation programs with different aero-d set-ups, different ballast and suspension adjustments, but it still ain't right.
So you are not the only one.
I asked my son, who has a lot of Mini experience what TP's he would start off with on a Mini on a race track and he said he would begin at about 46 psi front and 42 psi rear and do comparative lap times at different pressures and different fuel loads.

This is all very interesting, but F1 tyres are a world away from what we are talking about, in construction and materials.

If you want a real answer, ask the manufacturers, which you have done and they have given you an answer. I think at 46psi you'll have a massively balooned tyre offering less grip, but less roll. I doubt it will make the car quicker.

As a side, I run crossplys and have 18psi in the front and 14 in the rears. Again, different construction to the tyres being discussed, but this is correct for my car and tyre (it must be I hold 3 national hill records).

My son was not talking about F1 tyres. Read it again if you'll be so kind:

I asked my son, who has a lot of Mini experience what TP's he would start off with on a Mini on a race track and he said he would begin at about 46 psi front and 42 psi rear and do comparative lap times at different pressures and different fuel loads.

I'm probably having dinner with an internationally recognised Mini race driver this weekend, and if I do I'll get the actual and correct information from him in respect of racing on road tyres.

[Sputnik]

Wil_h and cooper man, thanks for your effort. It makes sense, but the pudding is in the test !!

I think that we are close to some answers.

Will h, what will you run the Dunlop D93's at ??

[Cooperman]

As promised I spoke to my old friend Barrie 'Whizzo' Williams about this last night at dinner. If you want to check his credentials for giving advice just 'Google' him.
He said that you should aim to run at around 45 psi to 50 psi when hot when using road tyres for racing. So you set a nominal pressure of around 38 psi, then do a few practice laps and come in and check the pressures which will be a lot higher then. Then increase or decrease them a bit to see what suits your driving style, suspension set-up and track conditions. Play around with the pressures a bit each way and change the differences back-to-front until you are doing your best lap times. If you still find that the overall speed through corners or the handling is not what you want you need to alter and improve the basic suspension settings, finally refining them to suit specific tracks.
I think that is the answer you've been looking for.

[ministar]

All i can say, is makesure your tyres are in good condition..

[Sputnik]

Ministar,

the tyres are brand new. Purchased them in Sept 2012 !!

[CMXCVIII]

So now will you please spend a few Rand on a day's testing to discover how to get the best out of them!

[Sputnik]

Day's testing is very expensive, at R400 (35GBP) per hour it is not possible.

Doing some track time in the afternoons, free of charge on Monday's and Tuesday's. Could not do today, but going to do an hour or so tomorrow evening.

Then on Thursday, Friday official practice and saterday race day again.

Cooper man, any ideas on the tyre pressures ?

[CMXCVIII]

Oh Gawd! Another World Champion wannabe!

Sputnik, let me ask you a couple of pertinent questions. How much did you pay for your Dunlop tyres in September? How long are they lasting or how long will they last? What lap time advantage are they giving you for all that money you spent?

The only way to find out why you bought those Dunlops is to test - systematically and methodically drive laps of the circuit and then measure and change things on the car and find out what you have and what you need!

There is no other way! Otherwise you're wasting much more of your own money than you're wasting our time here!

Uncle Cooperman has given you tyre pressures! Free of charge, Whizzo Williams has said 45-50psi hot. I too have raced against Whizzo and taken advice from him [and drunk with him!] and if he told me I'd be faster if I sat facing backwards and painted my feet pink, I'd go testing and try facing backwards with pink feet - and he'd probably be right!

But neither Whizzo nor Cooperman can know how abrasive your track surface is, nor how warm the ambient track temperature nor how your car changes tyre pressures as it heats up!

Let alone what will be fastest for you personally.

That's why you have to spend your time and a little bit of money testing!

If on the other hand you just want black and white answers from the internet, there's really only one place you can race ... Sell the car and take up virtual online racing games!

[Cooperman]

Day's testing is very expensive, at R400 (35GBP) per hour it is not possible.

Cooper man, any ideas on the tyre pressures ?

