[xk] taper wedge, axle to spring

XK
21

Yes, that’s how my old originals were positioned & that’s how the new
ones were installed.

http://www.jag-lovers.org/snaps/snap_view.php3?id=1089171068

Regards, Otto-----Original Message-----
From: GaryLindstro gary@cs.utah.edu
To: xk xk@jag-lovers.org
Sent: Fri, Sep 26, 2014 9:10 am
Subject: Re: [xk] taper wedge, axle to spring

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
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22

In reply to a message from Otto sent Fri 26 Sep 2014:

I don’t quite understand the reference to ‘‘caster’’ and ‘‘tail
shaft’’ because there is no caster angle on our rear axles,
and the wedge is not placed under the gearbox tail shaft.
There is no cross member clearance problem on the XKs.

Unless you mean that the wedge alters the angle of the ‘‘nose
shaft’’ of the axle relative to the gearbox tail shaft, which
is what I was trying to describe earlier. As I said, they
are supposed to be parallel most of the time.

I looked through all the 1946-60 service bulletins, and
though there are several dealing with rear springs, there
was not one single mention of wedges. SB90 says the C.3829
packing piece must be used with early 120 ENV axles and
stresses that it must not be used with the later ENV axles.
It does not however describe them or say anything about a
proper direction to install them.

Urs Schmid has a photo of a tapered aluminum packing piece
which he says is C.3829, but Bernard Viart has a drawing of
what looks like the same thing and says it was intended to
lower the body for competition and was not an official
Jaguar Modification.

Viart’s drawing indicates that this packing piece would
change the angle of the nose shaft by 2.73 degrees.

Has anybody actually measured the parallelism of their axle
input flange relative to their gearbox output flange? It
should be done with the springs fully laden of course. It
would be an interesting exercise.–
XK120 FHC, Mark V saloon, XJ12L Series II, S-Type 3.0
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23

In reply to a message from Rob Reilly sent Fri 26 Sep 2014:

So which is it, thin part of the wedge at the front or back?
Joel–
ex jag, '66 E-type S1 4.2, '56 XK140dhc, '97 XJ-6
Denison, TX, United States
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24

Gary, Ed

The wedge is fitted with the thicker end to the back.
That is why I was inclined to think it was there to compensate for springs wind-up under acceleration.
But, who knows ?
Francis THIBAUD
S675155
S815023DN

25

Gary, Ed,
What Francis said…Refer to the Viart/Payne treatise “Jaguar
XK140 Explored” page 183, illustration 3-e2 and this shows the wedge C3186
fitted with the thicker end towards the rear of the spring.

Ken Godbaz, S814013 & 672431-----Original Message-----
Francis THIBAUD
Sent: Sunday, 28 September 2014 5:31 a.m.
Subject: [xk] taper wedge, axle to spring

Gary, Ed

The wedge is fitted with the thicker end to the back.
That is why I was inclined to think it was there to compensate for springs
wind-up under acceleration.
But, who knows ?
Francis THIBAUD
S675155
S815023DN

26

In reply to a message from Ken Godbaz sent Sat 27 Sep 2014:

I just want to thank you fellows for bringing this wedge
topic up. I have since found both wedges and now I will
have to redo the work that was done by the past owner.
However, it is a lot better to find out about this now, as
I don’t have the body on the chassis yet.

Again … thank you; thank you–
The original message included these comments:

XK140 Explored’’ page 183, illustration 3-e2 and this shows the wedge C3186

–
Harv XK 140
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27

G’day Harv (and others).

Whilst restoring that part of my XK140 OTS - thus the source of all the
photographs used for the line-drawings in XK140 EXPLORED - as with
everything else, I really went very much into the detail and understanding
as best I could - so thus the greater degree of detail/captioning within the
XK140 EXPLORED plates.

But a few interesting observations.

My leaf-springs, still with 3/4 intact original Gaiters - were in perfect
condition still with no apparent sag, so all I did was disassemble them,
lubricate with a molybdenum-base grease, rebush them with accurate
metallastic bushes (and there are correct and not so correct repos
available) and I also had machined up slightly modified centre-bolts, then
reassembled springs with these ‘upgraded-bolts’.

The reason of course was the subject WEDGES.

My leaf springs had stamped on the lower-surface of the smallest leaf (I
think without checking notes/photos) a makers logo, Jaguar Part Number and
also a date, and both my leaves were 1953/4 dated so presumably old XK120
stock finally fitted to my 1955 XK140. But late XK120SE and XK140 use the
same rear-springs so that is fine.

