GTV6 Speedo

[Fylnn]

Folks,

I have managed to bring back to life my temperature gauge, my fuel level gauge, oil pressure gauge and with the help of an MSD tach adaptor I now have the Veglia tacho running off the Haltech.  It just looks that much better in Italian.  Which just leaves the speedo as not working.  I believe they were always a bit dodgy and the back of it has had the wiring jury rigged already, but I am not sure if it is the tacho or the sender that is causing the problem.

Has anybody got a method of how to test the sender for the speedo or that the speedo itself works?  I am building it as a PRC rally car, so my options are to get the old speedo working, fit a VDO speedo that will work off the Terratrip sender or does anyone having known working parts they want to sell?  It is a 1983 GTV6.

Thanks

[colcol]

If the GTV speedo is like the 33, and it may be as they are from the same era, then if there are 3 wires running out of the sensor \ pickup in the gearbox, on the 33 there is a red and white wire, put an ohm meter across them and you get about 4 ohms or so!, if no ohms then usually the sensor is dead, try getting a good second hand sensor for comparison, also the connectors are always a bit dodgy to say the most, between the sensor and the speedo, some auto electricians hard wire the speedo eliminating any plugs and connectors, i have always had a 'control' sensor that i know works, so when the speedo konks out i put in the working sensor in to see where the problem is, [sometimes the FRENCH made sendor!], Colin.

[Fylnn]

Thank you for this.  I have had a look at my sender and it is a 2 wire device, and when I check it, it has infinite resistance, which I suspect is not a great sign. 

I might try and jack it up at the weekend and spin the gearbox to see if it is like an on-off sensor.  I might have stopped it now in a off position

[colcol]

And if the GTV sendor is like the 33 sendor it will have a 'chopper' plate in it that looks like a gear, and sometimes they dislodge and come loose, the one on mine was loose and use to stay tight and the speedo worked ok when the gearbox was cold, when the oil warmed up the 'chopper' would loosen off on the output shaft and not spin at the same speed of the output shaft causing the speedo to tell me my speed was very slow when the gearbox was hot, but ok when the gearbox was cold, you gotta love Alfa's!

[MD]

FyInn,

I have had a lot to do with these speedo heads and solutions for them none of which I want to get into now. Take it from me, if you want a functional speedo with contemporary and more universal approaches, fit a VDO (or other)and get the Terratrip to provide the signal. In the end it will be the least drama and more readily replaced if it becomes defective.

[Fylnn]

MD,

Reluctantly I think you are right.  VDO works out at about $350 which is steep but I suppose you got to have one.  I am sure I can spend almost as much trying to coax the old one to work.

[Mat Francis]

I am sure I can spend almost as much trying to coax the old one to work.

And even then, it is still unlikely to be accurate. Make use of technology!

[MD]

Magnet Marelli are the parent company for the Veglia instruments and they are the biggest pricks on the planet. Doesn't matter how old their circuits are, they will not divulge them. So if you cannot buy a new instrument because it is out of production, stiff.

Some time ago  I used to make signal converters for these speedo heads but if I was to make you one today using good VDO gear, you wouldn't get any change out of your $350 and you would still have your old speedo head (for better or worse)

Info for what it's worth..

[shane wescott]

mine requires the occassional "tap" to get it going someimtes but apart from that works fine.

Mine is always a consistent 5klms BELOW the speed shown on the TomTom.

If it's original and if you could find someone with a GTV6 with the dash in bits you could always plug yours in and see if it sensors or speedo.

But I would have to go with the general opinion, fit a newy which will work and work well, but make sure you keep the original in the event you do sell the car down the track.

Catch ya

Shane

[colcol]

I went thru the speedo drama years ago, i had a speedo man fit new needles to my 33 speedo that had warped in the sun and he hadn't quite lined them up properly, so luckily the local council had 'SPEED KILLS', signs and a portable 'what speed are you doing now' speed readout, so i drove up and down the road repositioning the speedo needle until i got it to read the same speed council supplied speed readout, years later when i got a GPS i found that at low speed my speedo was quite accurate, but at 100kph, it was reading about 5 kph slow, but this could be due to worn \ new tyres that have a different rolling diameter and affect the speedo reading, tapping the top of the speedo to wake it up, tell me about it! i used to tap it and it would start working, hit a bump and it would stop working, so after a while the taps would become Mohamid Ali vs George Forman punches, so clearly a fix had to be found, what auto electricians seem to do is 'hard wire' the speedo eliminating the plug which has a history of poor connections, and also it hasn't got 12 volts to push the current through the dodgy plug as they sometimes run as low as 5 volts, so the auto electricians run the wires directly into the speedo, and this solution mostly works, Colin.

[shane wescott]

Cool Mate.

So part of the rebuild I was planning was a very ambitious removal of the dash and rewire. I know one of the club members in Adelaide has rewired a number of GTV6's and is a bit of an expert.

Yes learning where to tap and why has been a learning experience with the GTV6. I also have a "tap" issue with my dash lights, but this is more of a controlled thump.

Years of Martial Arts training has taught me how to turn on dash lights in a GTV6, not as quick as Bruce Lee, but sometimes it's all about brute force :-)

[MD]

If any electrical instrument needs a tap, smack, punch, kick and the occasional stick of TNT to make it work it is because it has:-

A circuit board dry joint
A cracked circuit on the board
A loose connection to the circuit board
A loose fitting fuse on the board

None of these things will   fix it in the long term and by doing the above can result in the problem getting worse like needle bearing movements getting knackered in the process.