John Deere 14SB Transmission

greenhandApril 26, 2006

Greetings! I have a John Deere 14SB self-propelled mower. The powered rear wheels on the unit will no longer engage and when I pull the mower backwards, both rear wheels lock. As of a couple of days ago, one of the rear wheels locks when it is moving forward also. Quite a workout mowing the lawn this week! I have seen several posts regarding transmission issues on this mower. Are these symptons problem an indication of said transmission issues? Any help is greatly appreciated before I rip into this thing. Thanks!

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I have a JX75 John Deere that is the same as yours. Before suspecting the transmission, the problem may simply be a buildup of dirt and grass around the rear axle, drive gears, and clogs in the rear wheels. The rear axle has a slot at each end into which a spring loaded key fits. The key engages steps inside a gear that in turn drives teeth inside the back wheels. When dirt and grass build up, the key is prevented from going in and out to engage the gear properly.

My first step would be to clean everything within the dust cap of both rear wheels, including the rear wheel, inner gears (made sure you note the left and right side), keys, springs, and axle. Check the dust cap to see that it is not damaged and that it seats in the groove in the wheels. If the keys, springs, or dust cap are worn, replace them.

I have also replaced my transmission, but your problem seems to be dirt buildup.

Good luck. Let me know if you need further help. E-bay always has owners manuals for sale. They are helpful at putting things together.

    Bookmark   April 26, 2006 at 9:12AM
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Thanks for the feedback. I cleaned and oiled today to no avail. I adjusted the traction control according to the manual, but the drive pulley still locks up when I engage the transmission. Belt won't turn and pulley just locks when I pull up on the "engage transmission bar".

    Bookmark   May 2, 2006 at 7:25PM
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Sorry to hear that the simple cleaning of the rear wheels, gears, keys does not fix your problem. I would then take off the black cover over the transmission and manually turn the pulley that the belt drives. Is it frozen? Does the transmission turn? Is the pulley tight on the shaft? Are there any unusual noises? Try putting it in each of the 5 gears to see if any gear is working. My transmission problem was the bearings that held the vertical shaft in place into which the pulley sat. If you took the mower over to a John Deere dealer, they could give you an idea of the extent of the problem. I was lucky to buy a transmission on e-bay. A new transmission is around $150, plus cost to put it in. Again, I hope you get it fixed. Keep me posted.

    Bookmark   May 2, 2006 at 9:20PM
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Hey, thanks again for the help. The pulley turns freely when the belt tension is not tight. When I pull up on the drive bar that tightens the belt and should engage the transmission, the pulley freezes. None of the five gears works, though a couple of them seem to "want" to work. The transmission has lost it's differential capabilities as well, meaning that when the mower is not running or when it is running and the transmission is NOT engaged, the wheels will not rotate properly during a turn. One will turn forward but the other will lock. They only both rotate in straight forward motion. They are both locked when I pull back.

Is the transmission hard to change out or should I have it done?

    Bookmark   May 3, 2006 at 7:19AM
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I would take the mower to a John Deere dealer to confirm that it is the transmission that needs replacing. Then get a price quote to replace the transmission. On my JX75, there is more than one transmission, so your serial number is critical. Whether to have it done or to do it yourself depends on the price quote of the John Deere dealer, the condition of the rest of the mower, and your mechanical ability. Consider also an independent small engine repair shop. Get one who has replaced this transmission. I have seen good used JX75's in the Twin Cities for $325 to $350. Compare that with the price of the repair. It may be that it is only worth it to repair yourself. If you need a repair manual, yet me know, and I can pdf you the applicable pages that will help put things back together.

    Bookmark   May 4, 2006 at 7:47AM
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lawnmowerdan(ne fla)

i would fix it no matter what. i consider these to be the best lawnmower made

    Bookmark   May 4, 2006 at 8:02AM
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Something like this just happened to my JX75. I removed the right rear wheel and found that three bolts that secure the wheel to the large gear inside the wheel had worked loose and were flopping around inside the wheel. One bolt was jammed between the plastic wheel gear and the metal drive gear, keeping it from moving either direction. I put the bolts back in and tightened them well and it works fine now, although the one of the teeth on the wheel gear was nicked. The other wheel was OK.

    Bookmark   May 20, 2006 at 2:18PM
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Ok, sorry to jump in on your thread here but I am having a very similar issue. I was hoping someone could answer a few questions to help me isolate the issue.
1. A complete explanation of how this whole tranny system works would be great :) Regarding what should spin when and how the engagement with the srping loaded key locks work, and why the pinion gear has the three half spiral depressions in it?

