suspension setup

[rabbittmaster]

hello, i have been looking on the internet for most of the day now and i can't find any information about the effects of positive camber other than the small bit on Wikipedia. i know enough about the negative camber but bugger all about the positive. HELP

[phoenix]

That is probably because it is good for absolutely nothing!

[RPD Motorsport]

Well basicly tyres (found through being run on tyre testing rigs) have an ideal slip angle and an ideal camber angle to produce maximum load under cornering. Typicly this is 0.8 to 1.2 deg of camber.

When your chassis rolls (almost always outwards unless you have a very strange roll centre), the angle of the tyre changes. The amount of camber change per deg of roll if dependent on the camber compensation of the given car (such as how much longer is the bottom wishbone to the top etc). A almost perfect setup gives about 65% if your lucky.

A 'typical' single seater rolls about 1.5 deg and a tin top about 3-5 deg. Assuming 60% camber comp that means that for 3deg of roll, the tyre changes angle by 1.8 deg. If the tyre opperates best at 0.8 deg, you end up with a 2.6 deg static camber for peak cornering speeds. However for best braking force you want the tyre squair - so you would normally end up with about 2.3 deg in the case above.

You would only ever need posative camber if you had massive reverse castor - which nothing does as you wouldnt be ablt to turn the wheel!

[elitemotorsport]

You might find that some old lorries used positive camber and reverse castor as a kind of power steering. The castor provided steering assitance force (like you might detect when reversing a normal car).

I remember my grandad telling me about it, but, like posted before bugger all use these days.

D

[GORDON STREETER]

Originally Posted by elitemotorsport

You might find that some old lorries used positive camber and reverse castor as a kind of power steering.
D

Quite right, a lot of the old crocks from yesterday year used positive camber simply to aid steering effort.
As they didn't go at any speed it made sod all difference to the cornering ability !