2003+ S-Type Subframe on 2003+ LS

[CTX-SLPR]

Has anyone gotten to the point of actually checking the fitment of an 2003 S-type subframe on a LS? Interchange wise there seems the same subframe for all 2003 S-Type's past a VIN split. Interchange also shows them using the XJ (X350) lower control arm and spindle setups which makes sense since the S-Type R brakes are the same. The upper control arm seems to be S-type specific.

In general, it looks like the S-type R using a bespoke spindle and matching brakes but otherwise uses standard S-type parts. If the subframes bolt in, sounds like a decent source of the basic parts to convert to the S-Type R (also X350 XJR and Super V8) brakes or just leave the brakes alone and enjoy the revised suspension.

 

[LS_InOK]

According to this article, STR brakes are a direct bolt on...

http://www.lincolnvscadillac.com/forum/showthread.php?83858-2007-Jaguar-STR-Brakes-Confirmed

 

[CTX-SLPR]

I guess I should have been a bit more specific... 2003-2006 4-piston Brembos for the S-Type R brakes I was referencing. The 2007 brakes likely point towards a compatibility of LS brakes with the 2003-2006 non-R spindles. However the lower ball joint orientation means you'd have to change spindles right off to get the new lower suspension geometry.

 

[Kumba]

I did some research on that a while back. Thread on here somewhere about it. Long story short in order to use the S-Type R breaks without making your own bracket for the knuckle you would have to change the subframe, UCA, knuckle, and the two-piece LCA. Basically you would put an S-Type R front end suspension on an LS. The LS shock could be used but the eyelet of the shock where it bolts to the subframe is too wide. It would have to be milled down so it's the right width or change the shocks/springs out to S-Type ones.

To my knowledge no one has measured the mount points to see if it will fit or attempted it. It is worth noting that the only S-Type R specific parts in the front suspension, versus standard S-Type parts, are the UCA, Knuckle, Shocks/springs, and brake setup. The subframe, two-piece LCA, hub, Ball Joint, etc, are all the same from an S-Type to S-Type R.

Going from the multiple-piece subframe on the LS to the single-piece subframe should stiffen the front end up a bit. The revised UCA along with the two-piece LCA should also give the suspension better geometry throughout it's range of motion.

That's the theory anyways.

For the rear brakes you just need the knuckle and some sort of e-brake cable set-up to go from the LS to the rear e-brake.

One thing I do not know is if the master cylinder is the same or different between an S-Type and S-Type R.

 

[CTX-SLPR]

I did some research on that a while back. Thread on here somewhere about it. Long story short in order to use the S-Type R breaks without making your own bracket for the knuckle you would have to change the subframe, UCA, knuckle, and the two-piece LCA. Basically you would put an S-Type R front end suspension on an LS. The LS shock could be used but the eyelet of the shock where it bolts to the subframe is too wide. It would have to be milled down so it's the right width or change the shocks/springs out to S-Type ones.

To my knowledge no one has measured the mount points to see if it will fit or attempted it. It is worth noting that the only S-Type R specific parts in the front suspension, versus standard S-Type parts, are the UCA, Knuckle, Shocks/springs, and brake setup. The subframe, two-piece LCA, hub, Ball Joint, etc, are all the same from an S-Type to S-Type R.

Going from the multiple-piece subframe on the LS to the single-piece subframe should stiffen the front end up a bit. The revised UCA along with the two-piece LCA should also give the suspension better geometry throughout it's range of motion.

That's the theory anyways.

For the rear brakes you just need the knuckle and some sort of e-brake cable set-up to go from the LS to the rear e-brake.

One thing I do not know is if the master cylinder is the same or different between an S-Type and S-Type R.

The UCA is specific to the R vs the standard S-Type? Interesting, guess they got crazy with the spindle/knuckle with more than the caliper mounts.

I also don't like solid rotors, if I did Brembos I'd adapt the Volvo S60R/V70R rear rotor and in hat parking brake since they share the same wheel bolt pattern. At least the tie rod ends are the same. I'm going to call a local yard and ask for the whole thing out of a regular S-type V8 and see what they say for the cost.

 

[tijoe]

I am a bit confused. Are you guys talking about the front suspension sub frames, rear suspension sub frames, or both?

