Wheel Hop, any cures for the JAG Rear

[davids2toys]

Took mmy car to the track last weekend and had a lot of problems with wheel hop, not only did I have to back out of the gas and hurt my time, but I dont want to damage my car.
I did a search on wheel hop and did not find anything addressing this...anybody have any cures?
I know with my 05 Mustang Gt it was easy, a set of LCA's and I was done, CURED! Something tells me this wont be so easy:confused:

[RJacobsen]

Dave, I don’t know if this will cure your problem but it is just a thought I had so here goes. Your car is only 4 chassis numbers newer than mine so they were built about the same time. Mine originally had a different suspension trailing arm set up than what is used now. I’m going out on a limb now because I’m not positive but I believe the older cars had the suspension link to the hub coming from a forward position on the frame and traveled back to the front of the hub. The newer set up comes from the back of the frame and travels forward to the rear of the hub. My car was updated to the newer set up and yours may have been too. The picture below shows the new set up. See if that is what you have. Hope this helps.

http://www.uniquecobra.com/gallery/files/1/5/0/5/rearsus5.jpg

[nolastyankee]

Guys,
Our chassis is 9122 and we had the trailing arm setup that linked forward to a point on the chassis outriggers. This is similar to the original Jag design, however, Alan swears switching the trailing arms to the rear makes a significant difference in handling. We installed this mod too and from my observation the rear pivot point is more neutral, and the arms are longer, both minimimizing the effect of the arm on the suspension geometry.

With that said, wheel hop begins with the suspension in a relatively static state and is induced by a harmonic vibration. My initial instinct says that, unless the suspension is way out of whack, the wheel hop is being induced somewhere other than the suspension arm. Since these cars are hand built with inconsistent parts all the way through I would think a good place to start is making sure everything is square and straight. On our car the rear end was not perfectly aligned to the chassis and we took an entire build day to ensure the whole car was as straight as possible. Because these rear ends are narrowed (meaning cut and re-welded) it is possible that there is a slight misalignment of the half shafts or suspension arms. I have not heard that wheel hop on these cars is a systemic issue so it is possible that it's vehicle specific?

[eliminator]

DONT HAVE ANY WHEEL HOP, no tire shake, just squats in the rear, a little tire spin, and LAUNCHES!!!!!!!!!!!!!!!

As long as it is pointed straight.............

[Aggressor]

Same as Eliminator. My 2001 chassis just hunkers down and goes with little wheel spin and no hop. It has rear trailing arms setup. I think the rear antisway bar really contributes also by forming another link and dampening any individual rear wheel lifting.
Image attached shows squatting under load.
-Geary

[nolastyankee]

Geary,
You mention "little wheel spin" on launch in your current setup. Not sure if you'll have the same experience with the twin Paxtons! May be something like "hunkers down, burns the skins to the rim at which point we head to the Goodyear store!"

[souzape]

1 question....do you have a limited slip axle??

Phil Souza

[davids2toys]

Dave, I don’t know if this will cure your problem but it is just a thought I had so here goes. Your car is only 4 chassis numbers newer than mine so they were built about the same time. Mine originally had a different suspension trailing arm set up than what is used now. I’m going out on a limb now because I’m not positive but I believe the older cars had the suspension link to the hub coming from a forward position on the frame and traveled back to the front of the hub. The newer set up comes from the back of the frame and travels forward to the rear of the hub. My car was updated to the newer set up and yours may have been too. The picture below shows the new set up. See if that is what you have. Hope this helps.

http://www.uniquecobra.com/gallery/files/1/5/0/5/rearsus5.jpg

Yes, this is what I have exactly, but my rear coilovers are NOT adjustable!

[pbrown]

I'm no expert but you may need to upgrade your shocks.

[davids2toys]

1 question....do you have a limited slip axle??

Phil Souza

Yes, I DO have posi.
I did not have the problem doing the burnout, I went thru the water , launched at 5000 in second gear, the actual run is where I had the problem, leaving the line at about 3000 in first.
i have notice that on the street if I am rolling at about 20 mph, put the clutch in, give it gas and let it out quickly, I get the same violent wheel Hop!

[davids2toys]

I'm no expert but you may need to upgrade your shocks.
I have pushed down on the rear fender to see if I get more than 1 bounce, and it did not go up and down, just up and stop!
If upgrading what would you recommend and how much!

[pbrown]

I think Unique offers an upgrade to Carrera coil over shocks. I'm sure Alan can give you a good price if you call.

[Justin Upchurch]

My car has a very violent wheel hop. So much so that I have never tried a burnout, even at the track. I am almost positive that this comes from rear wheel alignment being out of adjustment. The rear is toed in quite a bit and I will get the done next month ( I hope).
I would check this first. Most Uniques do not have wheel hop issues, even with the amount of power and rubber going to the ground.
On another note, do not rev the motor up and dump the clutch at 20 mph, unless you want to break something. A rolling dump of the clutch is even more of a shock to the drivetrain than going from a stand still because you are much more likely to hook up.

Justin

[davids2toys]

I think Unique offers an upgrade to Carrera coil over shocks. I'm sure Alan can give you a good price if you call.

I dont want to bother him unless I am ready to order...I just started this thread so I want to get a lot more input, maybe Alan will even chime in on this, I would like to call him, but i know he prefers questions and problems be worked out in the forums first, and calling him as a LAST RESORT!!!
Would this upgrade be adjustable? Any idea of price?

[davids2toys]

My car has a very violent wheel hop. So much so that I have never tried a burnout, even at the track. I am almost positive that this comes from rear wheel alignment being out of adjustment. The rear is toed in quite a bit and I will get the done next month ( I hope).
I would check this first. Most Uniques do not have wheel hop issues, even with the amount of power and rubber going to the ground.
On another note, do not rev the motor up and dump the clutch at 20 mph, unless you want to break something. A rolling dump of the clutch is even more of a shock to the drivetrain than going from a stand still because you are much more likely to hook up.

Justin

I would think just the opposite because you are already moving, it would be less shock:confused:

[rdorman]

This may seems like a stupid question but since I have run into it before...... I drove a car where the guys complained about wheel hop under certain conditions and it was actually severe clutch 'chatter'. Shook the car so hard, he thought it was wheel hop.

[pgermond]

I've never experienced wheel hop - just the smell of burning rubber. I have the Carrera coil over shock option.... don't know if that has anything to do with it or not.

[Justin Upchurch]

You may want to take a look at what Rick stated. If you can do a burn out than I don't know if it wheel hop. What happens when you peddel the car?
In my case I can not do a burn out, or launch hard in first gear, but spins just a little in second without the hop.

Justin

[davids2toys]

This is without a doubt wheel hop...their were people watching it, they said the tires were literally bouncing on the ground!