Hey Guys
I got the Exocet out with the new r888r's @ NCM. It was a lot of fun, but I also bought a pyrometer and started using it. The days were pretty cool (high 55* - and it was cool with wind chill). I followed the toyo startup guide which indicated much lower pressures for a car of I'm used to. The tires never even came close to coming up to temp, the highest being 105* or so, and more troubling to me they had an odd wear pattern on them? Like the car was driving only on the outside edge? I took them out today on the road and saw a similar thing (not driving them very hard or getting them up to temp). This pattern is consistent across all 4 tires.
Following setup instructions from a few others that mention Exocets don't love a ton of camber I've only got about 1* all the way around, a bit more in the rear.
http://www.racingtheexocet.com/?page_id=554
Is this the tire rolling over? Do I need to add air ? I'm only running about 20 psi cold based on this:
https://www.toyo.co.uk/page/index/identifier/set-up-advice
I did also get some cool video and pictures - I haven't edited through all the video yet!
accordionfolder said:
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I realize you’re on the curbing, but the LF tire is showing positive camber in this pic. 1-degree doesn’t seem like anywhere near enough, but I only know Miatas, not Exocets. However I’m running -4.1 degrees on the front of my car. You have less weight, so I’m sure you don’t need that much, but I’d think -2 to -2.5 would be more reasonable.
Also, with those cold temps I doubt you were really generating that much grip. I don’t know the R888’s very well, but it sure seems like that wear could be from sidewall deflection due to underinflation.
That looks like the classic "excessive toe in" pattern. Camber tends to wear a tire conically while toe mainly attacks the edge because the tread is deflecting sideways, forcing the edge into the road.
I'm thinking that your gut instinct is spot on - need more tire pressure. Or maybe wider wheels to support the tire better with low pressure.
In reply to Knurled. :
I'll go double check the toe settings. The tires are 225s.
Thanks guys!
I'm seeing about an 1/8" of tow in in the rear and 0 toe in the front.
What were the readings with the pyrometer?
It should tell you if your pressures were good and if your camber is good.
In reply to wvumtnbkr :
The only thing note worthy on the pyrometer that day (I'm a novice at this) was that the tires were not even close to coming up to temp. ~105* There was no obvious discrepancy left/center/right but they were so far from up to temp I wasn't sure how much attention I should pay..... You can buy the tools, but a monkey won't be able to interrupt them: I'll need to go with a stronger game plan next time....
In reply to accordionfolder :
Forgive my ignorance, but if the tires aren't getting near their opperating temps it seems reasonable to assume they weren't hitting a reasonable hot pressure. Seems likely that the pressure was too low and the tire was rolling over.
In reply to MTechnically :
That's what I'm hoping for (and attempting to confirm), I really liked the way it drove (and I hate changing alignment settings) - it seemed low on grip relatively speaking. I guess I'm just attempting to confirm I'm not doing something stupid - also following the toyo base specs I'm a bit nervous to go too high in pressures, since they say for a car this weight 17psi is a good starting ballpark, which seems to not even be close (I'm at 20psi now)? I'm concerned about ballooning the center. I guess I'll try 25 and go from there!
I used to think I had to run low pressures on light cars, but then I started adding pressure and going faster. The nice thing is that it's cheap, easy and you get answers very quickly :)
That's still a fair bit of rear toe. We usually use about half that. We also tend to use closer to 2* of negative camber.
Pressure-wise, too little will usually have worse effects than too much. So I'd tend to start a bit high and work my way down rather than working up.
In reply to accordionfolder :
I'm not suggesting that you have a toe issue, I'm thinking that the low tire pressures are allowing the tread to shift under side loads in the same manner that heavy toe would cause.
Roger, more pressure it is! Any clue what a good " high" starting point is?
I don't know the R888 all that well, but I'd start by aiming for the mid- to high-30's hot.
In reply to accordionfolder :
Those are the temps you work with. If they are even across the tread,pressure is good, higher on the outside edge means not enough neg. camber. How much pressure build up ? What is the suggested HOT pressure ?
You might have to start with a different pressure.
I hardly ever got the Hoosiers up to temp. on my ZX2SR I went by their suggested pressures.
