Caster setup & adjustment
Discussion
Hello all
My car (2000 model, K series) is a quite twitchy in road use and sensitive to steering input. Maybe I just need to have more finesse with my inputs but just looking at the current suspension setup I see (if I understand it correctly) that it's setup with minimum caster. That is all 4 washers (approx 1mm width) are forward of the lower wishbone rear location. I think I've read that the standard setup is 2 washers either side of the joint.
Can anyone say what the general handling traits would be for my current setup Vs the standard - in terms of stability, steering weight, feel, camber change, etc. Also if I were to change to standard setup, I guess I need to add washers of same size to the front wishbone joint.
Thanks in advance for any advice.
My car (2000 model, K series) is a quite twitchy in road use and sensitive to steering input. Maybe I just need to have more finesse with my inputs but just looking at the current suspension setup I see (if I understand it correctly) that it's setup with minimum caster. That is all 4 washers (approx 1mm width) are forward of the lower wishbone rear location. I think I've read that the standard setup is 2 washers either side of the joint.
Can anyone say what the general handling traits would be for my current setup Vs the standard - in terms of stability, steering weight, feel, camber change, etc. Also if I were to change to standard setup, I guess I need to add washers of same size to the front wishbone joint.
Thanks in advance for any advice.
The more caster you run, the heavier the steering will be and more feedback you'll get. No harm in trying different positions, just remember you'll need to add washers to the front as well if you are moving it forward. At extremes, it does compromise other settings so only go as far as you feel you need to and check the tracking (at least when you're happy with the caster). The metric SV chassis has it setup as you describe as standard.
Caster angle, as with all setup parameters, is a compromise.
Running some (or lots) of caster creates something called dynamic camber. Dynamic camber is where the camber of the outside wheel increases as you add steering lock. This is a desirable trait because it adds more camber through corners (for better grip) but returns to lesser camber at the straight ahead (for better breaking).
The compromise here is that caster creates heavier steering, and that may result in a lack of finesse from the driver due to the increased effort and reduction in feel.
You need to decide what your priorities and preferences are then set accordingly. There is no "right" answer.
To address your issue of twitchy and sensitive steering.. What steering rack do you have? If its the 22% race item then you'll probably want to switch to the 8% road one. Is the problem that the car darts around without any steering input? Or that the car is too sensitive and over-responds to your inputs?
Running some (or lots) of caster creates something called dynamic camber. Dynamic camber is where the camber of the outside wheel increases as you add steering lock. This is a desirable trait because it adds more camber through corners (for better grip) but returns to lesser camber at the straight ahead (for better breaking).
The compromise here is that caster creates heavier steering, and that may result in a lack of finesse from the driver due to the increased effort and reduction in feel.
You need to decide what your priorities and preferences are then set accordingly. There is no "right" answer.
To address your issue of twitchy and sensitive steering.. What steering rack do you have? If its the 22% race item then you'll probably want to switch to the 8% road one. Is the problem that the car darts around without any steering input? Or that the car is too sensitive and over-responds to your inputs?
Edited by mharris on Monday 20th July 12:05
Hi all and thanks again for info. I appreciate that other aspects like toe, camber, spring heights, tyres, etc. will also influence significantly.
I've got what appears to be supersport/lite suspension spec (adjustable platform all round + rear 4 position anti-roll bar) and running A021 tyres. I most likely need to take it to be professionally setup for my needs, but on seeing the caster figured I could adjust that initially myself. The rear anti-roll bar (looks standard type, no colour codes) was on stiffest position so I moved that one position forward. Although this has given me a little less ulimate front grip so a bit of dynamic negative camber change wouldn't do any harm.
It could well be that I'm simply getting major tramlining effects on more uneven surfaces due to toe / camber settings. So I'd at least want to get those properly measured & set.
BTW I'm in North Hamps, nr Basingstoke. Regards.
I've got what appears to be supersport/lite suspension spec (adjustable platform all round + rear 4 position anti-roll bar) and running A021 tyres. I most likely need to take it to be professionally setup for my needs, but on seeing the caster figured I could adjust that initially myself. The rear anti-roll bar (looks standard type, no colour codes) was on stiffest position so I moved that one position forward. Although this has given me a little less ulimate front grip so a bit of dynamic negative camber change wouldn't do any harm.
It could well be that I'm simply getting major tramlining effects on more uneven surfaces due to toe / camber settings. So I'd at least want to get those properly measured & set.
BTW I'm in North Hamps, nr Basingstoke. Regards.
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