MTFCA Forum

Hello,
I have a 1914 touring car with acetylene headlights. Last week I noticed the glass in one of the headlights tipped back. When I opened the headlight to put the glass back in correctly I noticed the grooved rubber thing around the glass had deteriorated so badly that it was breaking into little pieces. I looked on a couple of the parts suppliers websites and could not find a replacement. It might hold with just the spring metal clip, but I am worried that the glass will break. Does anyone know what it is called and/or where I could get a replacement??

I am not surprised that a rubber component has not survived. Those lights get really warm when lit.
The god of lamp restorers here used a red mastic which sets hard to mount the glass in the door. Unfortunately, he passed away a couple of years ago so I cannot find out what it was.

Allan from down under.

Silicon can take the heat. Was wondering if one of these two were used. The Prematex says "stays flexible". Both have the same heat range. There are other high temp RTV's

These are great ideas and I understand that I can create my own solution, but I was wondering how it came from the factory. Was there an original rubber piece around the glass from the factory? Or maybe something else?

Bryan,
Are you talking about the retaining ring shown in this headlamp rim?
I have John Brown 16s and made mine from brass rod which snaps in
the groove provided in the headlamp rim.

Ken,
My lights are just like that and I am able to hold the glass in with just the clip, but when I got the car there was a nice rubber piece with a groove for the glass to protect it from breakage. I am just trying to figure out if that was from the factory or if it was something the previous owner did.

I have been running my T for 58 years and the head light glasses have only ever been held in with the metal rod - never a problem.
I don't think there ever was any sort of rubber or other material for the glass.

Bryan,
I believe Peter is correct and that's all there was.

If you light with the car running there is considerable
vibration so I have a couple pieces of electrical tape
inside the rim to be sure the retainer does not come out
of the groove and the lens falls. Had the same lens for years.

Just be sure your mirrors are seated on a pad and snugged up.
You don't want them rubbing the silver on the rear of the bucket.

On original non adulterated headlamps I have found a very thin piece of paper like material between the door and glass. On occasion I have found the material between the door & glass plus the glass and spring rod that holds the glass in.

The parts list for accessories shows a wire retainer. Part 690H

If you want to aid in the wire retainer not slipping or rattling, then you could always slide a piece of electrical heat shrink over the wire and when you heat it the wrap would stick to the wire.

I came across some advice from the 1920s concerning care of silvered headlight reflectors. The point was made NOT to use rubber for gasket material in headlight units due to the fact that vulcanized rubber contains sulfur, and sulfur contributes to rapid tarnishing of silver. This warning would apply to any headlight that used a silvered reflector. I don't think cured silicon would cause any problems. Any material that contained sulfur might also contribute to brass tarnishing. Silver is very sensitive to sulfur and sulfur compounds.
As far as I know, plastic of any sort, including shrink type plastic, would cause no issues.

When the lamps are lit, the lenses heat-up and slightly expand.

Therefore, I believe any type of rubber gasket, sealant or caulking is not adviseable.

Just my two cents which is neither here nor there.

Eric, I did not consider the heat factor and that's a good point about the heat factor when adding a gasket type material or the electrical heat shrink tubing that I mentioned.

The heat shrink is a good idea.

Things to consider.
The glass will hardly expand from the heat.
From the internet
The coefficient in the table for 'Glass, hard' is 3.3 X 10-6 in/(in F). This means that each linear inch of glass will get 0.0000033" larger for each degree Fahrenheit that the temperature increases. If you have 10 inches of glass that get one degree warmer, you can expect it to expand by 0.000033".
500 degrees x 0.000033" = .0165"

From AI Bot
When a steel ring is placed inside a brass cylinder and heated, the brass cylinder will expand more than the steel ring due to brass having a higher coefficient of thermal expansion, meaning the ring will potentially become looser within the cylinder as the temperature increases.

So the "ring", 690H, is open and made of spring steel to allow for expansion

I think the heat shrink tubing would be a good idea. It's heat resistant, inert, and could help prevent rattles and glass chipping or cracking.

Thank you for the parts list Frank.....

Bryan,
Since good 6" mirrors are so hard to find, you may want to check
what kind of pad is behind your mirrors, or if there is one at all.

The back of the Mangin is silvered and coated with shellac and the
"MANGIN - BAD BACK" picture below is one I took out of a headlamp with
no pad. It rotated in the bucket and rubbed through both the shellac and
silver, all the way to the glass. To be sure that doesn't happen, I cut 2-inch
heat resistant webbing to fit/conform to the curve behind the mirror.

There is very little heat involved in acetylene headlamps, but it doesn't seem to have
trapped water between the mirror and rear of the bucket in the last ten years.
Also, provides a good cushion when snugging up the mirror to the bucket.

Can't seem to post but one picture for some reason, anyone??

Light 'em up!

Thank you everyone for such great posts. I believe the guy that had the car before me must have added the rubber around the glass because the exploded view of the lights does not show anything except for the metal ring holding the glass. The mirrors I have were not very good so I purchased a couple of those chrome plated brass ones from Snyders or Langs. They are pretty good, but not as good as real mirrors. I am running halogen bulbs right now, but I hope to switch it back to acetylene in the future.