See above. I hope that answers your question.

[Sputnik]

CMXCVIII,

Asking questions on the forum .... sorry for wasting your and the others time then. I am asking as I get different answers! I do not know the experience of each and every person responding, but from what I can gather, there is some very knowledgeable people on the forum, although the advice from different people gives different outcomes.

I was after an answer based on a platform to start from, but in my limited knowledge of mathematics there is quite a big difference between 26 and 50 psi ??

Take the time, read the thread again and tell me what would you have done ! Maybe that might answer my original question? Just for the record the D93's is half the price of A008's. One of the reason why I have changed to Dunlops. Also remember that the last mini sold here was in 1983, 30 years ago and the knowledge of the cars has disappeared over the years.

@ Cooperman, sorry I did not see your post of yesterday, hence the reason I've asked again. Thanks for your advice. I will try it out.

[Cooperman]

@ Cooperman, sorry I did not see your post of yesterday, hence the reason I've asked again. Thanks for your advice. I will try it out.

It wasn't my advice really, It was Barrie William's. It looks as though the best thing is to go to about 36 psi all round, do say 5 'hot' laps and see how it feels, timing each lap. As the tyres heat up the pressures will increase to mid to high 40's, so come in and measure the pressure after the 5th lap. Try a different pressure by adding or taking out a bit of air, and do 5 more laps timing each. You'll soon see whather you're going faster or slower and can make further adjustments as you go. If it's understeering a bit too much put the backs up a bit more or let the fronts down a bit. Just keep adjusting until it suits your driving style. Then, when you are winning championships people will ask you for your best advice on this sort of thing .

[smudger068]

I must say after having a read through this post is sounds very interesting different views etc etc.
Yes at the end of the day it comes down to driver preference and comprimise! Comprimise the operative word here!
I am gathering that you are using standard damper and cone setup (no adjustable coilovers basically)

understeer, oversteer is fundamenatlly due to lack of mechanical grip!!

Understeer lack of mechanical grip at the front
Oversteer lack of mechnical grip at the rear

Okay, so undertseer in slow corners with little body roll? back off the camber on the front if the body roll isnt drastic (add camber if the car rolls onto the wheel) Do you ever take tyre temperatures? everyone bashes about pressures but never temperatures, are your temps within 10 degrees of each other from inner middle to outer? are your inside temperatures getting to hot?

An ARB on the rear maybe an option!

Also to much camber on the rear can increase understeer because you cant get the back round but when it does, it comes round with aggressiveness causing loss of control. Have a little controlled and i emphasis controlled oversteer coming into the corner (FWD ONLY) gives me confidence because i know im not going to keep going straight helping reduce understeer when exiting the corner. because a FWD car will undertseer coming out of the corner due to toe change under acceleration (RWD can use the power to turn the corner)

I am going totally by you say that you have little roll, personally i would back a little camber and toe of the rear (again temperatures, if the body likes to roll onto this tyre then just adjust toe) because that does sound like you want the rear to stay put!! fair enough but its to much if you cant get the front round!!

Dampers, you say are stiff at the front, well you are resisting weight transfer immediately there, so thats something to think about. Dampers on the rear are soft, automatically soaking up weight transfer to the front.

Everything in your set up says understeer, simple as that!! and when the back does step out it ******* you up because its trying hard to stay planted!!

Have you thought about brake bias?

Tyre pressures upto 40-45 psi or whatever it was, is understandable on conventional mini suspension because it will help hold the tire under aggressive roll situations such as racing (as seen in the video because you can see the tyres folding there god knows what that would look like at 26-30 psi), stopping the tire from folding under, losing grip!! but if you have a very stiff setup then i would say these are to high!
(I personally wouldnt advice this on the road at all...just covering my ass)


Just to add, i suspect you will lose the rear by backing of the accelrator because your dampers are soft on the rear, giving up weight transfer quickly, fronts are stiff resisting the weight transfer causing an unstable situation throughout the car
www.funkmotorsport.com

Edited by smudger068, 29 October 2012 - 10:16 PM.