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Author Topic: JD 440A front-differential lock repair  (Read 605 times)

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Offline DGK

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JD 440A front-differential lock repair
« on: August 10, 2016, 11:07:36 am »
Hello all,

I am looking at a 440A that the owner says the front-differential lock does not work. It is always locked. He says that this is apparently a common problem with the old JD's. Does anyone know if this is truly a common issue and whether or not there is a common repair for such. I haven't any other details about what is broken as the owner has lived with it for 12 years and never bothered investigating or trying to repair. I would like to be able to have it work as I would like the easier turning characteristics of an unlocked differential.
Doug
Yukon, Canada

LT40G28 modified to dual pumped hydraulic plus , Bobcat S185, Logosol PH260M3, Sthil MS660's, MS460, MS260, Trailtech dump trailer, F350, F700 Tilt-Deck log/Lumber Hauler, JD440B Skidder

Online snowstorm

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Re: JD 440A front-differential lock repair
« Reply #1 on: August 10, 2016, 07:33:24 pm »
the diff lock works with hydraulic oil. the early  a   it pushed down to engage the later ones it pushed back. the only way it can stay engaged is bypass the valve. and run oil to it all the time. with it locked all the time it will be hard on drive train. or they put a rear in the front. they are locked . yes they will fit

Offline danbuendgen

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Re: JD 440A front-differential lock repair
« Reply #2 on: August 11, 2016, 07:53:57 pm »
the owner has lived with it for 12 years and never bothered investigating or trying to repair.

That would drive me nuts!

If the diff is locked at all times, it would make it very hard to steer the machine. I have never heard of this as a common problem. On the older JDs, there is a foot peddle that locks and unlocks it. It used hydraulic oil to engage and disengage. It could be stuck in the locked position. I would play around with that foot peddle and see if you can't see it that is working properly. You could also simply unhook the hydraulic line to get it to unlock until you can figure it out, if you want the machine that is.

Personally, if you are in the market for a small skidder, I would go with a Timberjack for sure. JD skidders are more tippy and parts are more expensive.
Husqvarna ~ TimberJack ~ Dodge Cummins

Offline DGK

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Re: JD 440A front-differential lock repair
« Reply #3 on: August 11, 2016, 11:46:27 pm »
Thanks for the replies. I'll be giving it a test drive on the weekend. Still trying to figure out why it would be stuck in the locked position.
Doug
Yukon, Canada

LT40G28 modified to dual pumped hydraulic plus , Bobcat S185, Logosol PH260M3, Sthil MS660's, MS460, MS260, Trailtech dump trailer, F350, F700 Tilt-Deck log/Lumber Hauler, JD440B Skidder