JD4300 -- Catastrophic Failure of the Shift Shaft

[Jim_Fisher]

I went ahead and ordered the parts to do the repair -- should be in Wednesday (parts below if interested):

YZ80993 BELL CRANK, RANGE 26.50 F37020111 O-RING 0.85 USD 2.55 USD YZ80859 SHAFT 32.25 YZ80858 LEVER, INT.30.75 F7125020HBK PIN,SPIRAL 1.25 USD 7.50 F21008SC PLUG, EXPANSION 1.65 USD 4.95 USD LVU11633 KNOB, CAP RANGE 9.50 M134678 BASE, SHIFT KNOB 2.65 24M7040 WASHER, METALLIC, ROUND HOLE 0.24 19M7774 SCREW, FLANGED, METRIC 0.41 11M7012 PIN, COTTER 0.15 USD

I ordered the shift shaft to either use as a replacement or as a model for my machine shop.

Hopefully, the procedure will go well and only the rockshaft cover will need to be removed.

Interesting finding while on the phone with the parts person: there has been an improvement to the shift forks for this series of tractors. I am assuming for smoother, safer, less-wearing, more durable shifting of the 3 ranges. I did not order the kit (assuming that the rockshaft cover will take care of my repair), but if I do end up splitting the tractor, I will certainly get that kit . . .

Richard Easley

Richard,


If you end up removing the rockshaft cover, you should probably make sure that you have a hydraulic filter and sufficient fluid on hand to for a complete change as well as a gasket for the housing that holds the suction screen.

Also make sure that you have a good magnet in case you can't catch the roll pin that holds the internal shift lever in place.

While you are under the tractor, make sure that the brake shafts are free. I had a brake hang this weekend and ended up having to loosen the adjustments on both sides and apply some kroil to the shafts to get them to work freely. The tractor was delivered with the brake adjustments a little bit on the tight side and after 1800+ hours of use, they have never needed adjustment. I left them a half turn looser on the turnbuckles in the hope that the extra travel will prevent them from hanging in the future.

 

[reasley]

Richard,


If you end up removing the rockshaft cover, you should probably make sure that you have a hydraulic filter and sufficient fluid on hand to for a complete change as well as a gasket for the housing that holds the suction screen.

Also make sure that you have a good magnet in case you can't catch the roll pin that holds the internal shift lever in place.

While you are under the tractor, make sure that the brake shafts are free. I had a brake hang this weekend and ended up having to loosen the adjustments on both sides and apply some kroil to the shafts to get them to work freely. The tractor was delivered with the brake adjustments a little bit on the tight side and after 1800+ hours of use, they have never needed adjustment. I left them a half turn looser on the turnbuckles in the hope that the extra travel will prevent them from hanging in the future.

Thanks for the reply, Jim -- good tips, all. Interesting what you say about the brakes. My technical experience has been primarily automobiles and it's interesting to see these things happen to a heavier-duty, simpler piece of machinery. Just goes to show that, because of the harsher operating environment (chemicals, grasses, manure, etc.), proper greasing and lubrication becomes even more critical.

Isn't that interesting about the improved fork kit? I'll jump all over that if I have to split the tractor, but I'm not going to split it just for that reason.

I talked to my machine shop friends today and they are going to look at the metal part tomorrow that is broken to determine if they can make a longer-lasting shaft. Also, I don't know what I'm getting in from John Deere -- the older, lever-on-the-outside setup or the newer lever-on-the-inside. If I get the older style as replacement, then I will hope that they can take that shaft, look at the diagrams and the lever, and make a new super-duper hard shaft that enables a reverse hook-up for the lever, making it face the case.

But -- first thing tomorrow, I will attempt the "epoxy-the-shaft-to pull-it-out-far-enough-to-weld" scenario. But -- I doubt that I will get enough of the shaft outside to both lock it in place and then weld an extension to it. But -- I will try!

Any other words of wisdom before I begin surgery appreciated!

Richard Easley

 

[mjncad]

I'm finding this thread quite interesting and I hope to take a look at my shift lever in the next few days.

I forgot to ask Richard earlier if he bought his 4300 new or used. If used, I'm wondering if the previous owner failed to inspect and maintain the tractor. Otherwise I'm wondering if this is a design defect that is covered under a "Fix as Found" recall like the battery leakage problem that caused HST oil coolers to fail. I know all too well about that one.

