[xj] lsd on an 83 xj6?

I was wondering if my jag might have a limited slip diff,as
i recently moved and as the car is not road legal right now
i had to trailer my baby to new house! whilst trying to load
it on the trailer I had quite a bit of wheel spin as the
trailer was quite steep, what made me wonder this is the
fact that the drivers side wheel was spinning, I could not
see teh passenger one but the car was trying to get sideways
on me! From what I remember with all my other cars an open
rear end would nearly always spin the right rear wheel!, is
there a code I should look for in the vin? or maybe a tag on
the diff?? any help greatly appreciated.

Thanks
Darren–
Darren B 83 xj6 brg 69k miles (up to 87k in 7 years!!!)
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A tag reading “PL” on the diff would be a good clue although these often go
missing over the years.

If yours is a USA spec car, and the diff is original, it’s very unlikely
that you have LSD. USA XJ6s were not so-equipped, at least not thru normal
channels.

Cheers
Doug Dwyer
Longview Washington USA
1995 XJRFrom: “darrenmb1968” darrenmb1968@cfl.rr.com

I was wondering if my jag might have a limited slip diff,

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In reply to a message from Doug Dwyer sent Sun 8 Jul 2012:

Photo of the PL tag and gearing tag here:

My 84 is not a Locking diff, and the drivers side wheel is
the one that spins (I think)…

If you need to know for sure, just jack up the entire rear
end… Spin the wheels… If they spin in the same
direction, you have a locking rear end… If they spin in
opposite directions, you have a non locking rear end…

Cheers
David
EverydayXJ.com–
The original message included these comments:

A tag reading ‘‘PL’’ on the diff would be a good clue although these often go
missing over the years.
If yours is a USA spec car, and the diff is original, it’s very unlikely
that you have LSD. USA XJ6s were not so-equipped, at least not thru normal
channels.


84 XJ6 (Driver) 89 XJS Convertable… Parts cars piling up.
Rockwell, NC, United States
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There is no mystery: If your car is a US-market car it does NOT have the
limited slip differential. It is as simple as that. The LSD was on the
Sovereign (sold in Canada but not sold in the US) and on the V12 version
(sold in Canada but not sold in the US).

Gregory
Victoria, Canada-----Original Message-----
From: owner-xj@jag-lovers.org [mailto:owner-xj@jag-lovers.org] On Behalf Of
darrenmb1968
Sent: July-08-12 7:56 AM
To: xj@jag-lovers.org
Subject: [xj] lsd on an 83 xj6???

I was wondering if my jag might have a limited slip diff,as i recently moved
and as the car is not road legal right now i had to trailer my baby to new
house! whilst trying to load it on the trailer I had quite a bit of wheel
spin as the trailer was quite steep, what made me wonder this is the fact
that the drivers side wheel was spinning, I could not see teh passenger one
but the car was trying to get sideways on me! From what I remember with all
my other cars an open rear end would nearly always spin the right rear
wheel!, is there a code I should look for in the vin? or maybe a tag on the
diff?? any help greatly appreciated.

Thanks
Darren

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In reply to a message from Dr Gregory Andrachuk sent Sun 8 Jul 2012:

Not sure the XJ6 got an LSD anywhere as standard.

Doing the 2-wheels in the air test requires the transmission to be
in neutral of course, otherwise the opposite wheel would turn the
opposite way (with some difficulty depending on how good the
clutches were).

Pete–
The original message included these comments:

There is no mystery: If your car is a US-market car it does NOT have the
limited slip differential. It is as simple as that. The LSD was on the


1E75339 66 D, 1R9720 69OTS
Gaithersburg (in transit), United States
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In reply to a message from darrenmb1968 sent Sun 8 Jul 2012:

As others have said, the US diffs were open. But I’m
confused about two things.

If the car was trying to get sideways on you, wouldn’t that
suggest that only one wheel was spinning (open diff)?

Also, I was unaware that one wheel preferentially spins with
open diffs (you say the right one). I thought that the
wheel with lowest traction would spin (the one that hits the
patch of ice at the end of my driveway :-). If one wheel is
preferred with an open diff, what’s the mechanism? I’m not
trying to argue about this, rather I’m curious as I know
pitifully little about differentials.–
The original message included these comments:

fact that the drivers side wheel was spinning, I could not
see teh passenger one but the car was trying to get sideways
on me! From what I remember with all my other cars an open
rear end would nearly always spin the right rear wheel!, is


Bob Wilkinson, 73 XJ6
Saint Louis, MO, United States
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If the car was trying to get sideways on you, wouldn’t that
suggest that only one wheel was spinning (open diff)?

No, not typically.

With one wheel spinning without traction and the other wheel not moving at
all, the car tends to remain in one spot…no left-right movement…as
the motionless wheel holds the car in position.

