Anti-lift geometry AND older vs. newer c900 balljoints

[Hans]

Anyone played with anti-lift on their car? I was reading on SaabCentral that the factory rally cars had this. Given how easily the lower arms are mounted, it's pretty easy to shim them and, with rubber bushings, shouldn't bind (I ASSume, anyway).

I know Subaru aftermarket shops have kits for this. Seems to me that maybe you could manage this with shock tuning for a drag car or something, but not one that needs to turn/stop/go/etc.

Thoughts/experience? Wasn't someone on this board under a Works car with a camera earlier this year? Didja see anything?

Linky: http://saabcentral.com/forums/showthread.php?t=114589

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EDIT: Also...

I have a doc from Saab that says the later c900 ball-joints (mid-89 change, IIRC) were re-designed to promote understeer; the difference is like 3mm in tie rod height vs. the older style. Anyone have any experience comparing these two styles? Both are still available; if it makes a difference, I might get a set of earlier ones and try 'em out...

[matt]

I have no input regarding the question, but Luke has been looking at possibly getting progressive springs, so I think this applies to his quest.

He also had some fascinating information about the suspension setup.
Apparently the rear springs from a ford scorpio ( possibly still branded granada in the uk ) are a direct fit onto the front of a 99/900. They are progressive, and get extremely stiff, avoid the car bottoming out. He also mentioned they changed the height of the lower wishbone mountings relative to each other, which had the result of pulling the front of the car DOWN under acceleration instead of upwards. I know this sounds crazy.. He mentioned it was very important to get the front of the car low enough to have the driveshafts straight.

[Crazyswede]

What exactly do you mean by anti lift?

[Luke]

Anti lift: a system installed in a saab rally car that gives you an electric shock every time you lift.

[Geoff]

I just looked through all my photos of the works cars. One of the cars was John Buffum's former works car which was actually a re-shelled car. The other was a white C900 with an aluminum cage. Neither had any spacers under the A-arm mounts... Could be a fun experiment though!

[Luke]

I've often noticed that the works cars had different bushing blocks where the a-arms mount, they are chunky looking like they were were milled from solid stock. The dimensions looked the same though. I always assumed they just remade the stock mounts in a stonger material like steel for durability.

[Geoff]

I seem to remember seeing that before now that you mention it. Do you have any pictures? The ones I took photos of in the museum looked like stock bushing blocks...

[Geoff]

I seem to remember seeing that before now that you mention it. Do you have any pictures? The ones I took photos of in the museum looked like stock bushing blocks...

[Hans]

What exactly do you mean by anti lift?

Having done a cursory search on the internets after reading the SaabCentral post, this is what I've come up with:

Anti-lift is a suspension design parameter that affects how much the front end lifts on acceleration. It's the opposite of "anti-dive" or "anti-squat," terms used when discussing braking and RWD acceleration, respectively. Some rear wheel suspensions use "rear anti-lift" geometry to keep the back end from rising up too much under braking. It's the same idea as front anti-lift on accel.

By changing the side-view angle of the lower control arm so that it declines down and back, the amount that the front end lifts under power can be decreased, thus increasing forward bite. Apparently, popular anti-lift kits for Subarus make up for the factory's economy-minded design decisions that affect corner-exit traction and understeer.

The drawback to anti-lift is more dive under braking, but, from what I've read, anyway, if the springs are sufficiently stiff, it's not an issue. NVH is an issue, too, and, again, from what I've read, too much of it will get you binding issues.

More on it: http://www.circletrack.com/techarticles ... index.html

There's info on "anti-lift kits" at nasioc.com (sounds like a device to combat guys with big trucks with gun racks and muddin' tires). Of course, there's always the googles.

It struck me as a simple modification if I knew how to calc the shimming; I assume it was valuable enough for Saab to do it...

[TRAILINGTHROTTLE]

all the anti-lift kits made for subarus do is replace the rear front control arm mount and bush. they replace the crappy stock rubber with decent poly and lower the rear a-arm pivot point. all this does is increase the caster angle, by approx. 1/2 of a degree static. i ran the whiteline ALK on my 1st gen. legacy for a time and then gave them away. the only real reason that it provided any "anti-lift" is because it had the control arms all bound up in the bushings. this is just a stop gap measure to try to hide the fact that subarus have terrible front suspension geometry. obviously 1/2 degree more caster will result in more camber relative to steering angle...but that would never account for any anti-lift by itself.

[james]

My ex-works 900 has had this done.

Both the control arm mounts and the ball joints have been modified to do what I can only assume is this. I was talking to some Swedish guys at one of the conventions about front end setup and they said a way to cheat is to swap the mounting blocks, front on the rear and rear on the front of the a-arm. Changes the angle of the arm, and in their words 'makes the car hook up like it has a limited slip.'

Basically you are running crazy high caster, the ball joints on the ex-works are machined to do this as well. If I had a digital camera I could take photos.

James
not dead yet...

[TRAILINGTHROTTLE]

i will admit that, on the subarus, the front end was "hooked up" with the "anti-lift" geometry change, more so than stock, but ONLY and i mean ONLY on power down corner exit. bringing the car in hard on a trail brake was scary to me as the car felt as though it had "super dive" as opposed to "anti-lift". if the saabs dont exhibit this same behavior than i would like to try this out on my C900. i had dismissed it due to my subie experiences. please send pics.

btw: in my previous post i was by no means talking trash on Whiteline, as i have had several vehicles that were totally Whitelined out...swaybars, springs, strutbraces, panhard rods, etc. everything that i have ever used by them was top notch, except for the ALK.

[SwedeSport]

How would this anti lift theory work on my c900 drag car for straight line accelleration????

Im thinking the setup is gonna be raked toward the front slightly, kinda low all around and real stiff in the rear. Not sure about sway bars though?

[Geoff]

As you accelerate your front end would start to hug the ground more instead of lift up keeping the weight from transferring to the rear.

[Jordan]

The same effect can be done by just adjusting the standard alignment shims (and probably in a more controllable way)... Unless you want some crazy degree of caster that is outside the physical boundaries of the shim or a-arm movements.