| Author | Message | ||
     Omar M. Shams Prolific User Username: omar Post Number: 187 Registered: 4-2009 |
I removed the speedo from my Ivory Wraith II because the odometer and trip meters stopped working. I have experience of replacing the little brown gear that usually fails. I expected to replace the gear and that would have been the end of that. When I removed the speedo, I noticed that only 3 wires were connected to the teminlas on the back of the speedo. The green wire was taped back and not connected. The car therefore had been working with only 3 of the 4 wire connections made. Any idea why this would have been done? I replaced the speedo after gear removal and recoonected only the 3 wires. To my horror, the repair did not result in the odometer or trip meters working. Obviously something else inside the speedo has failed as well as the brown gear. Before I proceed I need to know which wire goes where and what function test I can do to bench test the speedo. Many thanks | ||
| Joseph P. van Doorn New User Username: joseph65 Post Number: 2 Registered: 5-2011 |
Hi Omar, I've just opened the housing of a speedo and it has only 3 wires connected. The RED wire goes to the + terminal, the green one goes to the A terminal and the blue one goes to the 2 terminal. I have tested the speedo with a low frequency signal generator and found that at about 300 Hz you should have full scale reading (220Km). The green wire "A" is the pulse signal input from the sender on the gearbox. In my case the little brown gear has desintegrated itself and the ham question is... Where to get a spare one? Regards, Joseph | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 2486 Registered: 4-2003 |
Omar, Note that the SSII and your Turbo R have the same rating for the speedo and sender. The pulses per KM are always the same, although some dials of course go to 240 and others to 270km/h. A 270 speedo will be accurate if fitted in place of a 240 and vice versa. The plastic gear on the sender at the transmission is all that varies to suit tyres and final drive ratios. In fact, most speedos for most cars have a common pulse/km rate. The most common cause of your type of issue is the pulse sender. They are repairable,m and I have posted about it several times on this site. Essentially, the PCB becomes corroded. A good clean-up and relaquering will usually solve it. However, I usually fit a new transistor to be sure (PN100). Joseph, do a search on this site for Odometer Gear. You will find this for a start: ................................................ Omar, I repaired one on a Bentley Eight a few years back. I thing that I bought the gears from Palo Alto Speedometer Inc http://www.paspeedo.com/vdo_odometer_gears.htm at the time. However, these sites list our cars too: http://s144451996.onlinehome.us/ http://www.speedometergears.com/ but the test will be whether they sell gears alone. I recall that the gears are colour coded, but the tooth count is all important of course. Jaeger and VDO are both Siemens companies, but I don't know whether they share designe.. RT. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 2487 Registered: 4-2003 |
ps: a peek at the Technical Library will reveal the wiring diagramme for the speedo.  | ||
| Omar M. Shams Prolific User Username: omar Post Number: 231 Registered: 4-2009 |
Dear Joseph and Richard, I struggled to buy the brown gear on its own so I went to a video repair shop (in the old days when people still knew what video machines were) and bought many gears that I have kept in a small drawer at home. I had to buy two different gears and then machine parts off to make an equivalent to the brown gear. The best way would be to simply buy the correct gear. I did at that time find an outfit in the US that repaied the speedos and they had the gear - but they were selling them at $125!!!!! daylight robbery!!! so I made my own. Good luck Omar | ||
| Brian Vogel Frequent User Username: guyslp Post Number: 60 Registered: 6-2009 |
I will be the first to state that I am "gear illiterate" as far as knowing how the parameters for gears are described. I would have to believe that someone here may not be. I find it impossible to believe that these gears aren't available from common gear sources, e.g., smallparts.com gears page, if you can actually determine/describe the gear. Perhaps someone here knows how the necessary parameters for the gear in question are described and can determine whether some "gear vendor" has these for sale. The repair shops have to be getting them somewhere. |
