Lucas L745 lens cracking/gasket

[svenedin]

For the second time in a year or so one of the lenses on the rear lamp units on my 1969 car cracked where the attachment screw is located. This made the lens insecure and at risk of falling off. New lenses are aviable from ESM but they are expensive. All of them are inherently brittle, new or old, but old ones are especially brittle.

Since a lens broke twice and I was on my third lens I decided to think about why this is happening. Obviously, the lens to lamp body screws must be tightened with great care but I had been careful. I discovered the old grey foam gasket was very hard and not acting as either a seal or a cushion to the lens. My theory is that with a hardened gasket the lenses were cracking when there was a large jolt such as the car going over an unexpected pothole or possible with sustained lower level vibration or even expansion/contraction with extremes of temperature. I have replaced the gaskets with new (they are now black) and we shall see if my theory is correct!

Stephen


Old hardened gasket

IMG_2327.jpeg (2.54 MiB) Viewed 8638 times

New gasket

IMG_2328.jpeg (2.08 MiB) Viewed 8638 times