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M

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I just obtained a complete set of gauges for a TR3. They are in great condition... even better than the ones in my car. But there are two small details I am curious about:

1. The redline on the Tach in my 58TR3 is a red "line." But the redline on the tach I just received is more like a small triangle. Does this tell us something about the dates for the tachometers?

2. The speedometer I received has a trip odometer, but there is no adjustment -- or an opening for an adjustment -- to return it to Zero.

Has anyone ever seen any of this before?
 

TR3driver

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LexTR3 said:
1. The redline on the Tach in my 58TR3 is a red "line." But the redline on the tach I just received is more like a small triangle. Does this tell us something about the dates for the tachometers?
I believe so. But ISTR the wedge wasn't introduced until the "flat glass" gauges during the TR4 run.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]2. The speedometer I received has a trip odometer, but there is no adjustment -- or an opening for an adjustment -- to return it to Zero. [/QUOTE]
I'm guessing that means someone has used a tach housing and stuffed a speedo mechanism in it.
 

Geo Hahn

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I suppose you could simply drill a hole for the odo reset knob though, of course, you'll also need said knob.

On the speedo -- is the 4 digit number the same as your original one?
 

HerronScott

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Ed,

If you can post the numbers on the face of the gauges that would help identify them (pictures are always nice too!).

Scott
 
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Here are some numbers and photos.

First, however, I was wrong about the "new" speedometer. It has an opening and small attachment for the trip odometer reset, but the extension and knob are missing. I think I can find one...

The number on my "new" speedometer is SN6313/09 208062, while the number on the speedometer in my car is SN6307/04 1180. (Turns out the speedometer is for a TR4 and not a TR3).

Both of my "new" gauges have "curved glass," not "flat glass." Doesn't mean that someone hasn't placed a later speedo into an older case, however.

First photo is of the tachometer in my car. (BTW - the switch showing to the left is not really my Side and Head lights, it is an override switch for my radiator cooling fan).

The second photo is of the face of my "new" (just obtained) tachometer, with the redline as a wedge rather than a line. It has the number on its face of RN1409/02. The third photo is of the rear of this unit.

I obtained these gauges and the others (a complete set) not to replace any in my car but just to have them. Call it a "hobby" or something like that -- not an "investment" -- but I occasionally purchase parts that are no longer available (NA in the Moss and TRF catalogs) and just "put them away."

UPDATE: The Triumph Jaeger Tachometer with the "wedge" redline is, indeed, for a TR4, although the one I have has a curved glass and not a flat glass (substituted by some previous owner?). I'll keep it, but I will also get a proper TR3 Jaeger Tachometer from my source.

SECOND UPDATE: Turns out that early TR4 gauges had conveex glass and switched to flat glass later.
 

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TR3driver

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LexTR3 said:
First, however, I was wrong about the "new" speedometer. It has an opening and small attachment for the trip odometer reset, but the extension and knob are missing.
Look to see if there is a hole for a tiny cotter pin. All of mine have been broken off, right through that hole. Without it, I don't believe the original extension will work.

You can redrill the hole higher up, but then the cotter pin will hit the case when you try to reset the tripmeter. I got around the problem by machining a new extension with a groove and a short piece of safety wire that crimps down into the groove (below the surface of the extension).
 
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Randall,

Yes, the little hole is there, and in good shape.

Problem with all this is that I requested gauges for a TR3, and my source sent me a speedometer and tachometer for a TR4. Great gauges, in very nice shape, but not of any use to me.

I'm working with the guy to get the proper gauges. Perhaps I'll keep the TR4 ones and get another set -- of TR3 ones.
 

Geo Hahn

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LexTR3 said:
...I'm working with the guy to get the proper gauges. Perhaps I'll keep the TR4 ones and get another set -- of TR3 ones.

Ed -- the answer is simple:

You need to get a TR4 (ideally one with the 2 big gauges missing).
 
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George...


Ha, ha.... Love it! Yes, a TR4.... and an MGTD... But would have to get a new house with a garage that holds more than one car.

