Hi all,
I love the XKR power and sound but find that it all too easily loses traction even with a gentle right foot. I currently have Dunlop SP Sport Maxx tyres on the rear but despite that I've had the back end squirming around on hard acceleration from 60mph. Has anyone got any suggestions as to how to improve the grip? I'm interested to hear ideas on the topics of:

1. Choice of tyres
2. Better shocks/springs
3. Using polybushes

Look forward to hearing your thoughts

 

Race tires is about your only option, and those won't help a whole lot either. The softest compound you can find that are 'hopefully' street legal.
In the US many years ago there was a BFG Drag Radial, but I've not seen a replacement for those since they've gone away. I have a couple pair, but they are well worn and fit for an old Mustang of mine. They worked pretty well, but didn't last much at all. Gooey as all heck though. They were not for daily street use.
Maybe go full sticky slick for when you have the urge to go zoomie?

 

Race compound tyres or even hybrids like the Cup 2s require warming up before they get sticky. For straight line traction you want zero camber but for cornering traction you’ll need negative camber. Bushes, springs, coil overs will provide stiffer, more precise handling but not do much for traction. A good LSD like Quaife will make a difference but you’ve the e-diff so no option there.

 

Unfortunately slick tyres aren't an option for UK road use. Has anyone polybushes the subframes to reduce the amount of deflection in geometry under acceleration and cornering?

 

Do you know of any available? I’ve searched and not found any but could use a set.

 

Frankly, I like knowing there’s enough ponies to do that.
You’ve selected good tires… but not great. You haven’t mentioned the age or milage on them. Nor have you mentioned the ambient temperature or dampness on the road when this situation is exacerbated.

But there is one glaring omission: does your car have an LSD :-D

Poly bushes will not help with the traction. Shocks and springs may…. only while the car is in motion.
But don’t discount the right rubber and tire pressures and tread pattern for the road ahead. FWIW, I discovered that the Dunlops behaved as you describe …. (there may even be a posting on that) on the xjr. Replaced them within the month. The difference was substantial. Those particular tires take too long to warm up and the situation compounded by the weather here.

 

[QUOTE=DorsetJag;2475268]Hi all,
I love the XKR power and sound but find that it all too easily loses traction even with a gentle right foot. I currently have Dunlop SP Sport Maxx tyres on the rear but despite that I've had the back end squirming around on hard acceleration from 60mph. Has anyone got any suggestions as to how to improve the grip? I'm interested to hear ideas on the topics of:

1. Choice of tyres
2. Better shocks/springs
3. Using polybushes

Look forward to hearing your thoughts

 

Sorry about screwing up my last answer and posting it the wrong place. I drive a 2012 XKR convertible, The michelins are outstanding above 40° f. Since I only drive the car in the summer they're great for me. They're on my car most of the summer this year and I love the tires. The grip is like no other brand I've ever owned. I've had michelin's on another high performance car and was just as happy. If you're looking for all season tires I would look at Michelin as well. Make sure they're all season high performance. I think you'll be happy

 

I had worn out Michelin Pilot Sport All Season 4s--- on my x100 xk8 (low hp) and replaced with Dunlap Sps. They were very ‘greasy’, that is they gripped but not as well as the worn out Michelins and although controllable they were easy to get into sliding/slipping around turns at speed. At 10K I replaced them with Continental Extreme Contact Sport and they were much better in all aspects. The only reason I didn’t go back to the Michelins was cost.

My new to me xk150 (low hp) also had worn out Michelins on it and this time I have installed Sumitomo HTR Z5. It’s is too early to determine if this was a smart move or not, I have no complaints as to grip, noise, ride quality but with only 800 miles on them it wouldn’t be fair to make a real assessment. Once again the only reason I didn’t go for the known great tire (Michelin Pilot Sport 4s was cost-$1750 vs. $1200)

wj

 

You're a braver man than me - I've never tried hard acceleration from 60mph to know how much wheelspin there would be but I can imagine the Sport Maxx do not deal well with the sudden demand for more speed! I had them fitted to my 2011 XKR and even when the tyres were new, it was so easy to get the tail sliding out when accelerating away from a traffic island if the car was was not perfectly straight, and I always started off from a standstill in second gear to avoid the embarrassment of the inevitable wheelspin in first (I always drive in Dynamic mode using the paddle gear shifts). I changed them last year for Michelin Pilot Sport 4S which I find much better. I did a lot of on-line research before choosing them - they are well recommended, not cheap but I look at the cost over the lifetime of the tyres and for the extra annual cost, think worthwhile paying the premium. For a full set, I paid £804 from Blackcircles fitted at Tesco's tyre station at the local superstore.
The standard factory suspension set-up works well enough on what, for me, is exclusively, a road car where improving traction by better tyre choice is the best solution. My 5.0L XKR has an electronically controlled limited slip differential which the 4.2L does not have - which model is yours? Dynamic mode also firms up the suspension enough for my needs, too - any more would make it uncomfortable on long trips.

