Hey guys,
in my XB I have a single rail from an XF, and speedo guts also from an XF - installed them about a year ago and no dramas up until a few days ago. Speedo started to randomly drop then go back to speed, then just got worse and worse.. now it doesn't work 95% of the time... as you decelerate you occasionally see it blip up but the second you accelerate again it goes back to zero. I've had a quick look at the wiring (I did the wiring, not factory setup) , tried jiggling the wiring while driving slowly to see if it makes a difference, but nope. So....its either the speedo's slowly gone bad or the speed sensor in the gearbox.

From the symptoms I've given, what are your thoughts? The fact that it shows signs of life on deceleration makes me think it might be the sensor itself....any ideas much appreciated! I don't want to go get another speedo only to see its not actually the problem...

sounds like the transducer on the gearbox which should be the same part as e-series.

Ah, OK - anyone have any idea if they are the same between an auto box and a single rail manual/ (I'm just thinking I'll grab one from U pull it to see but you don't come across many manual anything these days....)

the auto ones fit and work correctly in my t5 so yes.

Cheers, thanks for that, i'll grab one.

The first to go is the little cog on the cable end or transducer. (XB run a cable) Look for chipped spline/teeth or a flat spot in the middle. Usually this indicates that the helical gear on the output shaft is also failing.
First replace the little cog & see how you go. If internal one is wearing it will again fail shortly. If it doesn't well and good but I suspect you will be replacing it too soon. With the cable/transducer out stick your finger in a feel across the top of the output shaft gear, it should be level. If it is hollow or dips in the middle, then there's your problem. Brace the gearbox at roughly normal height making sure the car is level. (Hoist or ramps & stands etc.) With it braced take the crossmember off, undo the gearshift (Lower slightly if need be to do from underneath but then return to level) then take the rear housing off. Fairly sure with it level it shouldn't leak oil. You will see the helical gear is held on by just one clip, depress it (Push down towards shaft) then slip the gear off. Instal new or good SH one in the reverse. I wont bet my life on it but I am reasonably sure all single rail, toploader, borg-warner autos & the E series autos all use the same gear & cog set ups just the number of teeth on the cog will alter the reading of the speedo. Less teeth faster reading, more teeth slower reading.

thanks for that mate, you're correct in that I replaced the small gear and it failed within about a day. (this was with an XF box and transducer - I know XB's are normally cable but mine has XF box and speedo guts)

Anyway, I ended up going the easy way out - bought a GPS unit that gives digital or analogue speedo display, speed limits, all camera's (fixed speed, school, red light etc) as well as the normal map type stuff of course - under 100 bucks.

the intermittent fluctuations described = failing transducer, i have replaced 4 of these usually after car trailer work and getting the gearbox a bit too warm, my cogs were all fine and if another transducer is obtained 2nd hand cheap or free then it's a 5 minute job.

I am pretty sure I have a manual cog in mine and you would not run a tranducer in an XB as it is cable drive to the speedo. It does sound like a worn gear (the one on the output shaft of the gearbox) or your speedo cable has melted on your extractors!

as stated in the first post he used xf box and speedo setup, i know that all falcons before xd were cable but since he has converted to electronic the symptoms scream failing transducer, only solution to replace it with one from an xf-ed possibly ef onwards too but can't confirm from personal experience.

I thought that was a misprint as that would be way more effort than is required In that case swap what I said about speedo and add "Replace Transducer" &"check the wiring that went along with the mod just incase it was a poor cut & shut job". I have heaps of spare transducers if required!

XF and EA are the same up to Early EB I think, but I believe transducer changes from either 91 or 92 up until end of EL at least.

Nigel