GM Bay Door Lock Cover

[richard5933]

I'm looking for a few of these (see photos).

They are used on the 4108 as covers for the bay door locks. They were installed by GM, and they are shown in the maintenance manual as optional equipment. Cannot find them in the parts manual (sect 25-47, I think)

Anyone know what they are? Anyone have any extras or maybe some on a parts bus?

They look identical to the Bell outlet covers currently in use, but the plate they are mounted on is much smaller than a standard electrical box cover. The bottom of this cover is at the lower edge of the door's handle, so a larger cover cannot be used.

Thoughts?

[Dave5Cs]

That one has been discontinued at Bell but try
Home depot will have them they are single hole 30 amp weather proof outlet cover plate.
Also could try Platt electric or a major electrical company.

Here one that might look similar.
https://www.leviton.com/en/products/7420-crg

[richard5933]

That one has been discontinued at Bell but try
Home depot will have them they are single hole 30 amp weather proof outlet cover plate.
Also could try Platt electric or a major electrical company.

Here one that might look similar.
https://www.leviton.com/en/products/7420-crg

Those are about 3" x 4.5", much larger than what I have. The center hole is also larger - the ones GM used would fit over a standard 15A outlet, not the larger 30A.

I assume they were an off-the-shelf part back in 1974. Problem is I can't find anything in that size, and I can't even find out what else that cover would have been used for.

[dtcerrato]

Richard those bay door lock covers in your photos are exactly what we installed on our 4104 and were purchased from GM back in the day. That cover is a single outlet cover that you should be able to purchase at an electrical supply house. Several manufacturers produce them. Ours are aluminum.

[richard5933]

Richard those bay door lock covers in your photos are exactly what we installed on our 4104 and were purchased from GM back in the day. That cover is a single outlet cover that you should be able to purchase at an electrical supply house. Several manufacturers produce them. Ours are aluminum.

I've seen the ones you're talking about in both plastic and aluminum. They are designed to fit a modern 1-gang box. On these the mounting plate extends about 5/8" below the bottom mounting screw and above the cover hinge. They are 4.5" tall.

If you look at the photos of the ones on my bus, you'll see that there is almost no mounting plate showing below the bottom screw or above the top hinge of the cover. These are only 2" w x 3" h. They can't be replaced by the larger modern covers due to the location of the lock in the handle. The larger ones would hang over about 1/2" on the left side and bottom of the handle.

I've been searching for NOS parts, but without the proper search term I'm striking out.

[dtcerrato]

We have the same cover as you have - the smaller one... I have seen the same cover (smaller one as you refer to it) in 75 ohm coax kits for RVs to bring interior wiring to skin of camper for easy plug in at campsites. They're out there just have to find them.

[Dave5Cs]

It may be only a 15 Amp but that's what it was originally. It was some kind of electrical cover if that small maybe a telephone box or fuse cover. Bell made most if not all of the covers in those days but I don't think you will find that today.

[richard5933]

It may be only a 15 Amp but that's what it was originally. It was some kind of electrical cover if that small maybe a telephone box or fuse cover. Bell made most if not all of the covers in those days but I don't think you will find that today.

The covers for 30-amp outlets have a physically larger footprint than these. Same for modern single outlet 15-amp covers. They are all designed to fit a regular residential box.

My guess is that they were originally designed for some type of industrial motor application to protect a single 110v outlet on the side of a piece of machinery. I can't find that there was ever a residential junction box that these things would fit on.

I'd love to find an old-school electrical supply house. All the big ones around here seem to only keep current parts on the shelves - if they sit too long they are sent back to free up shelf space. The small places are nearly all gone now.

[richard5933]

I can't even find a single example of the cover online - not one photo or image of it. I'm starting to wonder if GM didn't contract with Hubbell Bell to have them made to their specs instead of using a stock part.

If that's the case, then a parts bus is probably the only place I'm going to find one.

[buswarrior]

The big trucks had/have a cover over the single plug-in for the block/oil heater to plug in.

New Prevost H3 45 have two of these covers on the side of the bus, one for block/oil heater, the other for the built in battery charger.

Keep looking, the covers are out there, either in the wrecking yard or brand new.

Happy coaching!
Buswarrior

[dtcerrato]

IMHO an old fashioned parts guy in an old fashioned electrical parts outlet is your best bet...

[richard5933]

IMHO an old fashioned parts guy in an old fashioned electrical parts outlet is your best bet...

I agree. Still looking for one. Wishing I still had an old fashioned phone book to find that old fashioned parts outlet. Everything on the internet is corporate.

[dtcerrato]

Richard I've been looking through my past conversion receipts & haven't found it (yet). The receipt may have a part no. on it...

[richard5933]

Richard I've been looking through my past conversion receipts & haven't found it (yet). The receipt may have a part no. on it...

That might help.

In the interim, I did find the patent application. It appears that the same patent is used on the ones GM installed as well as on the ones with the larger residential base.

I found one of those on eBay, and I ordered it in the hopes that I can do a lid & hinge assembly transplant by drilling out the rivets.

Also discovered that the old Delta Unisaw's power switch appears to be mounted in a similar sized electrical box. My hunch is that the size cover plate used on the GM bay doors was originally designed to be used on industrial motors/equipment switches & outlets.