I know that all the Gen1 and Gen II rear sub frames mount the same between S-types and LS's Jaguar GenII rear sub-frames will fit in gen1 S-types and LS's but they changed the differential mounting between the different generation differential housings. There are also different emergency brake brackets. (Manual pull e-brake versus electric enabled E-brake.) I used a 2005 LS rear sub-frame for my rear end build for my 2000 S-type, so I know it fits. On the rear, Upper and Lower control arm all fit the same. But there were a couple of bushing variations/types used throughout the years. I prefer the newer lower rear control arms that have SC cast into them. Supposedly they are cast out of a better aluminum alloy. They started using this style on S-types in 2003. As stated above, the hub carriers are different between the STRs with Brembo and their separate E-brake caliper. The STR rear hub carriers that fit the Brembo's are very rare and coveted. Sellers try to get big dollars for the.

The front suspension is significantly different between the genI 1999.5 to 2002 and GenII 2003 forward S-types.
The front K-frames, lower controls arms and steering arms are completely different between the GenI S-type, LS and the STR and S-type GenII suspensions.
Jaguar owners complained that there was too much front end frame flex on the early S-types, so when they came out with the STR, they redesigned the front suspension. I can look again at my different S-types, but as I recall, they redesigned how the GenII K-frame and cross members mount onto the body. The lower control arm changed from a one-piece design to 2-piece and the steering arms that fit the Brembo has lower ball joint flipped. (As least the upper control arm remained the same.) I am sure that the newer 2-piece lower control arm is narrower where it mounts on the sub-frame.
I haven’t tried to swap a GenII front K-frame to to a GenI car, but I think it is a non-starter.

 

[CTX-SLPR]

I was referring to the mounting of the later S-type K-member/Subframe with all of it's supporting control arms and knuckle to the 2003+ LS as a unit. While STR Brembo's would be nice, I'd be equally happy with the upgraded 320mm discs and brackets that Kumba discovered bolt on paired with the revised S-type front suspension and it's greater shock/strut availability for far less. Part number cross referencing says that they put an XJ (X350) front suspension on the DEW98 S-type, or maybe more correctly they put the revised S-type on the XJ since the X350 came out in 2004 (US market) while the S-type R came out in 2003 (US Market). The UCA is one of the few pieces that doesn't cross to the XJ. This suggests that they built a subframe to bolt to the existing S-type unibody structure including UCA pickups but used the rest of the XJ suspension.

Thanks,

 

[Kumba]

The 2002+ S-Type recieved a one-piece K-member up front instead of the 4 seperate pieces that the first gen S-Type and all LS' use. I do not know if the actual mount points to the body are the same but having a single piece K-Member would significantly stiffen up flex in the front end. From what I can remember the K-Member is the same on regular and R versions of the S-Type. The lower 2-piece control arms are also the same between the regular and R version S-Type. Knucked (or steering arm) is different, as well as the UCA (changed the geometry on the R for bump steer), and probably parts of the steering like outer control rods and a different ratio rack. Suspension is also different but physically will interchange, although the R-Type suspension is electronic. Not that it matters on an LS.

I think your best bang for the buck would be to pull out the front suspension from a Gen2 S-Type (a regular one) and see if that bolts into the LS fine. Once you have that all worked out, try to find the knuckle, UCA, and brake set-up from an R-Type. Only other way to do it would be find a wrecked R-Type with a good front end and use it as a donor. As an added bonus you'd get the SC engine as well. Or maybe find one with a blown engine and get the front and rear suspension parts out of it. either way would work.

I've been curious for a while if the front suspension could be adapted but I don't have the time or place to do it. Too much other crap always going on.

 

[tijoe]

I crawled under my 2000 S-type and my 03 STR and the front body structure is significantly different. The GenII S-types use a single sub-frame assembly with very different mounting locations. The GenI S-types uses 2 separate cross beams. One that supports the radiator and one bushing on the lower control arm, and the other supports the engine and back bushing of the controls arm. See attached images.

 

[CTX-SLPR]

I crawled under my 2000 S-type and my 03 STR and the front body structure is significantly different. The GenII S-types use a single sub-frame assembly with very different mounting locations. The GenI S-types uses 2 separate cross beams. One that supports the radiator and one bushing on the lower control arm, and the other supports the engine and back bushing of the controls arm. See attached images.

If you could help us out by taking some measurements, please measure front to back on the right and left side attach bushing locations for the two as well as across and diagonal something like this:

*---------*
|...\..../...|
|....\../....|
|.....\/.....|
|...../\.....|
|..../..\....|
|.../....\...|
*---------*

That should tell us if the subframes will interchange with some reasonable level of assurity

Thanks,

 

[tijoe]

Since the engine is out of the STR, I can take somepics and measurements and them post them. It may be a few days before I can get to it. You guys will have to compare to one of your Ls's.

