Front Axle Slipping/4WD Slipping - Nortrac 254

[5030]

Looks like the ring gear suffered some damage from the broken parts too.

 

[430488]

No. Luckily nothing else got chewed up. I think what you are seeing in the photo is the lock retainers that go around the 4 of the 6 bolts that got sheared off. They are just thin metal but are mangled pretty good.

In searching all the posts this I didn't see any other references to the broken ring gear bolts. Lots of posts on broken axle shafts and drive shaft connections. I guess I am the lucky one!

 

[430488]

Here is a few more photos

 

[budvoss]

Good info here
thanks

 

[5030]

In your first pictures I can see damage on the ring gear on the edge of one tooth. You do realize that you'll have to reset the 'coast and drag' on the ring gear and pinion again right?

 

[430488]

Yeah. I guess there is a little bit. I figured it would be fine for a 14 year old low use, low speed tractor.

I would definitely welcome any insight on on resetting the ring gear and pinion. I marked the the big collars on the sides before I “unscrewed” them but I am not sure that will be close enough. Are there any specs I can follow?

 

[piper184]

Very good info. Thanks for posting the follow ups. You are adding to the public knowledge base.

Good to hear that taking the axle out was that easy. I was looking at mine the other day and wondering if it would be easier to do that or drain the coolant and pop the radiator off to get to the top of the axle. Your solution is the one to use.

It is curious why the bolts would shear. With the locks installed it seems unlikely that they came loose first. Perhaps they were improperly torqued in the first place or just not of good quality.

My operators manual actually has quite a lot of service manual information in it. Take a look at the second document found here: Harnerfarm Jinma 284 The front axle stuff starts about page 30. Hopefully it will help. The hardness grade of the metric bolts should be the number stamped on the head. 8.8 or 10.8 or some such number. You should be good to go with the same number if from a good quality source or perhaps jump up to the next hardness. Get or make new lock straps. I don't think using a thread locker is a bad idea either. Lots of vehicle service manuals call for new bolts in situations like this, simply because the new bolts come with thread locker already installed. (also they like to sell bolts)

I don't think any minor gear damage at the edge of a tooth will cause you any problems as long as it doesn't make contact with the gear it runs against.

Best of luck in the re-assembly

 

[Bob Rooks]

I'm going to go with improper torquing. Too tight = bolt stretch = weakens = reduced diameter X mass X velocity (slip) of ring gear on carrier. And then add shock loading (clutch popping) into the equation.

 

[430488]

All likely causes..... does anyone know the general torque specs of an M8 x 25MM 10.9 bolt?

After looking at the diagrams I also realized there are only four bolts holding the ring gear on. The other two are actually pins. One pin is longer than the other. I assume I can figure out which one goes where when I reassemble it.

 

[ptsg]

All likely causes..... does anyone know the general torque specs of an M8 x 25MM 10.9 bolt?

After looking at the diagrams I also realized there are only four bolts holding the ring gear on. The other two are actually pins. One pin is longer than the other. I assume I can figure out which one goes where when I reassemble it.