2008 JD 5103 4WD not engaging

Auction_regrets · Dec 27, 2022

Hello, looking for advice on a 5103 I purchased used. I picked it up spring of 2022. I have been using the tractor throughout the the year with a Tajfun winch knowing it has an issue with dragging brakes and it spins the PTO even when the lever is not engaged. Also, the diff lock pedal has always been stuck down in what I believe is locked position. Now today the first time using it in snow I realized the 4wd is not engaging. The linkage does not move very far, but down on the transmission there is a sheet metal piece on the end of the shaft that has a pocket that strikes a stationary pin (hits one side of the pocket when disengaged and the other side when in engaged position). It seems the pin serves as a mechanical hard stop to prevent over travel. Was curious if anyone has experience overcoming this issue with this series of tractors?

MTGreen · Dec 27, 2022

I would suggest starting diagnosis by exposing the mfwd driveshaft at both ends by unbolting and collapsing the plastic driveshaft cover. Inspect that the splines/collars/cotter pins on both ends are in place and undamaged, then run the tractor in gear with mfwd lever engaged on 4 jack stands with wheels off the ground.
This will allow you to determine if the problem is in the drop box, driveshaft spline assembly, or the front axle

zzvyb6 · Dec 27, 2022

If you have a loader, put the bucket down level and raise the front axle off the ground so the tires are off the ground. In 2wd, backing up should not turn the front wheels. Now in 4wd, the same procedure should show you the front tires turning, even though they are off the ground.

Auction_regrets · Dec 27, 2022

Thanks MTgreen, I took the plastic guard tubing loose and found the pin in the front collar was missing. The collar was slid back on the shaft and was not linked to the stub coming out of the front axle (pin 5 in attached pic was missing). Only thing holding the shaft up was the plastic guard tube. I also disconnected from the drop box and took the shaft completely out and drove forward a couple feet to verify the back stub shaft out of the drop box spun, and it did. I put it all back together with a new pin to hold the front collar in place. Now tomorrow I’ll find out if previous owner had it disconnected for some reason…. I apperciate the advise.