What is Wheel Hop? How Can I Fix Wheel Hop When Drag Racing?
WHAT IS WHEEL HOP?
Wheel hop is basically a gain and then loss of traction. Repeated in quick succession. This creates a little “hop” that’s not only a little bit violent but also costs you precious acceleration.
It might help to think of a record skipping. It’s playing, then it’s not, then it’s playing again. But now you’re so annoyed about the skipping, you can’t enjoy the song.
Is Wheel Hop Bad For Your Vehicle?
Unfortunately, just like a record skipping, wheel hop isn’t good for your vehicle. It puts a lot of strain on the suspension to go from spinning to not spinning and back again. So, you definitely want to address wheel hop.
The good news is that wheel hop won’t immediately break your car.
Is Wheel Hop Specific To Your Model?
Not at all. Actually, any powerful vehicle with IRS can suffer from wheel hop. Even FWD vehicles.
Can You Get Wheel Hop with a Solid Axle?
Sort of. A lot of people say they experience something like wheel hop caused by wheel slippage and a lack of grip. It’s not actually the same phenomenon though. If you’re getting “wheel hop” with a solid axle, you may want to look at upgrading your lower control arms.
Wheel hop is one of the reasons a lot of drag builds lean towards solid axles. But there are actually ways to keep the benefits of independent rear suspension and lose the hop.
IRS UPGRADES THAT FIX WHEEL HOP
Over the years, several solutions have been developed to help manage wheel hop. Most of them are small customizations to the suspension. As an added bonus, many of these fixes have other performance benefits.
Bushings
Bushings are thin tubes designed to reduce vibration and improve efficiency. They’re also the first suspension component to receive the torque. When your bushings are too soft or worn out, they can cause deflection, which makes the chassis move too much. This means less power going to the wheels.
All bushings need to have a little deflection built in. Otherwise, cars would be very uncomfortable, and you’d have to deal with significant noise, vibration, and harshness (NVH). Since your average driver cares a lot about comfort and NVH, most manufacturers use rubber bushings.
But if you’re researching wheel hop, it’s safe to assume you’re not the average driver. So, swapping out your rubber bushings might be a good solution for you.
Stiffer bushings won’t be as comfortable, and you’ll get more noise, but you’ll also get more power on the pavement and less deflection. Polyurethane (poly) bushings are one of the go-to solutions.
A subframe bushing support system is another option. These install on top of your factory rubber bushings and provide support against deflection. Because they still use your factory rubber bushings, you won’t notice an increase in NVH.
Bushing lockout kits are designed to eliminate wheel hop by preventing cradle bushing deflection. These keep bushings from moving. They also don’t increase NVH.
Rear Vertical Links
Vertical links are designed to keep your rear wheels planted. If you’re used to a solid axle suspension, they basically act like lower control arms. The factory links can also flex, which is another cause of wheel hop. So, upgrading your vertical links is a good idea.
Aftermarket rear vertical links are made out of tougher materials that’ll keep the rear suspension geometry in check. They also usually come with polyurethane, urethane, or delrin bushings. All three bushing styles are significantly stiffer than the rubber stock ones.
Adjustable Rear Toe Links
Toe links keep your vehicle's rear end stable and the tires planted. Factory toe links are rarely amazing.
Replacing your factory toe links with adjustable ones is another way to prevent wheel hop. This also will let you adjust your vehicle's suspension so that it matches your driving style. Someone who likes road course driving may prefer an aggressive camber setting.
IRS Subframe: Support Braces and Alignment Kit
Adding more support to the vehicle's subframe has been a popular mod for decades.
By giving your vehicle two extra support points, you’re strengthening the connection between the subframe and the rest of the car. You'll just have to adjust your alignment to prevent asymmetrical suspension geometry.
MORE WHEEL HOP FIXES
Some other wheel hop fixes are a little more universal. While these mods can improve wheel hop, they’re less targeted solutions and are more for improved driving in general.
Performance Tires
Soft, sticky tires that grip the road are a must for drivers who want to perform on the drag strip. Wider tires will also improve traction by creating a larger contact patch. With better traction, you should see less wheel hop and better ¼ mile times.
Even though performance is important, if you drive to the track, make sure you pick up a set of tires that’s also street legal.
Lowering Springs
Having a lower center of gravity can reduce wheel hop as well. And lowering springs are one of the ways you can lower your vehicle. The different suspension geometry and change in weight dynamics help to keep your rear planted. Lowering springs also help with handling and reduce body roll.
Wheel Hop – Causes, Effects and Cures
Standing starts are hard on a car, and there are a few NASA classes that begin races that way. A standing start is even harder on a car if it suffers from wheel hop, which occurs when a tire loses and gains traction in rapid succession.
Wheel hop also can occur on corner-exit in slower-speed turns where a car is in a low gear and torque multiplication is high. To find out more about what wheel hop is, why it occurs and how to cure the problem, we caught up with Pete Epple, a marketing technician with BMR Suspension, a company that specializes in suspension upgrades for early and late model domestic cars.
“Wheel hop can be caused by a variety of things, from the wrong shocks to a better surface than the tire can handle or more power than the tire can handle, but the biggest thing that we really see is bushing deflection within the suspension system,” Epple said. “In an IRS car, you would see cradle bushing deflection, differential bushing deflection, and it creates large amounts of movement within the system that causes the tire to lose traction and then gain traction and lose traction and gain traction.”
Bushing deflection sets in motion an oscillation that occurs throughout the entire rear suspension. The condition is somewhat common on cars with independent rear suspensions, but it can occur on cars with live axles, too, particularly those that use coil springs and control arms.
From the factory, bushings are made of rubber, often with voids within the material, which allow for significant deflection. Rubber is great for alleviating noise, vibration and harshness, but falls short of the requirements for track use and racing. The rapid and severe torsional loading and unloading during wheel hop can wreak havoc on a drivetrain.
“Through all of our testing and all my previous experience, I’ve seen wheel hop break everything from the actual differential housing to axles to ring and pinions to even breaking the welds on control arms,” Epple said. “It can be extremely violent.”
Regardless of whether your car has a live axle or independent rear suspension, the fixes are largely the same: replacing the soft rubber bushings with either polyurethane bushings or spherical bearings. The rub, of course, is a less-refined ride and more road noise transmitted to the interior.
For street applications, polyurethane bushings are probably enough to get the job done. For track cars and racecars, Epple recommends spherical bearings because they provide superior articulation and zero deflection. For HPDE cars driven to and from the track, BMR also has “in-between” models of control arms that have a spherical bearing on end that attaches to the axle and a polyurethane bushing for the end that fastens to the chassis.
“The benefit there is you get some of the cushion of a polyurethane and then more articulation that you would want from a bearing or a rod end that you don’t get with polyurethane. It gives you a good combination of both,” Epple said. “It’s definitely going to be noisier than a control arm that has polyurethane bushings on both ends, but it won’t be anywhere as noisy as one with spherical bearings on both ends. It’s a really good middle road for that.”
These principles apply to more than just the applications for which BMR Suspension makes parts. If your Spec E30 or your Honda Challenge car exhibits wheel hop during standing starts, you’ve got a problem with bushing deflection. Of course the rule book comes into play in terms of whether you can use polyurethane or spherical bearings, but a wheel-hop condition should tell you where to look on your suspension system.
“The more of that soft rubber you can get rid of and minimize that deflection,” Epple said, “be it with a bearing for a hardcore handling application or a polyurethane or like an elastomer for more of a street application, anytime you get rid of that deflection, or at least minimize it, you’re going to minimize the potential for wheel hop.”
Leave a comment