Converting Speedometer on 1973 350 SE

[gurrier]

The current speedometer on the vehicle is set out in MPH only. Fairly recently we in Ireland had all speed limits changed from M/PH to KM /PH. I have access to a Km/PH speedometer , is it possible to change the face on the speedometer from M/PH to KM/PH. (I need to hold onto my licence! ) I have looked and see that the pointer, which prevents a straight change over of the faces, seems to be firmly attached, obviously I do not want to cause damage

I of course want to retain the original mileage recorded on the vehicle otherwise a straight swop of the entire mechanism could be done.

The KM/PH spedometer comes from a 350SE also

 

[Styria]

Hi gurrier, you'd be best advised to simply change over the complete speedometer rather than transferring any features. If original mileage is an issue, I would suggest that you get an instrument maker to equalize the two mileages and you retain the original for future reference. Regards Styia

 

[WGB]

Hi gurrier, you'd be best advised to simply change over the complete speedometer rather than transferring any features. If original mileage is an issue, I would suggest that you get an instrument maker to equalize the two mileages and you retain the original for future reference. Regards Styia

Just make sure you have the correct speedo for your 350.

If it is from another model the marked gearshift points may be different and the odometer is differently geared for each different diff ratio.

Bill

 

[Styria]

Well, if anyone is interested in knowing, I can verify that fitting a 450 speedo to a 6.9 will make that speedo read SLOW by about 20%.

Now, I do have a 450 speedo for sale at $120.00 - in perfect perfect working order, and showing both MILES and kilometers - very unique, and VERY exclusive - in the land of OZ anyway. Any takers ? Ring on 0428-50-1800 for further details Regards Styria

 

[smueller99au]

I have had the similar situation just recently with my 350SLC. When I got it the speedo was in MPH. So I thought I'd do a swifty and headed down to pick-a-part. I got another two speedo's that looked the same and had similar numbers on the dial (not exactly the same because they didn't have any 350SLC's). Of course they were all different ratios. Evidently, the ratios are inprinted on the back of the speedo so that might help some people.

Anyways, with a W108 speedo apart to see what I had to do I started on getting the new facia ready - the one I had picked was a dual mph/kph dial with mph for the odometer. This meant that I could keep all my original workings and odo reading.

With great care the needle will actually come off. Of course the W108 speedo I disassembled ended up with a severly damaged needle but I learned how to do the job at least. What I had to do:
0. Lift the needle over the zero stop bar and mark exactly where it sits (it's zero position)
1. remove the housing of the speedo.
2. unscrew the bolts holding the input shaft housing onto the rest of the speedo - TAKE CARE HERE. There are a few cogs that need to be replaced in the same spot. This housing removes the magnetic centre for the speedo needle as well.
3. With the actual needle shaft exposed now (this is hard to explain), hold the rear end of the needle shaft (which has a bowl like a milk bottle top) so that it doesn't rotate. Now carefully grab the needle on the front side and rotate left and right until it releases itself. I did this on 3 speedos successfully so hopefully it works on all. Take care not to bend the needle.
4. Remove the screws holding the old facia and replace it with the new facia.
5. Don't put the needle back on yet.... that's last.
6. Reassemble the input shaft housing making sure that the needle shaft is exactly in the right spot - in fact I think the magnet should centre that anyway.
7. With the speedo held in the same position as when you marked the needle's zero position, carefully place the needle back onto the needle shaft. Make sure it sits in the same zero position after your fingers are clear. This took me three or four times to get right.
8. Install in car and use a GPS to confirm the speed is reading correctly.

It might sound like a bit of a painful exercise but it can all be done in one sitting of 'Two and a Half Men' (apart from the test drive). I hope this can help some people out.

Cheers.
Steve.