Cello Family 

1980 Triumph TR7 Drop Head Coupe DHC

Age has its issues:

TR7-8 Turn signal repair:

If you haven’t already had the failure… due to the age of the plastics I can almost guaranty it is imminent .

The failure most seem to have, and I have seen it on three mechanisms is the middle leg white plastic slide that is trapped over the signal shaft. The plastic breaks away and the high low detent is lost.

All of the contacts are corroded

All of the plastic is becoming brittle.

The off white plasticis the middle leg that breaks off.


The unit will be coated with dried out grease, and the copper will all be corroded. Pull each connection 1 at a time and use a fine file to clean the connections. I have been using dielectric grease on all the copper to copper connections, and non creeping brake grease as the lubricant. Clean all the old grease off the entire unit.

Repair any cracks first before lube. Use JB weld overnight drying which has the higher tinsel strength. 

I have found that Mequires Plastic Treatment actually gets absorbed and adds moisture back into Rubber really well and plastic as far as I can tell. It takes at least three applications on dry plastic and rubber.


Top of switch View of internal Mechanism

The signal mechanism has three springs with plastic or nylon glides on the tops and the bottoms.

The top left is holding in a ball bearing detent that will try to escape.

The top right is compressing down a copper rod that is the contact point for the electrical connection, that will try to escape.

The bottom spring is the second detent that has a deep cylinder plastic cup on the bottom and is keyed with a flat edge placed towards the outer plastic shell.

All have top caps, the copper rod has a bottom cap as well.

They have three different lengths and the copper rod has the larger diameter spring.

The longest is top left on the bearing.

Lift off the Plastic rocker center, exposing and releasing the Shift shaft and the White plastic slide.

Top of switch Mech 2, angle pict.
Turn signal Switch Springs, Plastic Caps, Copper Contact Rod
Top of switch Mech 3 Showing ball bearing slot.

Apply a light smear of grease under the center, and the end of the signal shaft, along with the detent points. And if you are lucky to still have the center leg on the White slide make sure to lube the center shaft, with the high beam detents itself, both sides.

The column clamp will likely have fractured and I used a ground in notch at the visible available edge to add extra surface for the epoxy and drilled a screw path at an oblique angle to insert  a a screw as a mechanical connection along with the epoxy.

I have not yet attempted to repair the missing center leg that has the detents for the high-beams. If anybody has a 3d printer, it would absolutely be worth dissecting a unit to do a 3d scan and print several replacement pieces.

High Beam Slide, Showing Detents


The wiper switch needs to be wiped down and re-lubed as well. Take note of the crossed legs of the spring on other side of pin 3 Down from top.


Wiper switch, top angle view
Wiper switch, Flat top view
Spring loccation

The armature for the wiper tends to break at the base from the amount of leverage applied. Slather a heavy coat of JB Weld on all exposed sides being careful  not to get any on a joint.

Images are silhouette template of the missing leg with detents. There are two notches, detents, *see higher above pict for clarity (flat part then slope down to notch, then tooth, and notch again, then flat again.)

I will attempt a JB weld repair, but there is no meat to glue too. It will likely require a pin embedded.

Reach out if you have questions I can might be able assist with.

If you find this has helped drop me a line, or if you find a better way. 


Best of luck.   


COPYRIGHT © 2020 Jay Farber - All rights reserved.

Los Angeles, California

Website By JFM Consulting, they can build one for you!


COPYRIGHT © 2022 Jay Farber - All rights reserved.

Los Angeles, California

Website By JFM Consulting, they can build one for you!

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