Pros/Cons of Locking Out Kinematic Toe
#17
Rennlist Member
#18
Guru
Lifetime Rennlist
Member
Rennlist Small
Business Sponsor
Lifetime Rennlist
Member
Rennlist Small
Business Sponsor
It essentially is a monoball. I have a few in my garage now that I can snap some images of if someone would like them. The rubber dust boots already cut off for access.
#19
Rennlist Member
Interesting discussion. So does this mean that if all 8 monoballs are installed, that the kinematic toe adjustment no longer occurs? Or is there enough deflection in the link arm?
#20
Rennlist Member
Right, if you install the monoball in the rear of the lower a-arms, then the kinematic effect no longer occurs.
#21
#22
BUT, isn't one of the keys here that when you replace the rear suspension with ALL monoballs, you are virtually eliminating bushing deflection and therefore most if not all of the rear wheel toe deflection under load that the KT was designed to compensate for?
So basically, when changing all rear bushings to monoballs, eliminating the KT function results in little or no negative dynamic results.
But, if you were to change the KT bushing to a monoball only, then you would be defeating the KT function yet the rest of the suspension would still deflect, allowing for increased toe-out under load. Not really a good thing.
So basically, when changing all rear bushings to monoballs, eliminating the KT function results in little or no negative dynamic results.
But, if you were to change the KT bushing to a monoball only, then you would be defeating the KT function yet the rest of the suspension would still deflect, allowing for increased toe-out under load. Not really a good thing.
#23
On the RS arms the rear bush definitely has a green spot indicating harder rubber, unfortunately I don't have any good pics of the leading arm bush and can't see a green dot in any of my pics(Mike, do you have any?)
#24
Rennlist Member
Correct me if I'm wrong, but doesn't the kinematic link control dynamic toe to some degree independent of the 'soft' bushing on the trailing link of the lower control arm?
#25
You still need to set it, on mine I used the race KT tool that hangs from the rear caliper and set it for the minimum that could be obtained on both side equally. The handling has been outstanding. I've also been in monoball equipped 993s and could not detect any better dynamic behavior. I'm sure it's there but way beyond where I was.
#26
I need to model this more to fully understand it, but that is the basics
#27
Rennlist Member
Also, setting KT is essentially setting rear castor. Which is kind of cools since most cars can't do that. The autometrics KT gauge, for example, is just a rear castor gauge.
That said, the dynamic toe change under loading (i.e. kinematic toe) has nothing to do with castor. It's simply a permissible bushing deflection that causes toe-in.
Confused yet?
That said, the dynamic toe change under loading (i.e. kinematic toe) has nothing to do with castor. It's simply a permissible bushing deflection that causes toe-in.
Confused yet?
#28
Rennlist Member
KT changes the axis of rotation for the rear wheels, go back to post #10 to look at the diagram showing the axis. the KT arm pushes the top of the axis laterally out and forward, or pulls it back laterally in and backwards. This changes the bump steer characteristic by increasing/decreasing toe change due to suspension travel.
Hence why I was asking re. kinematic control arm 'controlling' toe to some degree through sweep of the suspension.
The amount of possible dynamic toe of course depends on your ride height re. where you are on the sweep curve and spring rate re. how much range you allow.
I'm just still uncertain about the role of the flexible bushing in an otherwise moderately to high spring rate car with monoballs and low KT setting (mine is at 2).
Also, setting KT is essentially setting rear castor. Which is kind of cools since most cars can't do that. The autometrics KT gauge, for example, is just a rear castor gauge.
That said, the dynamic toe change under loading (i.e. kinematic toe) has nothing to do with castor. It's simply a permissible bushing deflection that causes toe-in.
Confused yet?
That said, the dynamic toe change under loading (i.e. kinematic toe) has nothing to do with castor. It's simply a permissible bushing deflection that causes toe-in.
Confused yet?
I get the castor component of the kinematic, but the arm angle isn't purely in the castor plane, but rather is a combination castor/camber/toe axis.
#29
Bill, I get that
Hence why I was asking re. kinematic control arm 'controlling' toe to some degree through sweep of the suspension.
The amount of possible dynamic toe of course depends on your ride height re. where you are on the sweep curve and spring rate re. how much range you allow.
I'm just still uncertain about the role of the flexible bushing in an otherwise moderately to high spring rate car with monoballs and low KT setting (mine is at 2).
Well, yeah
I get the castor component of the kinematic, but the arm angle isn't purely in the castor plane, but rather is a combination castor/camber/toe axis.
Hence why I was asking re. kinematic control arm 'controlling' toe to some degree through sweep of the suspension.
The amount of possible dynamic toe of course depends on your ride height re. where you are on the sweep curve and spring rate re. how much range you allow.
I'm just still uncertain about the role of the flexible bushing in an otherwise moderately to high spring rate car with monoballs and low KT setting (mine is at 2).
Well, yeah
I get the castor component of the kinematic, but the arm angle isn't purely in the castor plane, but rather is a combination castor/camber/toe axis.