Uneven wear on Yokohama A005 rear slicks

[CB72]

My rear Yokohama slicks ( 250/650*18) wear out quickly on the outside.
In fact the wear concentrates on the last inch or inch and a half???
I've tried low hot pressures ( 1.9 kg) to high pressures (2.3 kg) but nothing seems to work?
The tyres run on wheels that are 9.5 inch wide.
The last time I set the camber it was at -2°20' on both sides.
I believe it's maybe higher now as the car sits a little lower than before.
In any case the road tyres wear out strongly from the inside.
Do the Yokohama's required even more camber?
As I drive the car to the tracks that's not an option.
Any advice?

Thanks

John

 

[stuntman]

What's your pressures in psi front and rear?

Front tire size?

Front camber?

Front and rear toe?

Front and rear ride height?

Front and rear spring rates and swaybars?

Does the car oversteer or understeer? If so, where/how?

 

[CB72]

Hi Billy,
Thanks for taking interest in this case.
Here's the data:
Tyres: Front 210 soft compound, Rear 250 medium compound
Front geometry: camber -1.5°, toe 2mm out
Rear geometry: camber - 2.5°, toe 4mm in
Pressures ( hot ): F:29psi R:32psi ( I believe that as I go lower on the rear, the wear increases?)

Springs ans shocks: Zanardi on Bilsteins
F: 389lb, R: 296lb
Swaybars : Dali 22mm F and R

Ride Height ( measured as per NSX shop manual)
F: 155 mm ( stock 170 to 180) R: 193 mm ( stock 213 to 223 )

Handling

I kept on purpose the NSX understeer bias with the Zanardi spring ratio in order to be able to "throw" the car in the bends during "spirited" runs against the Porsche 911s.
The car feels absolutely wonderfull with limited understeer ( and only in the tight bends) while allowing great entry speed in the fast bends ( 120 mph).
Under rainy conditions with my road tyres, I saw many 911's go into a spin while trying to catch me...
In short, I love the balance but want to fix the wear on the rear.
Last data point, I once when through a pair of Pirelli P Zero Corsas ( 265/35*18) with absolutely even wear from one side to the other.
I hope this helps?
Thanks
John

 

[stuntman]

Hi Billy,
Thanks for taking interest in this case.
Here's the data:
Tyres: Front 210 soft compound, Rear 250 medium compound
Front geometry: camber -1.5°, toe 2mm out
Rear geometry: camber - 2.5°, toe 4mm in
Pressures ( hot ): F:29psi R:32psi ( I believe that as I go lower on the rear, the wear increases?)

Springs ans shocks: Zanardi on Bilsteins
F: 389lb, R: 296lb
Swaybars : Dali 22mm F and R

Ride Height ( measured as per NSX shop manual)
F: 155 mm ( stock 170 to 180) R: 193 mm ( stock 213 to 223 )

Handling

I kept on purpose the NSX understeer bias with the Zanardi spring ratio in order to be able to "throw" the car in the bends during "spirited" runs against the Porsche 911s.
The car feels absolutely wonderfull with limited understeer ( and only in the tight bends) while allowing great entry speed in the fast bends ( 120 mph).
Under rainy conditions with my road tyres, I saw many 911's go into a spin while trying to catch me...
In short, I love the balance but want to fix the wear on the rear.
Last data point, I once when through a pair of Pirelli P Zero Corsas ( 265/35*18) with absolutely even wear from one side to the other.
I hope this helps?
Thanks
John

Do you have a picture of your tires' wear?

Also do you use a PROBE-type tire pyrometer? If not, it would be a good idea in investing in one and recording your hot tire temps (outside, middle, inside) on all 4 tires. ***When measuring temps, do not measure within 1.5" from the edge of the inner or outermost edge of the tire.



Billy

 

[asylum]

With A005, I run -3.5° front and rear with a pretty even wear. I also have Dali track sway bars and Tein Flex. You have to add camber.

 

[docjohn]

With A005, I run -3.5° front and rear with a pretty even wear. I also have Dali track sway bars and Tein Flex. You have to add camber.

I like Billy's aproach but in the end your response is most likely his issue.

 

[nsxtasy]

My rear Yokohama slicks ( 250/650*18) wear out quickly on the outside.
.
.
.
In any case the road tyres wear out strongly from the inside.

 

[stuntman]

With A005, I run -3.5° front and rear with a pretty even wear. I also have Dali track sway bars and Tein Flex. You have to add camber.

What tire size and spring rates?

