Moss Motors, Ltd

Is there a turn signal adjustment on the lucas device on the dash of a 61 MGA? Everything works, but the lever returns to the off position after only a few seconds. I'd like it to stay on longer.

Thanks

backlog,

Yes, there is an adjustment. This timing device works by setting a vacuum piston in a cylinder. That piston has a leather cup which does the sealing. When everything is clean and the leather cup is lubricated with saddle soap or some modern equivalent, it will hold for a very long time before the spring overcomes the vacuum and pushes the piston down one side of the helix which pushed it up when you set the signal. In fact, it would stay too long if there were not a vacuum bleed hole at the very center of the rear of the switch cylinder. In that bleed hole is a screw which can be screwed in or out to vary the "on time". I explained all this because if the innards are'nt all clean and lubricated it will be difficult to get a satisfactory adjustment with the screw. The assembly is not hard to take apart, clean, and put back together. In fact, it's kind of a fun job. Just one caveat: It's very easy to break the threaded portion off the front of the switch where the knurled nut holds it into the dash. Be careful!

Have fun.

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Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon

My Lucas turn signal switch does not have a connection to a cylinder for vacuum. I believe the problem is with the diaphragm in the switch. Do you know where I can buy a new diaphragm? Or can it be something else? I am going to rebuild the switch as you suggested and want to make sure I have a source for any replacement parts I might need.

Thanks.

Perhaps I did not make myself clear. The vacuum does not come from the engine. It is created within the switch cylinder when you actuate it with the handle. I just went in the back and disassembled an original unit. There is a piston with a leather cup, as described, working against a stout little spring which is trying to pust the piston back home against the vacuum you create when you actuate it. The bleed screw regulates how quickly this negative pressure is relieved. If your unit uses a diaphragm, I believe it is not an MGA original switch, and all bets are off.

There are no replacement parts separately available commercially for the switches . But since so many have broken at the aforementioned mounting threads, there are many used units lying about from which inner parts can be scavanged. Usually however, all that is needed is a thorough cleaning and refitting to get things functioning properly.

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Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon

Thanks, yes I fully understand now. My unit is an original Lucas switch and I will be diving into it in a few days.