With a locking/LSD diff both wheels are spinning free so the rear end of the
car will tend to slew sideways to the right…if the surface is very
slippery and/or the driver intentionally sets up excessive wheel spin. This
slew-to-the-right is a source of delight to those having horsepower running
through their veins, not that I would know, of course :-).

It can also be a dangerous thing for an inexperienced driver on a slippery
surface.

Also, I was unaware that one wheel preferentially spins with
open diffs (you say the right one). I thought that the
wheel with lowest traction would spin

My understanding as well

Cheers
Doug Dwyer
Longview Washington USA
1995 XJRFrom: “Robert Wilkinson” wilk@wustl.edu

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In reply to a message from Doug Dwyer sent Sun 8 Jul 2012:

Got it. Thanks, Doug.

BTW, why does the LSD cause it to slide to the right? Crown
of the road perhaps (slide to the left in the UK)?–
The original message included these comments:

With a locking/LSD diff both wheels are spinning free so the rear end of the
car will tend to slew sideways to the right…if the surface is very
slippery and/or the driver intentionally sets up excessive wheel spin. This


Bob Wilkinson, 73 XJ6
Saint Louis, MO, United States
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In reply to a message from Robert Wilkinson sent Sun 8 Jul 2012:

You got it Robert - road camber plus gravity equals low
side lateral drift when traction is lost in a straight
line.

There IS however a tendency for one wheel to lose traction
more than the other with some solid axles and the C-type
(&D-type IIRC) tended to suffer with the right wheel
breaking away even though it was the driver’s side. I did
once understand the techincal explanation but that was
then and this is now :-).

It was to do with twisting reaction forces tending to
lift one wheel and press the other one into the tarmac I
think. I think it can be mitigated by the design of
appropriate axle linkages. Somewhere there’s a folk memory
lurking In the back of my mind about someone putting two
dampers on that side of a C-type for certain bumpy
circuits.

Someone here who actually knows what they are talking
about may explain it better. That’s not setting the bar
very high, of course…!–
1E75339 66 D, 1R9720 69OTS
Gaithersburg (in transit), United States
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Watch some drag racing videos, though, and you’ll often see the
slew-to-the-right even on a perfectly flat drag strip. In fact, I’ve had it
happen myself on the drag strip.

I always thought it was somehow related to engine and/or prop shaft
rotation?

Cheeers
Doug Dwyer
Longview Washington USA
1995 XJRFrom: “PeterCrespin” jag@thewritersbureau.com

You got it Robert - road camber plus gravity equals low
side lateral drift when traction is lost in a straight
line.

It was to do with twisting reaction forces tending to
lift one wheel and press the other one into the tarmac I
think.

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In reply to a message from Doug Dwyer sent Sun 8 Jul 2012:

I think that’s true for a solid axle car (as Pete says),
because the tire-ground contact is what opposes the
driveshaft torque (which, I suppose, would be about a third
of the torque at the rear wheels). So just as accelerating
loads the rear wheels and braking the front, one rear tire
would get loaded relative to the other and have more grip.

I can’t figure out if the same would apply to an IRS–seems
that the torque reaction would be transferred to the four
cage mounts, not the tires–just as engine torque is
transferred to the front subframe by the motor mounts (and
in fact at 1:1 tranny ratio it’s the same torque). If I
could return to my youth I might be able to figure it out.–
The original message included these comments:

I always thought it was somehow related to engine and/or prop shaft
rotation?


Bob Wilkinson, 73 XJ6
Saint Louis, MO, United States
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My XJR will slew to the right during wheel spin and it has IRS. I’ve driven
E-types and Corvettes that do the same.

I dunno; can’t 'splain it :slight_smile:

Cheers
Doug Dwyer
Longview Washington USA
1995 XJRFrom: “Robert Wilkinson” wilk@wustl.edu

I think that’s true for a solid axle car (as Pete says),

I can’t figure out if the same would apply to an IRS–

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In reply to a message from Doug Dwyer sent Sun 8 Jul 2012:

Of course! I think I was completely wrong. The driveshaft
torque reaction will just transfer to the wheels/tires via
the springs. Same for the engine torque at front.

If that’s right, there should be a little bit of body roll
on an IRS car when accelerating hard, but not with a solid
axle, and not when decelerating by braking.

I considered googling it, but why bother when Dwyer and
other hotrodders are on this list. Do you notice any body
roll? It might be slight, and there wouldn’t be any lateral
acceleration on your body like when roll is associated with
cornering.–
The original message included these comments:

My XJR will slew to the right during wheel spin and it has IRS. I’ve driven
E-types and Corvettes that do the same.