I would guess that with -2.5* of camber in the rear (what I run on the street) and not cornering aggressively on his street tires on the street, the negative camber wears out the insides of his tires from all the street/highway driving - while -2.5* might not be enough camber given the racing slick, spring rates, etc... where he is rolling over on the outer edge of the tire and wearing it out.

Because of this street/track compromise, it might not be easy or acceptable for the OP to crank in -3.5* of camber despite the 005 liking camber.

There has to be a compromise somewhere, whether its spring rates, camber, toe, ride height, as well as street tire vs. track tire wear.

A pyrometer paints a better picture.




0.02

 

[docjohn]

So Billy I'm impressed with your knowledge base and your analytic approach.For a young guy you post up as a more mature individual.I have read about your education but where did you learn your vehicle physics/dynamics and set up? Not every fast driver knows how to think like his pit crew/race engineer

 

[asylum]

I run 10/12 Tein Flex with the Dali race sways. Lack of camber is your main problem. After, we can say that Zanardi/Bilstein is perhaps to soft to run slick tires.

If you want to optimise the track handling, you have to go to -3,5°. I had friends who destructed their A005 because they had not enough camber and were running on the outside edge of the tire. A005 seem to be very sensitive tires regarding this parameter. But going -3,5°, you will have a lot of inside wear on your street tires (as it is already the case at -2.5°).

Choose your camp !

 

[CB72]

You guys are probably right: not enough camber for the track and too much for the street...
I found a picture showing the rear slick that's trying to "roll under"...
Maybe I should use DOT approved track tyres?
Any idea of the required camber for Toyo R 888's?
Thanks to all!
John

PS: I don't know how to attach a larger picture...

 

[eddie_82]

You've got way too much toe-in in the rear. 4mm? That's more than 1/8", which is a LOT. Back that off and I'm sure you'll see that extreme outside wear go away.

 

[stuntman]

You've got way too much toe-in in the rear. 4mm? That's more than 1/8", which is a LOT. Back that off and I'm sure you'll see that extreme outside wear go away.

It's just under 1/4". Excessive toe in at the rear usually increases the inner tire wear than the outer. I run this amount of toe-in and I don't think its that bad.

OP - invest in a PROBE-type tire pyrometer. Also maybe try running at 35psi hot in the rear.

 

[CB72]

I will be ckecking the geometry tomorrow to make sure the numbers are still valid.
In any case,the 4 mm toe-in is the TOTAL toe-in and corresponds to the REVISED toe-in for the NSX. I believe the first cars were shipped with 6mm of toe-in until Acura was obliged by consumer pressure in the USA to reduce it due to "abnormal" tyre wear. I believe the wear was on the inside?
I agree running with 35 psi when hot to reduce the issue...

 

[nsxtasy]

In any case,the 4 mm toe-in is the TOTAL toe-in and corresponds to the REVISED toe-in for the NSX. I believe the first cars were shipped with 6mm of toe-in until Acura was obliged by consumer pressure in the USA to reduce it due to "abnormal" tyre wear. I believe the wear was on the inside?

No. The tire wear was deemed "abnormal" by the claimants in litigation because the rear tires wore too fast (wore out after 3-5K miles), not because they wore unevenly.

 

[stuntman]

Sorry for the OT reply:

So Billy I'm impressed with your knowledge base and your analytic approach.For a young guy you post up as a more mature individual.I have read about your education but where did you learn your vehicle physics/dynamics and set up? Not every fast driver knows how to think like his pit crew/race engineer

When I first made the transition to cars from go-karts, I had a huge influence on the importance of understanding physics/vehicle dynamics. My childhood best friend's father was an engineer for the Audi Quattro's that raced in IMSA, CART cars, Indy Lights, and many more series. He stressed the importance for a driver to be knowledgeable of his car and understand how it works. The more precise and detailed the feedback a driver can give to the engineer, the engineer can make a better and more accurate change to make the car go faster.

Since then, I have had the fortune to work with engineers and drive for teams who've won the 24 Hours of LeMans, 24 hours of Daytona, 12 Hours of Sebring, Indy 500, Daytona 500, Brickyard 400, Formula 1, and everything in between. As well as some who've won championships in these series.

I agree that there are many fast drivers who do not understand vehicle dynamics or even can explain what the car does. Those drivers who do IMO have an advantage over those that dont.


Billy

 

[docjohn]

Thanks for the insight....Kudos to you for knowing what was important,and listening...best of luck in your endeavors.I along with those who know what you do apreciate your continued presence on prime.....ps don't forget to mention prime in any of your post race interviews:wink: