Replacement Alloys

[rosemary]

Advice needed.
My car a 3..0 litre D MY 2010 runs on 19 inch Carelia Alloys.
Compared to my S-Type MY 2005 running on 17 inch Alloys 235/50/17 tyre size the suspension is definitely
fussy e.g. It feels every imperfection in the roads ( except one very smooth section of the
Old A40 in to Oxford) and incidentally curbing of the alloys with these wheels and tyres 245-40
is very easily done also. My query is - would a change to 17 inch or 18 inch wheels and suitable
tyre size make any noticeable difference and give a more S-Type ride. What tyre size would be appropriate
as well. Any help would be appreciated.

[J44EAG]

Short answer is that LP types and larger rims will make for a more responsive, harder and rather less compliant ride. Dropping down a rim size or two may help comfort somewhat but don`t expect the car to handle anything like as precisely. That is the difference between a comfort suspension and a sport suspension.

Tyre sizes for alternative rim sizes are listed in your owners handbook together with alternative tyre pressures dependent on your use of the car. It is always worth trying different pressures to see if you can obtain the ride you desire before going to the expense of wheel and tyre changing.

Cars with highish mileages of around 80k+ may also need replacement dampers and or bush replacements which again greatly influence ride quality when age takes its toll. Worn upper front and rear wishbone bushes affect suspension noise, harshness and vibration. Disconnect the upper ball joints then lever the inner bushes around to find the true condition of those components which can remain hidden if the ball joints are still connected.

Cars with OE rubber standard bushes can deteriorate badly in a fairly short space of time and short mileage. That is why a new car rides rather better than a three year old equivalent example.

Examine all possibilities particularly with regard to suspension bushings and dampers before changing to different wheel sizes. Best to consult a knowledgeable independent maintenance man before shelling out for different tyre/rim specs.

Autoreserve and Eurojag may be a good source of alternative rims and tyres.

Mike K

[Rictus]

All XFs have a fussy ride. I have 19" wheels as standard and 18" for winter use. I can't really tell much difference although I can certainly notice the lower profile when I have driven models with 20" wheels. I can't speak for 17" but don't really think there'll be a great benefit as the characteristics of the ride are due to the inherent suspension set up of the XF. I have changed/adapted both my springs and dampers to overcome this issue and it is something I will cover in a future feature for the magazine and would be happy to hear from other XF owners who are not content with the 'jiggly' ride of the XF - or indeed those who haven't noticed it!

Peter

[rosemary]

Thanks Peter,thanks Mike for your quick responses, it's very helpful. I was a bit concerned that a change wouldn't
produce any noticeable improvement and I was aware of the possibility of suspension mods to try and improve the ride.
I think now though that acceptance of the jiggly ride is the order of the day and making sure bushes and tyres are kept in tip top order to provide the best compromise is essential. Just got to get used to it. Glad I've kept my S-Type though, I can use that if I feel like a relaxing drive experience occasionally.

[J44EAG]

One more thing to consider. Tyre make.

I found Pirelli tyres to be somewhat harsh in service. Gon`t get me wrong in this appraisal. They are a great tyre overall. When new, they grip extremely well but go "off" markedly towards the end of their useful life and can become a bit skittish at that point. The worst aspect I found personally was that they were quite rough riding.

By comparison, I found the Dunlop Mxx range a different kettle of fish. Quieter, great grip, nicer when cornering and longer lifed. One of my favouritism tyres. The Avons I am currently running though, I cannot fault in any respect. They have lasted extremely well and work even better with a recently fitted set of sports B6 gas uprated dampers.

Suspension tuning and the eventual result achieved is very subjective from an owners stand point. The combination of rim size, percentage aspect ratio of the tyre, the type of tyre, tyre pressures. selection of damper and spring rates together with the choice of bush density or chassis stiffness will all impact in some way on how the suspension performs in service. Change any one component and a significant effect can be noticed immediately. Having recently completely modified and replaced all suspension components on my S-type, I was able to gauge the effect on each and every component replaced. One of the most noticeable effects was where bushings were concerned. Changing the front bushes on front and rear lower registers was significant together with uprating all the upper wishbone bushings. I ended up with slightly more road noise transmission but vastly less noise on broken up potholed surfaces where previously the car could become very unsettled..

I found in the ast that the jiggly ride on an S-type improved when I fitted 19" rims and the Adamesh uprated and lowered spring kit. That even when fitted with the soft cruising dampers. It improved further with the addition of the stiffer Bilstein dampers which are a top level modification and one that I recommend especially for motorway use where keeping the car going in a straight line with soft dampers had previously been challenging.

Mike

[rosemary]

Hello Mike
Funny you should mention Pirelli's, I am currently running on 4 Pirelli P Zero's which all look a bit low, just ordered a digital tyre tread gauge from Amazon to check. I am tempted to change them all anyway and start afresh. I have in fact been looking at Avons and if I can get a good deal will do so. Thanks once again for all the info from you and Peter and am looking forward to the article on the suspension mods, I recently met another XF owner who in fact has had it done,not a member,I tried to persuade him, he recommended it.

[Rictus]

Hello Mike
Funny you should mention Pirelli's, I am currently running on 4 Pirelli P Zero's which all look a bit low, just ordered a digital tyre tread gauge from Amazon to check. I am tempted to change them all anyway and start afresh. I have in fact been looking at Avons and if I can get a good deal will do so. Thanks once again for all the info from you and Peter and am looking forward to the article on the suspension mods, I recently met another XF owner who in fact has had it done,not a member,I tried to persuade him, he recommended it.

Dave,

Did the XF owner divulge where he had the suspension mods done ?

I confronted this issue when I bought my XF new in 2009 and developed a 'Comfort Suspension' set up with a leading tuning company, but there may now be other companies out there offering similar services.

