www.jec.org.uk

The Manual says not to rotate the tires; but last visit, the dealer rotated the tires, and the ride was markedly changed for the worse. He says that the tires are supposed to be rotated, front to back. Are they?

I can't claim experience of BBS Milan rims, but I have always rotated the tyres on my X308s to even out tyre wear without any problems. All I can say is that the ride and handling on 19" Apollos (and I've had two different X308 XJRs running on them) is not nearly as good as the ride on 18" Penta rims or 17" Celtics.

Is it possible that you have unidirectional tyres and they've mixed them up so they're rotating the wrong way?

I don't rotate the tyres on my cars. If you look at worn rear tyres they always seem to have a wear bias across the tread, wearing more from the inside than the outside edges due to the slight angle from the IRS even at normal loads. The tread on the front tyres also gets a slight 'saw toothed' shaped effect from the reaction to braking forces. If you then put these tyres on the the opposite wheels it is not surprising that strange handling results.

Regularly rotating tyres dates back to the cross ply era. When cars progressed to independent front and rear suspension manufacturers stopped recommending rotating tyres. The front tyres wear curved and rear tyres wear flat so if they were rotated the front would be heavy and the rear would be light. Also if you kerb a wheel and put the track out either front or rear, rotating the tyres may hide the problem.
Bruce

As above with a good Laser four wheel alignment. I've used Hunter-fitted franchises with good results on both
my Passat (very sensitive to tracking, rear wheel alignment drifts out due to weak OEM bushes' wear) And more recently my XJ8 Exec (see previous thread Whrrrrr!)

Bush collapse is indeed one of the biggest maintenance challenges facing any car owner. Standard bushes are usually made from soft, degradable rubber and given around 50k miles of use, I`ve learned that one can begin to see the first signs of wear beginning to impact on handling, ride quality and tyre longevity.

Eventually an owner finds he is told that wear is evident on a couple of bushes. So he has those changed. Slightly later, a further number also need replacement. That done, the owner talks himself into a false sense of security and conciders his car to be back at a factory level of mechanical integrity. Not so, I`m afraid. If a couple of bushes have wear, then to a greater or lesser extent, so too will all the other bushes on the car be on the decline. If you doubt this, knock your car to bits, then come back and tell me what you found!

Any person who does his own bush replacement, soon finds that if he strips out all his wishbones, hub carriers, vertical legs and vertical ARB links and places them all on the bench for evaluation, finds that all bushings will probably have some degree of wear evident and at that point the need for replacement of the majority of bushes becomes obvious. Examination of bushes on a vehicle is rarely sufficient or does it allow sufficient examination potential due to triangulation issues. It is supprising how much bush wear can be camaflaged with all the component parts linked up in situe. Only when links are dismantled, does the true state become evident.

On S-type, X350 and XF models from MY2002.5 onwards, all share the same core suspension components. They can be swapped across the range without difficulties with only the rear lower wishbone being slightly different. That is easily addressed at reconditioning stage with either a changable 54mm or 59mm bush selection being possible to suit a particular application requirement.

Given that bush wear is so common and that at best bushes on our cars are really only any good for between 50k-80k of use, I fail completely to understand why most owners then replace these short life components with the same degradable and collapsable OE components. Would it not be more sensible and satisfactory to upgrade to more modern long life bushes? The usual uninformed bleat for not doing so is that an owner thinks that by installing poly-urethane bushes, his car will degenerate to have a ride like a mule. Not so if one takes the time to research and install the correct grade of bush in each application.

I now install only Powerflex bushes as replacements in any car I own or repair. I`ve done this for several years now and indeed the local Portsmouth Region boys have brought me wishbones for reconditioning and upgrading. With S-type, X350 or XF models, I recommend Purple Series 10% upgrade bushes in all front and rear upper wishbones. Fitting Black Series will give a very uncompliant ride. A similar regime would also be applied to X300/308 models if I were involved be reconditioning components fitted to that model.

