Corvette: 93 headlights

When my 93's headlights rotate the motors seem to stay on much longer than
needed, does anyone know if there is a timing adjustment for these as I
didn't see any limit switches?

In <3fbbf474$txucom.net>, "Russ" <com> writes: 

Hi Russ,

Here's the whole nine yards.

You are nearing a complete failure of the gearbox(s).
No limit switches. The control unit senses the current spike
when the headlamp bucket reaches the end-stop. Lacking
that, a timer eventually kills the power. When the guts of
the gearbox start to fail, the headlamp reaches limit then
the gearbox slips--further grinding itself apart. Eventually
the timer circuit shuts off the motor. (Sound familiar?)

At the dealer, about $ 550 with labor. (Do not accept
any repair that includes an used headlight assembly--it
will soon fail) You can "advertise" for someone to do
the repair. Chris Cook in Indianapolis used to do these
at $ 75 per gearbox so $ 100 is probably a reasonable
price. Post queries in <rec.autos.sport.info> and
<alt.autos.fiero>. Eckler's has a rebuild for $ 130 + 100
core. But, most of the work is in removing the gearbox
so, once you've got it out go ahead and do the repair
yourself. New motors are about $ 345 each but you
buy the same failure prone design.

The gearbox(s) probably have hardening / disintegration of
the packing in their center cavity. Eckler's # 29304 repair
kit for five bucks provides the fix. (This kit has three delrin
rollers to replace the "crumbs" inside the gearbox.) This
"locks up" the gearbox and removes all slip from the system.
While not the "engineered" solution that GM intended, this fix
works well, and will probably last longer than a new headlamp
assembly or new motor.

Occasionally the metal worm (motor shaft) chews the teeth
off the large nylon gear. Eckler's and Mid-America both sell
replacement gears--metal for about $ 60 and nylon for about
$ 25. They also throw in the three delrin rollers with this gear.
These kits don't come with instructions, making the five buck
kit better for the uninitiated.

The instruction sheet with Eckler's $ 5 kit is easy to follow
(after you get the headlamp assembly torn down.) Be very
careful with step #4 (Fig. 3). The motor screws and gearbox
housing have a dissimilar-metal corrosion problem. It's very
easy to sheer a screw. I think it's better to gently work the
large gear out of the housing without loosening the motor from
the gearbox. If loosening the motor becomes necessary:
1- Scrape off all paint from around the screw heads
and opposite ends of the screws. Then wet the screws
with penetrating oil for a day or two before you try to
loosen them. (try to keep the penetrating oil off the seal
between the motor and the gear housing)
2- If your vocabulary includes four-letter words, have
small children cleared from the area while you loosen
the motor screws. If you sheer one of these, you add a
couple of hours (and "great grief") to the job!

Hope this helps.

Regards, "Mike"
-- mikeellison3xxxatzzzyahoo.com --