Lovers,
In working on a friend’s XK140 DHC I noted his does not have the
taper wedges under the rear axle, see
http://xks.com/i-7087552-12-0053-taper-wedge-axle-to-spring.html
At $30 a pop I am wondering if they are really necessary. Can
anyone ejacate me on their function? Is it simply to take thrust
on acceleration, or is there a more subtle function?
Thanks,–
–Gary ('56 XK140 DHC S817720)
Salt Lake City, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from GaryLindstro sent Mon 22 Sep 2014:
That and horizontal alignment with the drive shaft.
I realize parts are expensive, but I would be weary about second
guessing the engineers. They were put there for a reason, and if
not necessary, would have been left out. JMTCW.
Joel–
ex jag, '66 E-type S1 4.2, '56 XK140dhc, '97 XJ-6
Denison, TX, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
In reply to a message from ex jag sent Mon 22 Sep 2014:
Right, the idea is that with a standard Hooke type universal
joint the input shaft of the differential must be parallel
with the output shaft of the gearbox. Not necessarily
inline, just parallel.
The reason is because Hooke joints are not constant velocity
joints, the proof of which involves sines, cosines, thetas
and omega squareds, probably beyond the scope of this forum.
Simplistically it means with the input turning at a constant
speed, the other side of the u-joint speeds up and slows
down twice per revolution. The angular settings of the two
u-joints cancel out this variable velocity effect.
With a leaf sprung axle you get some variance angle with
severe operation, so the setting would be ‘‘parallel at
normal riding height with average size passengers’’.
Apparently Heynes and his crew elected to achieve this with
wedges. Without them there might be some vibration in the
driveshaft transmitted to the chassis.
I see the part number in the 140 book is C.3186 taper wedge,
but I don’t find this number in my 120 book. Does this mean
not all of our cars have them?–
XK120 FHC, Mark V saloon, XJ12L Series II, S-Type 3.0
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
In reply to a message from Rob Reilly sent Mon 22 Sep 2014:
Very interesting and helpful, thanks!–
–Gary ('56 XK140 DHC S817720)
Salt Lake City, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
Rob R;
I am under the impression that, with respect to the XK120’s, only
the OTS was fitted with the differential assembly wedges… The Parts
Catalogue notes “C.3829 Piece, Packing, for Spring Seat” Required
only when rear axle C.3452, C.3821, C.4460, C.4461 or C.4462 is
fitted" and lists the following Chassis Numbers: 660001 thru 660515;
also to 660700, 660728, and 660729; 670001 to 671097. Also to
671130, 671131 and 671207. These are all ENV Rear Axles and
all RH & LH OTS cars…
So, were any 140’s fitted with the ENV Rear Axle Assemblies??
Interesting that the 140 wedge uses a part number (C.3186) that, in
theory, predates the wedge used on the 120’s (C.3829)…
BTW, the C.3829 part number can be found on page 43, Chassis
Section, XK120 Parts Catalogue (Plate #T.49)
Charles #677556.
http://xktx.org----- Original Message -----
From: “Rob Reilly”
I see the part number in the 140 book is C.3186 taper wedge,
but I don’t find this number in my 120 book. Does this mean
not all of our cars have them?XK120 FHC, Mark V saloon, XJ12L Series II, S-Type 3.0
In reply to a message from cb@XKTX.Org sent Mon 22 Sep 2014:
Yes, Charles, you guessed the reason I asked the question.
When I looked it up in the 140 book I didn’t know 140s had
wedges, so I checked the 120 book and noticed the different
part numbers. Up until I compared them I was under the
impression that only the early OTS cars with ENV axle had
the wedge. Are we making an invalid assumption that C.3829
even is a wedge? My 679187 has a later ENV axle but no wedges.–
XK120 FHC, Mark V saloon, XJ12L Series II, S-Type 3.0
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
You asked: “Are we making an invalid assumption that C.3829
even is a wedge?”
Rob R;
No sir, I looked in the XK120 Parts Catalogue Plate T (Chassis),
located part Plate Number T.49, which is located under the Rear
Springs, then referenced the information I typed… so, pretty much
a strictly “By-The-Book” deal…
Charles #677556.
http://xktx.org----- Original Message -----
From: “Rob Reilly”
Are we making an invalid assumption that C.3829
even is a wedge? My 679187 has a later ENV axle but no wedges.XK120 FHC, Mark V saloon, XJ12L Series II, S-Type 3.0
In reply to a message from Rob Reilly sent Mon 22 Sep 2014:
Jaguar { SS] had used wedges [ caster wedges] as long as they
had been making cars. On beam axles they are used to set
caster angle for front end alignment.
I don’t know that it’s that important on a rear axle [
although the are alignment settings for the Jag independent
rear ends.]
I think on the XKs they are used to alter the nose of the
diff slightly to clear some part of the chassis.
