[Amc-list] F('ing)ailing parts 2

[Tom Jennings <tomj@xxxxxxx>]

So the Rambler has a new trans! so I go to drive to dinner
last night, pull on the headlights -- flash -- off! A few pokes
finds the 30A fuse I added has gone intermittent. Back in the
yard it goes.

(Untold ages ago I installed Hella halogens with relays, a
10 gauge batter feed with it's own 30 amp fuse. The antique
headlight switch we all love (hate) only talks to the relays.)

This was one of those molded rubber inline blade-type fuse
holders with pigtails. I crimped and soldered spade lugs to it.
I packed the socket with silicone grease.

I don't know how old it is exactly, probably 8 - 10
years. Failing after 10 years sounds OK, until you consider
that 99% of the factory 1963 electrical connections are still in
perfect working order after 44 years. Those old wiring harnesses
with splices inside and all that ugliness, are well-designed.

So I took it to the bench and cut it open. It was spotlessly
clean, no sign of heating, the spring clips just got weak. I
could have squeezed it with pliers to tighten it, but I replaced
it with a fusible link instead.

This is the SECOND one of these that has failed. The first one
was not packed with grease, and the contacts burned up. The
grease really does help. (That one was in the cooling fan
circuit; I'm back to mechanical fan now.)

For this sort of failsafe fuse (where i'm protecting the wiring
harness or battery in an accident or slip-of-the-screwdriver, and
not delicate electronics) I'm switching totally to fusible links.

Fusible links are just short lengths of wire generally 4 wire
gauges smaller than the wiring you are protecting. There is fancy
'fusible link' insulated with that doesn't burn, but I'm just
using regular PVC wire.

In this case, I've got 10 gauge feeding the lighting relays,
which source from a barrier strip. The fuse on the barrier strip
I replaced with 2" of 20-gauge wire, crimped and soldered to
spade lugs.



Lessee what I can recall what else has failed electrically in
this car since 1988:

* Parking lamp sockets, front (electrical/water corrosion) NOTE L
* Headlight switch (burned up contacts) NOTE H
* Taillight sockets (electrical/water corrosion) NOTE L
* Weather Eye fan motor NOTE F
* Fuse-block fastons and fuse clips (can't recall which ones) NOTE K
* Ignition contact points (jettisonned by 1995)
* Brake light switch (repeated failures) (NOTE B)

Non-factory parts:
* Battery quick-disconnect (green-knob type in ground lead) NOTE Q

What do they all have in common?

AN ELECTRICAL CONNECTION THAT DEPENDS ON DRY METAL-TO-METAL
CONTACT UNDER SPRING TENSION, either constant (fuse clips,
fastons) or intermittent (headlight switch).

In electronics the technical term for this is:

CONNECTORS SUCK.

tomj

PS: Barrier strips suck too, but they suck a lot less. You can
see them; you can get (good ones) tight enough to be gas-tight.
They do not rely on spring tension. You can field-repair them.
Good ones are nickel-plated brass, buy those, they cost more.






NOTE K: Another chronic weak spot in Ramblers is the flimsy
little fuse block. Cheap rivets get loose with time, increased
resistance causes heating, heat causes spring clips to sprong
[sprong: the opposite of spring], causing heating, ... requires
creative solutions.

NOTE F: Bearings and commutators, 'nuf said.

NOTE L: No surprise here, moisture/condensation gets into the
socket over time and electrical current corroses brass and jams
the bulb into the socket. Cleaning/replacement then packing the
socket with grease (of any kind) before installing the bulb is
a long-term cure.

NOTE H: A chronic weak part, the headlight contacts are too
small, and the built-in circuit breaker gets hot. The contacts
are weakly crimped in, and the fast-on connectors get loose with
age, the whole thing gets REALLY HOT! and fails at inopportune
times. Even replacement isn't a good fix, because the part is
No Good. Relays in the headlamp circuits cures this.

NOTE Q: It seems to go high-resistance/open circuit every few
months, often in an odd mode where I can start the car (100
amps for a second or two) but then high resistance such that
the battery fails to charge!  The battery gets low, then the
car won't start. If I loosen the knob then tighten it again,
car starts and charges. I took it off, cleaned it spotlessly,
wire-brushed it then silicone greased it. If it fails even once
more it goes in the trash.

NOTE B: Years ago the brake light switch failed for the first
time I recall since I owned the car. I installed a replacement
bought at NAPA.  That lasted a year. I then went through at least
two more, to the point where I carried a spare in the glovebox. I
then bought an expensive unit from Ron Francis Wiring around
2002 -- no failure since then.  Conclusion: aftermarket parts
(in this case Echlin) are *crap*. I did a post-mortem on the
most-recent Echlin switch failure and I can assure you the
thing was made with garbage components and materials.
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