2. If that is too much I would settle for some basics such as; How should transmission work? I have all the line bearing and outer axle parts off. The transmission is still in the machine with the axle now able to move around a bit and move freely. Should both axles spin together constantly? Or should they spin in oposite direction more like a limmited slip dif in a car?

My issue was the wheels locking every once in a while in forward and the machine was only spinning one wheel. Also when turning the machine one way both wheels spun freely. When turning the other way the left wheel would lock up and click every half or quarter turn.

Thank you for any help, after reading your previous notes, I am leaning toward that spring loaded key being the issue as it was pretty messed up in there. Just would love more information on it's function and how to trouble shoot it.

Thanks in advance!

    Bookmark   May 21, 2006 at 12:54PM
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The axle, I believe, is one piece. The outer gears on the ends of the axle engage the teeth in the rear wheels, and they do this by the spring loaded key in the axle contacting the steps inside the axle gear. If the springs are weak, if the springs are dirty, if the key is worn, or if parts are dirty and can not move freely, the key will not extend out to contact these steps and drive the wheels. The steps also are necessary for turning, as one wheel can move faster then another by going up the inclines (ramps) and dropping off the steps. When putting the gears back into the axle, be sure the gears are put on the right way. The gears are identical, but must be put on so that the key, when engaging the axle to drive the mower forward, contacts the steps (and stop), rather than the ramps and go over them. I hope this explains a part of the principle of the workings.

    Bookmark   May 21, 2006 at 11:06PM
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Anybody ever try to change the belt. It look like I need to take the engine off of the deck in order to feed the belt through? Quite a project. Anyone else have feedback?

    Bookmark   May 29, 2006 at 8:50AM
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lawnmowerdan(ne fla)

yes you must remove the engine to change the belt but it isnt as hard as it looks.

    Bookmark   May 29, 2006 at 6:27PM
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Hi All! I have a John Deere 14SB self-propelled mower. The powered rear wheels on the unit engage OK when I squeeze the drive handle. However, when I pull the mower backwards, both rear wheels lock. I cleaned the packed grass and debris from around the tranny and drive axle but that did not help. I did notice that a piece of the deck is missing near the tranny. Would that cause the problem? I suspect the wheels lock because the spring loaded keys in the axle aren't working properly. The dealer will not work on the mower because of the piece missing from the deck. Liability issues! Any help is greatly appreciated before I take this thing apart. Please advise. Thanks!

    Bookmark   June 6, 2007 at 11:50AM
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Greetings garyncarol. I have a JA65. If your JD 14SB works like mine the source of your problem is the transmission clutch lever (mine fell off letting dirt and grass into the tranny). This lever engages/disengages a ball clutch inside the tranny. You are locked in the on position. A spring, mine fell off, is supposed to pull it back to the off position. There is an excellent description and graphics in US Patent 4915203 on this. It is a real nugget that I found on the 'net. Parts s/b available at the JD site. Good luck. Your mower is easily fixable but you may have to clean out the tranny if your lever fell off like mine did. Dissasembly can be done but takes time.

    Bookmark   July 16, 2007 at 7:31PM
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I know this is an old thread. But I figured this thing out. Maybe it will help someone before they disassemble wheels and the trans. Its likely a 50-cent spring that is so small it rots and breaks after several years. And this spring is not shown on any of Deere's spec sheets on their website.

There are actually two clutch mechanisms in the JX75. Both are activated when you pull up on the bar. The ratcheting pinion gear in both rear wheels allows you push the mower forward without turning the axle. These pinions must lock when you pull the mower backwards. If they didn't lock that way, they wouldn't be able to convey power to the wheels when you engaged the pulley clutch. So when you pull your mower backwards, you are turning the entire rear axle, including the transmission gears that are mounted on the rear axle. There is also an internal clutch inside the transmission that retracts the drive gears from the axle gears. This allows the axle to spin freely when you pull the mower backwards. If it doesn't disengage, you are trying to turn the entire transmission just to pull your mower backwards. This is likely where your problem is.

