77 replies to this topic

[Timinichelsea]

Depends how serious you want to get, but you could look at getting a GPS data logger installed, that way you can plot what happens on the track and try different lines to see how it affects the car further along the track.

some of the Mini7 guys i've worked with use this to good effect. Biggest effect i have seen comes from getting the tracking right and keeping it right, if you whack curbs a lot then you'll throw it out after a few corners and have to live with it for the rest of the race, whereas if you have a bit of mechanical sympathy and take care of it then you'll be in a better position at the end of the race.

[CMXCVIII]

Sputnik – reading back, the first thing I’m going to say is, it’s not meant to be comfortable! If you’re at the limit, you’re meant to be bricking it! Frightened round every corner, deal with it, then on to the next one!

If your lap times are slower when you try to drive quicker, it sounds as though you’re overdriving! Presumably going into corners too fast and coming out too slow! You mentioned tyre squealing and I know they’re road tyres but all that energy that goes into making noise wants to go into making speed!

More than that, you spoke of mashing the throttle in the middle of the corner. Of course a Mini ls going to understeer then. I don’t have to teach you to suck eggs talking about “a balanced throttle through the corner”. You sound as though you expect to turn in and then floor it immediately … which you can do if you do it Cooperman’s/John Rhodes’ way of flinging the car in sideways with the tail out!

But you have to be good to do that because, sucking eggs again, sideways, like squealing, is too often slower!

Anyway, enough trite advice from another one of those old men who "the older I get, the faster I was!" ... if you pay my way. I'll come down to Cape Town with a stopwatch and stand on a corner and advise you quite competently! Pay double and I'll invite Uncle Cooperman too!



Now ... If your pressures were 36 warm, what did you set them to cold? How much were they going up? And how fast? Over how many laps?

We've suggested it's not enough! You have a real reluctance to pump up your tyres so I'd suggest 40 front and [maybe*] 34 rear set COLD - and see what they go up to.

The asterisk and the maybe is because as I said, I've never raced a Mini. I'm guessing at that pressure differential. Others might tell us more PLEASE

Then, if the car's gripping and working, pump them up two pounds a time and see how it feels then.

[Sputnik]

CMXCVIII

Taking advice from those that already forgot what I must still learn !! I appreciate the advice.

The tyre supplier informed me that 40psi is the max for the D93J's. As I was always running at below 24 psi cold, I did not want to go to hard to fast. I will try it next week. Tyres pressure after 4 laps (we only race 8) goes up about 7psi in the front and 4psi at the back. When I was running softer ones the difference was much bigger, hence the reason I've taken a smaller increment for now.

It might be a mental block, but harder tyres to me means less grip, more squealing nag less speed!

Also, I do not think I would like to drive like smoking John. It might be a bit to mush to soon, but I can never say never.

Is it correct that you suggest that I enter the corner turn in a bit slower, balance the throttle trough the corner and only once about 90% straight again put the pedal to the metal ? I think I still drive on emotions, getting excited and overdriving the car out of the corners..... As I was told a mini should be the quickest car through a corner.

I am learning so much from this post and forum, absolutely priceless.

PS, the shipment of parts from the UK to SA is sometimes more than a flight ticket ! We can then fit cooper man into your luggage.

[Cooperman]

I would never dream of using less than 40 psi on a race track and even on our rally cars when there were laps of race tracks the service crew would pump them up to about 42 psi.
You must get back hard on the power as early as possible and hold the throttle flat on the floor to get the best exit speed and 'slingshot' you down the straight. if you are only 2 mph faster out of the corner you'll be 2 mph faster all the way until you brake next. That can represent a fair bit of time on a lap.
If you are not getting a bit of understeer through at least 50% of the corner it is probably a case that you've not set the car into the corner correctly and are late getting on the power. The reason the rear ARB can work is because it induces some initial oversteer which is immediately balanced by power application.
We rally guys drive on oversteer a lot because it's safer to go into a corner pointing the way we want to come out than to simply understeer off when the corner tightens a bit. Racing is lees oversteer- dependant, but nevertheless with an FWD car the power-on understeer needs to be counteracted early by a small amount of set-up oversteer. Without the oversteer the understeer will take over the direction of travel and the consequent lifting off will make for a very slow exit speed.
it's essential to 'carry the speed' through the corner.
One suggestion is to try a larger steering wheel. That may sound silly, but a 15" wheel for racing is not unusual.