Each lower rear wishbone should be fitted with two standard grade, tube and ball bushes which are available from Racing Green Cars. Each third bush register is best filled with a Black Series bush which improves vehicle straight line ability without causing any harshness. The front lower drop arms should also receive a Black Series, with the "banana arm" bush being filled with a Purple Series. The above combination produces a good ride and one has the assurance that these bushes are covered by warrenty for a lifetime period whilst the car is still in the hands of the person that fitted them. Is that not a better warrenty than supplied with standard OE bushes? Powerflex product fitting provides for a one time fit and negates the need for continued replacement as will always be required if OE bushes are fitted.

Post bush fitting, whether OE or upgrade will always require that a vehicle receives a full four wheel alignment check at the conclusion of any bush replacement work.

Mike K

+1 for Powerflex. When they first had a single franchise in the UK they were hard.
And that put off some Passrat drivers who commuted and had families.
But for those of us that also wanted a bit of fun they were fine.
I went for the sport springs and shocks combo too

Now Powerflex are available with slightly softer compounds than their original range.
If you've got bush problems <snigger> then they're the way to go

For springs & shocks Myton Automotive has:
tom.carr@mytonautomotive.com

This outfit in Germany (prior to € re-valuation) offered good deals on combos for the Passat
I did email them last year for a X308 springs & shocks' combo but they didn't seem to have then AFAICR
info@klapper-autoteile.de

The cheapest outlet for Powerflex in my experience is from upratedbushshop.com. This is PSI Tuning in Sheffield. Ade is the guy to speak to. Powerflex make bushes to order overnight once PSI and on shelf stock holding is minimal. Once you pay for the order at PSI, they instruct Powerflex to manufacture. Powerflex then send the consignment to PSI who then despatch it to you. Allow four days to a week for delivery for each consignment. Powerflex are a very approachable company and excellent to deal with at a sales and technical level. They were receiptive to me phoning in a couple of dimension changes needed on a couple of bushes.

http://www.google.co.uk/url?sa=t&rct=j& ... lg&cad=rja

All bushes have a compressability/deformation grading measured in units of Shore. Standard OE bushes used by most car manufacturers are about 70 Shore. Powerflex Purple Series are rated at 80 Shore and provide a slight upgrade over standard OE bushes. Powerflex Black Series are essentially 95 Shore competition grade. Using Blacks on a road car needs careful thought and application. My standard Powerflex fit on the identical S-type, X350 and XF is to put Black bushes on the lower rear, front wishbone bushes with the other two bushes being standard RG109 tube and ball units in the other four locations. Top rear wishbones always receive Purple. Front upper wishbones always receive Purple. The lower front drop arms receive Blacks with the front lower banana arm receiving a Purple. ARB bushes should be Purple if you want a soft ride, or Black if you are setting up for a more competition type feel.

My old S-type was fitted solely with Blacks. I wanted to see the effect of hard bushings. Great on the motorway but quite brutal on the potholed roads in our towns. Essentially, what you put in the upper wishbones has the biggest effect on NVH values and the overall ride of the car.(Noise, vibration and harshness).

For Bilstein dampers, Larkspeed or Motorsportworld seem to be the most competitive with prices. B4 units are what Jaguar install for comfort equiped spec cars. B6 is a gas uprate damper which is fitted by Jaguar at the factory for sport spec cars. B6 with a Bilstein label on it is uprated further by 30%. They will work equally as well with standard springs or uprates such as those supplied by Adamesh. Both Larkspeed and Motorsportworld also sell the American H&R and Eibach uprate springs. A 15mm drop is really all you want for road going use. A further 10mm drop usually occurs given a couple of years use on the road. Dropping too low is a pain. Speed bumps and potholes then become a real cuss and your driving attention has to be greatly increased in order not to burst types or smash alloys...be warned! See my "The Hole in Birmingham" post of several years ago in the S-type suspension section!!

There was a time when the £ to Euro exchange rate made buying Bilstein dampers direct from Germany a very good money saving activity. Rexbo.de were the boys to do business with. I learned it was a good idea to use the DHL express post as delivery could otherwise be very slow. The small punch on the nose was that there was extra delivery charges to be paid once in the UK as well as an import VAT eliment added. In addition, the delivery could often get fouled up by HMRC and the dampers would sit in a transit bond at Heathrow for several weeks. So if you go to import dampers, be aware of these frustrations and seemingly never ending delays. The best bit though was that I`d save 50% over Larkspeed prices.

Mike K