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  • Smiths Speedometer problems...

    I let my girlfriend drive the Roadster today and she went a bit too fast...
    Attached Files

  • #2
    Re: Smiths Speedometer problems...

    I have just written a lengthy description of the speedo problems and when I posted it - it gave me a 403 error so I've just lost it all. I'll have to do it again... The speedo is not working properly...

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    • #3
      Re: Smiths Speedometer problems...

      3 yrs ago the speedo worked but erratically, then it stopped working altogether. However the mileometer still worked. Then that gave up the ghost too and I discovered the cable was broken. I sent both off to a repairer in Swansea and 6 weeks later they sent the speedo repaired with a new cable to the replicate the original. However the car was in bits at the time and it was 6 months later that I finally had it on the road and discovered that although the speedo worked – it wasn’t accurate; typically reading 10mph faster than actual speed. The mileometer however, was perfect – very accurate. I remember phoning the company up and discussing it with them and they said it would be £XX and a six week turnaround to be correctly calibrated. (I had naively neglected to tell them what wheel size and engine / gearbox type it was for in the first instance)… However the car worked had an MOT & there was a summer of driving ahead of me – so I just left it as it was. I measured speed and taped little indicators to the outer dial to give me info that I needed.
      So today, we’re driving along at 40-50 and all was well with the world, the sun was shining, the birds were singing and we had the wind in our hair. Then I look at the speedo & it’s at zero! As we return home, on slowing to 10-12mph the speedo comes to life but it shows we’re doing 140mph! it runs beneath the graduated scale and around to the top and back eventually to zero when we’re either under speed or at a stop.
      I am back in the same situation once more – with the car working, the summer ahead of me and no speedo again. This time, I am a little hesitant to send it away to be repaired; certainly to that same company. I think I might be better off having a new unit instead of risking the same problem coming back again.
      So my thinking is at the end of the summer when I put her away again for the winter; can I just source and fit another speedo (off the shelf) – are they plug and play or do they need to be calibrated to the road wheels and gearbox?

      Comment


      • #4
        Re: Smiths Speedometer problems...

        At a guess the needle has come loose on the spindle as your marks are prety consistantly 10 fast. Take it apart, you've nothing to loose, and push the needle firmly on in approx the right place. If you hold the alloy disc that rotates the needle when at rest and press the needle on at zero it should be about right.
        They are quite a simple mechanism although look complicated.

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        • #5
          Re: Smiths Speedometer problems...

          Most Smiths MPH speedos are supplied calibrated to 1000rpm of the cable being 60mph.
          A small 1000 used to be printed on the face of the dial.
          Whether the Alfa speedo cable turns at that rate I have no idea, any variation in tyre size or axle ratio is generally coped with by a combination of different gear teeth on the wheel and pinion.
          A solution might be to fit a GPS speedo, no calibration issues, but they don’t work if the GPS signal fails in built up areas or through tunnels.
          MOC member since 05/97
          1984 Marlin Roadster SWB.
          1800TC, Unleaded ported head, stage 2 cam. Ford Type 9 gearbox, Dolomite Sprint rear axle fitted with MGF disc brakes.
          Three core radiator, Renault Clio vented front discs.
          The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.

          Loads of Marlin Reference can be found documents here or there.

          Comment


          • #6
            Re: Smiths Speedometer problems...

            Or visit these people https://www.etbinstruments.com/index...tegory&path=59 The speedo uses a magnet that can be placed just about anywhere, wheel, propshaft, diff etc. then programmed with the number of pulses per mile which is easy to do (apart from a few sums) does not require the speedo to be removed. ETB gauges can be made to your specification in terms of bezel profile and colour along with dial face colour, colour of legends and needles too.

            I set mine up approximately right then used a satnav to do the final calibration. Just to give myself a small margin I set it up so it overeads slightly. (Indicated 70 is satnav 68)

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            • #7
              Re: Smiths Speedometer problems...

