Johncracknell Posted June 26, 2013 Report Share Posted June 26, 2013 Just tried to check my speedo against a sat nav, now one of these is very wrong, trying to hold a steady 60 indicated on the tr6 tonight the app on my phone was reading 50 !! . So working out a mpg is a waste of time, never going to get a speeding ticket though !. Is there a way of adjusting the speedo- probably not - but that amount of difference makes a large difference to driving style if you want to get on with it a bit. The speedo also oscillates at speed so needs attention soon, probably a winter job. What's the preferred/ best fix and pitfalls of sorting the problem resulting in a reasonably accurate outcome, or anyway within 10% . Thanks John. Quote Link to post Share on other sites
Prefect Posted June 26, 2013 Report Share Posted June 26, 2013 Hi John You are not alone. The speed on my speedo bears no relation to the the GPS speed . Must be due to tyre size me thinks. But my 2013 Beemer is also wrong ! Pete Quote Link to post Share on other sites
AlanT Posted June 26, 2013 Report Share Posted June 26, 2013 I really dont think the manufacturers bothered to get this accurate. They erred on the side of precaution. In the 60's manufacturing just was not about accuracy. No computers, no CAD, nothing digital all analog and approximate. Quote Link to post Share on other sites
Guest ntc Posted June 26, 2013 Report Share Posted June 26, 2013 They did. Send it to JDO do you want points? Quote Link to post Share on other sites
Peter Cobbold Posted June 26, 2013 Report Share Posted June 26, 2013 (edited) Often a diff has been swapped for one with non-original ratio - the speedos were diff-specific, IIRC the ratio's marked on the dial, Or the speedo swapped for one with calibration that does not match the diff. Together with non standard tyre rolling radius and that 20% error is quite possible. Edited June 26, 2013 by Peter Cobbold Quote Link to post Share on other sites
WWT338J Posted June 26, 2013 Report Share Posted June 26, 2013 Lovely photo Pete Where's that? David Quote Link to post Share on other sites
cp25616 Posted June 27, 2013 Report Share Posted June 27, 2013 Looks like Spa Francorchamps too me. Alan Quote Link to post Share on other sites
Steves_TR6 Posted June 27, 2013 Report Share Posted June 27, 2013 I'm with Peter on this, combination of diff and tyre swap somewhere in the mists of time ! I checked my car against the gps and its within 5%. My last TR6 was more like 15% fast on the speedo. Quote Link to post Share on other sites
PaulAA Posted June 27, 2013 Report Share Posted June 27, 2013 I ran mine against the GPS and found, oddly enough, that it erred on the side of incaution - an indicated 50 was, according to the GPS, actually 60, making it 20% slow. I'm running on Coker 185/15s, but I haven't checked the diff to see whether its stock. Paul Quote Link to post Share on other sites
heckler Posted June 27, 2013 Report Share Posted June 27, 2013 If your speedo is oscillating .if you haven't already ,fit a new cable & poss angle drive.That could take all the movement out of the needle.You could then check it more accurately for discrepancy . Chris Quote Link to post Share on other sites
ChrisR-4A Posted June 27, 2013 Report Share Posted June 27, 2013 Hi John, I have a fairly new speedo on my 4A and I get a steady reading, When speedo reads 66 TomTom says true 61, when speedo reads 80 TomTom says 72. When speedo reads 90 wife says ! !* * *? and I get a pain in my left arm! I believe Triumph purposely set Speedos to read fast because if owners tried to go around travelling at a true 80 or 90 there would have been a lot more wrecked TRs. Quote Link to post Share on other sites
Johncracknell Posted June 27, 2013 Author Report Share Posted June 27, 2013 Speedo cable ordered ...... Quote Link to post Share on other sites
Johncracknell Posted June 27, 2013 Author Report Share Posted June 27, 2013 Actually, before I press the BUY button who does the best quality speedo cable, assuming there are different ones available, thanks guys. Quote Link to post Share on other sites
jemgee Posted June 27, 2013 Report Share Posted June 27, 2013 I think if you check a sat nav to a modern car speedo you will find the sat nav about 3mph slower than the car - its happened on every new car since i got the satnav Quote Link to post Share on other sites
Johncracknell Posted June 27, 2013 Author Report Share Posted June 27, 2013 With most cars having exaggerated indicated speeds you do wonder about the claimed Mpg for nearly all the vehicles out there, or to put it in real terms are we all paying 5% or even 20% more for petrol than we think????? COR BLIMEY. Quote Link to post Share on other sites
heckler Posted June 27, 2013 Report Share Posted June 27, 2013 If I remember correctly ,the left hand drive ones are longer & not such a tight fit. Unable to confirm which I bought as am away at moment . Perhaps someone can confirm or otherwise . Chris Quote Link to post Share on other sites
Smeggie Posted June 27, 2013 Report Share Posted June 27, 2013 Both lengths are at Rimmers for surprisingly the same price, last month Cheers Quote Link to post Share on other sites
rossgmattinson Posted January 28, 2016 Report Share Posted January 28, 2016 Does anyone know if there's a mod to turn the cable driven speedo into an electronic one. I have a ´72 TR6 with the older style Smiths gauges. The Speedo quit recently after a short period of bouncing around and then a squeaking noise from the back of the gauge before it rested gently on zero! I was wondering if this is an opportune time to update? Any thoughts anyone? Cheers Quote Link to post Share on other sites
russ55 Posted January 28, 2016 Report Share Posted January 28, 2016 you may find the car is fitted with a saloon gearbox, my car has a 2.5 pi saloon o/d box fitted and the speedo is miles slow, because it is geared for the 13 wheels of the saloon. Quote Link to post Share on other sites
Penfold Posted January 28, 2016 Report Share Posted January 28, 2016 (edited) I had the same problem a while back - oscillating needle and underestimating speed. Changed the cable and drive which actually made the oscillations more wild. In the end, sent the speedo to JDO and now it's rock solid and as accurate as it will ever be. A useful tip - you can check the diff, gearbox, wheels etc all in one go - drive a circuit of 10 miles in a modern car. Drive the same circuit in the TR6 - if it shows 10 miles distance (give or take a couple of tenths), you know the diff etc are all ok. If not, record the modern car and TR6 mileage difference shown (to the nearest tenth) and send the speedo to JDO for speed and odometer calibrating. It'll come back as near to perfect as you'll ever get - www.jdo1.com Edited January 28, 2016 by Penfold Quote Link to post Share on other sites
RogerH Posted January 28, 2016 Report Share Posted January 28, 2016 Hi Ross, they can be converted to electronic but you lose some of the facilties - SpeedyCables This company http://www.digital-speedos.co.uk do an encoder that fits on the gearbox. However you need to invent something for the back of the speedo I've been thinking about this for a couple of years now but have no time t play. Roger Quote Link to post Share on other sites
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