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Summary
  • Bump steer happens when a bump on the road interacts with a poorly installed suspension, causing your wheels to steer themselves.
  • To measure your vehicle’s bump steer, you’ll have to complete and set your front suspension, prepare the necessary tools, and use a quality bump steer gauge.
  • Misalignment and using the wrong size of tie rod can cause excessive bump steer.

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.

What Is Bump Steer?

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.

Measuring Your Vehicle’s Bump Steer

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.

, What Is Bump Steer? Definition, Measurement, and Causes

Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.

Pro Tip: Note, however, that suspension work of this type is best left to a front end specialist, because even if you determine you have a bump steer issue and manage to measure it, the chances are you won’t know what to do about it.

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:

Complete and Set Your Front Suspension

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.

Prepare the Necessary Tools

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.

Prepare Your Vehicle

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.

Use a Quality Bump Steer Gauge

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.

What Causes Bump Steer?

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.

Wrong Size of Tie Rod

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.

Misalignment

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.

How To Fix 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:

Replace Your Tie Rods

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.

Adjust Your Suspension

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.

Why Is Bump Steer Dangerous?

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.

About The Authors
Written By Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at CarParts.com

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

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.

File Under : Suspension , DIY
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