Hi folks,

I went out with a group of friends for a 100 mile drive today in a variety of nice cars. Because most of them were faster than my manual 2009 V8V and driven by more experienced people I was happy to bring up the rear.

The Good

I drove 30 gentle miles on the highway to the meeting spot, then 100 miles of spirited driving (4000-6000 RPM almost the whole time). Amazingly, I got an average of 15.7 MPG for these 130 miles. I'm pretty impressed since I did not hold back. The ride was comfortable and there were no heat issues or other problems -- she did great (and was the prettiest car there).

The Bad

For a lot of the windy roads the back end was a bit unstable and not reassuring. It seemed to hop around a fair bit and the traction control light was on constantly. I have the sports package and 19" wheels. I brought the tire pressure to 33/36 as recommended last night so that was not an issue. All in all this kept me going slower than I could have otherwise, because it felt unsafe to go faster.

Any thoughts on why this was the case? These were all nicely paved roads in perfect weather conditions on a warm day (mid-60s F I'd say), and my tires are recent. As I said I'm not an experienced driver but I don't think I did anything egregiously wrong. Is it common for the Vantage back end to bounce around and not stick very well, causing traction control to come on regularly?

Thanks!

 

When I had my previous 07 Vantage, I'd run with the Minnesota 928's who would cruise Wisconsins dairy roads at incredible speeds for a group of old Porsches that ranged from just over 200 to 316 Horsepower, most were stock. My Chevy powered 928 had some initial growing pains over time solved (450 hp). The few times the runs happened when the 928 was in the shop I used my Aston, and once the old cars hit over 100 mph, they were in their zone and I really had to push the Vantage to keep up with these geezers of sports cars. One time i passed an off duty cop doing about 130 mph, he eventually caught up with our group and i got ticketed for passing in a no passing zone, a minor offense... Ending my days of driving in a group of guys that leave common sense behind when the adrenalin of speed kicks in.

 

OP get the 4 wheel alignment checked & adjusted
It made a massive difference on my old sport pack car

 

Couple questions to help us understand;

What specific tires are you using?
When you say "rear end bouncing around", do you mean bouncing from shocks/springs (suspension), or more like sliding tires. In other words, was the movement in the rear end more vertical hopping, or lateral sliding?

 

This.

I've NEVER experienced anything like the OP talks about with my 07 sports pack and PSS tires. Even with undulations in the road, the back has always felt supremely planted in turns. I typically take turns at around 20-25 over the recommended speed. However, in 8 months of ownership I've only seen the traction control light twice. Maybe you're pushing the car too far? I'd certainly get the alignment checked though... these cars are very capable in the corners.

EDIT: Jealous of your MPG though. I usually get 10-12 when I'm pushing it. A short drive usually results in at least a 1/4 tank gone, if not 1/2.

 

What tires are you running on the car ?

 

I had the same feeling when I had hr springs on my car. My stock dampers were not able to handle the rebound and the car felt unsafe at high speeds when hitting bumps. It is much better now that I have kW v3 coilovers. I'm not saying this is your case but I would check the alignment and see if the dampers are holding up.


And lastly your mpg is amazing I never see double digits when driving aggressively.

 

Thanks all. The tires are Potenza RE050A, stock size (235/40/19 and 275/35/19 if memory serves).

I've never had the alignment checked, I will do that. Thanks for the tip. I've occasionally seen the traction come on on the highway on a long tight curve while sustaining speed, which seems surprising. I had heard it comes on a lot though which leads to the rear pads being used up before the front (which I've never heard of in another car).

The movement of the car is hard to describe. The back did not slide i.e. oversteer, the traction control prevented that. It was more that I felt jostled braking and turning into corners, which made braking and entering the turn feel less reassuring and safe than I wanted. I'm thinking that if the car was hopping in the rear this would have reduced grip and caused traction control to come on. Does that sound right?

On a related note, is there any adjustability (either mechanical or electronic) in the sports suspension that I could tweak? Or would it be a question of replacing parts?

 

Stock tyres then
I've had them on 7 cars now and I change them as soon as I can they are rubbish
Michelin PPS work well on the Vantage
The Aston traction control is quite invasive, it comes on well before the light does. I killed a set of rear pads in my stock S in 12k miles with only occasional flickering of the light.
On my S it is three stage and I was advised to put it in track mode, that made a big difference
the symptoms you describe are classic geo, though the RE050's feel unstable when they get to ~3mm IME
There is no adjustment on the sport pack dampers

 

I agree 100% with this.

 

I'm with these guys. Not a fan of 050's. really do like the Michelin PSS on my car. Something else, when I run performance street tires on a track, I start them lower then 33/36. Usually somewhere around 31. This wouldn't make them bounce in the manner you're talking about. Just that at higher starting pressures, with longer periods of aggressive driving, they could become greasier than optimal.

I will add, my personal general feeling is that the car is under damped.

So overall, I'd say check alignment, maybe different tires, and slightly lower pressures.

 

Are the Michelin PSS unidirectional (i.e. is there an arrow indicating direction of rotation)? Unfortunately their website doesn't say. The reason I ask is that given the different front and rear dimensions, if the tires are unidirectional they can't be rotated. If they are asymmetrical but can be rotated either way then they can be rotated by swapping left and right sides, which should extend their lifetime.

 

The Michelin PSS, as with the OEM tires, are not unidirectional. They simply have an indication of which tire face should be on the outside. You could potentially swap them left to right if you wanted to.

 

Thanks. I did see the word OUTSIDE on the Potenzas. At least I know they were put on right and that's not the problem.

By the way, when is the recommended time to replace brake pads? According to the January inspection I had 8mm left in the front and 4mm left in the rear, but the OEM ones are so dusty I might change them early anyway. Just wondering how much life is left in them.

 

Where did you get your KWV3's? I have them on my 911 and love it. Maybe I should get it instead of the HR's I have now...