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TR2/3/3A TR3 speedo parts

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Banjo

Banjo

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HEY all you parts hoarders! I need the two odometer/tripometer drive gears for my TR2 speedo. They were the same for at least the TR2-3s.
You know, the ones that set up inside the speedo housing, and the fiber teeth get stripped as soon as the cable gets turned after the car has been sitting for years
(note to restorers. I would highly reccomend disconnecting the speedo cable fom any project car that has been sitting for a long time BEFORE YOU EVER MOVE THE CAR! These are easy to free up, but it does no good once the teeth are stripped.)
If you have a TR and the odometer dosen't work, this is almost assuredly what has happened.
I opened mine up today, and found out that someone had removed all the odometer and tripometer drive mechanism long ago. I have everything to replace the missing bits but a good set of gears!
So who's got 'em??? hehehehe
Depending on how this goes, I may try to find a supplier for these gears (If I'm thinking right, there may be a market)
 
I'll open up a couple and look. Stand by...
 
Cool beans! thanks John.
I went out and popped open the TR4A speedo I have. It looks good inside, but the teeth on the gears are much finer than the TR2-3. Worst case I can put the rounded glass on the TR4A speedo and use it. But it's still a tad different in appearance.
 
Mine worked fine till one day in 2001 driving East through Kansas, I noticed that the main mileage counter was not working. The trip mileage was fine and the speedo needle still worked. After I got home, I found that two teeth were stripped off a small fiber gear. A few months later, after giving up all hope of finding one, I sent it all to Nysonger and for $125.00, they repaired it and re-calibrated it. Since then, I've driven another 35,000 miles and it's working fine.
 
O.K., Banjo, I opend a speedometer and took the little phenolic odometer gears out.

Unfortunately, I broke a tooth on the first one trying to prize it out with a screwdriver. Man are they ever fragile!

I learned my lesson, so I pushed the other one out from behind. But you need two gears, don't you? I think there's another speedometer over in the Laboratory. I'll go look.

I like saying phenolic. Phenolic.

O.K., that's enough.
 
I had the same problem with my speedo. I managed to get one gear from a spare unit laying around, but needed another one. I found some nylon gears at McMaster that were close in size and had the correct number of teeth. I had to drill the shaft hole a bit larger, and cut down the "hub" as it was too long. then, the OD of the gear was just a little too large. I spent about a half a hour re-filing the depth of the teeth with a teensy file. I finally got it to work...well, at least with the drill motor driving it. We'll see when I finally get the car together how long it lasts. /bcforum/images/%%GRAEMLIN_URL%%/driving.gif

BTW, those gears certainly don't look like phenolic. If they were, they might not shear so easily. They look like some sort of vegatable based fiber...one step stronger then cardboard. /bcforum/images/%%GRAEMLIN_URL%%/cryin.gif
 
Nothing is ever straightforward on these is it? I opened another speedometer and found that the pitch of the gear teeth is much more fine than the first one I opened.

So do you have the coarse-tooth worm gear or the fine-tooth worm gear? I can send you two fine-tooth gears or one coarse -toothe gear. Or send you the whole innards of the fine-tooth speedometer.

Art: But "vegetable-based fiber" isn't fun to say like Phenolic is!
 
Also, another thing I noticed when I pulled my speedo apart (No, not the one I wear!) was that the reason those gears shear off is because the shaft that is attached to the gear "freezes" up in the aluminium bore that it rides in. I believe it does that because the shaft and bore are lubed with GREASE, and when the car sits for a long time, the grease just gets stiff and glues the whole mess together. I think that OIL is more appropriate to lube that shaft with, and that's what I used when I put everything back together.
 
I too had that shaft freeze up... on a car driven regularly. Just a bit of old corrosion finally caused it to bind. I guess I was lucky, the speedo cable broke before the gears stripped.
 
Art, you're right on the money. that grease turns to glue if left to set for a spell. It happens to most of the TR2-3 speedos. That's whay I gave the warning to disconnect it till you have a chance to take it apart and inspect.
John, I should have warned ya about those gears. sorry. they are extremely fragile. I have the coarse toothed ones. the fine toothed ones are out of a TR4 or later (I believe) Those ones don't seem to bind up like the older ones. They probably changed the type of lube they used on those little shafts.
Well, ones better than nothing. I'd at least have an odometer. I'll get with ya on it here shortly.
Thanks.
Anybody have one more??? hehehe
 
Banjo said:
the fine toothed ones are out of a TR4 or later (I believe)
Click to expand...

The fine-tooth gears came from a speedometer with a convex glass so I thought it was from a TR3. I guess some TR4s have convex glass speedometers?
 
Good question john.. I'm quite sure that the change over from convex to flat was the beginning of TR4 production. a few possibilities are; the late TR3 speedos used the fine tooth arrangement?, some early TR4s had convex glass? or someone swapped the convex glass onto a TR4 speedo so they could have a functional odometer in thier TR3.
Any might be possible. I'm not a certified expert on the production changes.
I do know that the visual difference between my TR2 speedo and my TR4A speedo, aside from the glass,are very slight.
On the TR2 the "main beam" indicator is a small hole, where the TR4A one has a blue "jewel" over the hole. also the TR4A speedo had some "framing" around the odometer numbers to clean up thier appearance, where the TR2 one does not.
Thae housings are different too. The TR2 has holes for 2 panal lights and I'm pretty sure the TR4A has only 1, and the mounting studs are a tad different.
Maybe this description will help identify the application.
 
The speedo on my 1958 TR3A (TS 27489 LO) has a fully round back. It is the original speedo that came with the car when new.

The speedo for the late TR3A (TS 81551 L) that we finished last summer has a squar-ish box pressed into the sheetmetal case on the back. This speedo may have been changed from another car sometime in the past but it looks like it's right for a TR3A and it has curved glass.
 
Piggott's Original Triumph TR says:

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Most instruments were carried over onto the earlier TR4s from the TR3A...Later TR4s and all TR4As still used the familiar TR instruments, but now the glasses were flat rather than convex. [/QUOTE]

Piggott doesn't give a change point in this book, but maybe it's in Original Triumph TR4/4A/5/250 which I don't have.
 
For those of you that might be interested in trying what I did to replace one of those gears, here's a few facts and figures. This is for a TR3 speedo.

I bought several nylon spur gears from McMaster...part number 57655K15. It's a 20 tooth gear, same as original. There are several minor differences that had to be attended to to make it work. The bore in the new gear is 1/8" (.125). This had to be bored out larger to fit the original shaft of .197. I used a #9 drill (.196). In the picture, you will see a hub on the new gear. Edit: Actually, the picture I chose doesn't show the hub, as it it underneath the spur part of the gear. Most of that I cut off, but I did this last, as some other work needed to be done on the gear before it would mesh properly.

The original diameter of the TR gear is .433, and the new gear is .450. That in itself is not a problem, but the depth in which the teeth engage was not deep enough. I had to use a fine wheel on a Dremel to cut the depth on each tooth a little deeper. That's why it's a good idea to buy several more gears then you need. The first gear I messed up while cutting the grooves deeper. I finally got things to mesh real good. I also didn't cut off the hub completly, as it wasn't necessary, and that gave more area for the press on fit.

The odometer works fine with this gear in place when tested with a drill motor...reverse direction IIRC.

How longs this repair will last is up for grabs. I'll only know when I get the car together and running. I put this gear on the trip odo side, so if it does go south, my main odo will still work OK.

The picture shows the original gear in the middle, the new gear on the left, and the one on the right has been drilled, and generally messed with. /bcforum/images/%%GRAEMLIN_URL%%/thumbsup.gif
 
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