During my test drive of rebuilt trans the speedometer stopped working after 10+ miles...couple questions:

If trans is still in car and normal fluid level, will DexIII pour out when I pop the speedo gear housing out? If so, how much? Can I jack rearend higher than the front to avoid?

I put in a new 41 tooth gear when I installed in the car, maybe it stripped? I hope the mating gear on the tailshaft is ok. If not, can the tailshaft gear be replaced with transmission in the car?

Trying to figure out what parts need replaced before 500 mile filter/fluid change and get them ordered.

(BTW, I know its one or both of the two plastic gears because I put a cordless drill on my cable and speedometer gauge worked fine. I can also grab the end of the 41 tooth gear and it spins freely with trans in park, albeit a little "rough" in some spots)

 

Some will come out, yes. I wouldn't describe it as "pour" though.

Yes that will help.

As far as the gears, what gear tooth count did you take out?

 

I took out a 41 tooth purple and replaced it with a new 41 tooth plus new seal. The shaft and seal were worn out and leaking.

 

I thought you were talking about the drive gear, which would definitely leak from the tailshaft, but you're talking about the driven gear. Only a little bit dribbles out of there.
What gear ratio is in the rearend?...

 

The rear has 3.73 gears. The speedometer housing also has a right angle adapter with a .833 reduction. The speedometer was calibrated correctly before transmission swap. Before I put the replacement trans in the car the builder swapped the drive gear from my core and then I replaced the driven gear with a duplicate. I saved the old driven gear. I may put it back in with new seal and see if it leaks. That’s assuming the drive gear looks fine.

Old driven gear

Right angle adapter

 

Mystery solved! Hopefully just an inferior aftermarket part or manufacturing defect. Guess I will put the old one back in and see if the new seal holds. There were some grooves worn in the old shaft. Drive gear on tail shaft looked fine thru 360 degree of rotation. BTW, I jacked the rear up about 3-4 degrees over the front and barely any fluid was lost.

 

A brand new gear snapping makes me think you may have a bind of the speedo, cable, or adapter. Any electric drill can overcome friction that can kill a speedo gear. I didn't see you post tire size, but if a ratio adapter can be eliminated, it's usually a good thing.

 

If the car has cruise, I'd also suspect the regulator.

 

I put the old gear back in and its working so far. Will see if it leaks or breaks...

I know the right angle adapter is smooth as silk, not sure about cable or Autometer speedo gauge but I understand your point regarding the cordless drill.

Can't remember the tire size but if I changed the driven gear to eliminate the right angle adapter I would also have to replace the cable as it would not be long enough. Car does not have cruise.