alfas
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| posted on 18/10/14 at 08:54 PM |
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slicks, tyre pick-up
does anybody have an idea why my front wheels show identical tyre-pick up on both sides (driver and passenger wheel) after a 20min session on the
track?
outside temp was 17 degrees, sunny, dry, AVON slicks, pressure 1bar and the pick-up did not get loose even on high speed at the finishing straight.
tyre temerature after the 20mn was also very low. the pick-up covers around 80% of the tyre, only the outer edge is free.
[Edited on 18/10/14 by alfas]
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ali f27
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| posted on 18/10/14 at 09:32 PM |
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looks like a little bit to much neg and i mean a little bit and a little bit to much pressure would need to know compound to make more comment
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daniel mason
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| posted on 18/10/14 at 09:33 PM |
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Mine used to do that after about 2 or 3 minutes on the radical. Outer edge was fine, rest was completely covered. I was on avon a15 sprint compound.
Heat gun and scraper will sort them! Do you know the compound? They may be too soft
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JimSpencer
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| posted on 18/10/14 at 09:34 PM |
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Hi
Just elaborate a bit - do you mean:-
They were like that when you went on the track and didn't clean up.
or
They went on the track cleaned up and were like that when you came off.
Next bit
What car are they on - and what's it weigh roughly?
And
What size and compound are they?
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alfas
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| posted on 18/10/14 at 09:54 PM |
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those tyres are on my locost...530kg...x/flow powered.
size is 7.0/20.0-13
compound? hmmm....i havent found something...its written LFHH on the sides...does this indicate the compound?..there isnt any S or M like on
semi-slicks
before i went on the track they had been cleaned...so they picked up the shown amount of rubber in 20min driving.
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daniel mason
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| posted on 18/10/14 at 10:23 PM |
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Avon cross plys require very little or no negative camber. Your probably running way more.
The Avon radials need a bit more but the Dunlop radials need a lot!
You may benefit from a geometry setup or at least a setup check.
Compound is a number on the side of the tyre wall on avons. But you need to contact Avon or bmtr to find out. It also relates to when the tyre was
made.
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K13JOB
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| posted on 18/10/14 at 10:23 PM |
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I am confused by your term "Pick up" as I see no pick up on the tyres, just the centre part (most) getting hot and melting the surface, I
would suggest the pressure is a little (not dramatically) high. As it is fairly even looks like the camber is fine.
You could of course just have too soft a compound and they are simply getting hot.
[Edited on 18/10/14 by K13JOB]
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alfas
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| posted on 18/10/14 at 10:46 PM |
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the pic doesnt bring up the reality so clear:
its definately pick-up from the street, quite a few mm, not melting tyre. it can be peeled off easily.
tyre getting hot --> dont think so, as when i exited the track the tyres had been rather cold
[Edited on 18/10/14 by alfas]
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minitici
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| posted on 19/10/14 at 08:22 AM |
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quote:
Originally posted by alfas
the pic doesnt bring up the reality so clear:
its definately pick-up from the street, quite a few mm, not melting tyre. it can be peeled off easily.
tyre getting hot --> dont think so, as when i exited the track the tyres had been rather cold
[Edited on 18/10/14 by alfas]
That looks like your own dead rubber flowing across the tread and accumulating on the inner edge.
Your own dead rubber can be peeled off easily like you say.
Probably too much camber and/or toe-in.
Also possibly too soft a compound.
There also seems to be a bit of scooping near the outer edge - This could also be an indication of UNDER inflation.
The tread could be deforming and this could also give rise to excessive heat and wear.
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alfas
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| posted on 19/10/14 at 09:56 AM |
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"That looks like your own dead rubber flowing across the tread and accumulating on the inner edge. "
but this would mean massive wear on my tyres? but the wear indicators on the tyres seem show the opposite.
hmmm....so where to start now....season is over, next race / test wont be until next year.
from the handling the car feels good: straight driving during high or low speed, nothing nervous even not on uneven roads, good steering response.
[Edited on 19/10/14 by alfas]
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alfas
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| posted on 19/10/14 at 03:14 PM |
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found the compound:
ACB0 (according to mr. google a rather common compound within westfields wscc and caterham´s)
a mate also gave me a gauge for measruing the softness: the dial was showing 65shore
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daniel mason
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| posted on 19/10/14 at 03:34 PM |
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The tyre compounds are not listed as such on the tyre.
They are a numerical code acbo is probably the tyre name we run a15 or a92 compounds on our sprint/hillclimb cars but it's not listed on the
tyre
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mjkh
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| posted on 19/10/14 at 05:56 PM |
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You propably need to get more heat into the tires. You could try adding more pressure.
It really depends on the compound, but I'm guessing that you are not pushing hard enough and thus the tires are not working as designed.
It's also possible that you are picking up rubber when you come back to pits.
[Edited on 19/10/14 by mjkh]
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alfas
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| posted on 20/10/14 at 06:22 AM |
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same tyres on my mates car (sylva)...same car-weight...same engine...same track...nearly same lap time, his tyres pressure was 0.1bar higher...but he
has less pick-up.
oh...and his car has less neg. camber....
[Edited on 20/10/14 by alfas]
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daniel mason
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| posted on 20/10/14 at 06:40 AM |
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Like I said. Cross plys are designed to run far less negative camber!
What camber are you running up front?
I'd bolt a set of Dunlop radials on it.
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alfas
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| posted on 20/10/14 at 11:14 AM |
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cant tell anything bout my front settings as i never checked them since i bought the car.
the neg. camber thing makes sense as the car was originally setup with yoko semis
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daniel mason
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| posted on 20/10/14 at 01:18 PM |
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If you look head on at a caterham or westy race car. They always look to be be running massive camber!
I think on the radical the settings recommended for Dunlop radial fronts was 3-4 deg negative, avons around 1.8 - 2 deg negative.
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alfas
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| posted on 20/10/14 at 01:22 PM |
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from watching it looks 2, max 2.5 degrees negative.
i´m out for work...so will check next weekend.
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alfas
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| posted on 17/2/15 at 06:09 PM |
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long time now since my last posting:
any news...yes!!
winter time= garage time
i checked the suspension settings:
track was 0
camber left 2.7 neg
camber right 1.5 neg
the car behaved well on the track and on road and i was satisfied with its handling....even thse settings look a bit strange
due to the tyre-pick issue with my crossply slicks i now set the car to:
track 0
camber both sides 0,5 neg.
test drive on my local road today: feels nervous on straight line and uneven roads.
so tested the following:
toe out (first 1 turn each side on the steering arms, than 2) = totally nervous
toe in (first 1 turn each side on the steering arms, than 2)) = with 1 turn is better, 2 turns again a "strange" feeling
any ideas how to get the "old" handling back, even with less camber due to the crossply slicks being used on track (its a track car only
by the way)
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