XRAY - Model racing cars

Taken from FAQ section
2.) Rubber/carpet racing:
Racing with rubber tires on carpet is very different than foam/carpet racing. The difference between low grip tires such as Take-Off 27 and high grip tires such as Take-Off 22 is large and will require very different setups for each track and each type of tire.


This has caused my brain to think that maybe we are missing out. As an asphalt racer we normally use 22s or 27s depending on track temperature but it has never occured to me that if the temp gets to the point where we change the tyres, we should change the suspension settings also. Is this the case, are we missing out significantly by staying with the same suspension setup throughout the day?

It's hard to say one way or another. On way of thinking is that the setup is for a certain grip level. As the temps go up you get less grip (tyres overheat) so you go to a harder tyre re-establishing grip and thus making your setup work (better) again.

However, the other school of thought is that when temps are low you generally have better grip anyway, so changes are needed compared to low temps and hot temps. Personally I tend to minimize changes, but in most cases I would change damping and springs (go softer and maybe a bigger angle), and possibly run more flex. Changing geometry is something I seldom do in relation to changing temps simply because there is precious little time to test the change, it basically would have to be the right change right of the bat. I am pretty sure though that it will make a difference if you know what changes to make.

Thanks for that Tony, makes sense. I guess for us mere mortals there is a strong argument that if you have a setup working well for you don't tamper too much with it during an event! Definitely going to try it out during testing although the chances of the track temps in the UK now outrunning the 22s and rapidly receding!

When say "maybe a bigger angle" I take it you mean laying the springs down a bit more?

Tony, the set ups you change: damping and springs (go softer and maybe a bigger angle, is when temperatue is hot or cool?
Sorry for asking .

When the temperature is hot, my car starts to understering, on and off power, what should i do?

Good question as I think I have confused myself now. Experience, looking at tracktimes, says to me that as it gets hotter the lap times get better. Now it is also true that as the day progresses more rubber gets laid down. But maybe that is immaterial, the grip increases. So as it does the move if any would be to stiffen the suspension surely?

If we are not running control tryes we start normally with CS22. Once the track temeperature gets to a point we switch to CS27. This not at a point when we notice grip loss but when we know the tyes are going to start graining, which apart from stuffing the tyres (expensive commodity) would I guess quickly lead to grip loss.

When it gets hot...
Well caveats without knowing your setup and assuming your tyres are OK, it sounds to me as you are gaining too much grip in the rear tyres, so put a step harder spring on the rear and if needed also reduce the rear droop. I am guessing a bit now but as oyu have it at all points on the turn it might be a good idea (?) to mix it with a step softer spring at the front and some more dropp at the front.. My thinking is based on you making the change during the day, not at the start of the day when it is cooler. An altenative approach would be to put a sway bar on the rear - faster pit turnaround than changing springs and droop(assuming you already have the attachment points fitted awaiting the bar itself - actually it is probably faster even if you dont have the attachment points fitted)

Not this year, but last year we had multiple days like that. Besides, as I have raced in for instance Florida I have changed my points of reference.