First question: Are the OE springs in a STR different than the non-STR OE springs? (How? Is the spring rate greater? Are they lower? Or do they only work with CATS dampers?)

If yes to first question -- then second question: Will the STR springs fit in a non-R S-type? (Or do the springs that go with the CATS dampers not work with the standard Bilstein shocks, etc.?)

If yes to 1 and 2 -- third question: Has anyone put STR springs in a non-R S-type? (How did they work? Feel?)

If yes to 1 and 2 -- fourth question: Do any of you STR modders who have gone with aftermarket springs (H&R, Mina, Arden) have your OE springs for sale? It occurred to me that some of you STR guys must have a set of the OE springs you aren't using.

 

I have mine, would sell cheap. PM me...

 

Or does anyone know the OE spring rates? (and aftermarket for that matter)

It would be nice if there was a sticky with all the recomended OR spring rates with the aftermarket bilstein that would match them.

This would be nice for the aftermarket springs as well.

Any cross compatibility between the different models. 4.2 vs R vs Sport vs ?

Brian Shaw

 

I don't know what the spring rate is but I know the STR has a curb weight of 4,046 lbs. Do you know how much the non-STR 4.2L S Type weighs?

 

It weighs less, but how does the CATS affect it. Without knowing indivual spring rates, and I have not been able to find this anywhere, it is all a shot in the dark. I would think, given what they are trying to accomplish with the CATS system, that they have a softer spring rate. But really have no idea.

 

Edmunds.com shows the curb weight of a 2005 S-type 4.2 to be 3826 lbs, and the weight of the 2005 R to be 3969 lbs. Same for MSN Autos. For the 2003 MY, the curb weights are heavier: 4.2: 3874; R: 4046 lbs. (2003 steel hood, versus aluminum on 2005+? Options? Error in data?) The 2005 4.2 NA is showing as 48 lbs lighter than the 2003; the R is showing as 77 lbs lighter than the 2003. IF these numbers are correct, I suppose they are for no-option cars. The Alpine and Nav add some mass, but not a lot.

Anyone know the answers to questions 1 through 3? Will the STR springs even work in a non-STR? They probably will, but I am not assuming that -- for one thing, I don't know if the CATS dampers require a different spring that might not be compatible with non-CATS dampers.

ADDED: Good question/point, Brian. It is possible the STR springs are actually softer than the standard springs. Are the part numbers different for the STR OE springs versus standard? If the PNs are the same, we would at least know if there is any difference.

 

The problem you have is this. Yes the parts are the same dimensionally but remember Jaguar changed dozens if not hundreds of things to make a STR out of a standard S Type. We only know a very few of them.

We found out by accident the suspensions arms will bolt in but the STR has SC (Super Charged) on the arms. Why? No real explanation.

You can check the JEPC (Free on this site) and try to see what part numbers are the same and what ones are different. There really is a LOT to the making of an STR. Throwing random bits on a regular S Type most likely won't work very well or Jaguar would have done just that!!.

We don't have Mustangs so there are not thousands of street racers modifying and breaking everything that can break. That's how you get a great aftermarket from actual experience.

Even if the CATS are the same they are controlled by the PCM. What did Jaguar change in the programming to make the STR? Again nobody knows and we still don't even have a simple hand held programmer yet so no way to change anything anyway.

The STR is selling at giveaway prices now and that would be a much better way to go. You would have a great base to start with.
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Good points, tbird. I am not looking to change my NA into a SC R model. My questions in this thread were as much for the benefit of the forum and other members as for me. It had occurred to me that there are some spare OE STR springs laying around members' garages, so I thought I'd ask. I'm only looking to do any upgrades in 2014 -- this year I need to get a handle on fixes for things to bring my cat to perfect health first. As far as upgrades go, I am only interested in a few things, potentially: wheels and tires; dampers/shocks (but probably not springs); maybe audio connectivity.

Yes, STRs prices are super low -- if I hadn't have acquired my S-type 4.2 VDP for close to free (inheritance and deal with my brother), I'd be looking at STRs along with other Jags. In a year or two I might even buy another Jag -- looking at 2007+ XKs and X350/358 XJs (esp. XJR and Super V8). I've been bitten, and a sweet bite it is.

 

When I look up Parts on the S-Type 4.2

 

 

Bilstein Shocks

 

I would rely on the JEPC first then confirm with Jaguar before ordering. We have had a lot of problems with the aftermarket vendors improperly identify what parts fit which car. Be especially cautious with the STR. They almost always say it fits the R and then it does not!

Where did you get your parts listing?

Do you have the JEPC? It’s free on this site.
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Guadin Jaguar
Genuine Original Equipment Replacement Parts

2006 JAGUAR Parts - Direct JPLV Porsche Parts.com=



It does not seem to want to run correctly on my Windows 8 pc.

Thanks,
Brian Shaw

 

So, At this point I have about given up.
Not looking to Spend a whold lot of money on a car that may not be worth it. $2,000 for suspension and $2,000 for wheels/tires on a car that is worth about $10,000 is not a wise investment.

When it is time to install tires, I will put on a set of 245/45r17's.
When it is time for shocks, Bilstein Sports or maybe just stock jag replacements.
Possibly even grab a set of Mina springs while I am at it.

But, Thats all she wrote for me.
I cannot afford to play guinea pig.