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TR4/4A intermittent brake-light switch

Geo Hahn

Country flag
You are a crafty fellow -- but step 9: 'Buy a $5,000 lathe' is going to be a problem for me.

Seriously, good to see the innards of the original Delco switch. I wonder... if the failure is the wear on that brass head, could it be turned 90° to present a fresh surface to the contacts?

Oh, on second look I think I get it -- you made the replacement button longer to make up for the contacts being shorter after the worn ends were removed/broken off.
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Jedi Trainee


  • brassed-off.jpg
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Fill me in on a few things.

In the second set of pictures, there are a lot of chrome parts, several of which I don't see being made on a lathe. Which parts did you make in the second set of pictures and did you then send them off to be chromed?

Very nice work on all the switch. One of your last photos of the switch body in pieces shows what looks to be the tips of the contact fingers broken off. Did you also form new contact fingers from brass stock? I don't want to take anything away from what you have done as your car will certainly be very original by retaining the Delco switch. However, I followed the advice of another Triumph owner on this forum and recently purchased the brake light switch for a BMW 2002 to use the next time I need a replacement. No, it doesn't look original but not many people are going to see my brake light switch.

I have one of the Seig Chinese lathes from Micro-Mark. They are serviceable but your lathe is head and shoulders above what mine can do. You can make the Chinese lathes work better/well if you are willing to fabricate and tweak certain parts but they will never, ever match the ease of use and precision from a good, used South Bend hobby lathe or even some of the old Atlas table top lathes.


Jedi Trainee
All the parts shown in the links were made on the lathe, which is equipped with a milling slide.
What wouldn't machine was filed by hand. Nothing in the pictures is bought-in.

I cut 1/8in off the fingers at the point where they were worn through. Thats the bits you see.
The plunger is 1/8 longer to match the contacts.

All made from scrap ends leftover from other jobs in about 1 hour. Actually I could make ten sets in an hour from new stock by mandrel feeding but working short scrap makes for some extra work.

Forgot to say, Myford ML10, not got space for anything bigger. Superb build, finish and feel for a small machine.
Made nice lathes but no profits!


Great Pumpkin
Country flag
Most of us just go to a Honda one which is made out of metal


As I mentioned, I bought the BMW switch for the next brake switch failure on the cars I own. However, that does not mean I would throw the old British switch away. I always have a look inside to see if they can be fixed.

The last such switch project I worked on was the door jamb switch for our Spitfire. My repairs involved making a new plunger and cleaning the contacts. It lasted until I made a bone-head move holding the door open with a block of wood. Careless on my part. I gave up on the (NLA) Lucas door switch at that time and made a plastic bracket/plate to mount one of the cheap Unipart brake light switches for use as the door light switch. So far, so good.

Nice, nice work. I figured you had more equipment than just the basic lathe to make the parts in your picture links. Top notch work!



Well... probably not the people on THIS forum or those who own any collector car. Sadly however, it is probably accurate to say that most people today can't or won't be bothered with the amount of maintenance and upkeep required to drive a British car no matter how rewarding it might be to drive it.

Andrew Mace

Staff member
Country flag
Well, 'most' people would rather drive a Honda.
For me, it's not so much that I'd rather drive the Honda. But there's this little phenomenon in the Northeastern US called winter. Actually, right now I'm driving the Herald daily until I can get new front brakes on my Honda. :D
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