Can someone explain to me.., what it means to index torsion bars? Options

[mike_the_man]

I've heard this mentioned when lowering the front end, but I'm not real sure what it means. Do the torsion bar adjusting end caps have to be in the same spot (same number of splines) on each torsion bar? If not, and you start cranking on the adjuster till the ride height is even, would one bar be more pretensioned than the other? Does any of this make sense???

What's happening is that I lowered the front of the car, not a whole lot, and added the bump steer kit, but when I go over a bump, the front end feels light. It feels like I'm still getting some bump steer, or something. I'm not quite sure how best to describe it. I haven't had it aligned yet, so that could be part of the problem, but I want to make sure I have everything else set up right first, then get it aligned.

Sorry for the long post, and thanks,

[SLITS]

Indexing - interesting situation. Make a couple of assumptions here:

1.) The splined are broached parallel to each other

2.) The spring rate of each bar is exactly the same.

Indexing would be that both bars are installed the the housing in the exact same position.

1. If you place a reference mark on the adjuster end of the bar, say using the R & L stamps, you could install the bar in the front housing so that the R & L are vertical to the ground plane (assuming your car is exactly level).

2. Then place a reference mark on the adjuster.

3. Pull the suspension down on one side with a bar and install the adjuster and note the position of the reference mark on the end of the torsion bar in relation to the refererence mark on the adjuster.

4. Going to the other side and preforming the same operation, but making sure the distances between the reference marks is equal to the side you've already finished would be "indexing"

This is probably more trouble than it is worth, but it's your car.

We used this method on spark plugs where the high compression piston crown could feasibly hit the spark plug electrode at TDC - we "indexed" the plug so that we would know the position of the electrode in relation to the piston crown.

Twitchy Steering:

Bump steer is the result of angularity of the tie rods in realtion to the ground plane. The tie rod end moves in an arc. If the postion of the tie rod is at 90 degrees and is deflected upwards in a bump the degree of change effectively shortens the bar and pulls the front of the tire inward. The slowest rate of change would be, say 85 to 95 degrees in realtion to the ground plane.

If you have lowered the car and the tie rod is further up the arc, say at 75 degrees in realtion to the ground plane, the rate of "shortening" is increased for the same deflection of the suspension. Hence, the front of the tire is pulled inward at a greater rate resulting in "twitchy" steering on bumps.

If this doesn't make sense to you - draw it out on graph paper and swing the arc formed by the tie rod end when deflected by a bump.

Ok, that's my thesis for the day! <_<