Auto Racing: Racing tyres temperature taking,interpreting,suspension setup according to them, citroen ax gti, sarasota florida usa

Question
I am racing a Citroen AX GTI Group A car (front wheel drive with limited speed differential, about 130bhp/880kg weight-including driver- tyres Michelin 18/58-15 N21 Rally slicks)in hillclimbs of about 3km duration, temperatures from 15oC to 35oC.
I would like to tell me how and when to take tyre temperatures, how to interpret them and what suspension changes to make according to them
                 Thanking in advance,Regards

                    Georgios Dareiotis

Answer
Hello Georgios:

Tyre temperatures should be taken at the end of each run.  Immediately after, so it's helpful to have a crewman at the finish.  Alternatively, I carry the pyrometer close at hand and hop out, and even before removing my helmet, take the temps and write them down for later examination.   EAch tyre should be measured about 20 mm in from the outside edge, in the middle, and about 20 mm from the inside edge.

Here are some suspepnsion changes that are recomended.

Tyres are :
Hot in the middle: reduce air pressures about 2 PSI

Hot on the outside: Increase negative camber. about 1/2 degree.

Hot in the inside: Decrease negative camber. same above

Hot on the outside and in the middle: Check your toe in isn't excessive. I suggest you run a little toe OUT anyway, the car will turn better. About 1.5 mm per side.

Hot on the inside and in the middle: Increase your castor angle

Finally, see if you can find the book:  "How to Make Your Car Handle", by Fred Puhn.  Book stores should be able to order it for you , and it's and excellent source of information about suspension set ups.

Good luck !!!

Dan Liddy
Sarasota Florida USA