 

In my experience, that is your problem, especially if they are getting on a bit.

My '10 XKR had them as well when I bought it and they really didn't inspire confidence, especially on moist roads. The backend would step out with little provocation so I lost quite a bit of confidence in it. I switched to Michelin Pilot Sport 4S's and now have over 100bhp more than a standard XKR and find the car very sure footed.

I had the Sport Maxx's on my 4.2 XKR as well and thought I had an issue with a wheel bearing but discovered it was just that the tyres were very noisy.

 

I had the same problem with the dunlops . Back end would step out when passing . Worse at low speeds but containable and more of a concern at 60-70 mph range. Went to Conti's DWS 06 and started to feather the right foot. I have the Michelins on the new car and they ar stuck like glue but then again the engine is in the rear so that helps it stay planted.

 

*sigh*

 

continental DWS were good for me for a couple years, but then they gave up all at once from cracking in wintertime. now wearing yokohama advan apex v601 https://www.yokohamatire.com/tires/advan-apex-v601 which is decidedly grippier.

 

Having 700hp and 850nm i was unable to get any traction with a PilotSport 4S
Switched to semi-slick (road legal) Westlake SportRS and that really improved 0-100 acceleration (however still spinning a wheels up to 140kmh)

 

🥳 @MoscowLeaper , I luv that! It goes without saying you need to know how to drive/manage your car… and you do.
And yet I’m surrounded by those that just tromp on the accelerator and expect the active dynamics of the car to save them. What I particularly like about this car is its balance. I can choose to spin or not spin the rears on demand, thus able to move the car in all weather, all conditions and all roads. Of course if the fronts don’t grab you’ve got big problems. For the weather here I have 3 full sets of tires. i.e. the appropriate grip for all conditions.

 

Im not using TractionCtrl/DSC - the first thing i do after an engine start - is holding a button for a 10sec. So no adaptive dynamics control, except for a diff lockup and suspension adjustments and it's me who decides to spin or not to spin
However i have a 2nd set of tyres for winter, but that's a rather diffrent story.

 

same. i turn all the cr.. off. there’s a few of us who do.

 

I did on my 2008 MY 4.2, purples all around and black on front and rear anti roll bars. Did improve the turn in but also made the ride a little bit more unforgiving. I have not done this on the Dynamic R, it sits lower and turn is is great. I also used poly bushes on my S Type, which worked well, I was getting fed up of replacing the standard bushes and once fitted never had to replace them.

 

Hi all, thanks for the replies a great deal of useful information here. I will try and answer you all here:

@guy the current tyres are about 3 years old with 6000 miles on them. Still plenty of tread. I'm in the south of the UK where ambient temps are between 8c and 25c all year. We don't get many days where it's outside this range. Yes I have the 5.0 with the e-LSD. However on colder damp days I use Winter mode on my commute to prevent losing it, particularly when joining busy traffic when you're concentrating on getting out into a gap more than exactly how much gas you're giving it. I'm still adjusting from the previous car (chipped Porsche Macan Diesel S with a paltry 300bhp).

@donricardo440 yes I will look at Pilot Sports. The Dunlops have a hard somewhat greasy feel when you put your hand over them. My other concern with tyre choice is rim protection. Do the Michelins have a wide rim protector band? Anyone used Ally gaters?

@Marco Polo I was overtaking on one of our lovely Dorset roads with nice straights, downshifted manually ad got the back end shimmying and traction control light flashing. It was still very controllable though. Thanks for the buying advice. I've also used BlackCircles and found them good 👍

@u102768 I would love to hear what you have done to get the extra 100bhp?

@jahummer Powerflex sell a full set in the UK. Not sure about USA. Powerflex X150 link

@Mchammer interesting to hear your feedback. I was thinking of changing the torsion bar bushes to start rather than everything. The ride is already fairly firm and I don't want it to become jittery.

Again, thanks all for your contributions 😃