Keith66 Posted January 10, 2018 Report Share Posted January 10, 2018 Hi all Hopefully a quick question. Is it possible for me to test and or calibrate my Tacho? i bought the car non-running and when the tacho was in the car all those years ago it was "stuck" at approx 5500rpm or just at the red. Now going to put it back as part of the dash rebuild and it sits correctly at zero but i don't actually know whether it works or not. I assume i can kind of test it on a drill linked to the cable to see if it works but is do i need to calibrate in any way? Another question as part of my dash rebuild, are the 5 screws that hold to wooden facia to the metal structural dash chrome or black on a Jan 72 car. so i'm assuming build would be late 71, i'm suspecting chrome or some decorative metal finish, but its difficult to tell as the originals are kind of rusty. Cheers Keith Quote Link to post Share on other sites
ed_h Posted January 10, 2018 Report Share Posted January 10, 2018 (edited) Testing for basic function could be pretty simple as you describe, but calibration is a different matter. It is possible, though. Look near the bottom of the page: http://bullfire.net/TR6/TR6-40/TR6-40.html It is for a speedo, but the parts and process are the same. Ed Edited January 10, 2018 by ed_h Quote Link to post Share on other sites
HSM Posted January 11, 2018 Report Share Posted January 11, 2018 Fixing screws for dash are black Harvey S. Maitland Quote Link to post Share on other sites
astontr6 Posted January 11, 2018 Report Share Posted January 11, 2018 Fixing screws for dash are black Harvey S. Maitland They are Chemi. Blacked which is not a very good anti-rust treatment! Bruce. Quote Link to post Share on other sites
Mark69 Posted January 11, 2018 Report Share Posted January 11, 2018 Match the bezels on your clocks. Quote Link to post Share on other sites
Steves_TR6 Posted January 11, 2018 Report Share Posted January 11, 2018 Testing for basic function could be pretty simple as you describe, but calibration is a different matter. It is possible, though. Look near the bottom of the page: http://bullfire.net/TR6/TR6-40/TR6-40.html It is for a speedo, but the parts and process are the same. Ed Interesting ! When i installed the 123ignition tune+, complete with bluetooth based dashboard on a phone, the tacho readings were higher than the old mechanical tacho. For instance 3000 revs in overdrive was just under 90 mph, but with the mew electronic setup its just over 80 I was surprised, as i though the tacho would likely overrread not under. I’m about to rebuild the tacho and conver to electronic, will be interesting to see if the two electronic tachos agree! Steve Quote Link to post Share on other sites
barkerwilliams Posted January 11, 2018 Report Share Posted January 11, 2018 You can buy a cheap electronic tachometer on eBay for about £10. Just temporarily connect the wires to power, ground and coil and compare with your mechanical readings. Then you will know if mechanical tachometer is accurate'ish, it will never be accurate across the rev range but it should be "reasonably" correct. Alan Quote Link to post Share on other sites
colin3511 Posted January 11, 2018 Report Share Posted January 11, 2018 CP should have chrome screws. Quote Link to post Share on other sites
oldtuckunder Posted January 11, 2018 Report Share Posted January 11, 2018 For instance 3000 revs in overdrive was just under 90 mph, but with the mew electronic setup its just over 80 I was surprised, as i though the tacho would likely overrread not under. I’m about to rebuild the tacho and conver to electronic, will be interesting to see if the two electronic tachos agree! Given there is no direct connection between the spinning head and the needle, 40+ years of gunk on the needle spindle etc could well retard the mechanical needle swing. In my experience the mechanical Tacho's all over read a bit, just to match the over reading Speedo's. As regarding the two electronic tachos agreeing, they probably will as some point, but not everywhere. The pure electronic one you have will (should have) a sweep hand mechanism calibrated to the dial (unless its digital in which case unless proved incorrect assume correct). The conversion probably won't, they are sort of there/thereabouts but you will normally find that they either read about right down at the idle end (which apparently most people prefer) but are out at the high end, or vice versa. Personally with a conversion I don't worry about how accurate it is at idle, makes very little difference if its a few hundred rpm out, but I do want it accurate at the top end where under reading by 500+ rpm can mean straying into danger territory without knowing. The professional electronic conversion of my Vitesse one is unfortunately neither fish nor fowl, it over reads at idle (which I don't mind) but despite me requesting top end accurate rather than bottom, it actually under reads at the top end, I suspect probably because I didn't specify that top end meant 6.5 - 7K not around the 5.5K mark. Didn't discover this until fitting the data logger and discovered that I was regularly exceeding my desired max rpm by around 350 rpm. Alan Quote Link to post Share on other sites
Keith66 Posted January 17, 2018 Author Report Share Posted January 17, 2018 Hi All, OK so the tacho does work, well via the drill terst anyway, but is a bit jumpy and sticks, so i'm suspecting a drive cable problem, either worn out or just old and dirty. So the question is should it have a "lock" bit on both ends stopping the inner cable coming out or should it be like mine and the inner cable just comes out. If the latter and the cable should just slide out thinking of cleaning and lubing it and if its smooth in operation seeing what happens. Well going to do that anyway but just wanted some thoughts. Cheers Keith Quote Link to post Share on other sites
Mike C Posted January 17, 2018 Report Share Posted January 17, 2018 The inner cable comes out for lubrication. Don't over lubricate - I lubricated my cable and tacho internals last year an after an hour's fast running the tacho started reading 50-100% high. I suspect there is excess lubricant in the mechanism-another job on my list for next winter. Tacho cable lubing instructions are in the Brown Bible if you have a copy. Quote Link to post Share on other sites
Keith66 Posted January 17, 2018 Author Report Share Posted January 17, 2018 Mike, My thoughts as well, i'll clean it and give it a go with some WD40 alike stuff and see how it goes. I have a bible but its with the car and not me. Cheers Keith Quote Link to post Share on other sites
RogerH Posted January 17, 2018 Report Share Posted January 17, 2018 Hi Keith, rather than use a wet lubricant why not go for a Graphite or Teflon type. As for WD40 - the less said the better. Roger Quote Link to post Share on other sites
Mike C Posted January 17, 2018 Report Share Posted January 17, 2018 From memory I used either silicon or lithium lubricant spray to lubricate inside the tacho. It obviously upset something in the watch like internals. I had it out and apart to remove the blue light bulb covers in an attempt to get better illumination at night. Quote Link to post Share on other sites
Keith66 Posted March 6, 2018 Author Report Share Posted March 6, 2018 Hi All Thanks for the replies. Got some graphite lubricant powder for the cable, no better, then tried turning just the tacho with no cable and it still sticks on around 2.5-3k, so looked up the instrument refurb on Ed's site, mega useful as usual and i think i've dentified the problem. Ed's flat return spring, (i asssume thats what it is) in the mech behind the dial in one of his pics is nice and flat and circular, mine, err looks like a birds nest, so bad. On the assumption that i can't get a spring, can't get the pointer off (would hate to break it) i may have to send it off for refurb, unless someone can elighten me on those two points. Any reommendations on getting that done? I've contacted a few specialist instrument refurbers and so far Speedy looks V good but expensive, at around £80 but plus VAT and carriage. Richbrook is slightly less, but incl VAT and Carriage so works out at about £35 less and JDO is around £110. So any feed back on work done by these guys as i've no expereince of any of them or any alternatives in the Midlands, thus saving the risks and costs of carriage. Cosmetically the tacho is fine so it should be a simple refurb and calibration (hopefully!!) but I'm happy to pay the right amount for a good job rather than just cheap but clearly don't want to pay much more than i need too as there are always more new TR6 bits needed. Cheers Keith Quote Link to post Share on other sites
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