iain Posted January 11, 2018 Report Share Posted January 11, 2018 I had my Speedo refurbished and re-calibrated a 3-4 years ago. Trip and Mileage counters very accurate. So what causes the needle to bounce? Is it the cable or something in the instrument. It improved for a while when I fitted a Halda Gearbox between the cable and the Speedo head but is now starting to read inaccurately again. Iain . Quote Link to post Share on other sites
Lebro Posted January 11, 2018 Report Share Posted January 11, 2018 It could be either the cable snagging, or could also be tiny particles of iron / steel in the speedo its self. Any ferrous "dust" will migrate onto the spinning magnet, & it can then catch the aluminium disk, & give it a "nudge" which causes the needle to flick. Try driving the speedo direct from a drill (in reverse) if it is OK the problem is probably the cable. Bob. Quote Link to post Share on other sites
RogerH Posted January 11, 2018 Report Share Posted January 11, 2018 Hi Iain, do you have an angle drive - being a TR3A you shouldn't have. If you have check it out. Could be a split in the speedo cable outer sleeve allowing water in and rusting the inner. Tight bend on the cable. The square end on the inner cable where is drives gauge may not be engaged very well. Do you get a squeaking noise at the time of the bounce. A small drop of 3 in 1 oil on the input bearing of the gauge or Teflon spray. Roger Quote Link to post Share on other sites
Dave Larnder Posted January 11, 2018 Report Share Posted January 11, 2018 Iain Coat the inner cable with graphite powder. Dave Quote Link to post Share on other sites
Fireman049 Posted January 11, 2018 Report Share Posted January 11, 2018 +1 Dave ~ Tom. Quote Link to post Share on other sites
iain Posted January 11, 2018 Author Report Share Posted January 11, 2018 Hi All thanks for the suggestions No angle drive,no tight bends. Will try the suggestions Many thanks Iain Quote Link to post Share on other sites
Don H. Posted January 11, 2018 Report Share Posted January 11, 2018 This is a good troubleshooting guide (from the original source!) SMITHS -- The Care of Instruments Quote Link to post Share on other sites
iain Posted January 11, 2018 Author Report Share Posted January 11, 2018 Cheers Don thats a nice find. Iain Quote Link to post Share on other sites
Paul J Posted January 11, 2018 Report Share Posted January 11, 2018 Similar happened to my speedo, caused by the inner cable lube screwing its way into the speedo head, for me a good clean of the speedo head with electrical cleaner and also the inner cable, refitted the cable with graphite and so far no re-occurance. Paul Quote Link to post Share on other sites
iain Posted January 11, 2018 Author Report Share Posted January 11, 2018 Thanks Paul...I have my suspicions this is the case. Iain Quote Link to post Share on other sites
TorontoTim Posted January 12, 2018 Report Share Posted January 12, 2018 Where does one obtain graphite powder? (other than sharpening lots of pencils...) Quote Link to post Share on other sites
iain Posted January 12, 2018 Author Report Share Posted January 12, 2018 Hi Tim https://www.maplin.co.uk/p/ambersil-graphite-lock-lubricant-n68jb This would appear to be the stuff. Iain Quote Link to post Share on other sites
Don H. Posted January 12, 2018 Report Share Posted January 12, 2018 Where does one obtain graphite powder? (other than sharpening lots of pencils...) Any hardware store or big-box building store should have it, Tim. Quote Link to post Share on other sites
TorontoTim Posted January 12, 2018 Report Share Posted January 12, 2018 Thanks, Iain and Don! Quote Link to post Share on other sites
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