GTS Rear Wheel Hopping/Shifter slapping......Continued

[Andrew/USPWR]

The saga continues......
I Had two World renowned Viper experts put the car up on the lift this weekend, they could find nothing broken or loose under the car.
Still, (with the car pointed straight) I get the shifter slapping left and right when I breaking the rear tire's loose.
But, if the wheel is turned ie: to do a donut ( on wet surface) the shifter doesn't move. I don't know what to have looked at next. The Transmission?

The Riddler

 

[Vip-RT10]

It seems like the tires skip when you hit the gas and break the tires loose when the tires are cold. What type tyres do you have on? If you have the old Mich MXGTZ, that is the culprit. So it does it only when the car is breaking loose in first?

 

[Vipermed 97.01]

Not that easy Antonio,He has a 00.Tom and I looked at it this weekend.Andrew, i have been thinking a lot about it.have you tried doing the scenario with a bystander outside watching to see if in fact it is really wheel hop.Try that and give me a call i have a couple other ideas

Scott

 

[FE 065]

If there was something THAT wrong with the trans it'd seem you'd have a pile of ground metal instead of gears in the trans case by now. If it's not the trans mount.. maybe a broken motor mount letting the engine AND trans move around when straight, but when doing the doughnut the motor is held down by the effects of the car turning? A terrifying puzzler for sure.

 

[Vipermed 97.01]

If there was something THAT wrong with the trans it'd seem you'd have a pile of ground metal instead of gears in the trans case by now. If it's not the trans mount.. maybe a broken motor mount letting the engine AND trans move around when straight, but when doing the doughnut the motor is held down by the effects of the car turning? A terrifying puzzler for sure.

I drove Andrews car and when it did it for me i expected to find something obvious when putting on the rack,but to my surprise found nothing,trans mount/cross member fine,motor mts fine,rear suspension and differential tight.Whatever problem he is having definetly is not normal.He had some diff. and shaft upgrades recently.That seems to be the place to start.

 

[99 R/T 10]

Missing bolt out of the rear end? Sometimes it is hard to tell the mounts on the engine or trans are split unless under load. Just curious Scott, did you put a jack under each spot to see if a gap could be produced?

 

[Andrew/USPWR]

That was going to be my next step. Have someone video the car while I launch it and see what's shaking. Maybe even shoot the under carridge.
I'm not sure if I should let it worry me or just wait till something breaks and then take it in.
Andrew

 

[FE 065]

At first thought, if the only thing connecting the engine and trans to the rear end assembly is a drive shaft, how could anything in the rear make the trans twist sideways? Especially if the mounts are okay?
- Though stranger things have happened I suppose
Hey, how about putting on the parking brake, opening the hood, and easing out the clutch slightly in either first or reverse to see if the engine rises up excessively or the trans/shifter heels over ? The engine will normally twist to the right some, of course.

 

[Tom F&L GoR]

I vote for wheel hop - intermittent slip-stick traction with each wheel behaving independently. When a tire sticks, the driveshaft pulls (rotates) the transmission/engine over. When a tire slips, it lets go and the trans/engine falls back into place.

The rear is only attached via two large bushings above the differential and the long torque arm. I'm sure the folks have inspected the bushings, but if one or both were loose or the rubber cushion damaged, that may cause the wheel hop. In my case, I had the two bolts attaching the torque arm to the housing be a little loose. Not falling out loose, but not up to the torque spec either. (Thanks to Sean Roe for that suggestion.) That allowed the housing to rotate a little, causing some wheel hop.

Another fix for me (and perhaps a diagnostic tool for you) is to try higher tire pressure - the tire is a spring, after all. With a stiffer tire, the hop may change or go away. Same idea is to stiffen the rear shock setting. That turned out to be the magic bullet for me; OEM setting is full soft and I went 2 half turns (out of five half turns to full stiff.)

 

[Andrew/USPWR]

I'm sending video of the shifter slapping around and the back tire breaking loose to vipermed now.
I've been launching it on wet surfaces lately and it's not hoping. But what concerns me more is what the shifter is doing.

 

[SingleMalt]

I vote for wheel hop - intermittent slip-stick traction with each wheel behaving independently. When a tire sticks, the driveshaft pulls (rotates) the transmission/engine over. When a tire slips, it lets go and the trans/engine falls back into place.

The rear is only attached via two large bushings above the differential and the long torque arm. I'm sure the folks have inspected the bushings, but if one or both were loose or the rubber cushion damaged, that may cause the wheel hop. In my case, I had the two bolts attaching the torque arm to the housing be a little loose. Not falling out loose, but not up to the torque spec either. (Thanks to Sean Roe for that suggestion.) That allowed the housing to rotate a little, causing some wheel hop.

Another fix for me (and perhaps a diagnostic tool for you) is to try higher tire pressure - the tire is a spring, after all. With a stiffer tire, the hop may change or go away. Same idea is to stiffen the rear shock setting. That turned out to be the magic bullet for me; OEM setting is full soft and I went 2 half turns (out of five half turns to full stiff.)

I'm with you, Tom. Try this: Inflate the tires to 44 lbs and then see if you get the same craziness. I think you'll find either the sidewalls are the culprit or, like Tom says, you've got some bushing wear...

My .02

 

[Andrew/USPWR]

I've been getting the rear tire to spin without the hop, with 29 psi. but the shifter, regardless. beats the hell out of my center consul. That's want I'm really worried about.

Andrew

 

[Vipermed 97.01]

Andrew.....Youve got mail

 

[FE 065]

I vote for wheel hop - intermittent slip-stick traction with each wheel behaving independently. When a tire sticks, the driveshaft pulls (rotates) the transmission/engine over. When a tire slips, it lets go and the trans/engine falls back into place.

The rear is only attached via two large bushings above the differential and the long torque arm. I'm sure the folks have inspected the bushings, but if one or both were loose or the rubber cushion damaged, that may cause the wheel hop. In my case, I had the two bolts attaching the torque arm to the housing be a little loose. Not falling out loose, but not up to the torque spec either. (Thanks to Sean Roe for that suggestion.) That allowed the housing to rotate a little, causing some wheel hop.

Another fix for me (and perhaps a diagnostic tool for you) is to try higher tire pressure - the tire is a spring, after all. With a stiffer tire, the hop may change or go away. Same idea is to stiffen the rear shock setting. That turned out to be the magic bullet for me; OEM setting is full soft and I went 2 half turns (out of five half turns to full stiff.)

I'm no expert, but the engine and trans shouldn't be rising that much and 'falling back into place' if the mounts are intact should they?? : /