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Discussion Starter #1
helmets

Take a look at the attached pics. This is the result of three 20 minute sessions on the track at Streets of Willow. These tires were near new before the event. The car is totally stock.

The left front is the shredded one. The tires get better from rf to lr to rr. This would reflect the weight transfer when driving closkwise on the track, with mostly right turns. http://www.willowspringsraceway.com/trackinformation/images/StreetLg.gif

My idea of how to improve tire life is to alter (reduce) weight transfer on the left front by installing a bigger rear anti-away bar, increase front tire pressure, and possibley increase the front spring rate. The car also understeers moderately, so this plan should improve this characteristic too.

My question is what do you think of my idea to slow tire wear and improve handling, and how would you improve the situation? All responses appreciated.

Mike McBride
 

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I am assuming that the corded area of the lf was the outside shoulder and that those are 225 series V700's.

Given those assumptions I would say the best thing to do in addition to what you are already planning is to rotate the wheels between sessions. I corded my Ecsta's prematurely because I didn't keep a close eye on them. I plan to do what you are and also dial in a bunch of negative camber to get more even wear on the track and go with 245's to put more rubber to work for me.

The STi is a pretty heavy car and all those hard right turns really put a lot of energy into the tires which results in heavy wear.

My only last advise might be to slow down your corner entry so that you do not push at all and rely on the power at the apex and exit to get your speed up on the short straights. My autoX experience has shown me that this can give times that are just as fast without abusing the tires (wish I would have realized this before I corded mine also :( )

good luck.
 

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with wear that uneven, I would be looking at an alignment too...
 

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Colin & NASCAR - They must be joking!!!

Posted: Mon Sep 08, 2003 8:49 am

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with wear that uneven, I would be looking at an alignment too...
it's because he was driving clockwise in the track for 60 mins. Man, u must be driving hard Mike!
 

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NDMac writes:

it's because he was driving clockwise in the track for 60 mins. Man, u must be driving hard Mike!
Correct, battling the EVO after passing everone else! :) I don't think it's the alignment, but the shop will look at that factor also.

Xman posts:

rotate the wheels between sessions..........dial in a bunch of negative camber........slow down your corner entry so that you do not push at all and rely on the power at the apex and exit to get your speed up on the short straights.
Excellant advice. I am going to dial in on all these suggestions, especially the driving technique. I am still learning how to handle this truely outstanding machine. And next time I won't lose the wheel lug nut key so I can rotate between sessions! :roll: :roll: I actually lost it in the course of events at the track after replacing the street tires before the sessions. To remove the V700's I had to destroy the locking lugs. :cry:

Mike M [/quote]
 

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Thanks

Couple cents worth:

The problem you seem to be having is improper camber adjustment. The qualification for the word "improper" is "improper for the track, the day, and circuit rotation". If you are running this hard on the track, which I personally think is a great way to utilize the Sti, I think you should invest in camber plates (at least at the front, but seems like you can use them in the back as well), and a serious pyrometer.

With these tools, in between sessions, measure the heat differences across each of the tires and then make adjustments to camber accordingly. With the driver on the left side of the car, and running clockwise through sharp and/or fast sweepers for extended periods of time, the results are obvious :)

I would also like to note a misconception: you mentioned reducing or eliminating weight transfer. There is no such thing. Weight transfer happens in any condition, independent of equipment. One of the vehicles that is most sensitive to weight transfers are go-karts and they don't have any suspension components :)

However, anti-roll bars, springs, and similar devices help you "manage" weight transfer. And managing is about controlling how fast/slow weight transfers from side to side and front to/from back.
 

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FSelekler said:
However, anti-roll bars, springs, and similar devices help you "manage" weight transfer. And managing is about controlling how fast/slow weight transfers from side to side and front to/from back.
Excellent choice of words. May I use them in the future? This goes right along with my less than eloquent "overdriving the tires" reference.
 

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Xman said:
Excellent choice of words. May I use them in the future? This goes right along with my less than eloquent "overdriving the tires" reference.
LOL, thank you; sure you may use them, they are not exclusive to me or our company. We will be posting several technical white papers on our web site, when the site build is done, hopefully towards the end of September that will go in to more detail on exactly how these things do happen :)
 
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