I recently put a different speedometer in my 1800ES, and it stopped working after about 70 miles. I figured at first that it was probably a bad speedometer, but when I drove home I disconnected the speedo cable to see if it was turning, and it wasn't. Does the BW35 have a plastic speedo drive gear like the later transmissions? Trying to narrow things down before I start taking things apart...

So, here's what I think happened - the speedo was from a junkyard ES, and I think it hadn't moved in a long time. It spun fine when I tested it, but the part that connects to the speedo cable seized after driving for 10 miles or so. I think that it was dry from sitting too long. When I took the speedo out, it was stuck. I used some light machine oil and after a while I got it to spin again, but I don't know if I'd put it back in the car without a lot of testing.

Anyways, when the speedo seized, the cable held strong, so the nylon gear inside the transmission lost its teeth. Incidentally, the transmission speedo gear looks like it's the same between 1972 and 1973 automatic ES cars. I replaced the shredded gear and put in an old spare speedo and everything is working again. Thanks for the tips!

Fran;

If speedo cable is not truning, I'd remove the right angle drive and have a close look at it (if OK, clean and rebuild with Lubriplate)...and if you find nothing obvious to explain Speedo non-function, spin the speedo cable with a drill while a helper watches Speedo above...

Good Hunting!

Yes, nylon drive gear. Probably part #380861 but I don't know the colour or number of teeth. Info wanted on that. It's a bit of a one-off in these cars as I think it's the one with the 3.90 back axle. I stand to be corrected on this.