Dana 20 speedo gear, plastic vs steel

[iwlbcnu]

Any preference? I have two that seem to be tight enough but the speedo drops out after 20 miles, I'm down to trying to swapping rear output assemblies for now and have both steel and plastic.

 

[Viperwolf1]

The plastic one is pretty durable. You should check the tooth count on both and match the one you're using now. I have a steel gear with 6 teeth and a plastic one with 7. A change from one to the other will give you a 17% error to your current speedo/odo readings. To count the teeth look at the end of the gear and count the starting edges of each tooth. You can do this with the gear installed if you mark one of the gear edges then slow count as you rotate the shaft.

 

[DUSTINS74]

make sure the plastic gear on the output shaft is not slipping, that is what happened to mine.

 

[Viperwolf1]

The plastic gear has a steel center section so it doesn't get crushed with the bearing pre-load. The pre-load prevents it from spinning. If your gear spins you have a problem with the pre-load.

 

[iwlbcnu]

That's my problem, both are factory set, I tighted as tight as I could get and either have run out of threads on the shaft, or no more space and they both still spin. What i really don't get is the one that was working fine, the flange was loose so no preload at all. I have 2 more untouched cases and have pulled one output from them to try. I need to read up on resetting the shims.

 

[Viperwolf1]

There are shims to correct the endplay/preload. Just tightening the yoke won't do it.

 

[KyleQ]

Hrm - my stocker broken shaft was plastic, and the replacement I installed was steel... I don't even remember if the spedo worked after I took it for a test drive

 

[iwlbcnu]

There are shims to correct the endplay/preload. Just tightening the yoke won't do it.

Well, it theory, endplay/preload was set at the factory and "shouldn't" need adjustment, and with the flange nuts backing off on occasion, tightening could be a solution. But yes it looks like I get to play with 13 pain in the asses.

 

[KyleQ]

My spedo works - so I did something correct

 

[dougyounger]

So is there a correct or recommended method of installing the shims? (Such as how many shims or on which side of the gear do the shims go?)

Does adjusting the shims move the speedo gear on the output shaft forward and back slightly in addition to putting pressure on the gear so that it doesn't turn?

My speedo doesn't work and it sounds like this may alleviate the problem.

 

[Viperwolf1]

So is there a correct or recommended method of installing the shims? (Such as how many shims or on which side of the gear do the shims go?)

Does adjusting the shims move the speedo gear on the output shaft forward and back slightly in addition to putting pressure on the gear so that it doesn't turn?

My speedo doesn't work and it sounds like this may alleviate the problem.

The procedure is included in the rebuild manual. The shims go between the gear and the rear bearing so it doesn't move the gear forward or back.

 

[iwlbcnu]

I pulled apart a broken one I had sitting around, the plastic gear is epoxied to a metal bushing, so if your yoke is tight and you can spin the gear in the case by hand it is broken.
Gonna try reshimming the one in the truck tomorrow I hope.

 

[iwlbcnu]

in conclusion, the two that were dropping out had just a knurled spacer and the gears were all the way to the rear of the bushing, they weren't loose when cold, and no signs of movement, but the two I put back in were epoxied in the center of the bushing. So I'll see what happens after some miles get on them.