Well folks, still struggling with this. I picked up another used cluster today. It looks better in that it only has 197,000 kms on it versus my 281,000 kms. The speedometer and tachometer needles don't fall at all or just a mm maybe when the cluster is held inverted. BUT, this one's tachometer only goes to 5000 with a 4000 redline versus mine which is 6000 with no redline. Also, this new one's speedometer only goes to 160 km/h (100 mph) where mine is 180 km/h.
So, a couple of questions - what year/model would that be out of and would the speedometer/tachometer motors be the same "S" motors like mine has? If this cluster's speedometer is accurate I'll try swapping the motor over to my speedometer.
Thanks you,
Glenn
UPDATE:
Well, I tried that cluster. With a redline starting at 4000 and only going to 5000, I suspect it is out of a diesel, even though the gas gauge doesn't say Diesel Fuel Only. The speedometer is about 6 or 7 km/h high at 80-90 km/h and maybe 8 km/h high at 100 km/h.
Today I moved the speedometer motor over from the replacement cluster to my original. The speed error is the same as I noted with that cluster which means the fault is with my original motor and not the electrics in the cluster itself. The error with the lower mileage motor is: dead accurate up to 55 km/h, reads 63 km/r at actual 60, reads 75 km/h at 70, 86 at 80. In other words, my old one was 25-30% high at speeds up to 40-50 km/h and 17.5% high at 100 km/h. This one's maximum error is 7 or 8%.
Now, here's where it gets interesting. Both the speedometer and tachometer are "S" motors with the speedometer marked "S 1F" and the tachometer marked "S 1E". Apparently these motors can be interchanged. I think this might be a great idea because the tachometer spends most of its life at a needle position less than half of the speedometer needle position, relatively speaking. This could mean the tachometer motor works less than half as hard as the speedometer motor. It's always the speedometer that reads high, never the tach.
I tried this today and I really think it will work. Someday I may try it. The only thing that needs to be done is to trim off two little plastic locating tabs (about 2mm each) so the tach motor can be put in the speedometer location.
Cheers,
Glenn