While it may look to have clearance at rest torque reaction
under acceleration with leaf springs can change this noticeably
[ as I found out when I put cycle guards on my car and could
see what was happening.
I would imagine the thick end goes to the front. as this will
have the tendency to make the rear wheels track straight [ +
ive] caster]
I think some racing drivers used to bend the rear axle housing
a little to get toe in on the back end. Over that length the
wheel bearings apparently accommodated the slight misalignment
The use , or not on ENV may be due to variations between ENV
and Salisbury in the alignment of the pinion to the axle
centre line.–
Ed Nantes SS
Melbourne, Australia
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
In reply to a message from Ed Nantes sent Mon 22 Sep 2014:
What I was getting at was that the 120 book says only
‘‘C.3829 Piece, Packing, for Spring Seat’’. It doesn’t say it
was a wedge. Is it a parallel block? Is it intended to
compensate for inaccuracies in placement or size of spring
pads on early ENV axles?
Incidentally the XK150 book has ‘‘C.3186 Taper Wedge (Fibre)
between rear road spring and pads on axle (2)’’.
It is curious that such a low number as C.3186 would not be
found in the 120 book. Does anyone with a 120 have wedges
with a Salisbury axle?–
XK120 FHC, Mark V saloon, XJ12L Series II, S-Type 3.0
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
I will check if you will tell me what to look for.
David
54 XK120DHC
Does anyone with a 120 have wedges with a Salisbury axle?
In reply to a message from Dave Hammond sent Tue 23 Sep 2014:
Here is Gary’s link to the thin wedge offered by XKs
Unlimited that started this thread.
http://xks.com/i-7087552-12-0053-taper-wedge-axle-to-spring.html
They are located between the saddle on the axle tube and the
top leaf of the springs. Might be hard to see if you have
the gaiters on the springs.–
XK120 FHC, Mark V saloon, XJ12L Series II, S-Type 3.0
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
In reply to a message from Rob Reilly sent Tue 23 Sep 2014:
Rob,
curious stock levels they have . they say’stock remaining …
9 ’ but they can only be of use in pairs: >)
The ones I’ve seen usually have a slot from the thick end
rather than a hole, so they can be slid on, and not have to
remove the axle from the spring centre bolt.
They were commonly sold for use on trucks with beam axles
The width may vary… front axle Jaguar ones are for 2’’ wide
springs , rear are 1 3/4’’ but wider ones would be easily
narrowed. Anyone with a mill or mill drill and and adjustable
vise would make them pretty easily.–
The original message included these comments:
Here is Gary’s link to the thin wedge offered by XKs
Unlimited that started this thread.
http://xks.com/i-7087552-12-0053-taper-wedge-axle-to-spring.html
They are located between the saddle on the axle tube and the
top leaf of the springs. Might be hard to see if you have
the gaiters on the springs.
–
Ed Nantes SS
Melbourne, Australia
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
In reply to a message from Ed Nantes sent Tue 23 Sep 2014:
So … I checked all the bits I still have left from my 140
FHC. I do have one wedge and had no idea what it was for.
It measures 1-5/8’’ by 4-1/8’’ and has a taper from 1/8’’ to
7/16’’ and has a hole-slot in the centre. Part of the
casting has a large number formed in it … 5-828. I could
send a photo to anyone that may want to see it.
Cheers
Harv–
Harv XK 140
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
In reply to a message from Harv XK 140 sent Wed 24 Sep 2014:
My computer, because I’ve forgotten how to do sums in my head,
tells me that’s about 4 1/4 degrees.
Which seems a lot for a caster wedge on the front as the ones
I’ve seen were in the 1 1/2 to 2 degree range.
I don’t know what XKs had on the rear but if it’s right and
you have one, the other is easy to make.
Sit it on the mill with a piece of what ever you are making
the new one from clamped to it and mill across the new one. The
angle will come out the same and you can then drill a hole and
a slot
Aluminium is easy and tha’st what they were commonly made
from. The slot from the thick end will stop it being ‘squeezed’
out.–
The original message included these comments:
So … I checked all the bits I still have left from my 140
FHC. I do have one wedge and had no idea what it was for.
It measures 1-5/8’’ by 4-1/8’’ and has a taper from 1/8’’ to
7/16’’ and has a hole-slot in the centre. Part of the
casting has a large number formed in it … 5-828. I could
send a photo to anyone that may want to see it.
–
Ed Nantes SS
Melbourne, Australia
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
In reply to a message from Ed Nantes sent Thu 25 Sep 2014:
I can see where one would use wedges to set the caster angle
on the front end of an SS or Mark IV with it’s beam axle. An
alignment shop might have an assortment in 1/2 degree
increments.
But it’s nothing to do with XKs. I can only see one purpose
for these on an XK rear axle, which is to set the
differential pinion shaft where it is parallel to the
gearbox mainshaft most of the time under average driving
conditions. It seems odd that the factory couldn’t get this
right in the frame welding jig, so they wouldn’t need these
wedges in every car. Is there any evidence that maybe it was
an adjustment item, and not every car needed them? Are they
only needed with competition springs or something?
