Instrument gauge rubber

[John Loftus]

I need to replace the rubber sealing rings for all the gauges. When I removed the chrome trim ring for the tach and speedo there were remnants (crumbly, black, hard) of something that went between the glass and trim ring. In the catalogs they show a sealing ring but it looks like this goes between the instrument panel and gauge. Does anyone know exactly what is needed between:

1. the instrument panel and gauge
2. the glass and instrument
3. the glass and trim ring

Thanks,
John
BJ7

 

[Dave Russell]

Hi John,
Instrument panel & gage - The commonly available O rings
The glass & the instrument - Square section O rings, possibly available at your local O ring supplier
The glass & the trim ring - Nothing

My square section rings were in good condition so I reused them.
D

 

[Randy Forbes]

I purchased a set (four pieces; two large & two small) of the square section O-rings from an Ebay source. Seems he frequently lists them for about $8.00

Since my gauges (probably) need refurbishing, I didn't worry about the ones between the glass and chrome bezel.

 

[shorn]

For the tach and speedo, I used a couple of extra o rings that come with the crossland oil filters. They seemed to be a ideal fit. Haven't bothered to do the oil/water or the fuel guage yet.

 

[dklawson]

I never saw the magic in square cross-section o-rings. I know they were original... but why bother with something that only a purist or a concours judge would look for?

You can buy 1/16" o-ring cord stock and glue it together with "krazy glue" to form your seals between the gauge and dash. This is NOT an uncommon practice in industry. Static seals are routinely bonded this way.

There is often a paper spacer/seal between the inner gauge reflector and the back side of the glass. Not all gauges use this. When and where it was used you can substitute with dark colored gasket paper and cut your own. You may have to try various thicknesses to fill any annular land on the inner reflector. Alternatively, cardboard can be used and sprayed flat black to make these parts.

Between the glass and the chrome bezel you can use 1/8" o-ring cord stock (the fit may be a little loose and is helped by placing a few strips of paper between the o-ring and the inner surface of the chrome bezel). This does not need to be bonded as the 1/16" stock mentioned above. However, I prefer something with a little more "give" to it. I use 5/32" urethane air line tubing cut to length.

O-ring cord stock and urethane air line tubing are both available from McMaster-Carr (www.mcmaster.com). However, you may find that o-rings and cord stock are available from a local hardware store (not a big-box chain) along with 5/32 rubber or vinyl tubing.

 

[Keoke]

Well John, Shorn has revealed the source I also use to obtain the large "O" rings. The smaller ones I obtain at True Value hardware stores in the plumbing section.They do not come packaged do not have a part number on them and are just hung on a hook,so I don't have a clue as to their application but they are there.---Fwiw---Keoke

 

[John Loftus]

Thanks everyone for the feedback. I had a Moss order waiting to go out so I added the sealing rings that are in their catalog. We'll see if they are round or square. The black crumbly stuff behind the chrome bezel looks like some type of chaulking that could be 43 years old, perhaps to keep the glass from rattling although if everything is synched down tight it is probably not needed.

Cheers,
John

 

[GregW]

Hi John,
I also had some crumbly stuff between the chrome rim and glass. It may have been there to keep the glass from cracking.

 

[Keoke]

Hi DK, I think the square "O" rings were used to comphensate for variations in the instruement holes cut in the wooden dash.I have seen some factory cut dash holes that almost allow you to pass the complete instruement thru them. A better fix for these cases is to line the inside of the hole with layers of thin veneer to reduce its diameter.When the intruments are in place this fix does not show.---Fwiw---Keoke

 

[dklawson]

Keoke, the square rings I've seen were not more that about 1/16" square in section. That's why I suggested using 1/16" round cord stock. That too will cover any gaps around the openings. I'm not suggesting running without the rings. A layer or two of electrical tape around the OD of the gauge case just behind the bezel would also work like your veneer to center the gauge in the dash opening. This is readily available and doesn't require gluing to the dash.

John and Greg W, the dried goo on the inside of the chrome bezel is indeed there to prevent glass rattling as you said. However, if you don't put something in there the glass will rattle as you can't completely close up all the gaps. As I mentioned earlier, 1/8" o-ring stock (perhaps backed up with a thin piece of paper) or 5/32" vinyl or rubber tubing will work well for this application.

 

[John Loftus]

Doug,

Thanks for the suggestions. I will try the o-ring stock or tubing for the glass to bezel seal. I'm thinking it could also be fixed by filling the inside bezel with black silicon, placing a piece of 1/8" plastic (cut in a circle, same size as the glass) that has been waxed to provide a mold release. After a day or two to dry the plastic is removed and then there is a good wide area of contact for the glass.

