Have you ever experienced driving over a harsh bump on the road and suddenly your wheels turn in a different direction? This can make any experienced driver panic, but it’s especially dangerous when you’re racing or driving in heavy traffic. For your own safety, it’s always important to keep your vehicle’s bump steer in check.
Sometimes, your wheels change direction even without input from the steering wheel. It isn’t the work of ghosts or advanced technology. Rather, bump steer happens when a bump on the road interacts with a poorly installed or badly worn suspension, causing your wheels to steer themselves when impacted by a bump or a pothole in the road.
When your wheel goes over a bump, it moves up and down. If your suspension’s tie rods and control arms don’t match because of wear or damage, vertical movement will likely cause the wheel to toe in or out, which tends to cause the car to be bump steered.
Manufacturers know it’s a common dilemma, and you can rest assured they’ve done their part in making sure your new vehicle doesn’t violently swerve because of bump steer. However, things can get a little bit more complicated if you change your ride height or modify your suspension.
Did you make any recent changes to your suspension? If the answer’s yes, then you might want to measure your bump steer, just to make sure everything’s okay.
Bump steer is typically measured in degrees of steer per meter of an upward motion or degrees per foot. For the front wheels, you should get around two to ten degrees per meter.
We know measuring your vehicle’s bump steer is far from easy, but it doesn’t have to be rocket science. Here are some tips to help you:
Before everything else, make sure your front suspension is completely set. You won’t get far if it isn’t, so go ahead and double-check every part. Your vehicle’s tie rods, control arms, and everything else must be tight and in the proper position before you can begin.
Look carefully for any bent or worn parts. Compare one side to the other if you’re not sure, particularly when checking for bent suspension components.
Measuring your vehicle’s bump steer isn’t going to be a cakewalk, but you can certainly make things easier for yourself by preparing everything you need beforehand. At some point, you’ll have to remove your suspension spring and sway bar. Having a ball joint remover at hand can help you with that.
Park your vehicle in a safe location, preferably in a garage and on level ground. You’ll have to set your vehicle at ride height with your steering locked and centered.
To measure your vehicle’s bump steer, you’ll need to use a quality bump steer gauge. It isn’t going to be cheap, but it’s certainly a good investment if you’re into building cars or constantly tinkering with yours.
If you’re working alone, consider buying a single-dial gauge that displays everything you need in one glance. A two-dial gauge can be hard to read on your own, especially if your bump steer is out of adjustment.
Every vehicle with a rack and pinion steering system has several different parts, but let’s focus on two of them: control arms and tie rods. If there’s an issue with either of them, then your vehicle is likely to experience bump steer.
Is your tie rod too long or too short for your suspension? If the answer’s yes, then it might be the reason behind your vehicle’s bump steer. A too-short tie rod will cause your front-end wheels to toe in, while a too-long tie rod will cause your front-end wheels to toe out.
The upper and lower control arms connect your wheels to the chassis, which allows them to move up and down. Meanwhile, the tie rods connect your wheels to the steering rack, which moves your wheels from side to side.
Now, draw an imaginary line shooting from the upper control arm, lower control arm, and tie rod. The lines of the upper and lower control arms should intersect in the instant center, while the tie rod’s angle passes through it. If it doesn’t, then the tie rod or control arms are misaligned and will likely cause your vehicle to experience bump steer.
Is it possible to completely get rid of your vehicle’s bump steer? No, not really, but you can try to make it as least impactful as possible. After measuring your vehicle’s bump steer, you can minimize it by trying these suggestions:
Having tie rods that are too long or too short is a problem you can fix simply by replacing them. Make sure your new tie rod is the right length and has enough flexing area to curve up when you drive over bumps.
You can also try adjusting the tie rod’s angle as well as the suspension arm’s length. This should help prevent a disrupted front suspension geometry even when you drive over bumps on the road.
Almost every driver experiences bump steer in their lifetime, but that doesn’t mean you can just brush it off. In some cases, bump steer can create dangerous driving conditions, especially on the racetrack. Having your wheels suddenly steer themselves in the opposite direction while you’re speeding down the road can cause collisions.
Plus, driving with bump steer can also cause premature tire wear, which is a whole other problem you really don’t want to deal with.
Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.