Sloan85
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| posted on 3/9/13 at 11:04 PM |
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What tyre pressures to improve self centring?
What tyre pressures will improve self centring on an MK Indy with 13" wheels?
Cheers
http://mkindygsxr.blogspot.co.uk
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dhutch
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| posted on 4/9/13 at 04:28 AM |
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Not sometime I have looked into or done any work with, but my gut feel is that while is the is a slight amount, but not really enough, higher tyre
pressures will help then wheels to turn and hence self center, tyre pressure cant really effect or correct geometry.
Daniel
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deeceee09
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| posted on 4/9/13 at 06:56 AM |
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Seem to recall that I lowered the pressures to get better self-centering on the advice of Jeremy Phillips. Not sure if it helped but I passed.
Treachery and old age will always triumph over youthful enthusiasm.
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pekwah1
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| posted on 4/9/13 at 07:09 AM |
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I pumped mine to about 35psi for the IVA, centred ok!
Obviously let them back down to 18ish again after the test!
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skov
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| posted on 4/9/13 at 07:19 AM |
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Have you tried playing with the front toe setting?
I had to give my haynes a few degrees of toe-out to get it to self centre for IVA.
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pekwah1
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| posted on 4/9/13 at 08:16 AM |
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yeh i had a degree or two of toe out also for the IVA.
Now set to about 1 degree toe in
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Not Anumber
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| posted on 4/9/13 at 01:16 PM |
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To prove a point or to set up for the IVA changing the toe in and increasing the tyre pressures will help with toe in but at the expense of general
handling and driveability.
The permanent solution is to do something about the caster angle by changing to adjustable top wishbones, There are several people on the forum who
could make a set for you for under £ 100. I went for rose jointed ones from Phil at Talon, steering now self centres without any adverse affects.
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pekwah1
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| posted on 4/9/13 at 01:53 PM |
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i think part of the problem is that on certain kits, the castor angle is more difficult to attain than on others.
I certainly had this problem on the striker because of the inboard suspension and chassis design. I adjusted my rocker arms back as much as i could
which did increase the castor angle.
The other problem is that the IVA document refers to "evidence of self centring" but there are no specific guidelines of what is
acceptable, so what one tester passes, another may fail.
Giving slight toe out and increasing the tyre pressures was in my mind, just to make sure the self centring was as good as it possibly could be, and
then after the test put back to how it should be. My car does self centre with a standard toe and tyre setup, but again, is that acceptable enough
for IVA?
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dhutch
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| posted on 4/9/13 at 02:43 PM |
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quote:
Originally posted by pekwah1
i think part of the problem is that on certain kits, the castor angle is more difficult to attain than on others.
I certainly had this problem on the striker because of the inboard suspension and chassis design. I adjusted my rocker arms back as much as i could
which did increase the castor angle.
The other problem is that the IVA document refers to "evidence of self centring" but there are no specific guidelines of what is
acceptable, so what one tester passes, another may fail.
Giving slight toe out and increasing the tyre pressures was in my mind, just to make sure the self centring was as good as it possibly could be, and
then after the test put back to how it should be. My car does self centre with a standard toe and tyre setup, but again, is that acceptable enough
for IVA?
Hard to say isnt it.
Although personally I would say, for normal operation, you would want self centering. I actually cant think of a time when you wouldnt want to self
center, which is why to me its a surprise that there are ever any issues, and or, that people try to mask the issue rather than correct it.
Daniel
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pekwah1
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| posted on 4/9/13 at 03:08 PM |
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Again, my car does self centre, certainly good enough for me when i drive it.
At low speeds it doesn't self centre too much (less than 20mph).
But again, just because i am happy with how the car self centres, different IVA testers will have different ideas of what is required. So i'm
happy with the self centring during normal driving, so by tweaking the car so that mr IVA is also happy does not make a lot of difference for when i
return to normal
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