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tyre sizes and pressures for self centring
Chris Leonard - 19/4/04 at 01:07 PM

I am trying to get self centring steering and it's proving a bit of a problem. Unfortunately I only have about 50ft of drive to test it on and dont want to take the chance of blatting it down the road.

Anyway I have set some toe out but it still doesnt give the kick back that any 'normal road car' I have driven.

The SVA states a degree of self centring over 10mph - wants a degree? it doesnt seem to wander and brakes in a strtaight line.

Anyway - a question would tyre pressures and size make any difference - I still have the skinny MKII wheels will this help (they are about an inch or so thinner than the RS wheels I have - What about an increase in tyre pressures?

Finally 'put a lot of toe out' - whats a lot! 5mm dif from front to back 10 mm.......

Cheers Chris


stephen_gusterson - 19/4/04 at 01:26 PM

its castor that primarily sets self centering ability - anything else is a bodge in my limited reading on the subject......

but this is a suspension related question, and therefore a minefield


atb

steve

[Edited on 19/4/04 by stephen_gusterson]


jimgiblett - 19/4/04 at 01:35 PM

You could try lowering your tyre pressures as this will enhance the self centring. Castor is the way to do it and toe in/out is a bodge but it's just for the SVA isnt it?

My 2p

Cheers

Jim


britishtrident - 19/4/04 at 01:43 PM

Try 16 psi --- don't go lower than 14 or higher than 22.
Give the front as much castor as is sensible try 5 to 6 degrees.
You can also get more self centering action by changing the king pin inclination ; the only way to do this as give it some negative camber try -2 degrees for SVA and put back to -0.5 to -1.5 degrees for normal road/track use


Chris Leonard - 19/4/04 at 02:32 PM

thanks....

negative camber - wheels out at the top:

----/ ?

or in

/----


Peteff - 19/4/04 at 04:38 PM

Wheels in /-- neg wheels out --/ pos. Try some skinny tyres with low pressure as well if you can borrow some.