Many thanks,
Peter

[rosemary]

Hello Peter
The chap said that he had it done when he purchased the car from the dealer. He said the dealer was a Jaguar specialist but I don't recall the name. He attended the Caravan meet at Arholt organised by Simon Cronin a few weeks ago
with a friend who was towing with an XJS.
Dave

[rosemary]

Advice Needed
Well I've finally decided to buy a set of alloys 17 inch and fit Winter Tyres to them. There are quite a few sets of 17inch OE alloys for sale at reasonable prices on the various "for sale" sites, people seem to want to follow fashion and get outsize wheels like those caricature ceramic models you can buy with low profile tyres, the "edgy" ride , "precise" handling and "feel the road" (bumps), the larger diameter alloys afford. I think it's a good time to buy 17inch with appropriate profile tyres now before all these people discover the truth and the experience of curbed alloys, wandering all over the road as camber and grooves change and uncomfortable ride on our 3rd world roads. My question and advice needed arise from a small note on one of the for sale sites where the seller is quoted as saying these 17 inch OE alloys bought to fit winter tyres are for sale because they don't fit because his Front brake disc diameter is too large . My front brake disc is 355mm.
How do I know that the wheels I bid for will fit my car. I have calculated the rolling lengths of various sets of tyre profile, and all are more or less the same so would have little or no impact on instrumentation Without a doubt I prefer my S-Type for ride comfort and am knocking up the miles on that in preference to long journeys in the XF.

[Rictus]

I think you may need 18" wheels for that disc size. The early petrol XFs had 17" wheels and some of the later facelift (2.2D) ones but I think the front disc sizes were smaller at 326mm.
I have the same car as you and use 18" for my winter wheels and they are a cosy fit on the front so I'm inclined to say 17" would be too tight.
Peter

[rosemary]

Thanks Peter, I thought that might be the case.
Dave

[oldtimer]

Hi Folks,
I've just read through the whole of this thread and decided that I must be the must insensitive person to ever drive a four wheeled vehicle.

I have a S type 3 litre sport running on Pirelli 235 x50 x 17 tyres and I really don't understand the problems discussed. It appears not to be correct to talk about speed these days so I shall not venture down that road other than to say that the car remains stable and strait on the Motorway at any chosen speed. Additionally, it climbs the winding Stokenchurch Hill to my satisfaction. Whilst on that hill there appears not to be lot to choose between the S type and my Mini Cooper SD - both will keep to the chosen path even when driven quite aggressively.

The S type was delivered with Pirelli Asymmetrica tyres and am extremely nervous to try a different brand in fear of a less satisfactory performance. I am not prepared to spend large sums of money just for experimental purposes.

A wide tread of 255or more x 45 x something may be very fashionable but I am of the view that it is not practical in any way shape or form. I'm sure it is ideal for dry track work but then we don't normally take part do we. However we do take park in the use of potholed roads, sit in traffic jams and held up by Mr Slow.

To me, it was not so long ago that the 70 series tyres were the new kid on the block. ie. 205 x 70 x 15 which are fitted to my XJ12 and that was road tested at 148 mph

Just my thoughts on the subject

Very Oldtimer

PS Dave, I frequently go to Studley Green to the garden centre, for coffee.PM me if it suits

[rosemary]

Hello Oldtimer
Funny but we have a Mini Cooper D as well and we tend to use this car in the winter as opposed to the Jaguars.
The problem for me is not the S-Type,17 inch wheels, it's getting in the XF, 19 inch wheels, after using the S-Type it's disconcerting, the ride is very jiggly, some people would call it "sporting". To me it's just like a Vauxhall Astra 1300 Basic model I once owned in 1987 that was "jiggly" the only difference is the leather seats and power of the XF. I think my ideal car would be the S-Type its controls ,sat nag, windscreen wipers and washers but with the XF power train.
How do you pm on this site.

[J44EAG]

The PM button is on the bottom left of the panel that you type into when you compose your text.

Jiggly ride on the DEW98 based suspension platform is not uncommon. Similar issues can also be found on the S-type and the X350. This becomes more noticable as components age and mileage accumulates. This is why a new car drives better than a thre year old example.

Bushings in the wishbones can deteriorate very quickly and affect ride quality. ARB OE grade rubbers rarely last 50K miles. Wear on lower wishbone rubber components can quickly accumulate. I`ll no longer fit standard bushes due to that issue alone preferring to fit polyurethane after market components made by Powerflex. There have a lifetime warranty.

I`ve just completed another article on DEW98 suspensions for the magazine. You will find it in the S-type Forum pages in the next December 2015 edition. Text and images explain my proceedure for building a super hard competition suspension for my old V8 S-type. Although I used competition material for a specific reason, the softer Powerflex Purple Series road going may also be applied to make for a more generally acceptable road going car.

Damper selection can also greatly influence ride quality. Typical OE grade "comfort" dampers fitted at the factory, I personally find far too soft. Uprated sports, gas units in my experience go a long way towards controlling a jiggly ride. B6 Bilstein units make the grade for me and work well with standard springs.

Every single suspension component influences ride quality in some way. I consider standard DEW 98 components to be well past their prime by about 90k miles in my experience. Tearing an old suspension apart into individual pieces will often reveal an amazing amount of wear which is near impossible to find when several components are all bolted together. The more miles covered, the worse the ride becomes. Refitted with new parts, the ride can improve dramatically.

S-type, XF and X350 all share the same basic components and issues are also common. my x350 currently wanders. I know what the problem is. in short, the car requires a suspension rebuild which is currently taking place. That is at 80k miles and I am not suprised. A similar rebuild to that done on my old S-type is now in progress and i expect to find the same defects.

Mike K