If it is a design defect, then it brings up a concern I have with all manufacturers introducing new models on a frequent basis as if tractors are like cars subject to styling whims. I'd much rather have the manufacturer take the time to design it right and evolve a tractor over time instead of introducing a new model series every 2 to 4 years just to make the marketing boys happy.

 

[Jim_Fisher]

Thanks for the reply, Jim -- good tips, all. Interesting what you say about the brakes. My technical experience has been primarily automobiles and it's interesting to see these things happen to a heavier-duty, simpler piece of machinery. Just goes to show that, because of the harsher operating environment (chemicals, grasses, manure, etc.), proper greasing and lubrication becomes even more critical.

Isn't that interesting about the improved fork kit? I'll jump all over that if I have to split the tractor, but I'm not going to split it just for that reason.

I talked to my machine shop friends today and they are going to look at the metal part tomorrow that is broken to determine if they can make a longer-lasting shaft. Also, I don't know what I'm getting in from John Deere -- the older, lever-on-the-outside setup or the newer lever-on-the-inside. If I get the older style as replacement, then I will hope that they can take that shaft, look at the diagrams and the lever, and make a new super-duper hard shaft that enables a reverse hook-up for the lever, making it face the case.

But -- first thing tomorrow, I will attempt the "epoxy-the-shaft-to pull-it-out-far-enough-to-weld" scenario. But -- I doubt that I will get enough of the shaft outside to both lock it in place and then weld an extension to it. But -- I will try!

Any other words of wisdom before I begin surgery appreciated!

Richard Easley

Richard,

I doubt that the lever on the inside design was ever put into production. It would require changes to the linkage in order to maintain alignment. I also suspect that there might be a close clearance issue with the linkage and the housing if the design were to be implemented. The photographs in the manual were probably made using an early prototype.

The improved internal shifting design may address the root cause of the problem. Why don't you ask the dealer if there is a TSB (I think that the Deere terminology is DTAC) that describes the problem and solution?

The only words of wisdom that I can offer at this point are to apply a good penetrating lubricant to the shaft where it goes through the case and try your luck with with a magnet prior to attempting the epoxy strategy. It has been my experience that lucky beats smart ten times out of ten.

Good luck with the repair.

 

[reasley]

quote=mjncad]I'm finding this thread quite interesting and I hope to take a look at my shift lever in the next few days.

I forgot to ask Richard earlier if he bought his 4300 new or used. If used, I'm wondering if the previous owner failed to inspect and maintain the tractor. Otherwise I'm wondering if this is a design defect that is covered under a "Fix as Found" recall like the battery leakage problem that caused HST oil coolers to fail. I know all too well about that one.

If it is a design defect, then it brings up a concern I have with all manufacturers introducing new models on a frequent basis as if tractors are like cars subject to styling whims. I'd much rather have the manufacturer take the time to design it right and evolve a tractor over time instead of introducing a new model series every 2 to 4 years just to make the marketing boys happy.[/quote]



Good morning, mjncad (is that really your name? --

When I ordered the parts yesterday morning, the lady who ordered them for me took the initiative on her own to look up any potential warranty stuff. She said that it ran out in 2001. Still (and I did not press it at all with her), JD *should* replace this part as a goodwill gesture because it is clearly a defective design -- the leverage that the shift lever puts on the O-ring grooved area combined with a lack of lubrication of the outside area of the case bore (note: not from faulty maintenance but a design flaw) virtually guarantees that this part will fail at some point in time.

On the new model intros, hey, I'm a marketing guy, so be careful!!!

Speaking of that, check out the latest issue of Fortune magazine -- there's a great article about JD addressing a neglected segment of the market (hobby farmers who are bargain hunters) -- the article describes JD as basically stumbling onto this market in a backwards sort of fashion as opposed to doing market research to determine potentials. Interesting article.

Richard Easley

 

[reasley]

Richard,

I doubt that the lever on the inside design was ever put into production. It would require changes to the linkage in order to maintain alignment. I also suspect that there might be a close clearance issue with the linkage and the housing if the design were to be implemented. The photographs in the manual were probably made using an early prototype.

The improved internal shifting design may address the root cause of the problem. Why don't you ask the dealer if there is a TSB (I think that the Deere terminology is DTAC) that describes the problem and solution?

The only words of wisdom that I can offer at this point are to apply a good penetrating lubricant to the shaft where it goes through the case and try your luck with with a magnet prior to attempting the epoxy strategy. It has been my experience that lucky beats smart ten times out of ten.

Good luck with the repair.

Good morning, Jim --

Thanks again for your thoughts on the repair.

