851 transmission issue

bennevis · Nov 20, 2014

I have an 851 LPG & while using the box blade, I suddenly lost a couple of forward gears. I was in a bad spot & managed to get it into a gear (3rd, I believe) just to get it in a more convenient location. I haven't had time to check it closely, but I do know the PTO worked just fine even after the problem started. I was able to get it into reverse & a couple forward gears, but then that stopped as well. Again, the PTO is wrking fine & the clutch seemed to be working great. I had two other tractors to use, so I finished the day & haven't checked anything yet.

I have all the manuals, but I don't really know where to start checking on this one, could I get some advice from you guys? Thanks!

Soundguy · Nov 21, 2014

I'd be looking at shifter forks

wmonroe · Dec 4, 2014

Any update on your issue?

Soundguy · Dec 6, 2014

I hope he found something simple like a backed off set screw...

bennevis · Dec 7, 2014

Sorry for the delay - I was just able to check the tractor yesterday, but I didn't have time to REALLY check it out. I started the tractor & put it in gear - the issue seems to be AFTER the transmission, I hear a grinding that sounds like it's coming from the hubs. I have a parts tractor, I'm wondering if I should switch the rear end?

strum456 · Dec 7, 2014

bennevis said:
Sorry for the delay - I was just able to check the tractor yesterday, but I didn't have time to REALLY check it out. I started the tractor & put it in gear - the issue seems to be AFTER the transmission, I hear a grinding that sounds like it's coming from the hubs. I have a parts tractor, I'm wondering if I should switch the rear end?

This isn't really making sense. First, it worked in some, but not all gears. Now you think it is the rear end.

You could start by draining the transmission. Take off the top cover, then put the gear shift back on and see if the shift collars all move like they should. If there is nothing wrong, you have not wasted much time, because the trans would need to be drained for the next step anyway.

Next, drain the hydraulic and rear end. Then pull the PTO shaft and see if you can find a pile of ground up parts in the rear end.

Let us know what you find.

Soundguy · Dec 8, 2014

bennevis said:
. I have a parts tractor, I'm wondering if I should switch the rear end?

I'm thinking you need to identify the problem before you start fixing it!

hubs on the 55+ series are pretty robust. not that they can't wear.. but they aren't as bad as the old 47-53 types with spline to spline and axle nuts that loosen allowignthem to wobble, wear and strip.

Axles can break.. but once you get broken axles.. they usually slip no matter what once they shear.. occasionally you get a shorn one to grab and drive.. but it's a self limiting issue very very soon. this would follow true with pinion , pinion couleer and trans output shaft as well.

if it was a loose ring gear it would be all or nothing. eithe rthe bolts fell out / rivits sheared and it won't drive at all.. or it drives fine.

if it was a pinion to ring gear tooth issue, it would drive and clunk, no matter what gear.

again. diagnose it before you fix it!