[ministar]

Ok, ive done a fair bit of track driving and the nurburgring a few times, and always put my tyre pressures down to 24 f and 26 b from cold. Is this too cold? They are Yokohama 032r Semi slicks. The rest of the car is set up for track with cambers/castors/ride heights etc... and wonder if im missing out on something with tyres being too low on pressure?

Cheers, and look forward to replies.

[jaydee]

Wow you must be running a very stiff setup if using such a low pressure

[CMXCVIII]

If your Dunlop man says 40psi is the maximum, I'm not going to post from the safety of the internet that you should go over that! But let me repeat that tyre pressure is what holds the tread on the tarmac and keeps the sidewalls from flexing.

I totally agree that exit speed is the only important thing for any corner. As Cooperman said, if you get onto a straight 2mph faster, you'll carry those 2mph all the way down the straight - and the straight bits are at least half of any circuit!

by the way, I would argue against a large steering wheel for a circuit car because of the circumference distance you have to move your hands to go from lock to lock. It's basically the same argument for a quick steering rack so that you can go from lock to lock quickly without taking your hand off the wheel. That doesn't mean you want a silly 10" steering wheel that's only right for a clown's car or a single seater!

[Ivor Badger]

If your Dunlop man says 40psi is the maximum, I'm not going to post from the safety of the internet that you should go over that! But let me repeat that tyre pressure is what holds the tread on the tarmac and keeps the sidewalls from flexing.

I totally agree that exit speed is the only important thing for any corner. As Cooperman said, if you get onto a straight 2mph faster, you'll carry those 2mph all the way down the straight - and the straight bits are at least half of any circuit!

by the way, I would argue against a large steering wheel for a circuit car because of the circumference distance you have to move your hands to go from lock to lock. It's basically the same argument for a quick steering rack so that you can go from lock to lock quickly without taking your hand off the wheel. That doesn't mean you want a silly 10" steering wheel that's only right for a clown's car or a single seater!

I you have to go lock to lock, then you are doing something seriously wrong with the car. Hu Wheldon's rally cross car used to have a std mini steering wheel. Anyone here reckon they are quicker than him?

[CMXCVIII]

Unlike Hu Wheldon, I don't think Sputnik has a limited slip differential in his car, so his physical effort to steer the car is infinitely less. I've mentioned elsewhere how Trevor Reeves had a Morris Minor steering wheel in his lim slip road rally Mini ... but not in his smaller engined everyday Mini.

Nor, unlike Hu Wheldon, is he likely to fly through the air and have to deal with the steering kickback of ruts and holes and bumps on a rallycross track.

On the other hand, there might well come a time when Sputnik has to do some pretty quick steering input, possibly to correct snap oversteer or to avoid a spin, and it was for that reason that I suggested a smaller, but still practical steering wheel, rather than going larger.

[Wil_h]

From what I have read, there seems to be no real problem with the way the car behaves, understeer on exit is just what happens with a FWD car.

I'm with the lower pressure gang here though. Just because the tyre deforms less does not mean it offers more grip. Radial tyres have quite soft walls, so look like they move a lot, but this does not mean they are giving less grip. The more you pump a tyre up the more deformed the tread gets, reducing grip. The pressures that the manufacturers state are based on keeping the tread as flat as possible, offering the maximum grip and even wear. the camber you run is there to compensate for the tyre movement.

Sure, pumping the tyres up can make a softly sprung car feel less floaty on a track, but I doubt it will be quicker.

Look at cars on skid pans, what do they do to reduce the grip? that's rght, pump the tyres right up!

So, keeping the tyres a semsible psi is what I would do. And then alter the pressures to affect the balance.

I would also say the 2 deg camber at the rear is too much. although I agree, if it works then fine, but it seems it's hiding another issue.

[Ivor Badger]

The steering wheel is for controlling the car, not the accident. All the controls including the brakes and accelerator pedals are not on/off switches. Try finding some in car footage of Alain Prost and learn.

[Cooperman]

Personally I would not take a Mini on road tyres onto a track at less than 40 psi warm.

There is an interesting chart from Tire Rack, a USA based organisation:


www.tirerack.com › Tires › Tech

Edited by Cooperman, 24 October 2012 - 03:43 PM.

[Ivor Badger]

John Rhodes used around 52psi in the front.

[Cooperman]

John Rhodes used around 52psi in the front.

Sounds about right.

[mike.]

Do tyre pressures not depend on wheel size as well? Obviously 10" wheels have masses of side wall movement so a higher pressure might be needed, but 13" wheels don't so can they use much lower pressure?