Wheel hop

[Roger G.]

What causes wheel hop when hard accelerating from dead stop?

[Ronald W.]

Re: Wheel hop

What causes wheel hop when hard accelerating from dead stop?

Hard accelerating from a dead stop!

[Roger G.]

Re: Wheel hop

Hard accelerating from a dead stop!

So... Reading between the lines.... You are saying this is inherent in the rear suspension ?

[Walter F.]

Re: Wheel hop

Doesnt this only apply to solid axle cars?

[Mike F.]

Re: Wheel hop

If you applied more throttle, you would get a smooth burnout and eliminate the wheel hop..

[Terry M.]

Re: Wheel hop

What causes wheel hop when hard accelerating from dead stop?

I have no personal experience (yea, right) but I have been told a deteriorated pinion snubber can cause this in the independent rear Corvettes. You might want to check those bushings.

Edit add: And while you have the car in the air check ALL the rear end bushings. I would also look closely at the front trailing arm bushings even though they are hard to see.

[Duke W.]

Re: Wheel hop

All vehicles have hop and tramp natural frequencies that are functions of unsprung weight and spring rate. It can be bad if the hop and tramp frequencies are near the natural bending or torsional frequencies of the vehicle, which is typical of vintage cars. Solid axle cars tend to suffer the problem more that IRS cars, but all designs can exhibit the problem. Modern Corvettes have natural bending and torsional frequencies that are well above the hop and tramp frequencies, so they rarely experience the problem.

As Terry said make sure everything in the rear suspension is tight as possible. Beyond that more damping will help. Most replacement shocks are pretty limp to give a smooth ride. Adjustable shocks like Spax or QA-1 can be a big help.

If you want to see a very graphic demonstration of axle tramp, watch the chase scene in Bullitt where McQueen has to back up the Mustang after missing a corner.

Duke

[William C.]

Re: Wheel hop

Us ex-drag racers used to work very hard to stiffen the rear suspension to correct this problem, a band-aid approach started the "Traction Master" company back in the 1950's...Clamping some of the rear spring leaves tightly together helped also...

[Joe R.]

Re: Wheel hop

If you want to see a very graphic demonstration of axle tramp, watch the chase scene in Bullitt where McQueen has to back up the Mustang after missing a corner.
Duke

Hi Duke,

It's in this video, just before the three minute mark:

https://www.youtube.com/watch?v=-Lbs_nYW3-o

Joe

[Duke W.]

Re: Wheel hop

Hotchkiss (leaf spring) rear suspensions are particularly subject to tramp and hop because the torque reaction causes the axle to rotate/oscillate about the axle shaft centerline. Pinion snubbers, traction bars, snubber bars and ladder bars prevent this "windup" and the attendent hop and tramp it can lead to.

Late C1s got traction bars to control axle windup.

The C2-up frame mounted differenials transmit axle torque reaction directly to the frame, thus isolating the suspension from having to handle the torque reaction, but the front rubber cushions must be in good shape. They deteriorate with time, especially if the pinion seal leaks and soaks the rubber cushions in gear oil.

Duke

[Ed D.]

Re: Wheel hop

If you want to keep your supension and your car together, get off the gas if it sharts hopping.
Ed

[Roger G.]

Re: Wheel hop

All vehicles have hop and tramp natural frequencies that are functions of unsprung weight and spring rate. It can be bad if the hop and tramp frequencies are near the natural bending or torsional frequencies of the vehicle, which is typical of vintage cars. Solid axle cars tend to suffer the problem more that IRS cars, but all designs can exhibit the problem. Modern Corvettes have natural bending and torsional frequencies that are well above the hop and tramp frequencies, so they rarely experience the problem.

As Terry said make sure everything in the rear suspension is tight as possible. Beyond that more damping will help. Most replacement shocks are pretty limp to give a smooth ride. Adjustable shocks like Spax or QA-1 can be a big help.

If you want to see a very graphic demonstration of axle tramp, watch the chase scene in Bullitt where McQueen has to back up the Mustang after missing a corner.

Duke

Thanks Duke, I think you nailed it with the shocks. The rear suspension was rebuilt recently by the prior owner, with new bushings, but it was missing some trailing arm shims which were recently replaced. Now the rear doesn't slide, it hops.

The shocks may even be original, at least they look that way.

[Steven B.]

Re: Wheel hop

I have no personal experience (yea, right) but I have been told a deteriorated pinion snubber can cause this in the independent rear Corvettes. You might want to check those bushings.

Edit add: And while you have the car in the air check ALL the rear end bushings. I would also look closely at the front trailing arm bushings even though they are hard to see.

Yeah, what he said. Mine started hopping a little so I replaced the snubber and added Greenwood/Koni's (Remember those?). On the '57 I added a leaf and clamps. Happy now except everything needs replaced again. Steve