Hi Linda:
I would urge approaching the process of replacement with a goal of the
longest possible future service. Remember, of course, that I'm not a
mechanic. Most ethical mechanics give highest priority to giving "most
benefit with least effort (and expense to the owner). That's just what
I want , if the work is being done on a car that I replace with a new
one in five years or less. On the otherhand, if I have a classic car
that I intend to keep and enjoy forever, every cosmetic and maintenance
decision is made with the the same intention that something work as
intended, but also that it do so "forever" (or at least for the longest
possible time.
In the latter case, when I replace brake fluid, I always change from
the normal DOT-3 fluid (which is hygroscopic, or absorbs water and,
over time causes deterioration where such water collects in the brake
system) with DOT-5 fluid (which is not). Yes, there are minor
differences in the performance capabilities of the two different
fluids, but they each adequately serve the intended purpose with a
comfortable safety margin (unless subjected to demands that typically
only occur when racing).
Expanding on Lynn's recommendation to get the old wire "moving" with
vise grips and a hammer...don't just fixate on getting the old wire
out. It is abnormal friction which is responsible for abnormal
resistance to smooth and predicitable operation of the trim tab through
its normal operating range by means of the trim control. I suggest
that it is short sighted to concentrate on getting the trim system to
"work", as opposed to adopting the goal that it work WELL (smoothly)
for a long time.
Hartmut's suggestion to use the old wire thickened by corrosion as a
tool (of sorts) before removing it is an excellent one. He is another
who looks ahead whenever he undertakes a task. I would speculate that
it likely took longer to write what follows than the minimum required,
in terms of additional time to remove and replace a bad trim wire; and
in consideration of the extended and common frustration of the many
owners with stiff trim controls, well worth the effort.
I advocate the first steps of trim wire replacement as a two person
job. A person at the pilot end needs to get the broken end of the trim
wire absolutely straight (no kinking) and grinding or filing the edges
of the end of that wire as round as space permits, then clamping a vise
grip firmly at the end and grease the exposed wire liberally. A
person at the elevator end would disconnect the trim wire at the rear,
cut off any end kinking and grind or file the edges of that end of the
wire as round as possible, cleaning the wire with acetone of any
residual lubricant on the exposed section, clamps a vise grip firmly at
that end. Working sequentially together, the person at the pilot end
"works" the wire forward until just before the vise grip reaches the
cable sheath and then the person at the back "works" the wire back
until the vise grip on the forward end of the wire would stop the
travel of the wire. It should be possible to soon work the wire (still
dry at the elevator end) back and forth without the hammer, thus
accomplishing Hartmut's suggestion to use the older wire "thickened" by
corrosion to reduce the reduction in inner clearance caused by
corrosion inside of the cable sheathing at the elevator end. A half
dozen or so times back and forth will probably accomplish this to such
extent as is possible. At either end, Should the wire break (even in
the middle) in the process, at each end sufficient length should remain
exposed to re-clamp vise grips and thus remove it.
Now with each person alternately pulling the wire so that it moves back
and forth over the range of movement possible, add grease each time to
the exposed portion of the trim wire each time it reaches its rearmost
possible position before being pulled back forward a half dozen or so
times (to lubricate the inside of the cable sheathing as best
possible). Re-grease the wire one final time before pulling through
(removing) the old trim wire from the front. This should carry grease
further forward in the process of removal insofar as is possible.
John Coopers's suggestion of installing the new trim wire from the rear
has the worthwhile benefit of again allowing the liberal greasing of
the wire as it is being pushed forward to carry the most lasting
lubricant as far forward as possible from the rear into that section of
the trim sheathing where the friction from corrosion and/or kinking
usually occurs. Carrying this concept further, before "installing" the
new trim wire, take Lynn's advise to round each end of the new wire
before doing anything else. Then run it (liberally greased) forward
all the way through the rigid trim wire tubing, item 6 in Fig. 8 of the
Parts Catalog, p. 7. Then, again liberally greasing it, run it all the
way back through and out the back.
If it is determined necessary to replace the rear flexible conduit
(item 6 in Fig. 8 of the Parts Catalog, see Ercoupe Service Memorandum
No. 38 for worthwhile drawings and instructions), before installing the
new one I would perform the "pre-install" greasing described above
AFTER removal of the old one. Before installation of the new one, I
would slide the new flex. conduit up and down the new liberally greased
trim wire while it is "straight" so as to be confident that there is
ample grease throughout said conduit before installation.
In any case, while the trim tab wire is disconnected from the trim tab,
verify that the trim tab hinge operates freely (as has earlier been
suggested in various ways), and that the return spring is in good
condition and returns the tab firmly up against the stop. This
function is a retrofit required by AD on all Ercoupes with movable trim
tabs (refer to Ercoupe Service Memorandum 55A)
Since, as Tommy pointed out (and from your words) "...they broke it",
they should pay to fix it. He is also wise in suggesting you have your
guy do any necessary work for the very reasons he states.
Regards,
William R. Bayne
.____|-(o)-|____.
(Copyright 2009)
On Dec 18, 2009, at 10:17, [email protected] wrote:
Linda:
What Lynn said, plus...
Try to feed the cable in from the tail. That way you get the worst
over first, while the friction is lowest. If it becomes necessary to
disconnect the flex cable to facilitate the transition from the tube,
you'll be doing that in the cabin rather than in the tailcone.
The original wire was not stainless, although all the recent
replacement parts are.
Make sure the hinge is free. I would not recommend flying it that
way, but should you decide to, ensure that the springs and trim tab
stop are keeping the trim tab even with the chord of the elevator.
John
