Body Shims

Back from two weeks vacation and just catching the tail end of this thread.
The parts catalogue shows four different part numbers for the XK120 chassis
frame: C3387 for all alloy; C3387/1 for early steel OTS and early FHC;
C6692 for late OTS; C6762 for late FHC and all DHC. The changes in the
chassis from early to late OTS and from early to late FHC correspond to
changes in the front engine mounts and gearbox tailcase mount from
rectangular to round. I suspect there may also have been changes to the
outriggers, but I don't have enough info to confirm this. If your chassis
is from a late FHC, I believe this DHC body should be a straightforward
installation (at least as straightforward as these XK's ever are, ha,ha),
but be forewarned that the shimming will be a trial and error procedure. If
it is from an early FHC you may find other dissimilarities. Early FHC's
like mine and Carl's have thick rubber shims on the outriggers rather than
the aluminum blocks found on later FHC's and probably all DHC's as
mentioned by others. Also the brake master cylinder mounting bracket was
changed when they went to the tandem system (different bolt spacing). Rob
Reilly - XK120 FHC 679187

Rob, Were it that I was far along enough to face the "shimming and spacing'
tasks. But it will come and to that end, might you or anyone else have
described the procedure and pitfalls sometime in the past. Could one assume
that the stiffer body of an FHC will make the job less onerous or
conversely, might said stiffnes mask problems for later "discovery". Just
musing in anticipation - Klaus Nielsen

Rob, Sorry, I forgot to ask another question. I received my spacer/shim
collection comprising various thicknesses of aluminium and dark fiber
discs, all in a gallon can. They cannot be divided into four like sets, so
I assume they must go in "as needed" to fill the local void. Are there any
recommendations or convention wrt. fiber up, down, in between or what...
Thanks - Klaus Nielsen

Klaus, my limited experience shows that the aluminum/alloy spacers are
standard and fit between sheet metal support components and that the slack
is taken up by the fiber(fibre) spacers.  But I could be all wet (sorry,
been watching '40s movies) Jim Warren, '140 dhc

Klaus:  The combination of  aluminum and steel results in galvanic action.
I believe the aluminum becomes sacrificial in the process, but the steel
also shows an increasing tendency to corrode.  The fiber washer provides
insulation.  If you need two of the washers, put one on each side of the
aluminum shim.  It is interesting that my early FHC with rubber shims
showed no corrosion on the body or the chassis at the shim points!  I chalk
that up to the fact there was no aluminum. - Carl Hanson, 1951 XK120 FHC

Klaus, I thought fibre washers between steel and aluminium were about
stopping electrolytic action. (A lesson Aston took a long while to learn).
But as always, I'm probably  wrong. - Roger Learmonth

Jim, Thanks for the comments...both of them. - Klaus Nielsen

Carl   Thanks...and of course. I feel rather stupid, having had numerous
steel ejector pins freeze hard in wax injection mold dies made from 6061
and other alu' stock. As my shims have all beeen "sacrificed", might it be
worth passivating the new parts before installing them? Regards - Klaus
Nielsen

Roger, I am sure you are right, I was just denser than dense. - Thanks,
Klaus Nielsen

updatated 9/2/98...

Dear friends, since some of you (I am speaking of Dick Cavicke here) were
so kind to provide measurements of their cars in response to an inquiry
from Roger Learmouth, I am hoping for the same response to the following
question. What is the gap between body and chassis at each of your shim
locations on the XK120 FHC?  OK, if you don't want to dirty your clothes
and get under the firewall it's all right, because I am mainly interested
in the dimension at the rear shims.  I am in the process of shimming the
body and have no clear idea what the acceptable range is.  Porter's book
says the coupe body was raised 1 1/2 inches compared to the OTS using
aluminum blocks on the outriggers, but is that a uniform lift both front
and back?  My firewall appears to be lifted 1" off the frame, the sides 1
1/2" and the rear about 1". Does this agree with anyone else out there?  I
will thank you for any data you can provide. Suggestion:  Our library
should have a database of measurements for the various XK's. - Carl Hanson,
1951 XK120 FHC #679102 Bedford, MA, USA

I would like to second the idea that our library should have a database of
measurements for the
various XK's. - Skip Smith

Carl: I visited friends at Classic European Restorations in Oceanside, CA
today to view and ask questions about a 120 FHC they are finishing for a
local club member. Here's their explanation of the FHC body shims.
Basically they agree with the dimensions you have mentioned. The firewall
shims are only about 1", the sides 1 1/2"; however, the rear shims are "as
required". They said that after installing the front and side shims, the
rear is allowed to assume its own level and shims are fitted to hold it
there. The FHC they were working on had a 3/4" shims at the rear. I asked
if they would consider increasing the size of the rear shims if it had been
necessary to get more drip rail clearance above the door frame? They said
"yes". Incidentally, this car already had a generous 1/4" clearance between
the top of the door frames and the drip rail. They added that they have
several thicknesses of shims they use at the rear and always try to avoid
forcing that part of the body into a new position. - Good luck,   Dick
Cavicke

Thank you, Dick,  for your response.  As I align the body, I am temporarily
using wood blocks for shims to hold a shape that I can weld. I began to get
worried when I realized that my original shims were rubber and could have
squashed out to any dimension. The rear fender (wing) stays provide a limit
to how far the rear can be raised, I discovered.  As the body lifts, the
stays start pushing out the rear fender.  There is some take up available,
but not too much.  I hold a straight edge along the front fender and door
line to keep the rear fender in alignment. Thanks again. - Carl Hanson,
1951 XK120 FHC Bedford, MA

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