After reflecting on your first paragraph, I think that you are right that the pictures are based on an early prototype because I, too, had wondered about the alignment after looking at it closer night before last. It's a shame they didn't stick with that prototype!

I will check on the DTAC today and post what I find out.

On the last paragraph, BTDT on the pentrating lubricant and magnet -- there's too much spring tension and not enough "grab area" to do much with either the magnet (I had a perfectly-sized very strong one) or a pair of needle nose pliers. Bluntly, I don't expect the epoxy possibility to work because it is basically a butt weld, but with epoxy. If the shaft had a small bore through the middle, one could get a small easy-out and pull it out that way but it doesn't have one. Still, I have to spend 20 minutes trying the "epoxy pull" just to satisfy my curiosity.

Thanks again.

Richard Easley

 

[reasley]

R&R FOLLOW-UP

Early this morning, I took the shift lever with broken shift shaft to my machinist friend. He concurred with me that the O-ring groove, in conjunction with its location, the leverage exerted on it, and the weight of the shift lever all contributed to the breakage of the shaft. He quickly concluded that attempting to weld it would be futile, so I did not bother doing anything but R&R after that.

He is going to take the factory shaft that I should get in tomorrow and make a duplicate out of 4140 stainless for me without the problematic O-ring groove. This, along with the greater strength of the 4140 should solve the breakage problem.

After spending about 15 minutes there, I came home and began removal of the rockshaft cover hoping that this would be sufficient to do the job. Start-to-finish on R&R was, surprisingly, only 1.5 hours, and this included removal of the left fender which enables you to sit on a rolling seat right next to the transaxle case.

It was a great result: there is absolutely no need to split the tractor to replace this shaft. Indeed, the only reason that one would split the tractor relative to replacing this shaft is if you installed the updated shift fork kit which must come out the front. This is somewhat surprising since one of the dealers that I called for an estimate (out of town) said that the tractor must be split to replace the shaft. Either he is referring to installing the shift fork kit at the same time, or, I don稚 want to think of the alternative.

Once the rockshaft cover is off, it is wide open to get to the shaft. I've enclosed some pictures of the area as attachments.

About the shift kit: I had to drain the hydraulic fluid in order to inspect that area, because the oil level is above the shift forks. [Note for discussion in a minute that the shift shaft is well above the oil line.]

I could find no problems whatsoever with the shift forks and I looked hard for problems. No bits of anything in the suction filter area and nothing on the magnetic drain plug except for the normal amount of very, very fine, dark friction material from the 3 pt. arm unit.

I was pleasantly surprised regarding how simple this job was; it requires no special tools and accessibility is great.

I'm certain what I will do about oil seepage from this area w/o the O-ring. The use of an O-ring here is very, very poor design because of all that we have discussed. As mentioned previously, I will probably have the shift lever chamfered and put an O-ring in that will engage the side of the case which will serve the triple advantage of 1) keeping oil from seeping to the outside, 2) removing the weakened area of the shaft and, significantly, it will keep the entire bore lubricated (which the original doesn't) and that will prevent rust (and binding) in that area.

Another thing that I plan on doing is making up some type of locking device for the range shift lever so that I can lock it in "B" should I let someone borrow it. Indeed, the machinist has a Kubota which broke its shift forks a number of years ago. He lets a number of people borrow the tractor, so, after the repair, he literally cut the shift range lever off about 1 from the bottom. He feels the same way that I do about them: They have to be so long to reach the operator, that it is easy for anyone no matter how small to exert way too much leverage on those parts.

Richard Easley

 

[dfkrug]

[Another thing that I plan on doing is making up some type of locking device for the range shift lever so that I can lock it in "B" should I let someone borrow it. Indeed, the machinist has a Kubota which broke its shift forks a number of years ago. He lets a number of people borrow the tractor, so, after the repair, he literally cut the shift range lever off about 1 from the bottom. He feels the same way that I do about them: They have to be so long to reach the operator, that it is easy for anyone no matter how small to exert way too much leverage on those parts.

The rental yard I bought my first tractors from locks out all but the LOW
range on all its tractors. This is due to renter abuse. On the Kubotas,
they hacked off the lever near the gearbox case. On the JDs, they welded
some sheet metal over the slot that the lever went into when shifted.

Interesting thread, Richard. Great you were able to get at that rod without
cracking the tractor.

 

[mjncad]

Good morning, mjncad (is that really your name? --

On the new model intros, hey, I'm a marketing guy, so be careful!!!