But before I disassembled springs from rear-axle mounting brackets, after
thorough cleaning and inspection I had noticed that on one side I could see
the depressed crown of the spring centre-bolt only 1/2 engaged within the
thickness of the locating hole in the mounting-bracket. But on other side,
I could see daylight, with the crown of the centre-bolt offset from hole
about an 1/4". So after disassembly of the excruciatingly tight “U” bolts
secured by NUTS and LOCK NUTS, I was able to see that this one misaligned
Centre-bolt had either been not assembled properly located into the hole
(likely) or had ‘jumped’ out of hole during its low-mileage on-road use
(unlikely). So looking for the reason, I decided that adding these wedges
was an afterthought introduced maybe from XK120 initial use of Salisbury
Rear Axle, thus need for these wedges as it was too late to better slightly
redesign rear-axle bracket, or maybe an in-service design upgrade for later
XK120s recognising need for better alignment of prop-shaft to input pinion,
or as has been suggested, an improvement/modification introduced for XK140
rather than introduce another Rear-Axle Assembly part number and control for
production/support/spares reasons.

Thus I am interested in current comments from XK120 owners about these
wedges, but I am not hearing to much first-hand-awareness of them, so as
then, I still tend to think the wedges were introduced for XK140.

But by adding wedges, whilst still using unchanged spring centre-bolts,
means difficulty in reaching/aligning centre-bolt head with hole in
rear-axle mounting bracket, and once located, minimal engagement.
Thus my example - one side with minimal but correctly aligned engagement,
the other misaligned and not engaged, but bolted up tight causing head of
centre-bolt to punch an offset depression in rear-axle bracket.

So I repaired depression in bracket, but also decided to add height to the
head of the centre-bolts, such that on assembly with new WEDGES fitted, the
centre-bolts fully engaged to be flush at top surface of bracket, so no dirt
trap/obstruction through the bracket hole.

Now you don’t just go and buy new High-Tensile Steel XK140 Rear-Spring
Centre-Bolts with a modified /increased head height from your local
specialty-fastener shop, nor indeed the usual spare-parts-outlets.

So what I did was I looked for and found some High-Tensile Cap Setscrews
(those with a round head but with a female-hexagon-drive, that compared to
my original Centre-Bolts had an over-diameter and over-height head, the same
bolt shank length, and an over-length BSF thread. I machined the head down
to correct diameter, and down to my design increased-from-original head
height, and cut excessive BSF thread-length back to original bolt length.
End result was a HIGH TENSILE BSF Centre-bolt with a taller-head.

Should see me out, and my daughters inherited ownership, so all I have to do
is not tell any future Concours Judges about this non-authentic
modification, whilst being happy that I should never have a
rear-axle-alignment issue if I go bouncing over pot-hole roads at speed!

But worth having a close look at how yours is, and how well it all
re-assembles.

Roger Payne - XK140MC OTS; E-Type 4.2 S.1 OTS; DSV8.
Canberra.-----Original Message-----
From: owner-xk@jag-lovers.org [mailto:owner-xk@jag-lovers.org] On Behalf Of
Harv XK 140
Sent: Friday, 3 October 2014 7:30 AM
To: xk@jag-lovers.org
Subject: RE: [xk] taper wedge, axle to spring

In reply to a message from Ken Godbaz sent Sat 27 Sep 2014:

I just want to thank you fellows for bringing this wedge
topic up. I have since found both wedges and now I will
have to redo the work that was done by the past owner.
However, it is a lot better to find out about this now, as
I don’t have the body on the chassis yet.

Again … thank you; thank you

The original message included these comments:

XK140 Explored’’ page 183, illustration 3-e2 and this shows the wedge
C3186

–
Harv XK 140
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28

In reply to a message from Roger Payne sent Thu 2 Oct 2014:

This is an issue common to early beam axle Jaguar owners

Many decades ago I had the front axle move on an SS under braking
,… interesting.but normally if we need to put wedges or bigger
wedges, we just put a spacer under the head of the centre bolt to
increase its height. spacer OD the same as the original head]

So far so good.–
Ed Nantes SS
Melbourne, Australia
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29

In reply to a message from Ed Nantes sent Fri 3 Oct 2014:

I don’t quite understand. I thought the center bolt went
through the wedge, so it would never slide out of position.

And just to add some more confusion to this interesting
topic, the Salisbury rear axle from XK120 FHC 681114 does
not have separate bolts such as I think Roger was
describing, it has studs permanently fixed through the
saddle brackets, and the head is welded to the saddle
bracket, so you could never remove them. There is a
clearance hole in the bottom plate under the spring to
access the corresponding nut. There would be no chance of
the spring sliding out of place on this 120.

My Mark V Salisbury axle is the same way.–
XK120 FHC, Mark V saloon, XJ12L Series II, S-Type 3.0
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30

In reply to a message from Rob Reilly sent Sat 4 Oct 2014:

Rob

MK IV and SS had a centre bolt through all the spring leave s[
How else would it hold together?]

The head of this ocates in a hole in the bracket welded to the
axle tube.

ON these cars the wedges used on the front have a slot instead of
a hole , Ths enables them to be changed by sliding in and out,
without undoing the U bolts as far.–
Ed Nantes SS
Melbourne, Australia
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