Just been scouring previous threads for some info on this but I’ve come up with nothing. I’d like to know if anyone has experienced this problem and if they know what the cause is;
When on track and taking longer higher speed right-hand corners, I hear a noise as if the nearside rear tyre (i.e. on the side in compression) has picked up debris which is then continually hitting something within the wheel arch. However, it occurs consistently so cannot be debris everytime, so I’m wondering if it might be something driveshaft related? Slowing down / exiting the corner and the problem disappears.
It’s also peculiar in that it only ever happens on right-hand corners and not left-handers (i.e. with the offside rear wheel) of the same speed and duration.
The car is a 2010 S and sits on Ohlins and R888s. There is 1-2degs (can’t remember precisely) of negative camber on the rear wheels.
If the noise is a constant…ish low bassy sound I’d say your tyre is rubbing against the wheel arch liner, both fronts and rears do on mine, Ohlins also and on that kind of bend. Check for existing scarring, maybe paint the area before you are next on track and check if it appears again.
If it’s a higher pitched fast intermittent sound I’g go with Azrael on the rubber thing but usually I’d hear this on the way home.
Unless you are running the car very low it is hard to hit the arch liners on the road, on track with softer springs or low ride heights it is very easy, all 4 of my liners have holes in one place or another.
I must say though the rears only hit if they are not fitted correctly, the fronts I have holes big enough to get my fist through and am now wearing out the backs of the headlights…
Thanks for the replies, I’m glad to hear it’s not something that is Lots Of Trouble…
I’m inclined to believe it’s rubber rolling along the tyre and thus changing the guage of the wheel in the arch sufficiently that it starts to hit the liner.
Glad to hear also that “inspection holes” in the front arch liners are standard!
I now run much stiffer springs on my nitrons and the anti roll bar is set to full hard, it has now minimised my problems with hitting the back of the headlights even with the ride height at 105/115
I now run much stiffer springs on my nitrons and the anti roll bar is set to full hard, it has now minimised my problems with hitting the back of the headlights even with the ride height at 105/115 [/quote]
Yup, I run 550/700, don’t want to go much stiffer! I am 100kg, does that count! ride height now 115/125 from about where you are. The yellow Lotus ARB is at full hard. I’ve thought about getting a thicker one, but should really learn to drive what I’ve got first.
I’ll join in as I have holed both the front arch liners AND light clusters, although have just bought some new liners in order to keep the crap out of the lights (for now at least).
No such issues at the rear though. But I have melted the near side rear arch liner at the exhaust bend!
Ohlins/888’s/120ride height/non-adjustable ARB
Have been considering a switch to the yellow ARB for some time.
Toya says this about pressure;The R888 has a semi race construction (very stiff) and a race tread compound. The optimum tread temperature range is between 85C and 95C measured using a probe type pyrometer, and ideally a maximum difference across the tread of 9C. The maximum hot pressure we recommend is 40psi. Camber angles up to 5 degrees are permissible but the final setting will depend on tread temperatures. It is advisable to have as much positive castor as practical as castor induces a beneficial camber change during cornering. I recommend that the tyres be put through 2 heat cycles before hard use.
The pressures you use will initially depend on the weight of the car, too little pressure on a heavy car can lead to over deflection of the tyre and subsequent failure.
Below are some basic settings:
VEHICLE WEIGHT COLD PRESSURE HOT PRESSURE Very Light 1400kg 27 - 35 psi 37 - 40 psi
As a tyre gets hotter the pressure increases, this is due to the moisture in the air. The cold pressure you set to achieve a desired hot pressure will depend on the conditions on the day i.e. ambient and track temperature, wet or dry. If the day/track is cold you will need to start with a higher cold pressure as the tyre will not get as hot therefore the pressure increase will not be so great. Hot pressures must be balanced side to side. Once the tyres have cooled you will find that you will have a difference in pressure side to side, if you have been racing on a right hand track you will find the offside pressures will usually be higher than the nearside.
Changing hot inflation pressures by small amounts can be used to fine tune handling.
Reduce Oversteer Reduce rear pressures or increase front pressures Increase Oversteer Increase rear pressures or reduce front pressures Reduce Understeer Reduce front pressures or increase rear pressures Increase Understeer Increase front pressures or reduce rear pressures
Achieving the required tread temperatures will depend again on the conditions on the day i.e. ambient and track temperature, wet or dry.
You often here competitors saying �My tyres started to go of towards the end of the race�, this is usually due to the tread getting to hot.
The tread temperatures are constantly changing through out a race, hotter when cornering and cooler when on the straights and cooling even more when you are slowing to come into the pits. Therefore the temps you record in the pits will be lower than those during the race. So if you record temperatures within the range given above the probability is the temps will be too high during the race.
Increasing your tyre pressures will cause your tread temperatures to increase, more pressure stiffens the tyre�s casing which results in the tread having to do more work resulting in the tread getting hotter. Lowering your pressures will cause them to decrease.
Inevitably changing one thing will affect other things, the whole set up of your car is a compromise between anything that is adjustable.
Some of you are also asking about different compounds. Originally we only had one compound �GG� (medium hard), but we have now introduced some sizes in a �SG� (soft/wet) compound. This was done primarily for sprint/hillclimb (around 60 second runs) where the distances covered are relatively short and you need the tyres to work/heat up very quickly. This is not a compound I would recommend for race/trackday dry use as the tyres will go off very quickly