Here is a page that explains the math of the variable
angular velocity problem and how it is cancelled by having
two u-joints.
http://en.wikipedia.org/wiki/Universal_joint--
XK120 FHC, Mark V saloon, XJ12L Series II, S-Type 3.0
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
In reply to a message from Rob Reilly sent Thu 25 Sep 2014:
Rob
I would think the ’ average driving conditions [ height] is to
allow for suspension movement either side of ’ centre’
Universals have an optimum range of movement. The longer the
shaft, the less angle of movement.
The half shafts of an independent Jag rear end probably have a
bigger range of movement than the tail shaft of a MKVII
It may have been this factor that caused Jaguar to make gear
boxes with shorter rear extensions for SS100s and XK 140s.
I think the wedges were to lift the tail shaft up to clear it
over the middle cross member… The MK V and VII had similar
chassis but longer so not a problem and no wedges.
If it was too keep the joints parallel it would’t work at the
time when under greatest load… when accelerating, and the
springs wind up.
Do we know definitely whether only ENV diffs had the wedges?
If so it may be to do with the dimensions and placement of the
line of the pinion
The ENV being front loading the Salisbury rear loading, quite
possibly they differ.–
The original message included these comments:
But it’s nothing to do with XKs. I can only see one purpose
for these on an XK rear axle, which is to set the
differential pinion shaft where it is parallel to the
gearbox mainshaft most of the time under average driving
conditions. It seems odd that the factory couldn’t get this
–
Ed Nantes SS
Melbourne, Australia
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
Gentlemen,
I have been following this thread and like to try and clarify the discussion
so far. Some observations according to the parts catalogue for the 120.
Item T49 part number C3829 is described as a ‘packing piece’ used only on
ENV rear axles but not all ENV rear axles. Only rear axle part numbers
C3452, C3821, C4461 or C4462 had them. Rob’s car 679187 would have been
fitted with an ENV rear axle in the part number range C5150 through C5154
and therefore would not have required them to be fitted. At the present
point in time, I understand we do not know what form this packing piece
takes, as this elusive animal has not been sighted. It could be a tapered
packer or in fact, it could be nothing more than a large shim not designed
to change any angles.
As far as the 140 goes, according to the parts catalogue, all 140’s had a
fibre taper wedge P/N C3186 fitted and all cars had a 4HA rear axle fitted
although four different ratios were available.
Is this understanding correct? If this is correct what changed between the
last of the 120’s and the 140 to require the wedge?
Ken Godbaz, Auckland NZ
672431 & S814013-----Original Message-----
From: owner-xk@jag-lovers.org [mailto:owner-xk@jag-lovers.org] On Behalf Of
Ed Nantes
Sent: Friday, 26 September 2014 12:55 p.m.
To: xk@jag-lovers.org
Subject: RE: [xk] taper wedge, axle to spring
In reply to a message from Rob Reilly sent Thu 25 Sep 2014:
Rob
I would think the ’ average driving conditions [ height] is to
allow for suspension movement either side of ’ centre’
Universals have an optimum range of movement. The longer the
shaft, the less angle of movement.
The half shafts of an independent Jag rear end probably have a
bigger range of movement than the tail shaft of a MKVII
It may have been this factor that caused Jaguar to make gear
boxes with shorter rear extensions for SS100s and XK 140s.
I think the wedges were to lift the tail shaft up to clear it
over the middle cross member… The MK V and VII had similar
chassis but longer so not a problem and no wedges.
If it was too keep the joints parallel it would’t work at the
time when under greatest load… when accelerating, and the
springs wind up.
Do we know definitely whether only ENV diffs had the wedges?
The original message included these comments:
But it’s nothing to do with XKs. I can only see one purpose
for these on an XK rear axle, which is to set the
differential pinion shaft where it is parallel to the
gearbox mainshaft most of the time under average driving
conditions. It seems odd that the factory couldn’t get this
–
Ed Nantes SS
Melbourne, Australia
There are no such wedges on 120s ; the factory introduced them on 140s.
They must have realized it was necessary to compensate for springs wind-up under acceleration, especially as engine bhp increased.
Francis THIBAUD
S675155
S815023DN
In reply to a message from Francis THIBAUD sent Fri 26 Sep 2014:
This thread has indeed become quite interesting and informative.
May I return to basics and ask a simple question?
I installed my wedges with the thicker end toward the rear of the
car. Is this correct?
Thanks,–
–Gary ('56 XK140 DHC S817720)
Salt Lake City, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
In reply to a message from GaryLindstro sent Fri 26 Sep 2014:
Gary , I’d doubt it. apart from bringing the tail shaft closer to
the cross member, it tends towards negative caster on the rear
axle.–
Ed Nantes SS
Melbourne, Australia
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –