As usual at this time of year I start thinking about getting the westy trip-worthy. One of the items was getting the speedo and odometer working again.
The van has been without a speedometer and odometer for the last year. I got by using the miles-per-hour gauge on the ScanGauge2. (As I have a Bostig Zetec in my vanagon I can connect the ScanGauge to the OBD port.)
I had diagnosed the issue to be a problem with the speedo drive gear in the front differential: when I spun the speedo cable from the differential end the speedometer moved and when the front wheels were turning the speedo output on the side of the differential was stationary unless I gave it a bit of a twist manually, in which case it would turn about ¾ of a turn and stop again. Seemed like a few teeth were worn off the drive pinion gear.
There is a great thread at https://www.thesamba.com/vw/forum/viewtopic.php?t=482112 so I read that before attempting the job of replacing the drive gear. It was very helpful. I then prepared for the task by getting an inexpensive set of roll-pin punches and purchasing a new speedo drive pinion gear from T3 Technique in the states. (previously this was only available from the UK.)
There is an aluminum ‘sleeve’ held into the side of the front differential housing by a roll pin and as mentioned on that thesamba thread if you ‘extend’ your punch with a socket drive extension (I used an 10”, ½” drive extension and a 10 mm socket which fit perfectly over my roll-pin punch) it is a good set-up to drive the roll pin out.
Once the roll pin was out I used a similar method to the one described on thesamba to remove the aluminum sleeve from the diff housing (but used an old nut and part of a ball bearing as a spacer).
Exactly as I suspected, a few teeth were worn off the plastic pinion gear.
Next step was to make sure the new bronze gear from T3 had the same number of teeth as the old plastic one (they both have 19 teeth – well the plastic one maybe had 16 ½ left but started life with 19)
I then removed the old plastic gear with a hacksaw, cleaned the shaft and new gear with brake-clean, coated the knurls on the shaft with loc-tite 680 and pressed the shaft into the new gear.
According to the loc-tite website, 680 takes 24 hours to cure so I’ll put everything back together tomorrow. Looks like that should be an easy task. What I was most worried about on this job was the roll pin being stuck and possibly damaging the diff case like happened to one of the fellows on thesamba thread.
UPDATE: everything went together nicely and I now have a functional speedometer and odometer. The speedometer is a bit jumpy at low speeds though (below maybe 25 kmph). If I would have had a 10mm reamer I would have reamed out the housing the speedo pinion gear shaft fits into as there was a little resistance to turning there. I may still do that in the future, now I know this all comes apart fairly easily.