Coming from the LS world I thought I'd add what I know. I do not know at all how similar or possibly identical the LS to S-Type rear differential is.

On the 00-02 LS you can swap in a Ford 28 spline 8.8 trac-lok limited slip carrier with any year LS 8.0" gears. The stock 8.0" gears will bolt on the 8.8"carrier. Other aftermarket 8.8 limited slip carriers may or may not fit. Some will not bolt in but may with some case machining.

On the 03+ LS you can swap the 00-02 axles and carrier without issue. 00-02 LS has a 3.31, 03-06 have 3.58.

As stated some LS owners have swapped in Lincoln Mark VIII/10th gen Tbird/99-02 Mustang Cobra complete cases.These are 28 spline 8.8" Mark/Tbirds did not come with trac-loks while the Cobras did. The Mark/Cobras had an aluminum case. There are plenty of choices for gear ratios and differentials from the trac-lok to lockers. At minimum customer mounting brackets are required. I do not recall what if any axle/drive shaft issues will need to be addressed as well. Also I do not know how the Jag computer will react to a noticeable gear change. i.e. I went from stock 3.07 to 4.10s in my Mark VIII and shift points were off without a tune to correct.

Hope this new guy helped someone out there.

Thanks a bunch for the LSD info., a very frustrating topic for S-typers. We have one member who just swapped in a Quaffe LSD with stock gears into his 05 STR and swapped in an XKR TCM program.

Well we do know that changing the rear gear ratio on an S Type will immediately throw it into limp home mode. That's one big difference between the Ford and Jaguar electronics. We still need a programmer to fix this.

Someone had the entire rear end on their S Type changed out under warranty. The dealer put a 6 cylinder rear end in a V-8 car. Undrivable, the Lincoln does not care what the rear end gear is and the speedometer is still correct because the speed is driven by the wheel sensors for the ABS.
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Ditto on a programer, especially as this car approaches 500 hp.

Quaife makes good stuff but at well over $1000US I'd be much happier swapping in a $200 easily rebuildable if less durable trac-lok. If a STR does make it to my driveway in the next few months I will def be looking into this.

LostnEye, if u can put together a Traction Lok diff for the STR. we'd do your laundry.... Awesome that you may have an STR soon. Join us!

I'd pay 1000 to not have to rebuild the rear end all the time. Rear end rebuilds arent fun and require special tools you cant pick up at the local Auto Zone. I had to rebuild the rear end in my last car 3 times because of the manufacturer totally screwing up the material for their axles and I hated it everytime. I also had to do it in a van I had and I hated that one too. So if Quaife made one that dropped in I'd get that install it and it should be beafy enough to handle any power you threw at it. Breaking rear ends is not fun. Once you start shaving gears there is just to much other stuff that is toast or will have to be replaced. If you threw in a 200 one and some metal shaved off and started floating in there. The gears would be done because that would get inbetween them and if it only was in there a little bit it would still create pitting which would create harmonics which would annoy the crap out of me. Then the bearings would be shot, luckily with us having an independent rear the axles would still be good but when those go too that really gets expensive. I wont put anything that isnt durable in there.

Speaking of rear ends...I noticed a slight leak in my STR...I called nalley jag parts and was told basically all rear end parts for the STR are discounted...

The Traction-Loc 8.8 rearend is pretty stout.

off topic but is there a way to mod the stock tranny or get a reflash for the tcm for better shift points and etc???

Short answer yes, long answer no...

All that we're aware of is flashing the trans to a XKR shift points, I believe nothing else is changed...The big problem is finding a dealer local to you who's willing to do it or even know what you're talking about...
The file name is: Z65x5556x202fed.phx

what is the file name for? and out of curiosity how much do the dealer care for ecu/tcm reflashes?

I didn't mean to suggest the trac-lok was weak however it is a clutch based limited slip so they will wear out eventually. If/when that happens it just becomes an open dif like stock. While anything can happen and sometimes parts break there are manual cars with more power then STRs that have trac loks live a long time behind them. And I know people who has had 100k mile Mustangs with the stock trac lok 8.8 that would still leave two stripes no problem. The Quaife is a better design and would work better for a road racing car so for some people it may make more sense and be worth the added expense. For me it's about trying to get the car moving from the stop light or cutting better 60' times. I'll keep the extra $800+ for something else.

I don't have the tools or the knowledge to set up a rear. However where I am it's usually less then $400 labor.


I'll hold you to that :icon_mrgreen:

The problem (if it is one) would perhaps be persuading someone to reflash with a software version that according to the software tool (IDS or whatever) does not belong in the particular car.

It's for a specific VIN range and almost all STRs are out of that range.

The file name is not strictly needed but may be if you want to get around the checks the software will automatically perform.

The easiest way to fool IDS is probably to manually edit the XML file that refers to the above file. You'd substitute the file name for the one that is supposed to be used.

Whether this is wise? Dunno! Apparently it works but I've no first-hand experience of it.

Why don't you google dealerships around and ask the service dept?

It's a custom thing, there is no fixed price, dealership ABC may charge $250 while dealership XYZ may charge $100...

I contacted Martin Slade at Racing Green regarding putting a Quaife in an 06 STR. He thinks the QDF3W should drop in assuming the XKR and later STR diffs are equivalent. According to the interchange data I can back out of car-part.com, there are different versions:

XKR [03-06(XK8), 05-06(XKR)]
STR 2.87 [03-05, 06-08]

next step is to open an 06 STR diff and measure the center assembly to see if it matches the quaife drawing.

cheers,

TonyL

You could also contact Tom at TLJaguar in the UK, he also supplies the Quaife units and has actually already built unit for the STR, not sure for which year though.

STR diffs. should be same from 03 through 08 ?

As far as been reported all the STR's had the same rear end. The S Type and Lincoln LS had Gen I and Gen II rear ends.

1999-2002.5 S Type and 2000-2002 Lincoln LS are Gen I
2002.5-2008 S Type and 2003-2006 Lincoln LS are Gen II

So all STR's would have the Gen II rear end. Now what we don't know is the STR a heavy duty version or exactly the same? It looks like they are the same because the JEPC lists the 4.2 NA and the 4.2 SC as using the same part number for the differential (C2C 34878).

There are 4 rear end gear ratio's used on the S Type.
2.69:1 on manual Diesel only
2.87:1 on the 4.2 NA and all STR's
3.07:1 on various V-6 models manual and automatic
3.31:1 on most V-6 automatics except Diesel


If we could swap in that 3.31:1 set into the STR it would be a great help. That 2.87 is a daddy long legs rear end gear!

In fact Jaguar did just that when they released the 2009 XFR and installed 3.07:1 gears in the rear. They even topped it again in 2010 when they added the new direct injected 5.0 motor plus a 3.31:1 rear end and electronically controlled locking differential.

I would really like to see what a STR with a limited slip 3.31:1 rear end in it would do??
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Set codes? :(

Wonder which ones... would it be the ABS? And only the ABS?