What causes wheel hop in the 8?
 

I don't see other cars have much problem with wheelspin / wheel hop. Is it the wheels? The gearbox?

WHeel hop can be a combination of:

- tread/contact patch
- pressure
- torque
- surface

But mostly it's user error ;)

What about say 0-60 runs... It seems if you launch from >4000rpm ypu can get a lot of wheelhop and seriously damage your gearbox

It's not the high RPM's that cause it, it's not feathering the clutch properly. Dumping the clutch isn't always the best method, nor is spinning like mad. But as I alluded to, you can prevent wheel hop with feathering and tire pressures - just takes practice.

Lots of cars can exhibit wheel hop on hard acceleration. Keep reading, you'll find stories.

-Eric

Well you can re duce wheelhop a little by lowering tire pressure.

My theory is the motor mounts, If I had an 8 I would have already tried...but no one with an 8 seems to care that much.

Wheel hop is aggrevated by the 18" wheels. They use low profile tires. Tire sidewalls absorb shock, and when they are lower than 50 series or so, you will really make wheel hop much worse.

Those who drag race 3rd gen RX-7s find 15" rear wheels help a lot with 70 series tires (to keep overall diameter the same as the front) or special drag racing tires with really flexible side walls. Don't try this if you want to go around corners fast though. The higher sidewall flex in the rear will give you terrific oversteer, the most dangerous handling condition for most drivers.

Mazda RWD cars seem to suffer from wheel hop more than other brands. The Miata suffers from significant wheel hop even if running 60 series tires on 14" wheels. No one in the Miata forum has found a solution or truly knows the reason. The plus is Mazda RWD cars seem to be more agile than other brands.

I'm not buying the wheel size/tire aspect ratio argument given by a few here since there has been no correlation for this found on Miatas. What is known is that wheel hop is caused by stored energy suddenly being released. What we do not know is where is this energy being stored and what is the trigger for it being released. Energy is being stored in the suspension bushings and flex for the links in addition to the tires. Which one is the culprit and what is the trigger?

Energy is being stored in every flexible component of the drivetrain except the springs.
The trigger is the energy getting to the threshold where the last remaining storage point, the tires, are "full" and the traction limit is then exceded.
Each "hop" occurs as traction is lost and the only remaining energy absorber is the coil spring.
When traction is lost, the only effective vector is up and into the spring. Longitutionally, everything is already "full".

Yeah, I agree about Mazdas... the FD I drove wheel hopped badly if not careful. And I also don't agree about tire aspect ratio... I've driven Vette's from about 96 on with 17's and they don't exhibit *any* wheel hop, just wheelspin.

So how do we solve it?

Well, as previously mentioned, you could lower your tire pressures a bit, but cornering would suffer. A different tire might solve or reduce the issue, as well. However, if what MazdaManiac is saying is correct, I'd be interested to see if a new spring or coilover set up would eliminate wheel hop.

A friend of mine has a 3rd gen that runs 12.50's. He said he got a lot of wheel hop until he switched to street legal drag radials. He's big into drag racing so he doesn't mind giving up cornering for straigt line performance. All the other high performance summer tires he used would hop even with lower pressure.

Wheel hop is all about not being able to damp the very high spring rates of the rubber that the suspension is mounted in.

One of the fixes would be to change out the soft bushings with harder ones.

The other would be with adjustable racing shocks and crank up both bump and rebound damping.

The problem with bushings is that I don't think anyone makes aftermarket bushings yet.

The problem with custom racing shocks is that if you have so much damping to control crazy wheel hop that the car might jack down.

Time and trials...

Vince

Think of wheelhop as loose suspension windup and release.

Pin the motor and transmission. Hopefully someone comes up with upgraded motor/ tranny mounts. I know that the Fc and Fd Rx7s have upgraded motor/tranny/rearend mounts/and motor shocks.
Upper and lower bracing help.

Poly/increased durometer rubber bushings in the rear subframe/rear arms/rearendmounts will help reduce wheel hop.

Proper tire/spring/shock selection will also help with wheelhop. Any production car will have sacrifices to cater to most buyers.

Eliminate any/all slack in the drivetrain/unibody will help reduce wheel hop. Unibody xbraces and multipoint interior bars might help.

If something isn't developed yet, everyone needs to merge resources and get the aftermarket working on the '8 for more parts.

Power is worthless if it can't be harnessed.

This is what I have been saying all along.

The motor/tranny mounts are not solid. In fact they probably have rather large holes in them. This is for comfort, so the car does not vibrate at idle.

If you get some motor/tranny mount inserts made out of polyurethene to fill the holes then most of your wheelhop will be gone. (or you could fill the mounts with polly)

I would try motor mounts first, then tranny mounts if still needed.