Whiteline Front Roll Center Adjuster
Apr 15, 2010, 07:29 AM
#31
From our PM conversation:
Originally Posted by SmikeEvo
http://www.teamassociated.com/racerh..._handling.html
That has a really nice section on roll centers.
You can look at it without the sway bar working too. The control arms on the standard Evo have geometry S (stock). Once you lower the car you flatten out the angle of the control arm, changing the geometry to M (modified). At about 1.4-1.5 lowering, the geometry is altered enough that the car will have significant geometry issues at the limit. A RCK increases the geometry back towards the S realm (keeping steering the same). That alleviates the compression/travel issue of lowering past the S geometry and will allow the car to work better at the limit (resistance to plow into turns).
You have the control arm idea right. Lower car, flatter arm. That also changes suspension travel and camber.
GTWorx, Robi, myself/others recommend a RCK at the 1.4 mark (and definitely for racing). I did not run with one on my car with Swifts. But I was right at that limit. They would have been beneficial for my racing. I do have a RCK on my Focus SVT (ST170 out in the UK).
That has a really nice section on roll centers.
You can look at it without the sway bar working too. The control arms on the standard Evo have geometry S (stock). Once you lower the car you flatten out the angle of the control arm, changing the geometry to M (modified). At about 1.4-1.5 lowering, the geometry is altered enough that the car will have significant geometry issues at the limit. A RCK increases the geometry back towards the S realm (keeping steering the same). That alleviates the compression/travel issue of lowering past the S geometry and will allow the car to work better at the limit (resistance to plow into turns).
You have the control arm idea right. Lower car, flatter arm. That also changes suspension travel and camber.
GTWorx, Robi, myself/others recommend a RCK at the 1.4 mark (and definitely for racing). I did not run with one on my car with Swifts. But I was right at that limit. They would have been beneficial for my racing. I do have a RCK on my Focus SVT (ST170 out in the UK).
Apr 15, 2010, 07:37 AM
#32
ah yes i think your right the sole purpose of the anti-roll bar is to try to make the wheels mimic each other almost
the drawing doesn't exactly give away that the bar is set off center to the wheels by some distance too.
so why is roll worsened without the fix ?
LCA is obvious and correct as you say
.
yes i did look smike thanks
the drawing doesn't exactly give away that the bar is set off center to the wheels by some distance too.
so why is roll worsened without the fix ?
LCA is obvious and correct as you say
.
yes i did look smike thanks
Apr 16, 2010, 04:53 AM
#33
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I this is because the roll center is brought very close to the ground. Especially if you are low enough that your a-arms are angled downwards.
I'm not sure of this, but i think that the roll center will nominally either be somewhere between where the a-arm connects to the wheel, and where it connects to the frame or somewhere above the two inside points. In the case of a very lowered car; where the arms point down, this point could possibly be placed below the road.
The roll center is the point on a vertical line where you can apply a force to the side of the suspension, without creating any roll.
When cornering, the primary force, i think, will be pointing in the opposite direction, but at the same location, as your center of mass.
So basically, the closer the roll center and center of mass are, the less roll you get. And theoretically, if they were at the same location, you would have no body roll (no need for swaybars).
Any of this correct? I've been thinking about it recently
I'm not sure of this, but i think that the roll center will nominally either be somewhere between where the a-arm connects to the wheel, and where it connects to the frame or somewhere above the two inside points. In the case of a very lowered car; where the arms point down, this point could possibly be placed below the road.
The roll center is the point on a vertical line where you can apply a force to the side of the suspension, without creating any roll.
When cornering, the primary force, i think, will be pointing in the opposite direction, but at the same location, as your center of mass.
So basically, the closer the roll center and center of mass are, the less roll you get. And theoretically, if they were at the same location, you would have no body roll (no need for swaybars).
Any of this correct? I've been thinking about it recently
Apr 16, 2010, 08:50 AM
#35
Yes the greater the distance between the roll center and the center of gravity the more roll you get. And lowering the car lowers the roll center more than it lowers the center of gravity, so this distance is increased. This is the simple way to look at it, there's a bit more involved there.
- Andrew
- Andrew
Apr 16, 2010, 09:22 AM
#36
thx for all the replies.
i know there are tried and tested methods that you should just go with to save trying to understand the depths of it but its nice to touch on it
i know there are tried and tested methods that you should just go with to save trying to understand the depths of it but its nice to touch on it
May 22, 2010, 12:47 PM
#37
Oof. I got a few quotes for my bushing project and when they came in at about $7-800, I said ok, I have time, the knowledge, a helpful friend who just went through all of in the past few months and another with a shop press. There was no rush in getting it done this way but it was muchhhhhhh cheaper.
https://www.evolutionm.net/forums/ev...hop-press.html
May 22, 2010, 03:16 PM
#38
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My DIY thread for installing the Whiteline Roll Center Correction kit, WITHOUT a press, with tons of pics:
https://www.evolutionm.net/forums/ev...hop-press.html
https://www.evolutionm.net/forums/ev...hop-press.html
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