lfish

I need assistance in tracking down the cause for a change in my 6GT3's handling. Just recently I noticed that upon lane changes at freeway speeds the rear end has undamped lateral motions that feel like the tail is wagging the dog. The mechanic I trust has looked the car over and found minor issues with the alignment and some softness or play in the rear lower control arm bushings but feels that neither explains the aberrant handling. The car has two new rear Hankook Ventus EVO tires which are OEM size, and the issue of sidewall weakness was raised. I have used this brand previously at two DE last year and was satisfied with their performance. Tire pressures were normal (32 front, 35 rear). The engine and transmission are performing well, but I am wondering if a weakened motor mount could be the cause. The car is entirely stock with 18000 miles and no history of accidents. Any guidance would be much appreciated.

Burger

How new are the tires? Full tread Hankooks are fairly squirmy. They will stiffen up over time/heat cycles.

lfish

The tires were installed at the end of last year. The car was stored over the winter and driven occasionally when the temperature was in the forties (not often!)

AudiOn19s

Larry, sorry I didn't get back to you yesterday work got crazy and I was packing all night for Putnam.

If that the same set of Hankooks that you used at the track they should be good to go now. If that's a brand new set I almost guarantee that's the issue. I had the v12's on my M3 for about 1000 miles before I sold it and the tread squirm was sooo alarming that It ruined driving the car for me. I had read reviews that the squirm on those tires when new was really bad but it was beyond anything I had ever expected. It would set off the traction control in the M3 going around mild bends at "regular" speeds. Craziest thing I've ever experienced.

Matter of fact until I road in your car while instructing I thought that the V12 was possibly the worst tire ever but they did good on your car at the track once they were worn in.

lfish

Thanks for the input guys. Danny at P3 Auto in Centerville will be swapping the tires/wheels today for a set of MPSCs. I will be happy to provide an update once this is sorted out!

plima

I, too, made the bad mistake of installing those Hankook tires on my GT3. The only way to mitigate that wallow/squirm is to increase the tire pressures. I run 3 psi over the normal (Michelin friendly) 32/39 and they are OK. The decision to by Hankook (at $800 less than PS2) was clearly penny wise and pound foolish. Bad mistake

fbirch

I put a set of the V12's on my stock rims for street driving. Just for kicks I took them out on track once and didn't think that were that terrible. For me, they're about 4-5 sec a lap slower than Yokohama AD08's, and yes they do squirm around a bit, but on the plus side, they're very plush for street driving (and cheap).

Marv

Yes, those tires are as squirrelly as whale blubber on jello. I've been down that road twice with them.

It takes a few hundred miles to get them to the point where they become tolerable. They never will ride like the PS2s, but they do grip well. It is just that the side wells are squirmy and they are much worse when you have new tread.

Since I have two iterations under my belt I have returned to PS2s and will stick with them from now on.

lfish

Danny at P3 put a set of MPSC on the car and reported that the handling issue was not improved. Looking into performance bushings for the rear control arms...will keep you posted. BTW I have used the Hankooks on both my BMWs (E39 540i and E46 M3) and never had issues; successfully tracked both cars at MidOhio and Putnam Park with predictable behavior.

runet

At 18000 miles and 10 years your dampers are most likely starting to fail, and should be rebuild. My car behaved like you described when they needed rebuilding at about the same milage. DE/track work will accelerate wear.

If your LSD is original you have an open diff as well by this stage.

lfish

Thanks for the input. Control arms from Elephant Racing are ordered and should be installed next week. Will check into dampers and LSD as well.