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More aggressive front camber?

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I use my Evora S for a few trackways per year with standard chassis, but with PFC 08 pads all around and Kumho Ecsta V700 18" (Medium (K61) front, Hard (K91) rear) on track. I get similar average temperatures front and rear, but wrong lateral temperatur profile on the front tyres. It is not perfect on the rear tyres, but not wrong and kind of good enough for standard chassis setting. I can also see that the front tires tends to get the awful High-Low-Low-High wear, i.e. more in the middle. I therefore seriously consider more front axle camber, which I also read in the forum that the Evora 400 has.

So, has anyone any experience to share? When (at which camber angle) do you see negative handling effects? What is too much for street use?

My prior experience with road legal vehicles is mostly with front engined cars, especially FWD, or AWD and then 2-3 deg is just normal for combined trackday and road. I assume the Evora would go bananas with  such a front end ....

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z

Maybe it was a difficult topic. Anyhow, I went half way between the Evora 400 and 410 front camber, which means -0,7 deg. I have seen different values on standard settings for the Evora S, but mine was quite close to the figure stated in my "Owner's handbook".

  Evora S Evora 400 Evora 410 Before After
F Camber -0,3 -0,5 -0,9 0/-0,2 -0,7
R Camber -1,6 -1,8 -2,1 -1,6 -1,65

The castor angle was at around 6 deg and jumped up to 7 deg with this adjustment. I can see pros and cons to that high castor angle, but decided to keep it for this "rollercoaster track" trackday. As was described in another recent thread:

it is obviously ok to push the camber even more aggressively. I also got some input on Lotus recommended race settings and understand that the main difference is much smaller front castor (2-3 deg), while increasing front camber to -2,1 deg and just doing minor adjustments to the rear.

My main purpose was to achieve a better temperature profile and indirectly more even tyre wear and better handling. Now it is a bit difficult to measure on the surface after a cool down lap, but the result was definitely a step in the right direction while also improving overall feeling on the normal road (it had a bit toe in before). The average temperature difference is good for the inner section, while the outer section temperature is close to the mid section in most readings.

Section Recommended Front Rear
Inner T+5 +2/+3 +1/+3
Mid T T T
Outer T-5 -4/+1 -4/+1

  The ambient temperature increased a lot this sunny day, so the absolute tyre temperature rised by just over 20 deg C from morning to late afternoon.

 

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I'm not sure I fully understand your temperature profile table but you're aiming for an even temperature gradient across the profile.  If the mid section is close to the outer that would suggest that individual tyre pressure was a little high?  

http://www.trackdayguru.com/tyre-management.html

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Actually I am not aiming for an even temperature profile. The reference temperature T, measured in the mid section of the tyre, varies depending on tarmac temperature, driving intensity etc, and is not critical as long as it is within the tyre's operating window. What Kumho says is that what is important is to have 5 C higher temperature at the inside and 5 C lower at the outside, i.e. a temperature difference of 10 C from inside to outside.

I don't know if it is applicable to all R-spec tyres?

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Yep, that's what I meant, a linear temperature gradient.  Looks like you now have a reasonable camber setting that will generate the right temperature difference between the inside and the outside of the tyre.

From here, a simple optimisation is to adjust the individual tyre pressures so that the temperature at the mid section is half way between the inside and the outside (giving you the linear gradient).  If the middle is relatively too hot then reduce the pressure, if too cold then increase pressure.

 

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I see. Good point. Thanks!

For now, I consider the setting to be a good compromise between road and track.

The pressure was a bit at the low end in the morning, just at 2 bar, especially the right front tyre, while the left side approached 2,3 bar in the afternoon. 2,1-2,2 is said to be optimal.

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On 30/5/2017 at 09:51, #84 said:

z

Maybe it was a difficult topic. Anyhow, I went half way between the Evora 400 and 410 front camber, which means -0,7 deg. I have seen different values on standard settings for the Evora S, but mine was quite close to the figure stated in my "Owner's handbook".

  Evora S Evora 400 Evora 410 Before After
F Camber -0,3 -0,5 -0,9 0/-0,2 -0,7
R Camber -1,6 -1,8 -2,1 -1,6 -1,65

The castor angle was at around 6 deg and jumped up to 7 deg with this adjustment. I can see pros and cons to that high castor angle, but decided to keep it for this "rollercoaster track" trackday. As was described in another recent thread:

it is obviously ok to push the camber even more aggressively. I also got some input on Lotus recommended race settings and understand that the main difference is much smaller front castor (2-3 deg), while increasing front camber to -2,1 deg and just doing minor adjustments to the rear.

My main purpose was to achieve a better temperature profile and indirectly more even tyre wear and better handling. Now it is a bit difficult to measure on the surface after a cool down lap, but the result was definitely a step in the right direction while also improving overall feeling on the normal road (it had a bit toe in before). The average temperature difference is good for the inner section, while the outer section temperature is close to the mid section in most readings.

Section Recommended Front Rear
Inner T+5 +2/+3 +1/+3
Mid T T T
Outer T-5 -4/+1 -4/+1

  The ambient temperature increased a lot this sunny day, so the absolute tyre temperature rised by just over 20 deg C from morning to late afternoon.

 

I think I would have pushed the front camber even further... Like -1,2 or 1,3.

That's what I'm aiming for for my 400. A month ago, I gave it it's first geo (as it was brand new, it was a mess of course) and went for the Lotus Spec as you mentioned.

But 1 week ago, had my first trackday with the car and I clearly miss a strong front that pushes... Car is obviously understeering in that setup even playing around with the right warm tire pressure. As we can not adjust front and rear height of the car or play with the Antiroll bars. I'll give some camber and toe-in to the front

Edited by rallyesax

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