Discussion and questions related to the course Motorsport Wheel Alignment Fundamentals
Hello, do you have any suggestion to measure the bump steer correctly without removing the coil spring?
I would never try measuring bump steer without removing the springs & anti-roll bar, but you could try using a spring compressor -- the problem is while you are doing that you probably end up changing the alignment, so how will you know if it's bump steer, or just steer? But if you just compress the spring to the maximum bump (and hold it out of the way), then you can measure from there to full droop.
I would say if you don't want to remove the spring, you don't need to check the bump steer -- assume the designers of your suspension have already done that. See it's easy!
Well, you can kinda do half the job, which may give some indication of whether it could be a problem, especially as it approaches normal ride height.
Jack it up, fit the bump steer check tools (preferably on both sides so an average can be obtained, then lower it onto slip plates (or several sheets of plastic or oiled stel plates) and note the total change in toe as the suspension is compressed as the vehicle is lowered - the change in toe, if any, will be a result of bump steer. If the toe is fairly constant through full droop to ride height, that suggests it shouldn't be too much of an issue - but if it varies significantly, especially as the vehicle is fully lowered, it will need addressing.
As David said, you really need to go through the hassle of spring removal, etc, to do it properly, otherwise are you really serious about finding out?