JD4300 -- Catastrophic Failure of the Shift Shaft

[Kyle_in_Tex]

dfkrug, did your shaft fit?

 

[dfkrug]

dfkrug, did your shaft fit?

It is not installed yet, but after Richard's debacle, I miked it and it is
the same. This is one of several design deficiencies that I am not going
to fix. Keep an eye on yours.

 

[Kyle_in_Tex]

Almost forgot, YES Richard, it is HOT...

102 degrees

 

[reasley]

If you want to seal up a solid shaft like Richard has, I think the best way is to slightly chamfer the hole, then use an O-ring around the outside of the shaft, and a O-ring retainer that is bolted to the outside of the block. Not an easy job unless the gearbox is out.

I agree and your reply reminded me to clarify to those following this thread that when a manufacturer designs a product, they are faced with various constraints, not the least of which is the price/quality relationship. They have to provide a product that is 1) attractive to consumers, 2) competitive in the marketplace with others, and 3) returns a reasonable profit. Consequently, all of the things that we, as DIYers find that can be improved, could have certainly been designed into the product but the price point would probably be twice what we would be willing to pay! So, for the most part, improvements that we note in our products have probably already been considered by design engineers. Occasionally, something does slip through, though, and I think that this shat is one of those examples but probably only because of the extreme leverage that the gear lever can provide vis-a-vis the stubby shift lever on the side of the gear case.

I will try to remember to look under my tractor tomorrow and see if the "greasy seal" replacement for the O-ring and groove has prohibited oil leakage.

Richard Easley
China Spring, Texas

 

[passnbyu]

Hi, This is the exact thing that happened to my tractor. Do you have the measurments for the shaft so I can get someone to make me one? I think I'm going to get it made of stainless. Thanks for such an informing thread!!

Thanks Passnbyu

 

[reasley]

Hi, This is the exact thing that happened to my tractor. Do you have the measurments for the shaft so I can get someone to make me one? I think I'm going to get it made of stainless. Thanks for such an informing thread!!

Thanks Passnbyu

No problem. I don't have the measurements, but all you have to do is remove the old shaft (both pieces) and take them to your machine shop and they can easily make one for you.

Just used the tractor tonight -- the new shaft is still working great . . .

Richard Easley
Waco, Texas

 

[dfkrug]

Since this thread is getting resurrected....

My rebuilt 4300 has the OEM shift shaft, but I reduced the detent spring
pressure on the shift fork internally. This makes the shifter handle
move quite easily. A O-ring installed between the bellcrank and the
gearcase keeps water out (without chamfer). So far so good.

But....I just got another 4300 with a broken shifter. There is no way to
do what I did in the first one without taking the whole tractor apart.......

 

[reasley]

Since this thread is getting resurrected....

My rebuilt 4300 has the OEM shift shaft, but I reduced the detent spring
pressure on the shift fork internally. This makes the shifter handle
move quite easily. . .

Thanks for the reply. I don't think that the detent spring pressure is the causal factor for the broken shafts, though. Instead, I think that what causes the "O-ring-groove-weakened-shaft"s to break is *excess* pressure resulting from the incredible leverage that is inherent in the entire shifter "chain." First, the shift lever (to the left of the seat) is *very* long, providing "breaker bar" levels of torque, then this is transferred via linkage to the big "clunk" of metal that is attached to the shift rod lever outside of the case. Combine these things and *any* increased resistance puts undue stress on the inferior shifter shaft. My thinking is that, over time, if someone is trying to shift and the gears are not perfectly aligned, then there is a cumulative effect of this action that eventually results in a broken shaft.

Richard Easley
Waco, Texas

 

[dfkrug]

I think that what causes the "O-ring-groove-weakened-shaft"s to break is *excess* pressure resulting from the incredible leverage that is inherent in the entire shifter "chain."

Oh, I agree, its a bad design. All that leverage, and a weakened shaft.
In my case, the fix was to require lots less force to execute the shift. My
fix only makes sense if you crack the tractor, however. A stronger shaft
is the better fix. I may be doing that for this current tractor, as I am
not going to split it.

That shaft is so easy to break, it happens to lots of units that are not
in rental service, as mine were.

 

[rekees4300]

So far after 10 years the shifter on my 4300 hasn't broken but at times it is difficult to shift. After reading this thread I'm definitely going to limit shifting as well as not try to force it.

 

[mjncad]

So far after 10 years the shifter on my 4300 hasn't broken but at times it is difficult to shift. After reading this thread I'm definitely going to limit shifting as well as not try to force it.

I do the same gentle shifting on my 4200.