Bob Wilkinson, 73 XJ6
Saint Louis, MO, United States
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In reply to a message from Robert Wilkinson sent Sun 8 Jul 2012:

I disclaim expertise. But, my understandoig is that it is egoine
toque that causes the body to twioast and transfer load to one
side. Therefore traction on that side is better than the opposite.
An open differential will trsnsfer power via the spider gesrs to
the side with less traction and it may spin as the available
traction is inadquate for the tire to hook up.

A LSD differential will deliver power to both rear wheels, but if
one has less traction and it is ionadequate to hool up, it will
spin.

So, traction on one wheel and not the other or merely dissimilar
traction is seen as rear steering and the tail will come around.
A drastic case mens a 180 spin. Usually more likely on dirt or a
slippery surface.

If one ever tries to push a locked rear end equipped car, one
immediately notices it’s difficuloty to accept steering input. No
spiders to allow oe wheel to travel at a slower rate than the
other. LSD cars are similar, but not as much, dependent on the
clutch friction.

Ao, it is traction and torque that effect direction.

A good burnout can cause an interesting fish tail. Fun!!

Body roll is a factor whether solid axle or IRS. Useful in ovsal
racing. Good to get rtraction, but must be controlled or the hole
ting will roll. Too stiff sand no roll and it just drifts out.

Carl–
The original message included these comments:

My XJR will slew to the right during wheel spin and it has IRS. I’ve driven
E-types and Corvettes that do the same.


Carl Hutchins 1983 Jaguar XJ6 with LT1 and 1994 Jeep Grand
Walnut Creek, California, United States
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In reply to a message from Doug Dwyer sent Sun 8 Jul 2012:

I can. You’re a hooligan and it’s always wet in Seattle!–
The original message included these comments:

I dunno; can’t 'splain it :slight_smile:


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In reply to a message from Robert Wilkinson sent Sun 8 Jul 2012:

My D-types pitched to the right slightly when stationary
and blipping the throttle. A real one probably does so
much less, due to having a small-diameter multi-plate
clutch on a tiny flywheel. Any standard V12 car also rocks
noticeably on its suspension in torque reaction. The
effect is also enough to unsettle BMW and Moto Guzzi
riders, both stationary and changing down multiple gears
for corners. Honda being Honda used counter-rotating
clutches and other components to try and neutralise the
issue at source in their longitudinal crank shaft-drive
bikes. Others like Suzuki, Yamaha and Kawasaki used shafts
on the back of normal transverse engines so didn’t suffer
this quirky behaviour. Character I call it…

Petep–
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Doug Dwyer wrote:

My XJR will slew to the right during wheel spin and it has IRS. I’ve
driven E-types and Corvettes that do the same.

I dunno; can’t 'splain it :slight_smile:

I would say that no matter what suspension is fitted, Doug - torque
applied would put more wheight and traction on one wheel than the other
also slipping slightly later. And as the the wheels are assymetric to
the centerline of the car; it will push more in one direction than the
other. Which way takes a bit of sorting…:slight_smile:

With limited slip diff it gets a bit more complicated; as both wheels
are locked together an cannot turn independantly. More sophisticated for
either situation; as the torque will reduce the diameter of one tyre -
there is unequal force on the two…:))

Frank
xj6 85 Sov Europe (UK/NZ)> From: “Robert Wilkinson” wilk@wustl.edu

I think that’s true for a solid axle car (as Pete says),

I can’t figure out if the same would apply to an IRS–

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More precisely, a “hoon” :-).

Quite a discussion about this 10-12 years ago. It’s all in the archives
:slight_smile:

Cheers
Doug Dwyer
Longview Washington USA
1995 XJRFrom: “PeterCrespin” jag@thewritersbureau.com

I can. You’re a hooligan and it’s always wet in Seattle!

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Can’t say that I’ve noticed even slight body roll…but that doesn’t mean
it isn’t happening. I’ll pay closer attention next time :slight_smile:

Cheers
Doug Dwyer
Longview Washington USA
1995 XJRFrom: “Robert Wilkinson” wilk@wustl.edu

I considered googling it, but why bother when Dwyer and
other hotrodders are on this list. Do you notice any body
roll? It might be slight, and there wouldn’t be any lateral
acceleration on your body like when roll is associated with
cornering.

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In reply to a message from Doug Dwyer sent Mon 9 Jul 2012:

I remember that discussion Doug. Your hoonishness has been well
documented. Perhaps you just need more right rudder on that rocket
ship of yours.–
The original message included these comments:

More precisely, a ‘‘hoon’’ :-).
Quite a discussion about this 10-12 years ago. It’s all in the archives
:slight_smile:
Cheers
Doug Dwyer
From: ‘‘PeterCrespin’’ jag@thewritersbureau.com

I can. You’re a hooligan and it’s always wet in Seattle!


John Testrake 74XJ12L rhd, 87 XJ12/700R4
St.Louis, United States
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