 

[CTX-SLPR]

Since the engine is out of the STR, I can take somepics and measurements and them post them. It may be a few days before I can get to it. You guys will have to compare to one of your Ls's.

As long as I know where your datum points were I can try to replicate it on my 2003 LS. Many thanks for taking the time and if I ever go home to Pflugerville, will have to stop by and check your project out.

 

[Kumba]

Yeah, the key to this whole project is if the single piece S-Type k-member can be reasonably bolted up to the LS. I know you can make anything work but hopefully it's just a matter of moving a couple bolt holes and a little bit or reinforcement and not fabricating new body mount points for it.

I also remember that the revised UCA on the S-Type R was supposed to be beefier as well to handler more aggressive driving maneuvers without flexing as much. It also changed the geometry slightly to help with bump-steer and other undesirable handling traights you would run into when driving aggressively.

If you look up the same part with Jaguar, it's two part numbers. The R has a specific UCA related to it. Both pieces of the LCA is the same part number regardless of whether it's the R or not. In the rear it's just the knuckle that is R-Specific.

Like I said earlier I do not know if the steering (rack and it's tie-rods) are R specific or not. I would imagine the steering rack has a unique quicker ratio then the regular one. Considering the wheelbase is the same between the two I wouldn't expect the ackerman angle to be any different. Hopefully that means that the inner and outer tie rod are probably the same piece as the regular S-Type. You'll likely need the rack from the s-type since it will probably mount differently then the LS one does. Might as well get the tie-rods too in case the rack is a different length.

You also might need the engine mount brackets and other random things from the S-Type in order to mount up to the new K-member once you get it bolted in. Also need some pretty good measurements of the control arm mount point geometry from the S-Type to make sure you have it set-up correct in the LS. Not much of a point if the end result is uncorrectable caster or camber. I don't think there will be an issue with toe that can't be adjusted out.

I still think that if you are going to undergo this adventure that finding a rear-ended or t-boned past the B-pillar S-Type (or R) is the ideal donor car. Getting that K-Member set-up in the LS correctly is the whole crux of the problem IMHO. After that I feel confident that the rest would just bolt together.

 

[CTX-SLPR]

Tie rods are the same LS to S-Type to STR from my part number checking. Rack... Tijoe might be able to comment lock to lock.

Considering that both the S-Type and LS share the same engine families, I would expect that picking up the V6 or V8 frame side mounts would allow your engine side to bolt in. Looking forward to this experiment.

 

[Kumba]

Considering that both the S-Type and LS share the same engine families, I would expect that picking up the V6 or V8 frame side mounts would allow your engine side to bolt in. Looking forward to this experiment.

Mount point on the engine is likely the same but the location of the mount point on the K-Member might be located in a different spot. So the bracket for a Jag V8 might be different then the bracket for a LS V8.

 

[Telco]

If you need to use the STR rack instead of the Ackerman setup you may also need the STR power steering pump. No idea where you would find out what the pump pressure requirements are though. Perhaps that one factory manual site could verify whether the pumps have the same output pressure and flow rates.

 

[Kumba]

If you need to use the STR rack instead of the Ackerman setup you may also need the STR power steering pump. No idea where you would find out what the pump pressure requirements are though. Perhaps that one factory manual site could verify whether the pumps have the same output pressure and flow rates.

It would certainly be nice to get to that point.

 

[tijoe]

I was hoping to take some measurements over the weekend for you guys. I opened the hood on the car and looked into the engine bay, but physically I am still not able to crawl under and around the car. (I ruptured my RH quadriceps tend 6 weeks ago and the brace I wear makes it difficult to get horizontal under a car.)
I'll snap some images in the engine compartment ASAP.

Here are some images. Look and compare to your car's body/frame.

 

[clubairth]

Old thread but wanted to add some info about the steering rack and P/S Pump. I have both a 2003 V-8 LS and a 2005 STR. I have replaced the P/S pump on both cars.

For 2003 both the LS and the S Type got upgraded steering racks and both use the exact same ZF variable ratio-variable assist rack and pump.
This is ONLY for the V-8 models as I have not seen the V-6 cars but they should be the same.

The steering effort is controlled by the FEM and of course that is all different and will not swap over.

Thought this might help?
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