NM Mk2 Tacho Drive

[oehrick]

Having ferreted my way into into the regulator over the weekend and having no joy at finding why she's not charging normally despite cleaning the contacts and checking D & F wires are continuous from dynamo and not grounding (a crock clip link between Field & charge terminals for a few minites on tickover tops up the battery so I have time to dig through my S1LR spares where I think a spare regulator lurks - have downloaded the Lucas service docs for a chew over) I turned my attention to the dead Tacho drive, having ventured out on the road at last, don't want a speeding ticket

The front end of the bowden case had been taped up to the union so looked there first, I can get the dial needle to twitch by turning the cable, but could feel neither hole for this in the little gearbox unit, nor any sensation of this turning with the engine running, so brought the whole lot back home. I suspect that an old broken cable end remains in the hole but on turning the drive gear by hand it feels a bit graunchy so I'll strip and investigate, it looks as though the bores of both shafts are each capped by a disk crimped into place, can I simply cut back the crimp and tap out the cap or is anything inside spring loaded and just itching to launch ??

Cheers & beers

[Dandy Dave]

I've seen the gears in the drives stripped from there shafts.

[oehrick]

Much better outcome than that Dave I'm pleased to say Stripped it out this afternoon, the plug on the output shaft knocked out easily and the reason for no rotation was that the o/p gearshaft had been pushed towards the plug (big gap) & lost drive, (I wondered if when new the tacho end of this shaft was belled out in its housing after assembly to hold it in place ?? Praps Brian knows) the square in it was worn circular but a little patient work with a needle file on both 'ole and cable end has restored some degree of registration & drive, how much, time will tell, but next time its the 270 bottle!) the main reason seems to be the Bowden casing having been shortened without the cable being shortened by the same amount. the driven gear was worn a bit sharp at the edges and was not positioned mid drive gear so I gently filed the sharp edges off the teeth, skimmed the underside and shimmed out with a couple of shim washers - greased up with some Superlube (watch the UK contingent ask what that is ) and a drop of silicon oil - should see me out and then some !

Fortunately I had a slightly longer cable hanging on a nail with the casing damaged (but forward of where I needed to cut it) and one good termination gland, an abrasive disk soon cut this and after a good clean out of cable (as the gearbox) with diesel and freshly squashed air I looked at the problem of transplanting the original gearbox end ali gland which had a hexagonal crimp to the bowden casing. Turned up a drift to gently open the crimp and the inevitable happened and the old ali split after considering turning up a new one, securing with Loctite or Araldite it dawned on me that the assorter box of gas hose crimps I'd had cheap from ebay had some small ones in it (you know the Jubilee clip replacements with two wings that you close with carpenters pincers with a couple of steel tube 'extenders' being too mean to buy the proper ones ) well tried it and it looks & feels solid, more solid than the adhesive tape you so often used in haste...........

Cordless drill shows the actual tacho to be working over fsd (tip don''t stand them face down for safety or dust & paint flakes fall onto the inside of the glass - no doubt vibration will take care of this in due course), the back of the bezel is rolled over the flange of the can so I will not be removing this for internal attention.

May get a chance to re install tomorrow (still got a new gasket to cut) and if it works OK I can check how close to calibration it is and go back to fault finding the regulator - at least knowing if I'm at the prescribed rev's for testing or not.

[oehrick]

Refitting went without incident and paint flakes apart, the tacho is fully functional again

[Dandy Dave]

Nice. I love it when a plan comes together. Dandy Dave!

[oehrick]

I'm eating what I think you would call 'crow pie' Dave

Tipped some slime in a front tube which has a slow leak (new to me, not tried it before) Instructions say drive for 5 miles - well I hitched the harrows on and had a couple of hours running around, stopped near a 13 amp power supply as I have been meaning to vacuum / blow out a load of sawdust clogging some of the rad core (NO not that mixed with linseed recently put IN the rad stopping the leak!)

On restarting I noticed the tacho had stopped working slackened the gland nuts each end of the cable and restarted it worked again, obviously it had warmed up enough to let the cable / gear drift forward out of mesh again, I'd cut the cover a tad too short - serves me right for gloating about how easy the fix was !

I've some thin wall copper washers which will just fit the spigots and space both ends of the cover off a mm each end and if that doesn't work will have to gently whittle each end of the cable down a bit. I know replacements are relatively cheap but thats not like fixing it for nothing

[Dandy Dave]

Ya can't be a tight wad all the days, or you will never get anywhere or much of anything done worth while. Dandy Dave!

[super6954]

Ya can't be a tight wad all the days, or you will never get anywhere or much of anything done worth while. Dandy Dave!

There is a guy round here they recon is so tight he climbs over gates instead of opening them, so he don't wear the hinges out . I agree some days new is better than fixin, but unless the suppliers have there act together. The Made in the land of not quite right one , may be no better and need shortening to .
Regards Robert

[Dandy Dave]

Ya can't be a tight wad all the days, or you will never get anywhere or much of anything done worth while. Dandy Dave!

There is a guy round here they recon is so tight he climbs over gates instead of opening them, so he don't wear the hinges out .
Regards Robert

LOL. Now that is cheep! My old knees will not help me save the hinges. I bet when he does need to open the gate, he will find the hinges rusted fast. Dandy Dave!