Funny thing.... I look at these guages and they look like works of art to me. I'm thinking of putting the two TR4 gauges in a frame and hanging them on a a wall in my house. They don't make them that beautiful anymore...
 

HerronScott

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Ed,

Looks like you have all your answers. :smile:

Early TR4 gauges with convex lenses and with the speedometer configured for 3.7:1 differential and 590-15 tires (TR4 RHD to CT15053, TR4 LHD to CT11307).

Scott
 
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Scott,

Thanks for the information.

The differential ratio for the TR3 was 3.7:1 (or 4.1:1 optional when overdrive was fitted). If I am understanding you correctly, you point out that early TR4 gauges with convex lenses were configured for 3.7:1 differential ratio and 590-15 tires. The "new" TR4 gauge I received has a convex lense (which appears to be original to the unit).

Am I to conclude that I could use the early TR4 speedometer in a 1958 TR3 (although I don't have any reason to do that) because they are both 3.7:1?

I have no way of knowing what TR4 the speedometer came from: before CT11307 or post 11307.

UPDATE: I found this in a book on TR4s: "The standard axle ratio [for TR4] remained, as with the sidecscreen cars, at 3.7:1, achieved by a 37-tooth crown wheel mating with a 10-tooth pinion. This ratio continued to be the standard fitting whether or not overdrive was specified, although an optional 4.1:1 axle could be supplied to special order with overdrive. Cars fitted from new with the 4.1:1 axle ratio were rare... This standard 3.7:1 ratio provided almost exactly 20 mph per 1000 rpm in top..."


Original Triumph Tr4/4a/5/6, The Restorer's Guide, by Bill Piggott
 

TR3driver

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Yes, the early TR4 speedo will work reasonably well in your TR3. The calibration value may be slightly different (not even all TR3A had the same value, it changed with original tyre type as well as final drive ratio); but not enough to matter.

Bill's comment on the 4.1 ratio also applies to TR2-3B. The 4.1 option was normally only available in conjunction with the overdrive option, but most cars with factory overdrive did not have the 4.1 option.

And in spite of the way it was listed, it was possible to order a car with 4.1 and no overdrive; either from the factory or as a dealer option. But the only reason to do so IMO would be a car that was only for racing. The 4.1 axle is relatively useless on the street, IMO, especially with the "granny gear" 1st and extra-heavy flywheel.

Ironically, TS39781LO was one of the few cars equipped with 4.1 axle by the factory, but had been converted to 3.7 when it came to me. TS13571L did not have 4.1 from the factory, but had 4.1 gears when it came to me (and no overdrive). I only drove it for a few weeks before deciding that OD was an absolute must before driving to TRfest 2009; and I'm currently building a 3.45 axle to go in it.
 
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Randall,

Many thanks. I have no intention of using my "new" TR4 speedometer in a TR3, but it is good to know that it would work if it came to that.

Now here's a question: I had an OD added to my car when the engine/transmission were rebuilt in 2010. But as far as I know, the 3.7:1 axle ration was not changed. Is that a problem?

I note that you have written that most cars with OD did not have the 4.1:1 ratio.
 

TR3driver

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No, the A-type OD does not change the required speedo calibration. The speedo takeoff is after the OD and has the same gear ratio as the non-OD box.

Where folks get into troubles is swapping late TR6 gearboxes (and/or overdrives) for earlier units. Starting in 1973 (with the introduction of the J-type), the speedo drive ratio was changed to always use 1000 turns per mile at the cable, regardless of tire size and final drive ratio.
 
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Thanks, Randall.

I had an A-type OD installed in my car when the transmission was overhauled/rebuilt. Quite frankly, I'm sorry I did because I rarely use it. Most of my driving is up and down the Blue Ridge Mountains and on narrow, hilly back roads. Speed remains between 30 and 45 mph, and much of this in third gear or even second gear (on steep grades). But I figured that if I ever sold the car, someone would want OD.

