790

[rjp444us]

Has anyone besides me broke the spur gears in the front wheel drive on this tractor please let me kno this is my second set one on one side now the other side gears not hardened.....I for got the rockwell hardening number will post when I rember...

 

[RoyJackson]

Did I read your post correctly? You had a set of spur gears break twice on the same side? Or, once on both sides?

If it's twice on the same side, you might want to look elsewhere for what is putting undue stress on the front wheel assist. The chances of getting a replacement gear sharing the same failure mode is extremely unlikely, if production related.

Now, if it's the other side breaking this time...both gears probably came out of the same lot...perhaps were machined as a matched set.

Can you give us a bit more clarification, please?

 

[creeper]

I dont like hearing stories like that.what is going on ?

 

[rjp444us]

Ok now that it is back together and back to work I can explain
The second day I owned the tractor there was a clunk in the front end while pulling bushes. long story short covered under warranty this was the left side by the way.
now 2.5 years later was working last Saturday moving about 25 to 30 yards of dirt when I herd that sound again stopped the tractor right there loded it on the trailer and took it to the shop and pulled it apart to find the same as last time on the right side this time.

The axel spur gear popped a tooth and that went into the rest of the gears and wiped them out

Ok 450.00 dollars later it is fixed

After inspecting and mauling it over with the metallurgist at work ( I work at a research facility with these capability) the find was.

You know I should charge for this info but I have learned to much from these pages.

The gears are to hard 60 plus Rockwell and the oil is to light I have replaced the hydro oil which was in the front end with 90 wt oil

Result front end is very quit and don't know why but it goes in and out of 4wheel easier

 

[tpike35]

Does not the front end come with 80w 90 grear oil in it ? The specifications of the John Deere operator's manual (OMLVU14371 G3) on page 80 recommended lubricants are stated at 80w 90 gear oil /forums/images/graemlins/confused.gif Guess I better take a closer look at mine /forums/images/graemlins/crazy.gif Thanks for the heads up /forums/images/graemlins/cool.gif

 

[Conservative1]

I just dropped my 790 off at the dealer for this same problem. The first time I did it (last winter), I didn't know what I had done to break it. It was covered under warranty. This time, I was dragging a downed tree trunk in reverse, in a field, in 4wd, when I heard a clunk. I stopped, unhooked everything, and took it very slowly to the shop to get her out of the weather.
The front wheel locks up if I try to move her- it took 10 minutes to load it on my trailer.

I have a good dealer, who will make a little money on this repair. I'm glad he will- he's been very helpful thus far, and I don't begrudge him making money.

I'm disappointed that I did it again (right side first time, left side this time) and disappointed that this machine won't drag much weight in reverse, but what the heck... I'll pay, and call it stupid tax.
Seems the front end on the 790 just can't take much torque. I'll just hook to the drawbar to pull forward from now on.
C1