Speedometer Compatibility

[Peted7202]

On the Potteries site for a 4.55 diff there are 4 speedos. Three are bronze numbered SN4407/00, SN4467/00, SN445/15 and are 80MPH. The fourth is black SN4467/00 and is 90MPH. All are1504 TPM.
Does anyone know the significance of the SN designations?
Are all four interchangeable?

[King Kenny]

Try this site it may help.

https://potteries.mmoc.org.uk/ID/Speedo.htm

[don58van]

Perhaps the differences are the configuration of the warning lights.
Don

[liammonty]

The one that you've said is balck and 90 mph is listed on that site as bronze and 80 mph. that makes sense as all 948 speedos were (to the best of my knowledge) bronze and 80 mph. Early 1098 ones were still bronze, but 90 mph, before the change to black ones.

I can't answer regarding the differences, but I suspect it's' to do with configuration of lights as suggested, as there were a few of these (I think early 948s had a trafficator warning on the speedo).

[Peted7202]

Apologies for the error. Here is the correct listing.
4407/00 Traveller, 4467/00?, 4445/15 Traveller. These are Bronze, 1504, 80MPH and 4.55 diff.
4423/00 LCV is Black, 1504, 90MPH, 4.55 diff.

Would all of these be interchangeable whether 948 or 1098 gearbox and if light configuration is irrelevant?

[liammonty]

I'm pretty sure they would, as I think that the speedo drive gear is the same ratio in 948 and 1098 gearboxes (it's totally different in the earlier 803 boxes though). So, as long as the speedo is matched to the final drive it was intended for (i.e. 948) it will ready accurately. It's the 'TPM' or turns per mile figure that indicates if it will read correctly, and that figure is 1504 on all the examples you've shown so will work 'accurately'.

[Peted7202]

If I change my Bronze 4407/00 1504 for a Black 4423/04 1408 it will obviously need recalibration with my 4.55 diff but what will need to done with the fuel gauge? I am aware that the sender units are different. So will a later sender unit work with the black speedo? Do I need a voltage stabiliser?

[oliver90owner]

You may be surprised at the accuracy of the two. Most speedos of that era would read several percent optimistic - and likely were on vehicles using much higher-aspect tyres. Legal requirement is that the speedo must not read low and no more than 10% high (but any errors do not absolve the driver from any speeding offence!).

[don58van]

So will a later sender unit work with the black speedo? Do I need a voltage stabiliser?

If the black speedo has--or originally had--a stabiliser on it and it has its original fuel gauge, then you will need the later type sender. You will also need to have the stabiliser functioning.

An alternative that some people use to simplify matters when using a late-type speedo that incorporates a late-type fuel gauge together with an early sender is to replace the late (black) fuel gauge with an earlier gold one. This means that there is no need to change the sender and a stabiliser is not needed. Of course, you would need to be comfortable with the aesthetics of the mixture of gold and black.

Note that I have seen several reports on here of owners having trouble getting a satisfactory seal when they replace the sender. If you decide to replace the sender, it would be wise to do a search on here to see how others overcame leaks from the sender.

Don

[Peted7202]

Thanks Don

[Peted7202]

What alternative fuel gauges for a gold face have members used?