I am holding on to the TR4 speedometer and tachometer that I received from my source and am in the process of purchasing an appropriate TR3 speedometer and tachometer from him. There's no particularly good reason for my acquiring all these guages.... just want them. Eventually, I'll probably have them all rebuilt/refurbished and will then make the TR4 gauges available to someone who needs them.
 

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LexTR3 said:
Scott,

Thanks for the information.

The differential ratio for the TR3 was 3.7:1 (or 4.1:1 optional when overdrive was fitted). If I am understanding you correctly, you point out that early TR4 gauges with convex lenses were configured for 3.7:1 differential ratio and 590-15 tires. The "new" TR4 gauge I received has a convex lense (which appears to be original to the unit).

Ed,

Actually I was referring to the TR4 speedometer that you have with the part number SN6313/09 was for an early TR4 with that differential ratio and those size tires.

Here are the different options for MPH speedometers on TR4's and TR4A's excluding competition versions with associated differential and tire sizes. The SN6313/xx versions have convex glass and were fitted up to TR4 RHD from CT15054 and TR4 LHD from CT11308.

SN 6313/09 208062 3.7-1 590 x 15
SN 6313/11 208066 4.1-1 590 x 15
SN 6313/15 208064 3.7-1 155 x 15
SN 6313/13 208066 4.1-1 155 x 15
SN 6313/19 208655 3.7-1 165 x 15
SN 6313/17 208657 4.1-1 165 x 15
SN 6325/00 209182 3.7-1 6/62- 590 x 15
SN 6325/06 209184 4.1-1 6/62- 590 x 15
SN 6325/02 209188 3.7-1 6/62- 165 x 15
SN 6325/08 209186 4.1-1 6/62- 165 x 15

Scott
 
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Scott,

Many warm thanks. That is very useful information, especially identifying the TR4 speedometer that I have as an early one having 3.7:1 axle ratio. I'll make a note and attach it to the speedometer for future reference.


BTW: Where did you find this good information? And where would I find similar information regarding TR3 speedometers?
 

HerronScott

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Ed,

That list started with an old page from the early 80s from a Nisonger catalog but I supplemented it with information from the TR4/TR4A SPC and some vendor websites that use original part numbers as well.

I've started a list for the TR2/3 however there seems to be some conflicting information and the SPC doesn't list multiple part numbers like the TR4/TR4A SPC. The TRA judging guide seems to give some authoritative information but they don't even mention the non SN gauge part numbers which I believe were the earliest and make the common mistake of assuming speedometer differences between overdrive and non-overdrive when it was really due to differential differences so I wonder how accurate it is.

Part # Spec. Code
S 628 51 118 504 04 3.7:1
SN 6307/04 3.7:1
SN 6307/11 3.7:1 Optional Michelin X tyres
SN 6307/08 4.1:1
SN 6307/10 4.1:1 Optional Michelin X tyres

SN 6319/00 3.7:1
SN 6319/06 3.7:1 Optional Michelin X tyres
SN 6319/02 4.1:1
SN 6319/04 4.1:1 Optional Michelin X tyres

Scott
 

TR3driver

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HerronScott said:
the SPC doesn't list multiple part numbers like the TR4/TR4A SPC.
Some of them are in there, on page 143 (along with the listing for the 4.1 axle & gear set).

Here is some information I saved away from a long-ago post by Chris Kantarjiev:
<div class="ubbcode-block"><div class="ubbcode-header">Code:</div><div class="ubbcode-body ubbcode-pre" ><pre>
Axle Original Triumph part Jaeger part Revs/km Revs/mi
ratio tires
3.7 5.50/5.90 108192 SN6319/00 - 1180
3.7 5.50/5.90 108193 /01 740 -
4.1 5.90 113632 /02 820
4.1 5.90 113631 /03 - 1312
4.1 155X 119046 /04 - 1344
4.1 155X 120206 /05 820 -
3.7 155X 119047 /06 - 1216
3.7 155X 120205 /07 740 -
</pre>[/QUOTE]
 
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Scott and Randall,

Thank you for all this good information. I will add it to my manual.


The speedometer in my car (58TR3A) is SN6307/04 1180.
 
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