Tommy D

Sam you have a bazillion horse power

Actually for those of us with a bit more horsepower who must have traction on the street the Nitto 555R2 are great (see above). The Nitto Evos are not bad for those of us with a lightly modded car (but all bets are off when it gets cold outside..... cold tires on cold pavement ).

A set of Bilstein HD shocks should do the trick for anyone with wheelhop. I have a A4 with 3.15 gears and a 2800 converter and a set of bilstein HD shocks.

I had wheelhop on one run with my 17 inch MT Drag radials. I intend to upgrade the rear bushings to poly bushings and install a hardened axle for some insurance. In consideration that the A4 "hits" the tires harder than the A6, the installation of bilstein HD shocks or a equivelant should do the trick!

Tommy D

Sam you have a bazillion horse power

Actually for those of us with a bit more horsepower who must have traction on the street the Nitto 555R2 are great (see above). The Nitto Evos are not bad for those of us with a lightly modded car (but all bets are off when it gets cold outside..... cold tires on cold pavement ).

A set of Bilstein HD shocks should do the trick for anyone with wheelhop. I have a A4 with 3.15 gears and a 2800 converter and a set of bilstein HD shocks.

I had wheelhop on one run with my 17 inch MT Drag radials. I intend to upgrade the rear bushings to poly bushings and install a hardened axle for some insurance. In consideration that the A4 "hits" the tires harder than the A6, the installation of bilstein HD shocks or the equivalent should do the trick!

Pro Stock John

Have to ask yourself, why are you getting wheel hop.

Now with a stick car, they are set up different for drag racing (here is my theory). You want the shocks stiffer in back for a stick car, because the the shifts are more violent. You don't want stock street tires breaking loose and then hooking again with a lot of power because what's the weak link? The rear end.

Weight transfer I think plays a role too. If the car rocks front and back, that could exacerbate wheel hop issues.

I had some pretty major wheel hop with 325 DR's in an OT car that went 9.4 on a 1.35 as it's best. But I had an aborted 1.7 pass where the tires hopped so bad they made a skittering sound you can hear on the tape. It was suggested that I make sure I keep the nose of the car up and keep the tire pressure up.

I've heard of late model vette guys running poly bushings and stiffer shocks, which makes sense. If you run stiffer stuff you lessen the risk of the car rocking back and forth on shifts or when you are spinning.

Thanks for letting me check out your car Joel, I'll let you know if I get that one in TX.

PowerLabs

That was a very good start, but I think there is a more objective way of looking at it.
You asked the right question, but after asking that question, the next part of the question is: "What is wheel hop?"
Wheel hop happens when your tires, which have a certain spring constant ("Bounce") break traction and hop (jump) infinitesimally off the ground; when the spring constant of the tire matches a multiple of the resonant frequency of your spring, the two resonate, and instead of settling back on the ground, the bouces gain amplitude untill the tire starts to bounce higher and higher. Ultimately this destroys your drivetrain because the tire can speed up and accelerate as it is off the ground, then slam back down with force, effectively decelerating at a rate that exceeds the strength of your drivetrain's weakest link, whatever that happens to be. Incidentally you can find cars with very well built drivetrains coming apart at the track with average power levels; building up the drivetrain to withstand the wheelhop does not work; you have to eliminate the hop.

Since wheelhop is happening because the tires' spring contant resonates with the natural frequency (or a multiple of) the car's spring/shock combo, the proper way to fix it is by changing the natural frequency of the tires (change tires, let air out or inflate the tires) or the car (increase or decrease spring rate, or increase dampening).

My advice is to play with the tire pressure, and if that does not work try stiffer shocks (Bilstein HD or Bilstein Sport).

Of course, if the tires never brake lose, wheelhop never begins... Traction is another very good way of solving the problem

Leprkon

I personally disagree with changing the shocks on an F55 car. No real gain and will destroy the trade-in value. What you should do is upgrade to the Z51 rear sway with poly bushings. That will keep your tail end planted.

Pro Stock John

A few definitions:

Definition: An undesirable suspension characteristic in which a wheel (or several) moves up and down so violently that it actually leaves the ground. Wheel hop can be caused by many problems, including excessive unsprung weight, insufficient shock damping, or poor torsional axle control

What is wheel hop?
Wheel hop is a nasty action whereby the driven wheels of a car voilently shake, vibrate, hop, grab, and/or thump upon acceleration. It's usually quite obvious when your car suffers from this condition, for it sounds and feels like your car fell off a garage lift three times every second. Wheel hop doesn't just feel bad - it's bad for your car, too. For reasons that will be explained below, wheel hop can lead to broken drivetrain parts, including axles and rear differentials on a rear-wheel-drive car, and axles and transmissions on a front-wheel-drive car. If your car wheel hops - get it fixed!