Cheers,
John

 

[Dave Russell]

Hi John,
I am certain that my original rings for the glass to dial face are square cut. This makes sense because round section rings would tend to roll & work out of place. My rings were not glued in. There is no seal between glass & bezel as none is needed.

Square rings come in the same standard sizing as O rings. Sizes are per spec A5568A. Not sure what your particular gage sizes are. For my gages, the -133 size is 1 13/16" ID x 3/32" thick. The -154 size is 3 3/4" ID x 3/32" thick.

Just a little larger would be the -225 at 1 7/8" ID x 1/8" thick & the -240 at 3 3/4" ID x 1/8" thick.

You can find a sizing chart here:
https://www.marcorubber.com/sizingchart.htm

I would be amazed if your local supplier doesn't have these in stock. Making rings seems kind of make shift when the correct parts are available.
D

 

[John Loftus]

[ QUOTE ]
There is no seal between glass & bezel as none is needed.

[/ QUOTE ]

Hi Dave,

But mine and others had some kind of chaulking or sealant in there. Maybe it was only done on the later cars?

I'm o.k. with the glass to dial face. I was able to get the glass off finally .. it was sticking pretty good and didn't want to put too much pressure on the glass .. and the o-rings are still in good shape there. I've got the instrument to dash o-rings coming from Moss. So I'm just about there.

Cheers,
John

 

[dklawson]

The Smiths/Jaeger gauges I've disassembled all had seals (or seal residue) between the chrome bezel and glass. Where I have tried omitting this seal the glass has rattled. There is often a flat seal between the back side of the glass and the front reflector/diffuser. This is not the gauge face itself but it is a reverse cup shaped ring typically painted blue/white on its back side that reflects light from inside the gauge case to/on the number scale. On the gauges I've disassembled, this seal/ring has always been a high-density fiberboard material which is why I've replaced them with black painted cardboard or gasket paper.

When you are checking sources for o-rings, the series that Dave mentioned is "AS568". The AS568 prefix is appended with a three digit number that fully specifies the ID and cross-section of the ring. These are "inch" o-rings. You can also go to McMaster-Carr (www.mcmaster.com) and enter "o-ring" in the opening page's search field. You will be able to search for and specify the size ring you want from there. Be advised, however, that the "actual" o-ring size is not the same as its nominal size. (i.e., an AS568-006 o-ring is nominally 1/8" ID x 1/16" cross-section. The actual size is 0.114"+/-005" x 0.070"+/-0.003" ) The most common (and least expensive) material is Buna-N (nitrile) and this will be fine for gauges.

 

[Jerry]

Our car club went on a drive and one of the cars never put the oil ring back to seal the glass. Well we got diverted to a dirt road. A lot of dirt ended up in his gauges which he had to take apart and clean. I would put a seal on if you can.

Jerry

 

[Keoke]

Hi Jerry, I thought that was why a seal was used between the glass and bezel. when I did mine I simply used Plumbers putty and cut the excess out.---Fwiw---Keoke

 

[dklawson]

Plumbers putty or glazing compound would indeed work to seal the unit from the front. I'm hesitant about using any compound like that though as they tend to "set" over time making future disassembly difficult.

 

[Keoke]

[ QUOTE ]
Plumbers putty or glazing compound would indeed work to seal the unit from the front. I'm hesitant about using any compound like that though as they tend to "set" over time making future disassembly difficult.

[/ QUOTE ]

Yep DK, you are right ,but it takes about 20 years for that to happen.---Keoke /ubbthreads/images/graemlins/laugh.gif

 

[Ed_K]

My oil/temp gage had a black tar like residue under the glass. It was so bad, I could not read the gauges. Took it off and cleaned out the goo. Put RTV under the chrome ring and reassembled it. I then cleaned the excess RTV off of the face of the glass and what squished outside the chrome ring. It is interesting to learn from this topic that the goo used to be some kind of fiber board material. Guess it couldn't hold up under paint solvent fumes.

 

[Dave Russell]

Hey guys,
What am I missing. A simple standard square section "O" ring seals the glass to the gage housing. When the chrome ring is twist locked into place, it compresses the square ring a bit & completely seals the glass to the gage. No possibility of rattling or leaking.

The "cushion ring" around the outside of the gage could be square or round, it doesn't really seal the gage from anything. What is all this sealer, glue, etc?

See the attached sketch.
D