[xk] XK 120 steering box question

Gentlemen and assembled holders of knowledge;

I’ve a few questions about the steering box on my late 120.
At the bottom of the box is a large castellated nut which secures
the drop arm (pitman arm to us yanks) to the splined rocker shaft.
This nut cannot be removed while the box is installed in the car.
On my car, the drop arm (pitman arm) has some free play between the
nut and the shaft. This causes the drop arm to have a little bit of
up & down slop. I can see it move on it’s shaft. The steering box
is correctly adjusted and there is little to no play / slop in the
steering box. The play is at the bottom where the rocker shaft &
drop arm join. The drop arm end where it meets with the track rod
moves up & down as the drop arm moves on the shaft.
My question is: are there shims to be used to tighten up the drop
arm on the shaft? Is the drop arm / rocker shaft union a tapered
splined connection? If I, at great effort, loosen the nut on the
bottom of the rocker shaft, will I be able to tighten up the nut
and eliminate the slop in the drop arm / rocker shaft relationship?

Your advice & guidance are welcomed.
Roger–
Roger, 1954 120 DHC BRG, S678300
Tamarac, South Fla., United States
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Roger,

Believe it or not the “trouble” you described is what originally brought
me into the “Jaguar world” so many years ago!

You see my car originally suffered from what was described to me as a
slight shimmy but something that a NY Jag shop estimated to repair at
about $!800 (1960 dollars) causing the young PO to put it up for sale!

Since I drove it only making left turns (the PO’ parents had an estate on
Long Island with a circular driveway and fountain), I closed the deal and
bought it with the intent to come back in the evening and take it home.
It didn’t even shimmy going round and round!!!

It took almost 4 hours for a 30 mile trip as the car shook violently at
20mph. It didn’t shimmy, it wobbled like a shopping cart with a bad
wheel.

The day after getting the car home (to NYC) I found the trouble as you
described and using what was at hand, fixed the wobble by shimming the
tapered shaft with a large washer opened up to allow the shaft to enter
it.

I reamed the washer that’s about 3/16 thick with an old brace and tapered
pipe ream. It is still on the car today and that “fix” has gone through
at least 100K miles of hard driving.

You can back the nut off the shaft if you hold the arm fast (as I did
back then) by applying a large Stillson (pipe) wrench perpindicular to it
between the box and link pivot.

Although the box is quite robust the wrench holding the arm will take the
shock when your mate smacks the handle of the other wrench (on the nut)
with a big wooden mallet. (Impact it off!)

What I’ve found is that the fit of shaft to arm is very close indeed, and
that there is very little “draw-in” tolerance before the nut bottoms on
the thread against the taper. Should it loosen a trifle it works up and
down wearing the shaft and perhaps stretching the “eye” of the pitman arm
until it manifests as a trouble. The natural tendency for a shop is to
tighten on the nut, but at that point it’s far too late.

Do examine the arm once you loosen it and assure it is not cracked and
that there will be enough clearance once reassembled.

Although it is an essential part of the steering it is substantially
stronger than much of the modern rack and pinion rods, links, and mounts.
If you are troubled with the possibility of loosening again, you can
fabricate your shim washer to have sufficient stock to allow for tabs to
bend up and down to thwart reverse spin off of the nut.

Regards and let us know!

Rick
677342-DHC

Roger,

What was the outcome of your loose pitman arm on your 120?

Regards,

Rick

In reply to a message from holland-rick@juno.com sent Fri 11 Nov 2005:

I went to ebay and found a 1 7/16’’ wrench at a price I would pay &
then jacked up the car, removed the left front wheel & removed the
cotter pin from that BIG nut. I then very slowly tightened the
nut. I got about a half a turn, maybe a little less, maybe a
little more. Replaced the cotter pin, wheel and problem was gone.
It was not by any means as easy as it sounds in words, but what is
on our beloved cats.

Roger–
Roger, 1954 120 DHC BRG, S678300
Tamarac, South Fla., United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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In reply to a message from Velocette sent Fri 11 Nov 2005:

re: inexpensive off-sized tools

One of the benefits of the widespread availability of ‘‘inexpensive’’
wrenches and socket sets these days is that one can afford to keep
sets of sizes, or other systems - full like metric, that were not
really affordable previously when we were used to buying Snap-on or
Craftsman tools.

These cheapies may not be tools that one would want to use to make
a living, but I find I am now able to have full metric and SAE up
to 3/4-inch drives and the really big box and combination wrenches
for the ‘‘once in a lifetime’’ situations such as mentioned in this
post.

Karl–
The original message included these comments:

I went to ebay and found a 1 7/16’’ wrench at a price I would pay &


karl
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