View Full Version : TR2/3/3A tr3 speedometer trip reset

04-30-2008, 10:20 AM
Someone in the past posted about a broken trip reset on an early tr3 speedometer. I think they actually fabricated up one. I need one. Does anyone remember what they made it out of? It looks like maybe a 3/32 rod about 5 inches would be a good start and I guess you could glue or weld on the little nail head looking thing, but my biggest problem would be drilling the two little holes in the rod. The holes are so small that it looks like a jewelry shop would have to do it. I actually think if I remember right that whoever it was that made them had made some extra.

04-30-2008, 12:13 PM
That would be me. :yesnod: Unfortunately, I can't find the post concerning the reset knob. I did make several of them, and gave some away. I don't know if I have any left. I'll look when I get home. As far as making them, I did the job here at work during my lunch hours, so I had access to a lathe and Bridgeport. Either way, I'll post the dimensional data. There are a few things that have to be watched out for. I had an original one that was broken where the cotter pin goes, so I was able to clone it.

04-30-2008, 12:17 PM
Art you the man and please do check.

04-30-2008, 03:39 PM
OK, Unfortunately, I don't have any reset knobs left. I've got a picture, and I do have all of the dimensional data. This was for an earlier style speedo. The later style is a different lenght. I don't remember if it was longer or shorter, but I can call someone I gave one to. He has a TR3B, and I think he said it stuck down farther then his original, which would mean that the later one is shorter. I'll verify that.

Anyway, here is the dimensional data.

Shaft -- Diam. 7/32" (0.218") Length 1 19/32" (1.593") not critical.

Drill a 1/8" (0.125") hole in top of shaft 1/2" (0.500") deep.

Cross drill for cotter pin. Center of hole 1/8" (0.125") from top of shaft. Use a #52 (0.0635") drill, and drill all the way through. Then use a #45 (0.082") drill and drill through the same hole, but only go through to the hole drilled earlier in the end of the shaft. This will give you two different size holes where the cotter pin goes through. The reason for this is that the end loop of the cotter pin has to go partway into the shaft, or it will not clear the opening in the speedo housing when pushing up to reset the trip odo. Also, the ends of the cotter pin have to wrap tightly around the shaft, so cut the length if neccessary.

The other end has a brass knurled knob. It is 3/8" (0.375") in diameter, and 5/16" (0.312") in height. It is pressed onto the shaft, so drill for an interference fit. I knurled the brass piece after pressing on.

Hope this helps.
Sorry I don't have any left.

Edit: The one in the picture is an original that I used for dimensional data.

04-30-2008, 03:42 PM
Yours is much nicer than mine! I drilled into the end of a bolt and then put in the hole for the split pin. It is not very professional looking and it hurts your fingers when using it a lot! Very necessary for historic rallies though.

04-30-2008, 04:07 PM
Hi Art and thanks for going to the trouble. Woops however, the piece I was referring to is the piece that that hooks into. Mine broke at the meal rod that holds the turning piece. I should have made myself clearer. Most of the early speedos are missing the trip counter because the rod broke inside the speedo. I misunderstood your post. I guess this will give the chance to make some of the inner rods. They would not be as hard as the turning thing you made.