What causes wheel hop?
A lot of people don't know why wheel hop occurs, which often leads to them throwing the incorrect parts at the car in an effort to eliminate the issue. Fortunately understanding (and correcting) wheel hop is not difficult. Here is what happens. When a car accelerates, you can picture the forces involved as something (the ground) pushing the driven wheels of the car forward. Obviously if you push the wheels forward, the car is going to move forward also. However, the wheels are not rigidly fixed to the chassis, so when the ground pushes on the wheels, they move forward a bit in the wheel well. Normally a car's acceleration is so small that this motion is negligible, but when a car accelerates quickly, especially during a launch, the wheels can move forward quite a bit in the wheel wells. As the wheels move forward, significant toe changes occur. Now, everybody knows that a tire can provide the most grip when it is perpendicular to the ground, parallel with the acceleration, and pressurized to provide the optimal contact patch. That being said, if the toe of the driven wheels changes during acceleration, the grip of the tire must be changing. Wheel hop is a result of this change in grip. Here is the sequence of events:

1.) Acceleration begins with good grip.
2.) The wheels move forward, toe changes, and available grip is reduced. Wheelspin occurs.
3.) During wheelspin, acceleration is very small. The wheels move back again, toe changes back, and the tire regains grip.
4.) Acceleration begins again, and the process repeats itself.

This rapid switching between grippy acceleration and wheelspin is wheel hop. My above description of the wheel hop process sounds tame, but the frequency of the grip changes and the magnitude of the forces involved is what makes wheel hop so violent. Race tires can prevent wheel hop since they have more grip (i.e., they don't lose grip even with the toe change), but cars that wheel hop with race tires will do so in a much more violent fashion.

How do I get rid of wheel hop?
Getting rid of wheel hop really isn't difficult. If you can limit the motion of the wheel with respect to the chassis, then the toe changes during acceleration will be small and the tire will not suddenly lose grip. If the tire does lose grip (common on a high-HP car of course), then it won't suddenly regain grip due to the wheel moving back to it's static position. How do you keep the wheel from moving with respect to the chassis? Well, assuming your car has reasonably rigid suspension arms, then all you need to look at are the suspension bushings! The wheel can move with respect to the chassis because the bushings flex...especially old, stock rubber bushings. Sometimes simply replacing old rubber bushings with new rubber bushings is all that is required. However, on a modified car that posesses more horsepower than the designer's intended, upgrading to stiffer materials like nylon or polyurethane may be required. The ultimate solution is to use rod ends or spherical bearings at every suspension joint, but that is unreasonable unless your car will never again see public roadways. Anyway, by simply upgrading your bushings, the suspension bushings will not flex as much under strong acceleration, the wheel will not move far forward in the wheel well, the toe of the car will not appreciably change, and your tires will not lose grip. Wheel hop will have been eliminated.

In some cases weak shocks can allow a perturbed wheel to continue hopping up and down since the motion is not damped. This is a less likely scenario, but shocks should not be ruled out as a potential culprit.


When horsepower is suddenly delivered to the differential, whether from a clutch or a torque converter, the pinion attempts to "climb" the ring gear. This sudden shock of torque causes the entire rear axle housing to rotate backwards in a counter-clockwise direction. This causes the springs to distort, resulting in severe driveshaft/U-joint misalignment.The axle housing is allowed to continue its rotation until it meets resistance from the suspension/springs, which then try to "snap" the housing back to its original position. As power continues to the differential, the housing is once again allowed to rotate back against the springs. This action/reaction of the suspension, commonly known as "wheel hop," continues much like a tug-of-war. Instead of launching your car forward, you sit there bouncing around and spinning your wheels.

Pro Stock John

Generally, stiff shocks in back are a good thing when you have a car that wheel hops a lot. When I've had wheel hop in a drag car, I've typically run the rear shocks at 50/50, or stiffer. I've run the fronts softer than stock.

I remember we swapped OEM F1 tires to Nitto drag radials back about 10 years ago, and I think the wheel hop was noticeably reduced. Car then had better grip and spun less overall so the one of the initial sources of wheel hope (wheelspin) was minimized.

HOXXOH

So getting back to the OP's concerns now, because a lot of the conversation has focused on definations for causes and cures that don't necessarily apply in his case.

Here's what we know:

The car is a 2009 LS3 A6 F55.

