Mark Posted August 23, 2021 Share Posted August 23, 2021 Hi all Been using the Gt6 a bit more of late but will need to do something with the Speedo accuracy. 30 mph is close to the correct speed but will then bounce to 35mph, sometimes to 40mph and then back. Don't think it is the cable, got a feeling it's the Speedo. Think the price to recon is probably similar to a new after market Speedo. Anybody had any success with a DIY repair. Short term I may get a cheap eBay digital dash top Speedo to make sure I stay on the right side, speed/average speed camera heaven where I live, until I can rely on the cars Speedo. Was thinking ahead as I have a 2.5 to fit to the car at some point, with the option to fit an OD saloon box, if and when the D type gt6 box gives up. Knowing the mods envolved maybe now is the time to fit an after market Speedo that runs off the prop. What's your thoughts? Link to comment Share on other sites More sharing options...
ed_h Posted August 23, 2021 Share Posted August 23, 2021 You should positively eliminate the cable as the culprit, since it could account for the symptoms. As for a DIY repair if the instrument itself, this may help if you decide to try it: http://bullfire.net/GT6/GT6-27/GT6-27.html Ed 1 Link to comment Share on other sites More sharing options...
Escadrille Ecosse Posted August 23, 2021 Share Posted August 23, 2021 1 hour ago, ed_h said: You should positively eliminate the cable as the culprit, since it could account for the symptoms. Agree with this. The speedo mechanusm itself can get gummed up but that tends to show as a sticky needle more often than a bounce. Link to comment Share on other sites More sharing options...
PeteStupps Posted August 23, 2021 Share Posted August 23, 2021 5 hours ago, Mark said: Anybody had any success with a DIY repair. I've had mixed results after taking a few apart, either totally killed them or had partial success doing something trivial. Is yours an occasional bounce rather than the usual wobble behaviour? My rev clock started doing an occasional flick, which gradually deteriorated until it was doing it constantly so got disconnected and replaced. I presume something picked up between the spinning magnet and cup part, and maybe it would have been possible to intervene earlier and save it. Or maybe not... Cheap ones do come up on Ebay but obviously a gamble. I ended up buying 4 or 5 clocks to get 2 that work correctly. Your mileage may vary, if you'll pardon the pun. Link to comment Share on other sites More sharing options...
Nick Jones Posted August 24, 2021 Share Posted August 24, 2021 Speedograph Richfield do a refurb/calibrate for £ 75 iirc. Cable condition/routing would be my prime suspect though. Link to comment Share on other sites More sharing options...
Hamish Posted August 24, 2021 Share Posted August 24, 2021 Speedy cables recalibrated my Speedo when I changed diff. good service. think it was more money that nicks tho Link to comment Share on other sites More sharing options...
Mark Posted August 24, 2021 Author Share Posted August 24, 2021 Thanks lads I've ordered a new cable from Canley's this morning. Link to comment Share on other sites More sharing options...
Mark Posted August 28, 2021 Author Share Posted August 28, 2021 Renewed Speedo cable, now a silky smooth reading, so you were all right. I can now determine it's over reading by almost exactly 10mph compared to GPS, throughout the range, tested up to 60mph actual speed. OD gearbox, 3.89 diff 13" wheels. Pretty sure it's the original OD Speedo, but need to check as I think they are different to the non OD Speedo. Forgot how tight it is under the dash to get to the Speedo cable on a gt6 compared to a Vitesse. Found it easier to remove the speedo clamps and pull the gauge out from thd front of the dash, to get to the cable. Link to comment Share on other sites More sharing options...
Escadrille Ecosse Posted August 28, 2021 Share Posted August 28, 2021 Good news Mark. And yes there isn't a lot of space back there! Link to comment Share on other sites More sharing options...
ed_h Posted August 28, 2021 Share Posted August 28, 2021 Mark--10 MPH off over the range is an offset error. It can usually be corrected by resetting the pointer on its spindle. Its a fiddly job, though, and a little risky. Might be best to just do the continuous mental correction. Ed 1 Link to comment Share on other sites More sharing options...
Mark Posted August 29, 2021 Author Share Posted August 29, 2021 2 hours ago, ed_h said: It can usually be corrected by resetting the pointer on its spindle. Thats a good idea Forgot about that. May give that a try. I had to do something similar changing a speedo dial face on a mazda Eunos import from kph to mph. Thanks Ed. Link to comment Share on other sites More sharing options...
