Thread: Series 3 Speedo

Mine alwys Bounced, New cable and all 8O

Tip for keeping the cable to the back of the speedo , small hose clamp [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img]

Actually it doesn't bounce as much as it did, it just isn't showing the right speed :?

Mine did that as well - then died 8O

As you said the end for the Gbox is different, the input for the speedo drive may be slipping or similar.

Pull the speed drive gear out and check the play with the cable in the shaft.

I never like 4WD their speedo cables. My original one fell apart 8O So i got a better one [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img]

Did you change anything else like the gear? To get a new ratio?

Dave.

That series website for "Sandie" would show what the difference between the speedo reading and actual ground speed a result of. Something to do with the speedo head calibration can't put 109 speedo into 88 as something or other is different inside the speedo head and if it is the reading is slow by this many km/hr.

Goes into great detail about calibration of the speedo.... someone would have the link for it as I've moved it somewhere out of the usual folder otherwise I'd list it.

G'day Phoenix, just a thought, the Series 2 & 2A's (ex-mil) have a code number on the face of the speedo and this code denotes what ratio the speedo is calibrated for re tyres. Do you still have your old dead one, if so check to see if has the same numbers as the current one in use. Another thing you could check on is at the rear of the Transfer case if all else fails and you will need maybe some further advice on this but I was always led to believe that the spacers there were to apply/lighten the pressure on the speedo drive as well as doing other load tension work, if this housing has too many spacers on it it would allow the speedo worm drive to slip on the output shaft anyway thats just a thought cheers Dennis :roll: :wink:

Almost certainly you need to tighten the big nut on the end of the output shaft of the transfer case (need to disconnect the prop shaft to get at it). The worm that drives the speedo gear is only kept to the same speed as the shaft by friction, clamped between the output flange that carries the handbrake drum and the inner race of the rear bearing. A common problem.

THat sounds like it could be it. I've only replaced the speedo cable, not the head unit, so there shouldn't be any incompatibility issues. I didn't do anything but replace the speedo cable, although what you said JDNSW about neeting to tighten things up. there is some slop in the drivetran at the moment, that could solve a couple of niggles. i'll have to have a look when I get the chance :wink:

If there was only just enough friction to drive the worm before you changed the cable, the slightly greater friction from the new cable, or even the slightly different radius of the bends, can cause slipping to start, and once it does, it will get worse as the friction surfaces will be better lubricated and any slight wear will make the situation worse. I have never been able to work out why the tension is lost in the first place. I suppose that what happens is that there is very slight movement on the spline each time you accelerate or decellerate, and this means slight movement of the flange relative to both the nut/washer and the worm, so that a small amount of wear takes place, and relieves the preload. This will have nothing to do with the free play in the transmission. Unless there is a specific fault, it is probably just a collection of small amounts of play that add up to a lot altogether. These are, from the engine back (ignoring the front drive and indirect gears) :-
Clutch plate; clutch plate to input shaft; top gear synchro assembly; synchro assembly to output shaft; t/c input gear onto shaft; tooth clearance on transfer gears; end play on idler gear*; high range dog clutch; output shaft spline; front u-joint*; prop shaft spline*; rear u-joint*; rear diff input flange to pinion spline; tooth play on crown wheel and pinion and differential gears; end play on sun gear thrust washers*; inner end of half axle to sun gear splines; outer end of half axle spline to drive flange*. The points marked * are where fairly large amounts of play are quite likely and should be checked and rectified if overall play is excessive. Note that the effects of slop in the drive line are exacerbated by poor driving or by a dragging handbrake.

Hope this helps