Speaking of that, check out the latest issue of Fortune magazine -- there's a great article about JD addressing a neglected segment of the market (hobby farmers who are bargain hunters) -- the article describes JD as basically stumbling onto this market in a backwards sort of fashion as opposed to doing market research to determine potentials. Interesting article.

Richard Easley

MJN are my initials and CAD comes from my former life as a CADD Dweeb for 24-years in the engineering world. Engineering and Marketing...sounds like something out of Dilbert.

I'll have to see if that Fortune article is online. The only paper magazine I subscribe to anymore is Fine Homebuilding.

Matt

 

[Jim_Fisher]

View attachment 100428

View attachment 100429

View attachment 100430R&R FOLLOW-UP

Early this morning, I took the shift lever with broken shift shaft to my machinist friend. He concurred with me that the O-ring groove, in conjunction with its location, the leverage exerted on it, and the weight of the shift lever all contributed to the breakage of the shaft. He quickly concluded that attempting to weld it would be futile, so I did not bother doing anything but R&R after that.

He is going to take the factory shaft that I should get in tomorrow and make a duplicate out of 4140 stainless for me without the problematic O-ring groove. This, along with the greater strength of the 4140 should solve the breakage problem.

After spending about 15 minutes there, I came home and began removal of the rockshaft cover hoping that this would be sufficient to do the job. Start-to-finish on R&R was, surprisingly, only 1.5 hours, and this included removal of the left fender which enables you to sit on a rolling seat right next to the transaxle case.

It was a great result: there is absolutely no need to split the tractor to replace this shaft. Indeed, the only reason that one would split the tractor relative to replacing this shaft is if you installed the updated shift fork kit which must come out the front. This is somewhat surprising since one of the dealers that I called for an estimate (out of town) said that the tractor must be split to replace the shaft. Either he is referring to installing the shift fork kit at the same time, or, I don稚 want to think of the alternative.

Once the rockshaft cover is off, it is wide open to get to the shaft. I've enclosed some pictures of the area as attachments.

About the shift kit: I had to drain the hydraulic fluid in order to inspect that area, because the oil level is above the shift forks. [Note for discussion in a minute that the shift shaft is well above the oil line.]

I could find no problems whatsoever with the shift forks and I looked hard for problems. No bits of anything in the suction filter area and nothing on the magnetic drain plug except for the normal amount of very, very fine, dark friction material from the 3 pt. arm unit.

I was pleasantly surprised regarding how simple this job was; it requires no special tools and accessibility is great.

I'm certain what I will do about oil seepage from this area w/o the O-ring. The use of an O-ring here is very, very poor design because of all that we have discussed. As mentioned previously, I will probably have the shift lever chamfered and put an O-ring in that will engage the side of the case which will serve the triple advantage of 1) keeping oil from seeping to the outside, 2) removing the weakened area of the shaft and, significantly, it will keep the entire bore lubricated (which the original doesn't) and that will prevent rust (and binding) in that area.

Another thing that I plan on doing is making up some type of locking device for the range shift lever so that I can lock it in "B" should I let someone borrow it. Indeed, the machinist has a Kubota which broke its shift forks a number of years ago. He lets a number of people borrow the tractor, so, after the repair, he literally cut the shift range lever off about 1 from the bottom. He feels the same way that I do about them: They have to be so long to reach the operator, that it is easy for anyone no matter how small to exert way too much leverage on those parts.

Richard Easley

Richard,


Can your machinist cut a circular recess in the bell crank (YZ80993) where it contacts the housing? I'm thinking a quad ring that resides in the bell crank and protrudes slightly so that it is in constant contact with the housing. Keeps the oil in and the moisture and dirt out. Since this is a common sump tractor, keeping foreign matter out is quite important.

At one time, Deere offered a rental yard upgrade kit that locked out the C range. I suspect that the purpose was to limit travel speed. On my tractor, the shift between A and B is usually quite easy, It appears that the cogs on the shift collars are always aligned between the low and mid ranges. Shifting between B and C almost always involves a touch to a hydro pedal to bring the collars into alignment and is probably where the most potential for failure occurs. I'm not sure that I'd want the tractor locked in B. If it is doing a job in the B range that really should be done in the A range, there is potential to overload the hydrostatic transmission and build heat. Locking out C, which could be done top side, at the lever mount, would probably be a better choice.

Thanks for taking the time to document the repair. Hopefully, this thread will make all of us more alert for any changes in the way that the range shift operates and any failures can be avoided with a little bit of lubrication.