Speedo Question

[TR3BGeorge]

Hello Folks,

 

I am looking for a "new" speedo on eBay. The numbers on my speedo are SN6319/00 and 1184. Is there any other speedo that will work in my car, OR SHOULD I LOOK ONLY FOR MATCHING NUMBERS? For example, there is a TR4 speedo, SN6325/02 and 1182 or 1152. Would this work?

 

Also, is there the overdrive/non-overdrive issue with speedos? That is, if I do not have overdrive, do I have to ensure that I do not get an overdrive speedo?

 

What do these numbers on the speedos signify?

 

Thanks in advance.

[TR 2100]

 

I am looking for a "new" speedo on eBay. The numbers on my speedo are SN6319/00 and 1184.

Is there any other speedo that will work in my car, OR SHOULD I LOOK ONLY FOR MATCHING NUMBERS?

For example, there is a TR4 speedo, SN6325/02 and 1182 or 1152. Would this work?

 

Also, is there the overdrive/non-overdrive issue with speedos?

That is, if I do not have overdrive, do I have to ensure that I do not get an overdrive speedo?

 

What do these numbers on the speedos signify?

 

Thanks in advance.

 

 

Speedos are the same for overdrive and non-overdrive cars.

 

The numbers represent the number of wheel revolutions per mile -

this is related to the type of (cross ply) tyres originally fitted.

You won't be able to match that exactly anyway, so I would ignore

the numbers.

 

TR4 speedo will work OK, but after 1962 TR4 production, the glass

changed from curved to flat - you would probably want a curved

glass one (although you could always change over the glass).

 

AlanR

[ianc]

Get as close to 1184 as you can. 1152 would give you a reading about 2.5% higher than before. That said, cross ply and radial tyres were somewhat different in overall rolling circumference.

You haven't said what tyres you are using, and width and profile can make a significant difference. A modern 195/65 or 185/70 radial is almost the same as the old (1970s) 165 radial, but lower profile tyres upset the revolutions/mile figure.

Ian Cornish

[TR3BGeorge]

Thanks, guys. I will try to get as close to 1184 as I can. Right now, the car has 195s on there. I will replace them with 165s this year or next, depending on my finances.

 

Also, I am happy to hear that there is no OD/non-OD issue. It would have made assembly-line operation a nightmare!

 

Food for thought: as I learn more about the workings of the Triumph assembly plants, I wonder how many of the options (OD, heater, windshield washer, wire wheels) were matched to SPECIFIC cars coming down the line vs. "whatever." In other words, did that Primrose Yellow car receive the OD and wire wheels because a specific dealer requested it, or because the next rolling chassis had wire wheels and the next engine had an OD tranny. Very interesting.

 

Maybe one of you will know the auto industry well enough, either over there or here in the States, to know what percentage of cars coming off the assembly line are "specific order" cars. I suspect that it is less than 10 percent. So, getting back to my original OD/non-OD issue, your yellow TR with the WW and OD was simply an Act of God. (I hate to be a name-dropper.)

 

Final question: So, if there were a 1184, 1180, and 1152 speedo, the number was to match the SIZE OF THE TIRES on the car? Live and learn!

 

It is mid-60s this week. Side curtains are off, top is down, gas tank is full. Sacre bleu!!

[Mychael]

Get as close to 1184 as you can. 1152 would give you a reading about 2.5% higher than before. That said, cross ply and radial tyres were somewhat different in overall rolling circumference.

You haven't said what tyres you are using, and width and profile can make a significant difference. A modern 195/65 or 185/70 radial is almost the same as the old (1970s) 165 radial, but lower profile tyres upset the revolutions/mile figure.

Ian Cornish

 

 

In the end it probably does not matter a whole lot which speedo you have unless your planning on fitting it without overhaul. Most old speedos are by now wildly inaccurate anyway due to wear. When I wanted one I just picked the one with the best face and sent it up for overhaul.

The instrument guys got me to count speedo cable revolutions to wheel revolutions,tell them what tyre profile I have on what sized rim. The set up my speedo from that and it's now quite accurate.

 

Mychael

Edited March 8, 2010 by Mychael