Limited Slip Differential
#41
02-12-2012, 10:25 AM
Veteran Member
So, who wants to be the first to buy a 3.31 diff and weld the spider gears? A long time ago I went in my friend's 5.0 notchback mustang who welded his rear...Wasn't bad, inside tire would squeal on tight turns and also always when in parking lots...Big concern is if you ever lose control of the car, it's going to handle very differently than you're used to...
#42
02-12-2012, 03:12 PM
#43
02-12-2012, 03:30 PM
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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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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I have read on here so far no one has tuned the computer for a different gear ratio. And not doing so results in limp mode.
#44
02-12-2012, 03:31 PM
So, who wants to be the first to buy a 3.31 diff and weld the spider gears? A long time ago I went in my friend's 5.0 notchback mustang who welded his rear...Wasn't bad, inside tire would squeal on tight turns and also always when in parking lots...Big concern is if you ever lose control of the car, it's going to handle very differently than you're used to...
#45
02-12-2012, 04:18 PM
Veteran Member
Very good point about the 3.58:1 LS gear set. Your right it should fit but no one has done it yet so I wanted to be careful. The four Jaguar ratios for sure would fit.
Yes the first gen S Type should be able to install the Ford part but without any experience I am just guessing? Same with fitting the Gen I stuff to the Gen II on the S Type. I don't think that will work because of the large changes in the suspension.
Also the limited slip on the Gen I LS can only use gears for the LS which limits it to two gears to choose from. 3.58:1 and 3.31:1. One or two people have gone the custom route and used a Lincoln VIII rear end. It's an IRS and not too difficult to fit but adds a lot of cost. Then you have almost unlimited gear choice. Since the LS does not care what the rear gear is no error codes are thrown. At least one or two LS's are running 4.10 and 4.56 ratios.
We need some brave soul to start trying these things to see what fits what!!
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Yes the first gen S Type should be able to install the Ford part but without any experience I am just guessing? Same with fitting the Gen I stuff to the Gen II on the S Type. I don't think that will work because of the large changes in the suspension.
Also the limited slip on the Gen I LS can only use gears for the LS which limits it to two gears to choose from. 3.58:1 and 3.31:1. One or two people have gone the custom route and used a Lincoln VIII rear end. It's an IRS and not too difficult to fit but adds a lot of cost. Then you have almost unlimited gear choice. Since the LS does not care what the rear gear is no error codes are thrown. At least one or two LS's are running 4.10 and 4.56 ratios.
We need some brave soul to start trying these things to see what fits what!!
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#46
02-16-2012, 10:27 PM
cheers,
TonyL
#47
02-17-2012, 08:50 AM
Veteran Member
#48
02-17-2012, 09:36 AM
Veteran Member
#49
02-17-2012, 10:29 AM
Actually that is before VAT. Shipping is not trivial but I might be able to pick it up and pay baggage fees on it instead. One should consider that the core plus diff is about 1150 gbp of that.
I am guessing that a number of folks waited for the used STR price to drop to something reasonable [like I did], but it still remains that we are talking about cars that cost $50k-$60k, not $15k-$20k like nice ones are on the used market. Also this diff is essentially equivalent to a 'racing part', so with that perspective this price is now nothing unusual.
That IS a lot of cash, so one must consider carefully how much one really wants it, but there you have a documented solution for this thread.
cheers,
TonyL
I am guessing that a number of folks waited for the used STR price to drop to something reasonable [like I did], but it still remains that we are talking about cars that cost $50k-$60k, not $15k-$20k like nice ones are on the used market. Also this diff is essentially equivalent to a 'racing part', so with that perspective this price is now nothing unusual.
That IS a lot of cash, so one must consider carefully how much one really wants it, but there you have a documented solution for this thread.
cheers,
TonyL
#50
02-17-2012, 11:01 AM
Veteran Member
#52
02-17-2012, 12:22 PM
Veteran Member
#53
02-17-2012, 03:50 PM
Veteran Member
#54
02-18-2012, 07:33 PM
That is way more then I am willing to spend. From reading other threads it seems the S-Type and the LS share the same housing with the same change gen1 to gen2. I'm sure a gen1 LS rear dif assembly from the salvage yard is not to expensive. I can't spending more then $1000 all in including salvage housing new trac lok and seals, bearings, labor. I'd rather have the extra $2000 in my pocket for other mods. If I have to spend $500 every 5 yrs or whatever to rebuild everything that's worth it to me. If money isn't a concern or are auto crossing the car then you might be better off with the Quiafe unit.
#55
02-18-2012, 08:20 PM
The unit that Tom builds actually requires machine work. I've exchanged a few emails with him and its a Quaife unit that either the casing has been machined or the LSD unit has been machined he would not go into any detail for obvious reasons. This is why the price is so high and why they would need your rear end.
#57
02-19-2012, 02:11 PM
Give me three years Seth and I will have a diff for us. Once I get done with school and settle somewhere my STR will be paid off and I'll have another car so I can tear into the STR and start working on some projects. This will most likely be my first project. Lets just hope I get a job with some resources that will allow some of the projects in my head to go faster.
#58
02-19-2012, 08:02 PM
Veteran Member
#59
02-19-2012, 10:23 PM
I have not Seth. I havent been messing with my STR much lately since I've kinda swamped myself this semester in school. Taking 17 credit hours. I ride my motorcycle to school so my STR is not my daily driver I really only take her out about once a week to do some errands that I cant do on my bike and to get the fluids going through her. So just been doing oil changes and fluid checks with an occasional wash. I've been tearing into my bike more so I've mainly just been lurking here and posting over on their forums. Had to rebuild the forks, get new tires, and fix a blown oil cooler, so thats been keeping me busy. The gas savings has been helping me tons though. Once I'm done with school I can drive more and will start playing with her more since my bike will become more of a nice day rider. If you get ahold of Mafioso let me know how he is.
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bfsgross (02-20-2012)
#60
02-20-2012, 07:41 AM
I want to get my car to the dyno and then the track here in the next few weeks and get some real numbers for it. After that I am pulling the car down for a little performance project where the blower comes off. I am going to pull the rear apart and look it over since I wanted to change the rear end dope anyway. I want to see if I can come up with something, I am getting to the point that a LSD would be a huge advantage. I did think about getting another assembly from a junkyard and just welding it and swapping it in for the track for a easy in the meantime solution.