PeteStupps Posted August 29, 2021 Share Posted August 29, 2021 2 hours ago, ed_h said: -10 MPH off over the range is an offset error. It can usually be corrected by resetting the pointer on its spindle +1, it is a bit fiddly but one of the 'trivial' fixes I managed on my speedo. If you take the gauge out and remove the bezel, glass and then rear housing it's not too tricky. Hold the drag cup part still with the pointer at some speed e.g. 20mph, then just push the pointer back to the desired position of 10mph Link to comment Share on other sites More sharing options...
ed_h Posted August 29, 2021 Share Posted August 29, 2021 3 hours ago, PeteStupps said: +1, it is a bit fiddly but one of the 'trivial' fixes I managed on my speedo. If you take the gauge out and remove the bezel, glass and then rear housing it's not too tricky. Hold the drag cup part still with the pointer at some speed e.g. 20mph, then just push the pointer back to the desired position of 10mph I think the first thing I'd try is to put the pointer back at the factory setting. There is a tiny white dot on the instrument face just below the pointer stop. Remove the pointer and let the spindle come to rest. Push on the pointer so that it is pointing at the dot. Retract the stop and move the pointer past it. Release the stop. and the pointer should bear lightly against the stop. This sets the proper preload for the pointer spring. Ed [img]http://bullfire.net/TR6/TR6-40/SDC12005a.JPG[/img] Link to comment Share on other sites More sharing options...
ed_h Posted August 29, 2021 Share Posted August 29, 2021 Sorry, pic didn't work. Is there really no way to edit posts? Link to comment Share on other sites More sharing options...
Escadrille Ecosse Posted August 29, 2021 Share Posted August 29, 2021 3 hours ago, ed_h said: I think the first thing I'd try is to put the pointer back at the factory setting. There is a tiny white dot on the instrument face just below the pointer stop. Remove the pointer and let the spindle come to rest. Push on the pointer so that it is pointing at the dot. Retract the stop and move the pointer past it. Release the stop. and the pointer should bear lightly against the stop. This sets the proper preload for the pointer spring. Ed [img]http://bullfire.net/TR6/TR6-40/SDC12005a.JPG[/img] Looking at your picture try Ed's method first as it looks like your pointer is not on the 'dots'. As for editing your own posts. Click on the three dots top right of your post and it will give you a drop down menu with edit in there Link to comment Share on other sites More sharing options...
Nick Jones Posted August 29, 2021 Share Posted August 29, 2021 If the odometer is fairly accurate then what Ed says (backed up by others) is the way to go. The ability to edit posts is a donors perk iirc….. Link to comment Share on other sites More sharing options...
Escadrille Ecosse Posted August 29, 2021 Share Posted August 29, 2021 For editing your own post only as screenshot here from my phone Link to comment Share on other sites More sharing options...
Mark Posted August 29, 2021 Author Share Posted August 29, 2021 2 hours ago, Escadrille Ecosse said: Looking at your picture try Ed's method first as it looks like your pointer is not on the 'dots'. That's not my Speedo, that's Eds post. Thanks for all the info, I'll give that a try today. Speedo has to come out again anyway, just discovered no indicators, thought I could see a spare green wire with no home hanging up there . Need some new glasses. Link to comment Share on other sites More sharing options...
Nick Jones Posted August 29, 2021 Share Posted August 29, 2021 4 hours ago, Mark said: Speedo has to come out again anyway I hate fighting with GT6 dash items…. To much stuff in too small an area. Right place and right order both matter and no room for gorilla paws or even medium size hands! Link to comment Share on other sites More sharing options...
Escadrille Ecosse Posted August 29, 2021 Share Posted August 29, 2021 4 hours ago, Mark said: That's not my Speedo, that's Eds post. Sorry Mark, looking at that on my phone without my glasses on Link to comment Share on other sites More sharing options...
ed_h Posted August 29, 2021 Share Posted August 29, 2021 9 hours ago, Nick Jones said: The ability to edit posts is a donors perk iirc….. That appears to be the problem. I subscribe to maybe half a dozen related forums, and am a paid member of the couple that I use the most, but not Sideways. Yet. Ed Link to comment Share on other sites More sharing options...
Mark Posted September 8, 2021 Author Share Posted September 8, 2021 (edited) Managed to have a play with the speedo, but only just been able to get the car up to a range of speeds due a a misfire. Speedo has been in and out three times, and as mentioned earlier, is a b*gger to get to. Gave up using my eyes, and can now remove and replace in under 10 mins by feel. Took a few hours to get sensation back to my fingers, and to be able to sit up straight again . Got the Speedo operating consistently through a range of speeds now where the speedo is reading slightly higher than the actual speed, so no fear of inadvertently speeding, getting caught on camera. First pic show pointer turned back 10 mph. Second pic shows the white spot, pointer stop removed, pointer sitting close to factory setting as in Eds post. Been tweaked a couple more times since, to get more accurate readings Edited September 8, 2021 by Mark 1 Link to comment Share on other sites More sharing options...
Escadrille Ecosse Posted September 8, 2021 Share Posted September 8, 2021 I really do like the dials on the earlier GT6 gauges Link to comment Share on other sites More sharing options...
Hamish Posted September 9, 2021 Share Posted September 9, 2021 (edited) My gran had a 1300 vandam plus that has gauges like that I’m sure lovely classic look with all the warning light in them Edited September 9, 2021 by Hamish Link to comment Share on other sites More sharing options...
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