My car: 2010 XKR 75, 30k miles, Pirelli PZeros

Has anyone had the experience of their car becoming unsettled when pushing on through bends and adverse camber on our, sometimes, rubbish road surfaces in the UK?

I’ve had a few different XKRs over the years but found my current XKR75 back in Feb and couldn’t resist. I’m much more confident in my driving ability in these cars now that had experience.

But I’ve found the sudden instability or unsettledness a bit unnerving and I wondered if I could find some advice on making some changes to the setup without ruining it.

My first thought was to change the types from PZeros to Michelin’s PS 4Ss as I’ve heard nothing but good things.

My second thought was upgraded bushes. To this end I contacted Paramount (or VIEZU) for some advice, to which they responded with this:



I have no experience in this field but I was assured that this is regarded as an excellent handling package and one that is recommended for improved handling.

Whilst I do not doubt the above, I simply wouldn’t know. Could anyone advise?

 

Rumour has it my car is frequently driven on the 'appropriate' limits of equally windy roads, in adverse conditions, some of which are even not paved.
In these situations there is no denying the importance of tires, suspension, brakes... and for those with ample experience, turn off the traction control. and use the paddles.
Though many speak highly of their conversion to poly bushings, this is just one factor. The clouds will not part and the rains will not subside. But the feel of the road will become pronounced.

The balance of our cars never ceases to amaze me.

I would offer the suggestion, drive a car with poly bushes and see for yourself. I have elected to go back to the specs as I prefer the XKR handling (and feeling) as a GT.
In the case of tires, (and not meaning any disrespect) are your pressures appropriate. Some pump up their tires like balloons and expect good handling.
Moreover, I get an alignment done annually. And replace the tires more frequently than most.

 

Hey guy, thanks for coming back to me.

Re: tyre pressures, I wondered the same (over inflation) so on my most recent run, I re-checked the pressures and treads before I set-off. They weren’t spot on (they were lower than they should’ve been) so I made some adjustment and all where they should’ve been when I checked them against Jag’s specifications.

My confusion was around why some parts/bushes were being upgraded but others weren’t and whether that would promote additional stress on non upgrades parts or do we rely on the advice and services provided by automotive experts.

 

Harder bushings (assume that is what Paramount is recommending) will make your ride harsher. After you determine that there is no mechanical issue with existing suspension, upgrade tires. "the sudden instability or unsettledness" is exactly how I remember Pzeros that came with my car. MP4S are superior in every way, but they are not magic. Make sure you are not driving past your ability.

I highly recommend taking a racing course that focuses on recovery, as it is invaluable skill to know how to save yourself in case car loses traction. Also, remember than traction is "shared" between turning and acceleration - if you accelerate while turning you are increasing your chance of a slide or spin.

 

I can tell you I put the Michelin Pilot Sport 4S' on my Audi A8 twin-turbo V8 and they made the car come alive...... The Pirelli P-zero's were grade-school playground stuff compared to the Pilot Sports.

 

Tyre type first, then check alignment and and any failed/worn bushes. The benefits of poly bushes is invaluable substantially increasing the life expectancy of your suspension bits many times over as well as less body roll. Yes the ride will be firmer with more road feel but tyre type can also affect that as in touring vs. motorsports. I fitted Powerflex black bushes where available 5 years ago and have had zero problems.

 

I'm oftened complained about the tendency for these cars to understeer when pushed hard just we need to remember even with suspension upgrades they're still a big GT and will always handle like a GT and not a 911 or lotus

 

More gas pedal pressure? Take traction control off. I have frequently stay with wrx’ in inclement weather. Can’t do the with understeer.

 

very good. I think it more the case of the fact they don’t manufacture the other bushings...
Good job confirming the pressures by ‘driving feel’. The tire debates will get heated here ;-). I am usually in your neck of the world quite frequently. Despite the current weather, if you pick a tire ‘capable’ at cooler temperatures and grab in the damp, in the z rated category - you may be more pleased.... or even take it down a notch as this is difficult to obtain. That is, I very much prefer my summer tires. But they only work in the summer. Of the 12 months in a year, they really only work 3 of them. The other fun 6 months deserve a different tire if you are interested in really driving the car. Then there’s that other 3. Where I’m from, you are an idiot if you don’t put on proper sport winter tires.

Instead of the dealer, visit a tire shop that has a reputation of listening and prescribing useful solutions.
keep us filled in!
cheers

 

This drives me crazy. There's a freeway on-ramp in my town where there must be a vortex or something, because whenever I get on it the front end seems to want to fly away to Vegas or something. It gets me nervous even, while still under 100 mph. I'd never dare to take that ramp fast with only one hand. Spooky ****, seriously. I think I need to either lower my car or get a front splitter.

 

I have MPS4S's, wortec discs and ebc pads, black polybushes and live in the UK. I don't seem to have this issue, even when I'm 'having a play' with other cars (porsches, bmw's and latest a Noble M12 (they've all lost btw) the handling, turn in/out has been superb. Hopefully know a little about 'racing line' as competed in KZ/2 and superkarts back in the 80's

Personally I'd stick to standard bushings unless your tracking the car as have to make a conscious effort to keep my mouth closed but my teeth apart (top and bottom sets) but that may well be age!

True the bushes will not wear out but on 20 rims is sometimes a pita or should I say pitt?

Problem I have is weirdly in a straight line accelerating spiritedly (read as mashing the loud pedal in dynamic mode) from 40-100 and the back stepping out before the e-diff reigns it back in...and my tyres have over 6mm left.

In truth it may be the tarmac compound used on UK roads, it's a wee bit too soft in 75f+ temps (that we rarely see).

PS: my alignment has been done as has the fluid in my e-diff

 

Thank you all so much guys - it’s genuinely interesting to read your responses... I’ve done a little more investigation and here’s my observations

those in the UK may understand this more

The main episode I noticed the behaviour has on A and B roads between Bibury and Towcester.

I was in a spirited convoy and we’re all reasonable to expert drivers (professionals) who have spent a decent time showing me better technique for roads (not track)..

The stretches of roads I noticed this were not well maintained or had been recently damaged. As usual the cambers on some B roads are sometimes challenging so approaching, traversing and exiting of bends and corners were treated with some restraint

Many of these routes were new to me but not to the others.

On better surfaces I have had no stability or unsettled behaviour unless I’ve made a mistake.

I re-took the route yesterday and paid more attention to the road conditions - I’m not saying they were dreadful all over and at a sedate pace there’s no problem, the car was more than capable. However if I had been driving a track prepared car i would have been bottoming out or having the suspension limits crashing in places where there were damaged parts.

So I get why the car was unsettled at times. Road quality and a route I wasn’t familiar with. revisiting it gave me some prewarning and less mistakes.

Conclusion... I think I’ll start with a set of MPS4Ss and an alignment for that additional traction and bite before I consider a handling pack. I need to understand better how those components inter-exist before sucking and seeing how they affect the drivability - chattery teeth isn’t something I want to invest nearly a thousand pounds in 😉

 

Agreed, the MPS4S is a brilliant multi- use tyre and a little more negative camber will
help them stick to the road.