bborkey

Just wanted to dbl check that rear Toe arms on my 00 AP1 would be illegal in STR? can i do anything to correct the toe change?

djsilverjohnson

I don't think so, as it's a change in suspension geometry. Hopefully someone with more STR experience will reply, but in the mean-time here are the rules. I do know if you lower the car you will have to readjust toe for your new ride height and that's just an alignment parameter, so it's legal.

http://cdn.growassets.net/user_files...pdf?1458856541

imstimpy

Yes, they can be legal. Many manufacturers like to change the bushing type though. You also need to watch out for rollcenter adjusting arms.

djsilverjohnson

I looked at several of the BSK kits and see that they lower the outboard pivot point for the toe-arm in various amounts, to change how the arc of the toe-arm interacts with the arc of the A-arms as the car is lowered. I can see from the wording that you could replace the LCA with one that's adjustable at both inner pivot points and rotate the knuckle to lower the toe-link, but I don't see where in the wording it allows you to change the effective outer pivot point otherwise. Maybe I just don't see it, so feel free to 'splain it.

bborkey

Thanks for the reply guys, but still not sure if they are legal. The way i read the rules kinda seemed like they were not allowed? i take it roll center adjusters up ft would also b illegal? any input would help

JamesD89

Roll center adjusters are illegal

s2000ellier

100% illegal

djsilverjohnson

Ball joint spacers, long shank ball joints, or other methods to adjust the roll-center front or rear are not legal.

What rules explicitly offer is the ability to run an adjustable upper or lower A-arm, but not both, and it doesn't restrict it to cars that don't already have a way to adjust camber. It also clarifies that "Changes in suspension geometry are not allowed except as incidental to the effective arm length change."

Now, on the S2K, the factory camber adjustment is made with an eccentric on the leading inner pivot of the lower control arm. When you adjust that eccentric, it also rolls the knuckle and changes the vertical position of the toe-link slightly. That changes the toe of the rear wheel, so the toe-arm has an eccentric on the inboard end to correct the static toe setting. It also has an incidental effect on the toe-curve and bump-steer characteristics.

The rules don't allow you to change from bushings to spherical bearings, but it doesn't say how you make the length change to the UCA or LCA. For example, most folks would just make the LCA longer or UCA shorter, but you could make an A-arm that has the front, rear, or both inner bushings attached to the A-arm in a way that you could adjust them in or out to change the effective length of the arm for camber adjustment. The LCA has the OEM eccentric on the leading inner pivot, so if you used the allowance to use an aftermarket UCA with an adjuster on the trailing inner pivot, you could use a combination of the LCA and UCA adjusters to set camber in a way that has "incidental" changes in the vertical position of the toe-arm and the resulting change in the bump-steer curve. Both the OEM and any aftermarket method of doing this also changes the vertical alignment of the upper and lower ball-joints in a way that changes the rear-wheel caster, but with the minute amount of rear-steer involved is a minor consideration. This is my interpretation and opinion and is worth exactly how much you paid for it! ;-)

imstimpy

This provision is to introduce another means of adjusting alignment parameters, not to alter suspension geometry. Relocating pivot points and balljoints is a geometry change and not allowed. Replacing rubber bushings with spherical bearings is a bearing type change and not allowed. If you took the stock arms, cut them in half, welded a threaded insert on one half and a threaded rod on the other, that is what you are ok installing.

djsilverjohnson

That will work!

So to the OP, you can replace either the upper A-arm or the lower A-arm with a length adjustable A-arm, but not both, and it cannot have spherical bearings in place of rubber bushings and it can't have extended shank ball joints to change roll-center. As far as I can see, there's no allowance for replacing the toe-link, but it does already have an eccentric adjuster on it, and if you need more adjustment you can add an offset bushing on the inboard end.

If it was me, this would be what I would do; Since the rear lower A-arm already has a camber adjustment eccentric on the leading inner corner, I would make or buy an aftermarket rear upper A-arm with an adjuster on either the trailing inner bushing, or both leading and trailing. One possible cheap option would be to use "camber-bolts to replace the inner bolts on the OEM upper A-arm. That will allow you more than one way to adjust static camber changes, as well as compensate for the incidental changes in static toe and bump steer effects of lowering the car.