pinion gear JD 790 faulty??

[egbinor]

I put this on the JD forum and thought afterwards, maybe I should have posted it here. I'm sending pics as well. Neighbors tractor and he says the fwd just quit. He says he never heard any strangs noises ( he's not mechanically inclined). The pinon gear is completly gone and the ring gear and spiders look just fine. No particles in the oil any bigger than a grain of salt. I've worked on hvy trucks for about 35 years and never seen this before. No sign of abuse and no sign of heat or improperr oil. I'm thinking the pinion gear was never hardened properly? 1300 hrs on the tractor. Any have an idea or seen this before or know where I could find a used unit? Thanks in advance! EGBinOR


 

[Mike M]

That happened alot in Kubota's from the late 80's early 90's with front end loaders on them. Hopefully they got better ? I think most chewed up both pieces pretty good though. I worked at a Deere/Kubota dealer back then. Didn't see it in the Deere's of that era.
 

[John B.]

I saw that in a dodge full time four wheel drive on the front axle. The differential was out of oil. The pinion usually always goes first since the teeth mesh more times than the teeth on the ring gear. It only needs to be run low once on oil and it wears the hardness off the outer part of the teeth.
 

[embashaw@q.com]

You could be right... The only thing that puzzles me about that is you would think it would show signs of heat? Thanks for your input. It makes sense regarding the pinion traveling faster and the hardness being concentrated on the outer part of the gear. Are the teeth actually harder on the outer extremeties though? Thanks again EGBinOR