My front suspension is measuring 11’’ above ground at the front
chassis member compared with the listed height of 7.125’’, so it
requires substantial adjustment. The method of adjustment in the
workshop manual is to release the reaction lever locking bolts and
rotate the adjustment barrel nut either clockwise (increase
tension) or anticlock (reduce tension). If you reach the end of
travel position, it is necessary to reposition the the torsion bar
in relation to the lower wishbone member by rotating the front
splined muff, after releasing the two securing bolts, and removing
the rear reaction locking bolts.
I can understand the first part, but the rotation of the muffs
beats me. I do not understand how you can replace the rear rection
locking bolts after removal, due to their position behind the
chassis cross member. I also do not understand how you rotate the
muffs.
Has anyone carried out this procedure, and can explain it in more
detail?–
Philip Heneghan
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In reply to a message from Philip Heneghan sent Mon 3 Nov 2008:
Hold on there, Philip.
The 7.125’’ measurement is taken at the lowest point of the
side rails, not the front cross member. Let’s first be sure
on that. At the front cross member it will indeed be much
higher, and this is where later models are measured.
Second, never turn the barrel nuts with the full weight of
the car on the wheels. Always lift the car first, otherwise
you might twist off the square head on the upper end of the
reaction bolt. Guess how I know. Then let the car down and
measure again.
Third, rotation of the muffs means to change the position of
the front and rear splines relative to each other at the
relaxed initial position. You first take off all the
tension, then knock the torsion bar rearwards out of the
muff and reaction lever simultaneously, then put it back in
new positions, so the reaction lever starts out at a new
initial angle.–
XK120 FHC, Mark V saloon, XJ12L Series II
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In reply to a message from Rob Reilly sent Mon 3 Nov 2008:
Phillip and Rob
I took of the muff in the front. Seemed to be the easiest way.
Remember loosing the bar tension completly !!! by the brass nut.
I checked the hight left/right by the rear springs box in front.
I followed the instruction in my 150 ‘‘service handbook’’.
Surely the same for all XK�s.
The height 7 1/8’’, 18.1 cm, both front and rear.
The hights by the wheelarches became very much the same.
I set in a foto in my fotoalbum
Remember to fasten the lock bolts again.
Leo–
LeoN - Denmark
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In reply to a message from Leo Nyg sent Sun 9 Nov 2008:
Leo
XK120 body height adjustment
Thanks for this response. Rob sent me an email that referred to
XK150 service bulletin 139 dated Jan 54 advising a height of 11.25’’
from floor to front cross member of the chassis. This is close to
what I have currently, but a long way off 7.125’’. Confused or what?
I now know how to adjust, but not to what.
Phil–
Philip Heneghan
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In reply to a message from Philip Heneghan sent Mon 10 Nov 2008:
Philip
You were absolute right in your first reply about the two hights.
So no need to confusion.
I have thought about another thing : What does it mean if the
hight in the front not is exactly correct after specifications?
I prefere to adjust the front after the rear to make the car look
god from the side, meaning that the wheel and the wheelarch
follows each other.
Notice, that my words and spelling reflects, that I live in Denmark.
Could desturbe the meaning.
Leo–
LeoN - Denmark
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In reply to a message from Leo Nyg sent Tue 11 Nov 2008:
Your spelling is OK. I am quite clear as to what you mean. The
reason I am concerned to get the right height is that it may affect
the steering, and I am unhappy about the steering on my car. It
feels ‘twitchy’, that is to say there is a lot of feel from the
road, and it feels as though the alignment is off.
The car has been modified to rack and pinion steering, and this amy
be the cause of the problem, but I’m trying everything.
Phil–
Philip Heneghan
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Philip;
The original “worm & gear” type steering of the XK120 was hardly
“twitchy”… If anything, it was like driving a truck! Especially at sub
30mph speeds.
You mention that your 120 was “converted” to Rack & Pinion… I know of no
known “conversions”, so it’s probably a “highly modified” (maybe a polite
way of saying “shade-tree”?) installation… The first course of action
would be to determine the “breed” of R&P that is installed (hopefully it’s a
140 or 150 unit), then start inspecting the mounts (how it’s mounted and the
“mountings”, especially if “custom made”, along with “how” the R&P is
connected to the 120’s steering column-- a VERY important thing to have done
correctly, not to mention, safely!), look at the Tie-Rods and Upper & Lower
ball joints… any “slop” in these items could make for some “twitchy” (and
exciting) steering… That said, the “stock” steering of the 120 did give a
“comfortable” bit of “road feedback”… however, the steering wheel should
not be beating you to death from vibrations and/or oscillations.
On “Ride Height” (both front & rear), you are correct, it will affect the
front-end alignment, if too high or low… What it immediately affects is
the “King-Pin Inclination”… of course, our cars don’t have “king pins”,
but I use the term for the imaginary line (camber) that bisects the upper
and lower ball joints on each side (think of this like the “rake” or angle
of a motorcycle’s front-end forks )… The 120 Service Manual gives full
specs on the various “settings” of the stock front-end… Even with R&P, the
wheels have to be pointed in the correct directions ;-}
Hope this is of some help…
Charles #677556.----- Original Message -----
From: “Philip Heneghan”
Your spelling is OK. I am quite clear as to what you mean. The
reason I am concerned to get the right height is that it may affect
the steering, and I am unhappy about the steering on my car. It
feels ‘twitchy’, that is to say there is a lot of feel from the
road, and it feels as though the alignment is off.
The car has been modified to rack and pinion steering, and this amy
be the cause of the problem, but I’m trying everything.Phil
Philip Heneghan
In reply to a message from Philip Heneghan sent Wed 12 Nov 2008:
OH - the plot thickens. I doubt the ride height is the issue.
Assuming that you have checked the easy stuff - like the static toe-
in - it sounds like you have a bump-steer issue generated by bad
steering geometry due to the R&P conversion. Did the R&P
conversion retain the stock XK steering arms and or radiator
location? It would be very difficult to obtain a satisfactory
geometric relationship without relocating the XK-120 radiator, as
was done on the R&P XK-140’s & 150’s. See:
You almost need a good race car engineer to sort out these bump
steer issues.
Regards to all,–
The original message included these comments:
the steering, and I am unhappy about the steering on my car. It
feels ‘twitchy’, that is to say there is a lot of feel from the
road, and it feels as though the alignment is off.
The car has been modified to rack and pinion steering, and this amy
be the cause of the problem, but I’m trying everything.
Phil
–
Mike Spoelker 672027
Louisville, KY, United States
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In reply to a message from MikeSpoelker sent Wed 12 Nov 2008:
Sadly, you are correct in saying the conversion used the existing
arms and radiator location, so this is probably the source of the
steering instability if these were changed on the XK150.
The rack is a nondescript Ford pattern, but fits the bill for
dimensions. It is mounted directly onto the chassis in front of
the radiator.
Sounds to me like it’s back to the drawing board, with a choice of
either a new 140 type radiator with the rack re-mounted to the
rear, or return to the original steering gearbox arrangement.
All the front bushes and the wheel bearings have been replaced and
there is no significant play anywhere up front.
I will re-check the the chassis height, but it sounds OK from
current information.–
Philip Heneghan
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