The speedometer gauges on my 90 tristar were cracked and ugly.
I know the gauge lens is available from classic boat works, but I wanted to see if I could do it and save a little money.
I looked around for a source of cheap plastic and found a plastic picture frame from the Dollar Tree.
I also needed to find something that had a similar dome shape that resembled the lens. I also found this at the Dollar Tree.
This is the profile of the light.
The process of shaping the clear plastic into a convex shape is done with a heat gun. The goal is not to use the whole light as a pattern, but just the top 4 inch diameter. I got a coffee cup a little bigger in diameter than the lens...probably about 4 inches. I placed the clear plastic over the coffee cup with at least an inch or two overlay at the edge of the cup. You could probably cut the plastic picture frame into fourths to make it easier to manage. I cut the plastic with a cut-off wheel on a grinder. The cut-off wheel will melt the plastic rather than cut it. In order to soften the plastic, heat the clear plastic with the heat gun until you can see it deform/sag. Quickly push the light dome over the coffee cup and push down and hold for approximately 10 seconds. The clear plastic will not stick to light dome as long as the plastic is not too hot. Now the clear plastic should match the shape of the light dome. Next use the old lens as a template to trace out the circumference of the lens and proceed to cut out with a grinder or dremel. Use the old lens as a template to drill the adjustment hole. I replaced the rubber grommets with new ones that I previously had. You can also take out the grommet from the old lens if needed. I found that heating the grommet with the heat gun for a few seconds made it easier to install. I chose not to remove/install the pointer from the old lens.
This is the gauge with the new lens.
I went through one picture frame while practicing, therefore,I have about $3.00 in supplies for both lenses.