james christie Posted September 1, 2022 Report Share Posted September 1, 2022 After a few years of my speedo needle on my 3A doing the usual dance, today I finally got pro-active to try and do something about it and emulate the rev. counter which is rock steady. Like most I was expecting the culprit to be the cable and its internal run from OD gearbox to the speedo - it’s a left hooker. By elimination I determined it was the speedo itself, so began to take it apart (thanks Anthony Rhodes). After a bit of a look around, I found the trip meter plastic pinion has a radial crack which although very minor is enough to cause what Anthony calls « cyclic resistance against turning resulting in wavering » The pinion itself would seem to be a push on fit, maybe to much push on, hence the crack. It would seem a fairly simple operation to change it. Has anybody been in there and from where can I get the pinion. james Quote Link to post Share on other sites
Lebro Posted September 1, 2022 Report Share Posted September 1, 2022 I probably have what you need, can you show a photo of the part? Bob Quote Link to post Share on other sites
james christie Posted September 1, 2022 Author Report Share Posted September 1, 2022 Thanks Bob, but I’ve put it all back together now and programmed it as yet another winter project! It’s the plastic/nylon pinion on the trip meter, driven by the worm gear. james Quote Link to post Share on other sites
Lebro Posted September 1, 2022 Report Share Posted September 1, 2022 I have a TR3 speedo in bits which I have been stealing bits from to repair others, as yet no one has needed any odometer / trip meter parts, so I should have them. Just let me know if / when you need it. Bob Quote Link to post Share on other sites
ed_h Posted September 2, 2022 Report Share Posted September 2, 2022 (edited) 7 hours ago, james christie said: After a bit of a look around, I found the trip meter plastic pinion has a radial crack which although very minor is enough to cause what Anthony calls « cyclic resistance against turning resulting in wavering » The pinion itself would seem to be a push on fit, maybe to much push on, hence the crack. It would seem a fairly simple operation to change it. Has anybody been in there and from where can I get the pinion. james I've felt that pain, James, though on a 69 GT6. Not sure if they are the same or not. The crack separated a couple of the teeth so that the gear would bind on those teeth. I assumed the plastic gear was molded on to the shaft, but don't really know. i fixed mine by reshaping the offending teeth until they didn't bind. Couple more pics here: http://bullfire.net/GT6/GT6-27/GT6-27.html Ed Edited September 2, 2022 by ed_h Quote Link to post Share on other sites
ctc77965o Posted September 2, 2022 Report Share Posted September 2, 2022 Here's a source of new plastic gears: https://www.odometergears.com/products/Smiths-Jaeger/All/38 Quote Link to post Share on other sites
james christie Posted September 2, 2022 Author Report Share Posted September 2, 2022 My thanks to all for help and advice. I believe the number of teeth on these little spur wheels/pinions is dependent on whether the odometers, both trip and total distance, are in kms or miles. The crack is exactly as ed_h ‘s photo Although, I have put it all back together now - I need the car this afternoon - my initial objective was to do something about the dancing speedo needle. I might just have it apart again this w/e and remove the offending pinion, the one that drives the trip meter, so sacrificing the trip meter and tackle the replacement later over the winter. Ed, a question for you. Is this feasable or will nothing at all work? james Quote Link to post Share on other sites
Ian Vincent Posted September 2, 2022 Report Share Posted September 2, 2022 I have a dancing speedometer needle that has thus far resisted all my efforts to clean an lubricate the cable. On my list winter jobs is the removal of the speedo so that I can bench test it with an electric drill. Rgds Ian Quote Link to post Share on other sites
ed_h Posted September 3, 2022 Report Share Posted September 3, 2022 16 hours ago, james christie said: Ed, a question for you. Is this feasable or will nothing at all work? Sort of going by memory here James, but I don't think there should be a problem in running with the trip odometer gear removed. Ed Quote Link to post Share on other sites
Lebro Posted September 3, 2022 Report Share Posted September 3, 2022 No problem at all, it will just be a bit less load on the drive to the speedo, & odometer. The rev counter is exactly the same construction, but with no gears fitted for mile counting. Bob Quote Link to post Share on other sites
james christie Posted September 3, 2022 Author Report Share Posted September 3, 2022 Bit of an autosatisfaction crisis here this morning! I’ve removed the cracked tripmeter pinion drive (20 teeth on mine, because km) and the gubbins that drives the tripmeter. It required delicate fingers, which I don’t have, in particular to remove a very fine spring on the pawl. A road test shows a totally steady and even accurate speedometer needle for the first time in well over a decade of faffing about with cables and their fitting, but at the cost of a provisionally sacrificed trip meter. Has anybody used this supplier of new nylon pinions? https://partworks.de/en-gearworks-de-Components-for-Speedometer-Gears-odometer-Z32-gear-for-Smiths-Jaeger-speedometer-odometer-repair.html james Quote Link to post Share on other sites
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