He will have roughly 450 rwhp +/- when the mods are done.

He wants to avoid trans/rear end problems.

He wants to run 10's

He would like to use original RF's, but is open to DR's if necessary.

His biggest concern on this thread is wheel hop.

I think most of us agree he will need DR's.

I think most of us agree wheel hop is primarily a manual trans problem.

Have any of us had, or know of someone who has had, a wheel hop problem on a car similarily equipped?

I can say with 75+ 1/4 mi. passes and a bunch of parking lot test launches on my LS3, A6, F55 car with RF's, Nitto Invo, & DR's, that I have never experienced wheel hop.

The OP mods include a 2600 (why that?) converter which should additionally soak up the shock potential.

I'm just saying I don't feel it's wise to suggest fixes to eliminate a future problem that hasn't yet been identified as such. If anyone can confirm that problem exists someplace, please share that knowledge.

mcwire

I've had wheel hop, with my F55. It seems that it's related to several factors, some of which are -- temp of tires, and road surface, -- texture of road surface, -- RPM's at launch, etc. -- I'm running stock tires / no mods. -- --

Pro Stock John

If I was OP, I'd run what I have, take it easy on the first 1-2 runs at the track, and then get progressively more aggressive. If it has wheel hop, I'd back down, and also consider getting drag radials since they are probably more consistent and less prone to that grip/spin/grip/spin of stock tires.

HOXXOH

Did any of the wheel hop occur during launch at a drag strip? If so, what did you do to cure it?

mcwire

-- It occurred on the street, but I'd be real nervous on a sticky strip. -- What I did was, avoid full throttle blasts, since that time. -- --

HOXXOH

I've been real picky about the surface and locations to do WOT test launches. I've tried to use private parking lots that closely match the track surface. Avoiding public streets because of poor traction and inconsistent surfaces. That could be the reason I've never had wheel hop.

siffert

I never had wheel hop and I do WOT on all kinds of street surfaces
from a dig. I find my runflats get best traction on newly paved & smooth asphalt and DR's on old & worn out asphalt (more apt to spin on the new & smooth). I only use private parking lots to do burnouts to wear down new DR's...and I bring my own water jug.

Maxx Schlick

I am new at Drag racing about 20 passes so far. Driving a 2006 Z06 with runflats, and it will wheel hop badly as soon as it spins the tires.
Tried doing a dry burn out twice (by advice from some guys at the track) and got nothing but hop.

My only 2 half way decent runs were very conservative launches, almost like leaving a traffic light, and then just rolling on to full gas. Got zero wheel spin and both runs were at 12.7 at 117mph, and 60ft at 2.1
All other runs were varying degrees of too much throttle resulting in spin/hop and 13.5 to 13.9 second Ets and average of about 2.3 to 2.6 60 foot times. Obviously too much throttle and spin/hop gets you no-where slow.

I plan to put some Hoosier R compound rears on this friday, and see how it goes compared to the runflats. At our track Pueblo Motorsports Park, they make the street tires guys launch in the unprepaired dirty outside lanes, and don't let you burn out from the water box.
At least with the R compound Hoosiers I will be able to back into the water box and do a wet burnout, and then launch in the VHT prepped lane. I am hoping this will help eliminate the dreaded wheel hop.
If not, I may go with the advice from, Pro Stock John, (sounds like he knows of what he speaks) and upgrade the bushings and maybe shocks. This hop has to stop.

So here is my question...
Assuming you have to do a burn out (wheel spin)to get the tires hot...and wheel spin is the main culprit that induces hop, How do you do a good burn out without hopping the crap out of the tires?
Is it just a perfect amount of spin, or is it that the water keeps the tire from actually getting (and then loosing) traction, that will keep the hop from happening?

PS: when I first got the car back in 06 I naturally did about a dozen red line burnouts about a 1000 ft down my street and never got ZIPZERO wheel hop, just a new set of rear tires. I now have over 16k on the odo, with about 4000 laps on the local road race tracks. It could very well be that my bushings and shocks are getting worn a bit.

2006c6keller

Good summary of facts.

The 2009 ZR1 (uses F55 type shocks with higher heat resistant fluid because of CC brakes and a different computer program) eliminates wheel hop in several ways:

1. On WOT the rear end "squats",

2. Different diameter half shafts to reduce harmonics.

Ragtop 99

The water helps the tire break traction and spin easier. Because it spins easier there is less chance of wheel hop.

My experience is that wheel hop is created when you are trying to modulate the power between spin and no spin. During a burnout you blow past that point and go into a high speed spin, hence no wheel hop.