 

[kennyd]

So far after 10 years the shifter on my 4300 hasn't broken but at times it is difficult to shift. After reading this thread I'm definitely going to limit shifting as well as not try to force it.

I do the same gentle shifting on my 4200.

Make sure also to keep the area where the shaft enters the tranny lubricated to prevent corrosion...Fluid Film works great!

 

[RoyJackson]

Make sure also to keep the area where the shaft enters the tranny lubricated to prevent corrosion...Fluid Film works great!

I'm really glad this thread was posted (although I'm sorry when anyone's tractor breaks). It's been an eye-opener, no doubt about it.
And, Kenny's suggestion about keeping that area lubed makes a lot of sense, especially for machines that set for extended times (like my 44000 during the winter).
Just I just happen to have a recently purchased can of Fluid Film too!

That shaft is so easy to break, it happens to lots of units that are not
in rental service, as mine were.

I'm not sure why you wrote that, dfkrug. In the 10 years I've been on TBN, I cannot recall any other posts discussing such a failure. Gotta admit, since I didn't have a 4x00 series machine, I did not follow all of those threads.

UPDATE: I just got back from spraying those fittings (on a reverser, you have the range selector and shift lever. Looks like the same fittings). I used Fluid Film (thanks, Kenny!!)
I don't seen a bad design as long as those fittings are lubricated. The levers are long, but springy (looks like .25-.31 wire). That springiness would reduce sudden or undue torque on the fittings going into the case. As long as the fittings are lubricated regularly, I doubt they'll fail, although I'd rather the diameter of the necked down section (where it enters the case) be about an 1/8th larger. If Deere doesn't require lubrication (my manual isn't handy), they should.
So, for all of us owners of 4x00 series tractors...add lubing those fittings to your rouine lubrication. When you're under there greasing the zerks, hit those range/shifting fittings with a spray lube of some sort. You do not have to pull a tire, but you will want one of those small straws on your spray can. Be liberal...

 

[dfkrug]

I'm not sure why you wrote that, dfkrug

This has come up more than just this once on TBN, though I do not
recall how many times. I have heard of this issue thru other sources,
too.

It takes a lot of force to manually rotate the shifter bellcrank with
everything lubed and working as intended. In my rebuild, I operated the
shifter crank numerous times, and it required a wrench to get the leverage
required to overcome the shifter fork detent ball and spring. It is my
opinion that the weakness introduced by the O-ring groove cut into the
shaft is a bad design. Some of the shafts were done this way, and
others used conventional seals that did not require such a groove to
be cut. JD made the wrong choice for the shifter shaft, IMO.

As far as I know, all 10 of the 4300s owned by the rental company that
I got my units from experienced this problem. But that is rental service.

 

[RoyJackson]

This has come up more than just this once on TBN, though I do not recall how many times. I have heard of this issue thru other sources,
too.

It takes a lot of force to manually rotate the shifter bellcrank with
everything lubed and working as intended.

Now, my range and shifter levers move quite easily (even before lubricating).
After this thread, I'll definitely be keeping track of how much force has to be used.

 

[Egon]

The range shift lever moves easily on my JD 4200. If it does bind a touch on the reverse pedal loosens it right up.:thumbsup:

Used hydro oil seems to work as a lubricant for me. I use a spray bottle from a domestic product to apply it.

 

[mfreund]

I have a 4310 so I hopefully do not have this problem. What I do to shift ranges is find the most level ground near me and use the brakes to reduce pressure on the trans. Using the brakes to "unload" the gears works best IMO.

 

[rekees4300]

Using the brakes to "unload" the gears works best IMO.

This weekend did some FEL hauling requiring many shifts. Using the brakes does in fact seem to allow the shift level to operate more easily. Is there a mechanical or electronic connection between the brakes and transmission?

 

[Kyle_in_Tex]

Is there a mechanical or electronic connection between the brakes and transmission?

Not that I know of that would effect the range lever.

Keep the shaft lubed where it goes into the case.

And most importantly, use finesse when changing ranges. Don't force it. And when you loan it to your father in law, make sure he understands this.

 

[jpinca]

I wonder how many of the failures are on hydro units? I think the nature of hydro cause them to put tension on the gear train even without any pedal pressure. Unless the ground is perfectly smooth and the pedal linkage is dead on (no creep), they bind.

Mine shifts smooth as butter without any bind (i.e. engine off), but can bind up pretty tight during operation. A little tap of one or both of the pedals is usually enough to release the bind. Having gone through the effort of repairing the shaft, I pause before trying to force it. If mine were still a rental, I doubt I'd be so gentle.