I have to disagree here. Bump-steer is an available measurement on the John Bean alignment racks, and most likely the Coates, Hunter, and the others as well. Whether the shop/tech knows how to use it, though, is a different matter. It's a simple measurement to take on a rack: Once you have a static toe measurement, either raise (jack on frame) or lower (come-along to the base of the rack) the front suspension around 2", and let the rack take a new snapshot. That will show your bump-steer, also called "toe curve change."
When it comes to actually making the adjustments, on mine at least it was simple. 18x9.5" wheels, +35mm offset, and there was MORE than enough room to leave the car on the pads, pull the bottom Nylock, rearrange the spacers, and put the Nylock back on. Total time per side was less than 5 minutes to reset, including resetting toe after each change. I spent less than 45 minutes total on the rack, and that included a minor caster adjustment, resetting camber, toe, AND adjusting bump-steer. If you budget two hours for the whole process, including the alignment, you'll have a comfortable cushion. Now, at a $95 labor rate, that comes to $190, but if you back out the "standard" $100 charge for a 4-wheel alignment, you really only spent $90 to bump-steer the car. Note that adjusting bump-steer is NOT a regular maintenance item! You set it once for your suspension setup, and you're done. No need to touch it again unless you make some significant change to your setup, like dropping the ride-height another inch, or changing ball-joint length, relocating the control arm pickup points, significant caster angle change, etc. If you track the car regularly, or have made significant changes to the suspension, then I think it's well worth doing, even if it turns out you're fine.
I couldn't agree more! The key word in your assertion is "problematic." If, however, you notice the car gets darty under braking, tends to carom off at some random angle when you whack a berm on track, or tends to veer off course with a one-wheel compression over a speed bump, you may have PROBLEMATIC bump-steer issues. Easy enough to fix, though. Hell, you can do it at home. Assuming you have a fixed caster angle, or have that set properly now, you can measure and reset bump steer easily. First, park the car with the front tires on 3-4 sheets of newsprint, to allow a lower-friction pivot point, on as plane a floor as you can find. Use a simple set of toe plates (3"x1" aluminum angle stock, about 2' long per side), and measure the difference in width right in front of and behind the tires. This will give you a toe dimension. Next, measure from the floor to the top of the fender opening, pop the hood, drop a moving blanket over the radiator support, and pile sandbags, salt bags, scrap rotors or whatever on it to weight down the front end until you drop the car by around 2". Re-measure the toe differential. If it's the same, or say within 1/16", you're good. If you really want to be anal-retentive, you can plot the numbers every 1/2" or so, all the way through bump and rebound.
The "proper" way is to measure the ride-height at a specific point on the frame, fabricate a wood block to that length, pull the spring, and put the car on the block. That lets you cycle the suspension pretty easily while you measure toe change with DIAL INDICATORS... For the average guy (or even the track junkie that isn't pro), that's kind of overkill, and the toe plates work well enough.
