Right then, what spares would be worth carrying?

[Victor Meldrew]

HI John

Regarding locking the rears, brake all the way to the corner, and change down last thing. Ali Crozier is probably the best person to watch do this, I'm sure he could point to some of his in car stuff to see what i mean, exceptionally smooth, and no wasted effort/gear changes etc. (which in turn will reduce the amount of locking up)

The RLC would lock up, but this was due to the car being able to generate way more braking force than the tyres could cope with (RS14's & AO48's), and changing gear just excerabated the entire thing. Loosing engine braking was enough to trigger this. While you can minimise this, I ultimately just drove through it, while trying to reduce it as much as i could. Slight brake pedal moderation at this point may help?

Start braking with increased pressure, and leave the gear change till way later if you can.

With regards to the tyres feeling like they are falling off the rims, mine used to feel like that for the first 2 corners....ultimately though if you think its working for you, ignore us, just trying to help. If you are more confident (being the key to it all) with the tyres at higher pressure, then that will most likely count for more time improvements regardless.

Kames, as FD has said, is also very hard on the tyres, the Atom just hated the place - although it was awesome to drive round it - it was very very hard on the car and tyres.

When you said the front wasnt gripping, do you mean it wasnt turning in? In this case is it not more likely that the difference between the nitron settings front to rear wasnt enough or the front was set to hard?

What settings did you run at?

[alicrozier]

OK, in the dry you normally wouldn't need additional rear brake bias so can afford to downchange later (and shortcut any changes e.g. 4-2, etc., this helps as you don't have as much braking time in the dry). Most people (me included) find it easier to threshold brake if they don't have to fanny about h&t'ing - you must have been doing this effectively.

You have to modulate the braking a little as you heel and toe - when out of practice it's all too easy increase brake force when you blip the throttle. Hence as Andy says, maximise the early part of the braking and downchange late in the braking phase.

Counter to this though I'd suggest it's possible you were changing a bit too late as at that point the engine wasn't providing any braking - it was actually keeping the rears turning if the rears locked when you dipped the clutch. Kames hairpin is a fair bit slower 2nd gear corner than KH hairpin for example so intuitively you may have done this.
If that's the case try down changing a wee bit earlier, you want to find that sweet spot where dipping the clutch doesn't affect the brake bias too much.

I think I mentioned before that somewhere like Kames isn't the best place to resolve these kind of issues. A trackday at KH, short runs with tweaks to settings and time (and space) to try out different techniques would be beneficial.

[Victor Meldrew]

I may have overlooked on fundamental by obvious thing.... I am running soft 888's on the front and medium 888's on the ear.. obvious when you think about it.....

[Andy G]

with regards to what John?

Would have thought they would have helped turn in? And def run at lower temp?

Interesting all these various variables

[Victor Meldrew]

with regards to what John?

Would have thought they would have helped turn in? And def run at lower temp?

Interesting all these various variables

Well the soft front tires will grip more than the medium rears.. if the rears were the same soft compound it would have the "normal" grip balance front to rear.. Looks like I need soft rears..

[mckeann]

i used to run M fronts and MH rears and didnt get those problems, so i think you need to look elsewhere. Start with looking at your driving, then the car.

I'm happy to have a drive and see if theres anything wrong with it. Also, happy to give you a few pointers on heel and toe, on the road

[Victor Meldrew]

i used to run M fronts and MH rears and didnt get those problems, so i think you need to look elsewhere. Start with looking at your driving, then the car.

I'm happy to have a drive and see if theres anything wrong with it. Also, happy to give you a few pointers on heel and toe, on the road

That's something I would be happy to arrange for the next time I get home. My gut feeling is its either the tires or me changing down wrong. Walshy day would help with one of them.

[Victor Meldrew]

with regards to what John?

Would have thought they would have helped turn in? And def run at lower temp?

Interesting all these various variables

Been doing more research on this and I now think I understand the reason for the improved grip at the higher pressure. I don't like it when things don't act as expected. Basically it was a very cold day and at normal pressure F22psi/R24psi I wasn't getting any heat into them. Because I pushed the pressure way up it forced more heat and grip into the tyre making it feel better to drive. I wish I had managed to record the track surface temp for reference.

So I will be starting the next run with the "conventional wisdom" F20-22 psi/R22-24 psi.

[Victor Meldrew]

Toyo R888 set up advice
by gambler on Tue Feb 10, 2009 4:51 pm

Sent from toyo -

What I would like to do is to offer some advice on tyre temperatures and pressures and how to achieve the best from our tyres when taking part in either trackdays or racing.

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 < 800kg 17 - 22 psi 22 - 29 psi
Light 800kg - 1000kg 20 - 26 psi 24 - 32 psi
Heavy 1000kg - 1400kg 23 - 27 psi 28 - 40 psi
Very Heavy > 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..

Found the thing I was looking for eventually.

One way of looking at the advice is that the "hot pressure" is the optimum working pressure for the carcass of the tyre. Over a 90-120 second run, there was normally only a 1 psi increase and the highest rise seen was a 2 psi increase. So should I not be setting the pressure at the start to give me the optimum pressure at the end of the run? So looking at the chart above, I should just set it to the normal Lotus road recommended pressures and just drive the damned thing.

[Victor Meldrew]

Speaking to Dan on the phone he is a bit worried about the fuelling. He thinks it could be a bit on the lean side at high revs so he is going to check this out as well as doing the Geo set up.

Gearbox is a bit notchy s well going into first.

This should be the final little bits, the one outstanding thing from the inspection by the scrutineer is the fitting of the cat which Dan will do for me as well.

I could have done most of the bits myself but still riddled with a chest infection so stuck at home under house arrest from SWMBO.

Thanks again for taking the car down Noops.

We need to have that conversation about double entry again... (cue shug)

[Victor Meldrew]

got some feedback from Dan. Car isnnt fueled right after 5800 rpm peak power at 5500rpm. However 155 bhp at 5500 revs ain't too shoddy. Engine will eventualy be set up to run to 7400rpm.

Very good torque band.

Steering rack worn, not the track rod end as diagnosed by somebody else.

Still waiting for the carbon Lorain pads to come from Hofmans.

Also Dans fixed an oil leak from a pressure sender that someone else had changed.

Oh and the exhaust manifold is loose, wasn't fitted right.

[Victor Meldrew]

Well Noops dropped the car off tonight, should get out in it tomorrow for a good shakedown. Antibiotics finish tomorrow but the cough is still there, should be Ok for the weekend.

[Victor Meldrew]

Full write up on the Blog, http://www.elise135.com

[Victor Meldrew]

everything loaded ready to go.

[tut]

Good luck John, expect you to take at least third in your Class.

Not too much chance against Graeme and Jennifer with their 240hp Exige.

tut