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Old 11-20-2014, 05:43 PM
minspd minspd is offline
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Default Keeping tires under FWD cars

I seem to be unable to get good tire life on front wheel drive cars. As some of you know, on my Civic I wore through front tires in 3 days* and this was with a welded front differential and about 3 degrees of camber. Since then I bought an Integra which had 1.5 degrees of camber and an open differential, and this car wore through a full set of tires (rotated) in 6 days* - the same 3 days per pair of tires wear rate. I felt 1.5 degrees of camber to having had been way insufficient in terms of cornering grip and tire rollover feeling.

The way I see it, as long as a car is understeering at corner exit (and all cars should, slightly) it is faster to apply throttle than lift. If a FWD car is being overdriven it would still be fastest under power. A RWD car I imagine cannot really be overdriven in the same way as a FWD car can be...

But unless the car is set up perfectly, it may understeer all the time. In fact, Integra was this way on street coilovers. If I never push the car I must go very slowly through corners.

Am I missing something here?

(*) DE days, assume 1.5-2 hours of track time per day. Which would translate to about 3 SCCA race weekends?

For reference, I probably get 20+ days out of a set of tires on Miata.
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Old 11-20-2014, 07:02 PM
eage8 eage8 is offline
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How much power do you have and what tires are you using?

My corolla has ~-2.5* of camber up front and I have about 6-8 DE days and a ton of autocrosses on my current RS3s and they still have at least 50% tread on them.

~140whp + helical LSD

a welded differential on a fwd car sounds absolutely horrible.
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Old 11-20-2014, 07:30 PM
Matt93SE Matt93SE is online now
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4 comps wear a LOT faster than street tires. Not exactly a fair comparison there.

Check alignment on the Teg. Unfortunately my old Maxima would eat a set of 235/45/17 RA1 on the front in a single DE weekend. If I rotated front to rear sat afternoon then flipped them on the rims after the event, I could get three weekends out of a full set.

Too hard on corner entry will eat outside shoulders. Too hard on exit will eat inside shoulders and look like camber wear.

And yes, you can drive a FWD too hard on exit. If you're spinning wheels until it understeers horribly, then you're going too hard- turn the dial down a notch to reduce wheel spin and get the car more neutral.
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Old 11-20-2014, 08:27 PM
minspd minspd is offline
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Quote:
Originally Posted by eage8 View Post
How much power do you have and what tires are you using?
Civic: 120 whp, 2200 lbs.
Integra: 150 whp?, 2600 lbs? - estimated

Civic tires: 225/45-13 R888, 13x6 wheel
Integra tires: 205/55-14 NT-01, 14x6 wheel

Civic destroyed inside 2/3 of the tire, with the very inside edge just showing tread, and outside 1/3 showing a bunch of tread. Perhaps the wheel was too narrow and inflation pressure too high.

Integra tire wear was even throughout front tires but the car understeered like crazy due to street suspension.

Integra has ABS, and I was using it. Civic has ABS via welded diff, and I think I was also using it.

Quote:
My corolla has ~-2.5* of camber up front and I have about 6-8 DE days and a ton of autocrosses on my current RS3s and they still have at least 50% tread on them.
Yep, street tires last forever. But where's the fun?

Quote:
a welded differential on a fwd car sounds absolutely horrible.
It is not at all, alignment makes a big difference also.
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Old 11-20-2014, 08:39 PM
minspd minspd is offline
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Quote:
Originally Posted by Matt93SE View Post
Check alignment on the Teg. Unfortunately my old Maxima would eat a set of 235/45/17 RA1 on the front in a single DE weekend. If I rotated front to rear sat afternoon then flipped them on the rims after the event, I could get three weekends out of a full set.
Will do.

Civic nuked its tires with zero front toe. Previous owner had the front toed in.

Quote:
Too hard on corner entry will eat outside shoulders. Too hard on exit will eat inside shoulders and look like camber wear.
Integra was wearing an outside "band" first, but cords there were not showing until I flatspotted all tires (did I mention the car had ABS? Apparently ABS permits both front and rear tire lockup). Overall wear looked very even, but tires were begging for mercy in pretty much every single corner.

Civic inside edge looked nearly untouched with 2 degrees of camber that I got from the previous owner.

Quote:
And yes, you can drive a FWD too hard on exit. If you're spinning wheels until it understeers horribly, then you're going too hard- turn the dial down a notch to reduce wheel spin and get the car more neutral.
I kind of figured this much, but "go slower" is not a recipe for enjoying the car :-)

I would rather make setup changes or equipment changes.

One thing that is coming to mind now is when I bought Civic it came with toe in in the front and power oversteer tendencies. I do not recall sliding the car on its front tires then - perhaps this was not needed, perhaps this was not possible, perhaps it was too aggressive of a move given that the car felt like it would spin at any second. I'm thinking to add some toe in next year and see what would happen.
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Old 11-20-2014, 09:45 PM
Matt93SE Matt93SE is online now
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Toe in or maybe less Ackerman. You want less dynamic toe out. Under hard cornering, you have little weight and lots of power and lots of steering on the inside tire. If you toe it in or adjust Ackerman, it'll lessen the dynamic toe out and hopefully help the problems..
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Old 11-20-2014, 10:37 PM
Matt93SE Matt93SE is online now
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Quote:
Originally Posted by minspd View Post
I kind of figured this much, but "go slower" is not a recipe for enjoying the car :-)

I would rather make setup changes or equipment changes.
If you're spinning tires on exit, then you're beyond the limits of the car. Yes you can make setup changes to get mor power down, but then you just go a touch faster through the turn and still wind up mashing the gas and under steering out of the turn.
Spinning tires is not the fastest way around. Notice I didn't say to slow down above-- I said to turn it down a notch- ie back off the gas a bit. 80% throttle instead of 100%. What's the point in an engine that can put out 400hp if you only have tire and traction for 100hp? Use just enough throttle to get as much acceleration as you can before it starts pushing and you will be faster and easier on the tires.
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I don't care what color they are as long as they are LONG AND HARD.
'04 G35 Sedan 6MT- The DD
'96 240SX- The Track Toy
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Old 11-21-2014, 07:48 AM
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Yep, sounds like too much power on corner exit, which just chews a tire up, and is really easy to overheat narrow tires like that.

That's the main problem you always fight with FWD cars on track, is you're asking the front tires, which carry most the weight, to both turn and accelerate and do most the braking. Push any one of those a little too far and the tires are going to get a flogging.

BTW - you should not be dipping into ABS often on track. Threshold brake, and use ABS to save your ass if you go over. If you are going into ABS more than once every few laps even when going 10/10ths, you need to refine your braking.
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Old 11-21-2014, 09:25 AM
minspd minspd is offline
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Neither car can spin front tires under power (which is why staying on throttle seems to me to be faster than not).

Integra also heavily understeers everywhere, not just at corner exit. I got it to rotate at entries by unhooking the front sway bar, and there is much trailbraking going on although trailbraking seems to be less effective than it is on other cars for reasons not yet known to me.
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Old 11-21-2014, 08:57 PM
gawdzilla gawdzilla is offline
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Oleg, u got a Teg? Got some pics? Did u end up selling the s14 yet?
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