              Car builder Solutions sell a GPS speedo for but £65. When the speedometer on my S1Landrover goes erratic I pull out the inner cable and clean and oil it That usually sorts it for a few years.

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              • #8
                Re: Smiths Speedometer problems...

                I'm not sure if a GPS speedo will pass your MOT
                I think it's not kosher here (NZ)

                But I found a nice GPS speedo that does not say GPS on it! - so it should pass ok
                - it was 45 GBP
                Damn - that is a Km one

                Here is the MPH one - for some reason it's a bit more expensive

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                • #9
                  Re: Smiths Speedometer problems...

                  I like the idea of the GPS speedo - certainly it'd resolve the problem - but whether I would find one that matched the style of the smiths gauges is another matter; currently everything looks right, a new different style (even the same size) speedo might not look right. However, the idea of a self fix is not beyond the realms of possibility... after all - I have nothing to lose really... except maybe the mileometer working and that wouldn't be too great a loss...

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                  • #10
                    Re: Smiths Speedometer problems...

                    GPS Speedos dont work in tunnels or underground parking garages

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                    • #11
                      Re: Smiths Speedometer problems...

                      Originally posted by AdminUser View Post
                      GPS Speedos dont work in tunnels or underground parking garages
                      I seem to remember reading that they are not legal in France?

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                      • #12
                        Re: Smiths Speedometer problems...

                        My speedo is a Smiths electronic one, looks exactly the same but uses a pick up sensor, mine detects the revolving bolt heads on the prop shaft to the final drive flange. The mechanical one I had was not accurate enough for the SVA, re programming was simple when I changed the final drive from a 3.91:1 to a 3.38:1 last year.

                        Comment


                        • #13
                          Re: Smiths Speedometer problems...

                          I fitted an electronic speedo from CAI some while ago. At the time of ordering I requested in writing that the mileometer was set at the current mileage so the mileage history was preserved for all the documentation (MOT / Insurance etc). Mine also has a sensor that picks up from the diff flange. The diff bolts are not equispaced on my Siera diff so I used split tubes pressed into the other redundant equispaced holes in the diff flange so they protrude at the back of the flange. There is a post somewhere on the forum with photos. Peter.

                          Comment


                          • #14
                            Re: Smiths Speedometer problems...

                            Originally posted by AdminUser View Post
                            GPS Speedos dont work in tunnels or underground parking garages
                            Ive never seen a speed camera in an underground parking garage.
                            MOC member since 05/97
                            1984 Marlin Roadster SWB.
                            1800TC, Unleaded ported head, stage 2 cam. Ford Type 9 gearbox, Dolomite Sprint rear axle fitted with MGF disc brakes.
                            Three core radiator, Renault Clio vented front discs.
                            The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.

                            Loads of Marlin Reference can be found documents here or there.

                            Comment


                            • #15
                              Re: Smiths Speedometer problems...

                              While my Roadster is in the garage sick with its oil leak problem.. I have been hunting online for options and came across a small business in Lanarkshire (Classic spares and engineering) that refurbishes and repairs classic guages. It transpires that they can repair my speedo for £80 with a 2 week turnaround (not like 6 weeks with speedy cables). So as I can't use the car atm, I thought why not take the speedo out and send it while I'm getting bits and pieces to repair the oil leak...

                              I get in the car and using a torch and a mirror, I manage to undo the clips and remove it.. then as I do I realize somethings not right.. it is full of oil! I don't pretend to understand how speedo's work but I'm pretty sure they are not meant to have a volume of oil in them! It must have travelled up the inside of the cable from the gearbox and into the instument. Now I have a dilemma - because if I send it to be repaired (the fault is highly likely to be as a result of the inner mechanism being contaminated with oil) - it is very likely to just fill with oil again... I am flumoxed as to what to do next!

                              Looked at some alternative speedos (gps & non gps) but my trouble is the hole in the dash was custom made for this size instrument & I'd have to find one that fits an 81mm hole..

                              It's an unusual situation... but any advice would be appreciated!
                              Attached Files

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