Tyre Issues at Broadford

[Evan Bottcher]

Also I'd agree a little more camber might help with more even wear, although Broadford and Winton are always going to chew the crap out of the front left on a FWD car.  My front left tyre doesn't last very long on the Sud, and 3 degrees of camber doesn't fix it.  Out of interest what is your camber now?

[alanm]

I agree with Evan re the need to take wheels and tyres to sprint events.

Cooper and I used to run a road set and a track set on the 75, fitting the track set (Direzza Z1) before an event and driving to the track. Now we just leave the Direzzas on the car on the car all the time because they are so much better than your average high performance road tyres IMHO. Every time he drives in the wet I feel good about the fact that he is on a really good tyres that are designed for grip not longevity.

Dunlop do the Direzza, Yokohama do the Advan Neova AD08 and Federal do the 595 RSR – all road legal I think.

A blurb about the Yokos below...


The ADVAN Neova AD08 bridges the gap between street tyres and race tyres. Street tyres work well when cold. Conventional rubber compounds reach their limit during high speed driving as heat softening quickly saps the tyres ability to grip the road. Using street tyres on the track can lead to slower lap times and rapid tread wear.

Cheers,
Al

[aggie57]

As others have said, classic overheating and very common on softly sprung FWD cars.  Given it's the left tyre I'd hazard a guess that long right hander at the end of the lap is to blame.

You can try track tyres but frankly I wouldn't waste my money if you're sticking to standard suspension. They'll do exactly the same thing, maybe even faster if they're soft.

BTW, fallacy to say road tyres need to be bought up to temp before a run. They're a dish best served cold.  They're not slicks.

[jayarr]

Also I'd agree a little more camber might help with more even wear, although Broadford and Winton are always going to chew the crap out of the front left on a FWD car.  My front left tyre doesn't last very long on the Sud, and 3 degrees of camber doesn't fix it.  Out of interest what is your camber now?

Hi,
At Broadford had 0.9 degrees negative camber. Unfortunately did not measure the toe prior to the tyres being replaced, and aligned.
Prior to Sandown, have setup the front with 2.7 degrees negative, and 1mm total toe out.

Tyre wear seems to be much more even, and temperatures are within 5 degrees across the tyres - albeit when measured on return to the pits. Looking forward to seeing results at other tracks.

The negative camber does not appear to have impacted braking, maybe the electronic traction nanny is taking care of that

For those interested, camber was altered by redrilling the upper stub axle bolt hole through the shock absorber mount. Moving the hole inward by each 0.5mm gets you about 0.5 degrees camber.
Nifty tool find, digital inclinometer $30 to the door from Ebay. Has a magnetic base so you can stick it on the brake rotor for checking camber readily. Stated repeatability of 0.2 degrees, which from experimentation is bang on. Love the digital gadgets available now.

Cheers.

[Doug Gould]

Broadford was built for bikes not cars and as such has some challenges. From memory the Alfa Club run the same direction as the bikes (Which is probably what most CAMS clubs do) but when we used to use it we ran the opposite direction. FPV & HSV used to use it for suspension development and they also ran it in the opposite direction to the bikes.

The standard bike direction has a decreasing radius downhill corner which I suspect may be the culprit of your tyre issue. Downhill gives more weight transfer to the front and the decreasing radius just means you haul harder on the steering wheel.

I'd suggest 37 psi hot is under done. I'd be looking for 40 or maybe a touch more. As a starting point you'd be looking for 4 psi or more differential front to rear. But, look at tyre temperatures and use pressure to try and make them more even. If you trim tyre pressure by tyre temperature, you may have similar pressures all round hot, but cold the pressure may be different for each of the 4 tyres.

You need the car to turn in better. Some toe-out at the rear may help this, maybe more at the rear than front. Anything you can do to help weight balance will help - boot absolutely empty, low fuel, etc. Beyond this its trying different lines.  A slower entry and later apex may be faster and gentler on the car.