Adjustable LCA question..

[DrEvyl]

I have LG Motorsports single adjustable LCAs on my Formula, and I've been messing with it for a while to get the set up correct...

When I originally put them on, I had some issues getting them back in with them extended out at all, so I installed them with the adjustment all the way in... Comparing that to the stock LCA, I realized that was way too short, so I took it apart again, and lengthened them....

Right now they are adjusted so that the heim end is rotated out 4 complete turns. There is about 1/2" of threads available. The length is just slightly longer than stock, like maybe 2-3 millimeters... If my measurements were right, stock should be about 3 turns out... I turned them one more just to get a little more angle.

Just curious.... I really don't know how to analyze suspension geometry, so I don't know if I have them adjusted correctly. How would I know?

Is there any disadvantage to having them longer than stock?

What affect is adjusting them one way or the other going to have on how the car handles?

[FireRoc]

I suspect that a couple of millimeters more or less is not going to have a significant effect on the handling. But.....

The location of the axle will determine how much of the driveshaft yoke is in or out of the tailshaft housing of the transmission. This yoke moves in and out as the axle moves up and down. I do not know off-hand what the specs are for how far the yoke should be out of the tailshaft housing.

and.....

The LCAs determine if the axle is running perpendicular to the centerline of the car. If the axle is crooked it will have a thrust angle. This will cause the car to pull to one side, and if it is significant enough the car will dog track. It can be checked on a wheel alignmnet machine (four wheel alignment) and adjusted with the adjustable LCAs.

[DrEvyl]

The car tracked straight with the stock LCAs on it, and it tracks straight now. It's hard to tell what effect it has on the handling because my shocks are completely toasted... new ones coming soon. But it does feel like it handles better *now* versus how it did before I lengthened the LCAs.

I am pretty sure I have them both adjusted to exactly the same length. At least from eyeballing them stacked on top of each other they matched up.

I can jack it up and see how much the driveshaft yoke extends out of the transmission...

Is there any spec as far as what is good, and what is too much?

[FireRoc]

The rear axle must be loaded when you check the yoke depth in the tranny.

There is a spec most likely, but I do not know what it is.

Glad to hear it tracks better and straight.

[jmd]

Originally posted by DrEvyl
single adjustable LCAs on my Formula

lengthened them....

heim end is rotated out 4 complete turns.

The length is just slightly longer than stock, like maybe 2-3 millimeters... If my measurements were right, stock should be about 3 turns out... I turned them one more just to get a little more angle.

Not gonna happen. The pinion angle is set by the torque arm. If you lengthen the pair of LCAs, all you're doing is moving the rear axle back, not adjusting pinion angle.

In the case of the torque arm / panhard setup on the 82-02 F's, adjustable LCAs are basically for centering the wheel in the wheel well fore & aft.


Just curious.... I really don't know how to analyze suspension geometry, so I don't know if I have them adjusted correctly. How would I know?

Is there any disadvantage to having them longer?

Proper: Your tires don't rub the fenderwell and a 4 wheel alignment indicates the rear of the car being aligned.

Nope.

What affect is adjusting them one way or the other going to have on how the car handles?

Very minimal.

-Matthew

[jmd]

Additionally,

The yoke is furthest into the trans. when the rear is at full droop.

Slipyoke depth will not be an issue on your car.

[DrEvyl]

Wheels don't rub... car tracks straight.

I actually lengthened them slightly hoping to get a little more traction bite out of the car on launches...

Is that a misconception?

[jmd]

Yes.

Moving the rear axle back (a very tiny amount in this case) just reduces weight over the rear wheels (again, a very minute amt.)

Think of those altered wheelbase cars from the ~60's with the front and rear axles both moved forward; they were trying to get weight over the rear axle.

I see on your site no mention of a torque arm. In the wings / plans? I'd be wanting pinion angle adjustability. :yup: