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Speedometer with/without OD part numbers

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Brosky

Brosky

Great Pumpkin
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Could someone, maybe several TR6 owners, with matching later speedometers check the part numbers at the bottom of their respective speedometers for me? Ideally, if one with Overdrive and then one without could verify the numbers, that would be great.

It will either be SN6411/10 1000 or, SN6411/025 1120. At least, that's what these two spares are.

I want to send the proper one to Nisonger's for rebuilding and calibration. That will take a while and hopefully I can get the new dash all built here at home and ready for a swap when the weather warms up in my garage. Much easier to do with warm fingers and top down for the season.

Thanks......
 
Okay -- since you've had no replies in 6 hours I'll ask...

Why would a speedometer care whether you have overdrive or not? Isn't it measuring the output after the OD?

Now if you have a different rear end that would require a different speedo.
 
Paul:

My '74 TR6 is a non-overdrive car.

It has the speedometer with SN6411/025 1120

Hope this helps.

Matt

<span style="font-style: italic">Wait ... never mind. I replaced my original speedometer with one from TSI's junkyard. I will look tomorrow for my original to see what it had. Sorry for the mistake.</span>
 
Thanks Matt. I'll be curious to see what you have. I can get mine late Monday, but wanted to ship before that.

George, from what I understand, Triumph used two, one for O/D and one for non O/D. Mine seems accurate with the O/D transmission in the car and Nisonger said to let them know that the speedo needs to be calibrated for O/D when I send it in, so there must be some difference.

This discussion, like many others here, happened a long time back when I had no O/D or gauges to restore, so it didn't matter then. I remembered that it was discussed, which I why I posted again in hopes of getting the answer.
 
Thanks David. One confirmed and one to go. Now if an original O/D owner comes back with the other numbers, the case is solved.
 
1976 with factory OD Speedo

zODspeedo.jpg


.
 
Paul:

I found my original speedometer (along with a whole bunch of other parts I had misplaced!
grin.gif
)

It is also a SN6411/025 1120

Again, it is a '74 Non-OD car.

Matt
 
Geo Hahn said:
Why would a speedometer care whether you have overdrive or not? Isn't it measuring the output after the OD?
Click to expand...
IF it does care, it would be because the speedo drive gears in the OD are a different ratio than the ones in the standard gearbox.

There was a change during the TR6 run; before that, the speedo drive ratio was always 5:2 and the speedo calibration was changed to accomodate changes in tire size, final drive ratio, etc. 11xx for the 3.7 axle; 10xx for 3.45, 13xx for 4.10, etc. After the change, the speedo calibration was always 1000 tpm (for mph speedos) and the drive ratio was changed to suit. As far as I know, that change applied to both OD and non-OD cars. Meaning that Paul's 1120 is from an earlier TR6, and 1000 from a later TR6.

However there is a further complication in the fact that lots of folks are installing overdrives from different cars, which means they frequently get the wrong drive ratios. Perhaps that was what Nisongers was talking about, I don't know.

Or, there is a popular misconception that all TR3-4 with factory overdrive also had a 4.1 final drive ratio. Perhaps that's it (though that wouldn't apply to a TR6)?
 
Thanks to all. I've sent this same info to Nisonger's and before I send them anything I'll wait to see their reply.

David & Matt's 74's non OD are the SN6411/025 1120

Stirkle's 76 with OD is SN6411/10 1000

Per Randall's detailed definition (thank you!), the later must be 75 & 76 as the two 74's are both the same.
 
This is a gray area. I added OD to my TR6. I needed speedo repair and looked for new. Apparently, there are 2 listed, one is OD, the other non OD. If I remember right, neither of the 2 you show is the later model OD speedo. I do remember that it exists, because a supplied in NE had the OD speedo for a 76, but I wasn't willing to mortgage my house to get it. The number on the one he had, NOS, matched the number in the parts cataloges, and it wasn't either of the 2 you have listed. So, I just had mine rebuilt. Now, the only problem is, the car is going faster than the speedo says, 3-5 MPH. The best way to get it right, Put speedo in car with OD, use GPS to see if it is accurate. If not, tell the rebuilder how much it is off. If you find more info on this, I would like to know the difference between the 2. One of the speedos you have listed is for a 75-76, the othere is a 73. The/10 is the same as my 76, but since I didn't buy the car new, can't say if it came in it, however it was an original non OD car. Also, if you are using a Volvo OD, you are opening a can on night crawlers.
 
Not quite a can of worms yet. I'm using factory "J" type O/D.

I just remembered that I still had my original TRF Green and Blue catalogs. In the Green catalog, on page 309 there is a breakdown of the speedometers. Taking out the PI cars (which are all listed with 3.45 axles) and the units calibrated in kilometers, there are two listed for the 1973-1976 models, which all appear to have 3.70 rear axle ratios.

One is for vehicles from CF1 up to CF35000 and the other is from CF35001 and up. But there is no further distinction between them. Oddly, there is no mention of the O/D in the TRF catalog.

From the Moss Modification Chart, the CF35001 cars began in the 1975 model year, which matches what you and Stirkle have confirmed.

So unless TRF is wrong in their original catalogs, which I had since the late 80's when a lot more of the parts were still available, there were only ever two for US non PI cars and they were broken down from 1973-1974 1/2 and for 1975-1976, but nothing about O/D.

I'll be curious to see what Nisonger says about this. This is a good as time as any to have them calibrate in my 205/70/15 tires as well, which they said that they could do.
 
Paul, my car has its original speedo in it, and it did not have OD when I bought it. Adding OD (J), I sent it to Nisonger and had it rebuilt and did the push-down-the-road-watching-my-cable-trick and I added slightly shorter tires; Nisonger did a wonderful job of making it work and look new.

Now, if I can only get my engine back together.....
 
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Now, if I can only get my engine back together.....[/QUOTE]

Sigh.....Bill, I know what you mean. I think that I've finally taken the last part required to the machine shop. He has a big plastic tub there with a lid that is full of my parts. He didn't want to start until we had everything, so he could just keep going on it.

The line boring and cam bearings are due to start tomorrow. The crank is ground and polished and ready to be balanced. The head and block were both cooked out last week and I delivered the new intake valves on Friday, so he's going to do the head, while the slow line boring is going on.
 
Brosky said:
I'm using factory "J" type O/D.
Click to expand...
The "can of worms" effect comes in because the J-type was fitted to many different cars, with many different axle ratios and wheel sizes. Even one originally installed by the Triumph factory might have been installed on a Spitfire with 13" wheels and a 3.89 axle ratio. Both the driven gear and the driving gear (for the speedo output) can be changed; but it takes a total tear-down to change the driving gear.

Not saying you have a problem Paul, just trying to explain the pitfalls. I even goofed with my Stag OD, apparently picked up the driving gear from the Volvo unit I was robbing for parts without noticing it had the wrong number of 'starts'. Now my speedo reads some 30% high. Part of that is probably the instrument itself, but the odometer also reads high, so I must've stuck the wrong gears in. Oh well.
 
Randall,

John from Quantum Mechanics built my O/D and matched he speedo gears to the original car. I had my wife drive beside me with cell phones on speaker as we clocked off a measured mile in tenths and compared various speeds to see how close it is to my 2008 Taurus. I found it to be between one and two mph off (slow) at 70 mph.

Peter at Nisonger said that they can tweak that right in, so no problem there.

Oddly enough, when I asked him to check the numbers for the speedo's that I posted pictures of earlier, with his parts listings, none of the numbers that we discussed here match with what his Smith manuals say should be in a 1974 TR6. There is no distinction between with or without O/D, but there are two numbers and they are 6411/09 and a 6410/0? Go figure.....

I'm going a different route though, because the pricing to rebuild/calibrate these will be $115 each for the small gauges and $170 for the two big units. That's $800 for the gauge rebuilding. ARGHHHHHHH!!!!!! That's what happens to poor Dale in PR.

These (or my originals) will get a cleanup, painted needles, new gaskets and new bulbs on my workbench before I spend that much.
 
Paul
mine is a '74 OD model. Number is SN 6411/00.
Regards
Craig
 
Thanks Craig.

Mine are getting cleaned and freshened right here. I just got two other prices and they are $75 to $100 dollars higher than Nisonger. And these gauges are in very good condition, not rat restoration projects.
 
Paul
my instruments are in good shape for their age, but I put up with a jumping pointer on my speedo for years until someone on this forum said a service will fix it. From a local instrument specialist, for $80 I practically got a new speedo, rock solid and only 1km out at 50km/hr (as tested on a gps).
Best money spent so far..........
Regards
Craig
 
Craig,

The best price on fixing that now is $170. There are no local speedo guys anymore. Dying breed, like machinists who know what they are doing.
 
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