Am I correct in thinking that anti-dive can be adjusted in the front by raising or lowering the rear mounting point of the front lower control arm? Thanks.

I know anti-dive or anti-squat kits are pretty popular in the Subie world, but I have not heard much about people messing with it on the EVO.

 

Altough there are many ways to achieve anti-dive (lower control arm, upper control arm or both), the easiest and most common method of achieving it is to angle the inner pivots of the upper A-arm down toward the back.

This method places the rear pivot lower than the front. There's some simple geometry involved in this but simply put, locating the upper control arm in this manner causes the path of the upper joint at the upright to move back during compression. I believe it is better done that way because the lower arms are happiest when angled down at their outer pivot or at the most level with both inner and outer pivot parallel to the ground.

 

"anti dive" and "anti squat" are pretty much the same thing as the "roll center" except were using side view instead of front and/or rear view.

Adjusting control arm points will determine how much of the acceleration, braking, or cornering forces go through the suspension joints instead of the springs/dampers. Generally, changing one changes all the others. The rub is that suspension links are much stiffer than a spring/damper so the load builds up quicker on the tire, using too much "anti" can take away from grip and driveability.

 

Just thinking out loud here - would changing the rake angle of the car 1-2* by raising or lowering the rear ride height have the same effect on anti-dive as changing the rake angle (side view) of the lower front control arm?

 

No, because your moving the entire car independently of the control arm when moving the control arm, but when you adjust rake your mostly influencing distribution, not the way in which the LCA reacts with weight put on it.

Scorke

 

QFT

Scorke

 

Anyone else? Seems like it has to do with the orientation of the control arms relative to the ground, not relative to the rest of the chassis. . .

 

EVO’s seem to lift the wheel while diving into the corner/mid corner. The Bimmer is lifting the wheel exiting the corner.

 

Changing rake can change the antis, as it does the roll centers. It depends on the geometry you are working with. Also, the moment arm of the contact patch force to the chassis changes with ride height. In a round about way it all changes but what you should really do is move the control arms about. The antis/roll centers are dependent on the relative position of the ground to the tire center of force to the suspension geometry to the sprung CG in simple terms. The tire bone is connected to the chassis bone...

This isn't a simple task, especially to get everything else right at the same time. Its easy to get an anti where you want it and lose your scrub (example). I don't think you need to spend hours in a program, but go test and and take measurements, log some data, you'll find out what you need.

 

Got this from swifts website and my question is on the HKS Hipermax RS can I move up 1000kg in front and back which would put me at 7kg front and 6kg rear without revalving? I like the setup, but the front feels a little sloppy. Also could I upgrade the front to swift in the same 6kg and feel an improvement?



5. But the coilover manufacturer said switching springs can damage the valving of my coilover systems is this true?

It depends on the range. If you have a street designed coilover system and add 24kg/mm springs then the answer is No. We too have heard of customers and even racers hearing feedbacks from manufacturer’s statements like: “Shocks are designed for our springs only”,”Swift springs can damage valving because it’s different”. If this was true than they would have to sell separate coilover shocks for every spring rate at the very least.

The most important factor in valving is the durability and quality of the valving design, materials, and manufacturing in the first place. So if a manufacturer tells you it will damage the shock, the next phone call should be to a Motorsports suspension tuner, they will most likely give you most experienced and unbiased opinion.

 

Many Nissan FWD cars have this LCA problem and lowering the car makes it worse ...camber under bump rapidly goes positive... roll center disappears way under ground and the car basically pivots on its nose grossly overloading the front and losing grip badly

QUOTE=Bryan at JRZUSA;6809590]"anti dive" and "anti squat" are pretty much the same thing as the "roll center" except were using side view instead of front and/or rear view.

Adjusting control arm points will determine how much of the acceleration, braking, or cornering forces go through the suspension joints instead of the springs/dampers. Generally, changing one changes all the others. The rub is that suspension links are much stiffer than a spring/damper so the load builds up quicker on the tire, using too much "anti" can take away from grip and driveability.[/QUOTE]

I agree. I might add the following..if you try to fix the geometry in one area you end up making things worse in another. For example, changing LCA geometry in a Strut based car fixes one thing camber and maybe a bit of caster. But it doesnt change bumpsteer induced by incorrect angles on the steering arm when you lower the car. Keeping the front roll center above ground does do good things, IMHO. The Whiteline roll center kit does help here.. If you limit the range of curves through spring rate you do keep things to a minimum, but the car pitches and skitters over bumps and irregularities. Way too stiff for DD stuff. You have to have compliance and droop. In the end there is only so much you can do with a production based suspension system. And it comes down to what YOUR car is being used for.

For me I'd rather keep all four down. The front roll center stays up. And the load on the outside front is less implying you can change your driving style to take advantage of it. As noted in this thread wheel rate and lateral spring rate help to do this. Setting up the rear to rotate more with suspension settings and rear bar then is easier, allowing the car to point better, reducing steering angle and allowing more power to the ground. Until you overpower the front grip :-0 :-)

My 2 cents

Milburn

 

Most manufacturers will quote the valving is good for +/- 2 kgs without re-valving.
Having an experienced suspension tuner very familiar with the pieces and setup is a great help. IMHO if you have to move the spring rate 2 kg you'd be better off re-valving in the long run in terms of durability.

Milburn

 

Thanks for the info, I think I will move them up 1 kg.

 

^ Yup, 1kg should be perfectly fine.

- Andrew

 

Swift asks for 3 criteria when ordering coilover replacement springs. Weight, Diameter and Length. I have the Weight and Diameter down, but how do I know what length to purchase. Do I purchase the length equivalent to what I currently have and what are the disadvantages of choosing a short length or longer length. Thanks.