Twitchy Back End

[Blueone]

Dodgy title I know.

This is my first autumn/winter with my F-Type and I’ve noticed that the back end is extremely twitchy under medium to hard acceleration. Snakes about at the back quite badly when trying to accelerate almost to the point where I’m wondering if there’s something wrong. This happened yesterday afternoon when the road wasn’t wet (or at least didn’t didn’t look wet) and the temperature was 5/6°.

I’ve only got the 340 and don’t consider it to be a particularly fast/powerful car so I wasn’t expecting it. My 2002 M3 wasn’t as twitchy and had about the same power.

Is this normal for the F-Type? I’m wondering if it’s the stock tires shipped with the car?

[simpleR]

Check your tyre pressures? My 400 is "loose" for want of a better word if below 37psi (20" wheels).

[scm]

Do you have AWD/ If so, I'm surprised - my V8 feels really planted (mayeb it's the extra weight!), and I have tried to get it to twitch! My test corner, where I'd easily lose the back end of my previous XKR is taken without drama in the F-Type.

Regarding tyres, lots of folk reckon the Pirellis are duds compared to the Michelin PS4S, if true I'm looking forward to even better grip when I replace the tyres.

[Derivative]

Mine's all over the place at the moment with greasy, salted, damp, leaf covered, muddy roads. Needs a good downpour to wash that lot away.

[Blueone]

Check your tyre pressures? My 400 is "loose" for want of a better word if below 37psi (20" wheels).

Thanks for this. I think this may be it as I had a tyre pressure light come on a few days later. I’m also on 20” wheels. Where do you set them at for optimum grip? I assumed the more deflated they were, the more surface area so less slip. But that’s probably me showing my ignorance when it comes to basic physics...

SCM - RWD on mine. I can see why they make the 400AWD and obviously the V8. No way you could put that down through the rear wheels only.

Derivative - Thanks. Makes me feel like I’m not alone with this at the moment!

[simpleR]

Thanks for this. I think this may be it as I had a tyre pressure light come on a few days later. I’m also on 20” wheels. Where do you set them at for optimum grip? I assumed the more deflated they were, the more surface area so less slip. But that’s probably me showing my ignorance when it comes to basic physics...

That's the challenge!

I set mine to 37PSI all around when it was about 5C
When it was -3C last week they were at 34PSI from cold start but soon got to 37PSI
However on the motorway for 100 miles at 9C the fronts warmed to 38/39PSI and the rears to 39/40PSI.
Tricky with temperature changes.

If you have the tyre pressure amber warning light on then you have a tyre lower than 32PSI. I am not a physics person either but a quick Google said:

Less pressure means less grip - An under-inflated tyre will only touch the road on the edges and not in the middle; less surface area means less grip, especially when cornering. Driving through surface water on tyres with low pressure increases the risk of aqua-plaining. As a result, less grip increases the risk of skidding and having a collision.

[scm]

And it's easy to check the pressures through the menu system - I check mine on start-up and occasionally peep at them during a drive!

[chicb]

The problem is that summer tyres are no use below 7 degrees C. That is why your grip is reduced. You can play about with pressures as much as you want, but the problem is the rubber compound, it just goes hard in low temps. You really need winter tyres
Check out these 2 videos. Even 4 wheel drive on summer tyres is not as good as 2 wheel drive on winter tyres (second video) This is probably the best video as its not so technical

[RPSN]

I’m assuming your tyres have plenty of tread on them so first thing to do is ensure your tyre pressures are 37 psi all round (for speeds up to 155 mph). You can check the tyre pressures through the vehicle information menu. This should be done when the tyres are cold and the vehicle has been stationary for more than 3 hours.

If, after doing this, your car is still extremely twitchy under medium to hard acceleration then the cause of it is the stock tyres that came with your car.

I’m running Michelin Pilot Sport 4 S tyres (275/35ZR19) on the rear and Michelin Pilot Sport 4 (245/40ZR19) on the front of my V6 S 380PS (RWD). The reason for the slight difference is that Michelin don't make a 245/40ZR19 PS4S for the fronts. I’ve had no problems with the back end snaking under medium to hard acceleration.

These tyres are the choice of many F-Type owners due to their outstanding qualities.

[JFT2016]

I had exactly the same experience with my RWD 340 V6. It came on 18" wheels with Continental Sport Contact tyres. Those tyres were utter rubbish in the wet and made the car feel quite unerving at times. Embarrassing to exit a roundabout at 25mph sideways in a skid! Unfortunately the better tyres such as the Michelin pilot sports aren't available under 19" but I now have Dunlop sport maxx RT tyres and the car has been transformed.