Take the plastic belt cover off. Get on the left side of your mower. You will need a flashlight. On the top of the transmission, inward of the left rear wheel, you will notice a small rectangular lever that can be moved just slightly forward and backwards. This is the transmission clutch. The forward position (moved nearest to the motor) in disengage. Rearward is engage. There is no linkage controlling this clutch lever. When you squeeze the bar (like when you are mowing) you will see the belt tighten and engage. Not so obvious is that a metal arm simultaneously strikes this transmission clutch arm and pushes it rearward. When you release the control bar, the belt loosens and this striker arm retracts. The striker arm does not pull the transmission clutch lever to disengage because there is no linkage. The clutch itself must be disengaged by a spring that keeps constant tension on the transmission clutch lever. That spring is so small that it rots and breaks. Without the spring, the trans will engage, but it can't disengage.

Where is the spring? If you look close, you will notice a small hole in the top of the transmission clutch lever. One end of the spring hooks in here. You will see a metal protrusion on the right and left side of the pulley, just outside of the fan belt. It almost looks like a guard or retainer for the belt. The one on the left has a tiny hole in it for the other end of the spring. Feel around. You will likely find remnants of the broken spring hanging from this hole. You can get springs at any auto parts store or just hack and reform one that is close. Very little spring tension is needed to pull this arm.

I hope this helps somebody.
Any questions:

    Bookmark   September 25, 2007 at 1:00PM
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George, your fix worked for me !! Thanks for the detailed explanation, I never would have seen that broken spring without it. Once I re-formed the end of that spring and re-attached it, I could pull my JX75 mower backwards again. You saved me a trip to my John Deere dealer and probably a lot of $$$. Thanks again.

    Bookmark   March 2, 2008 at 9:53AM
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My drive belt has broken (hence "sore arms"). I see from this thread that I have to remove the engine to replace the belt. Can anyone help with some "how to" for this procedure?

    Bookmark   April 26, 2008 at 6:10PM
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I know this is an old thread, but I found it while researching my problem with a 14sb JD lawnmower. It's been great, but age may be taking its toll. I can only pull the starter string when the blade is engaged. It runs, but tieing the blade engage lever defeats the purpose and I'm concerned something else might go wrong. Any ideas out there would be greatly appreciated.

    Bookmark   April 5, 2009 at 12:08AM
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One would assume the clutch would need to be replaced, or maybe you could service it. Could be the bearing is tight. Does it kill the engine when the bail is released?

    Bookmark   April 5, 2009 at 12:40AM
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I have a similar prob with my jx75. It won't come out of the top(5th) gear. The owners manual says to adjust the speed selector cable and pictures a different set-up than my mower. There is no cable tension adjustment on mine. The cable goes directly into the transmission housing and is tight. So now if I mow, I have to push this damned heavy thing or run! Symptoms sound familiar to anyone?

    Bookmark   May 21, 2009 at 6:41PM
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Hello- I have a used, low-hour transmission for the 14SB/SE as well as some other parts available.

    Bookmark   May 18, 2010 at 5:32PM
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may be needing that contact email is . Mine is a jx 75 .Thanks Dave Vuchetich

    Bookmark   May 31, 2010 at 10:50PM
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I have a 14sb my uncle had at a cabin. It sat for years as he had other mowers and a rider. After he passed away I ran it a little and found the Kawasaki was shot. I have disassembled it not wanting to spend a lot on replacing the engine and I saved parts for a JD 14 push mower I have. I think it only had a few hours on it. I have the trans and wheel assy which has a bit of play in the drive pully shaft. It doesn't leak. If someone could use it I'd sell it cheap plus whatever it cost to ship. Denny

    Bookmark   June 2, 2010 at 9:57PM
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I have a 14SB runs good except I some how broke the plastic tab that actuates the blade enngagement,I found the part number but it is for the whole control and not the part I need the part number is AM121395 and seems to be an old number(control is on the right side)so far not able to find,so looking for one that you are parting out and would sell part.

    Bookmark   June 11, 2010 at 3:20PM
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My 14SB drive belt needs replacing. I understand the engine needs removing. Are their any other secrets? Ray

    Bookmark   June 25, 2010 at 3:17PM
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Sorry to chime in too, but I would like some assistance on replacing the drive belt on a 14SB also.

Thank you in advance.

    Bookmark   July 3, 2010 at 5:24PM
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If anyone is interested or is in the need. I have an extra transmission that will fit 14 and JA series push mowers. Everything is intact, wheel drive gears, pulley and shift cable. It works great no problems. I purchased it in error.
Contact me.

    Bookmark   May 27, 2011 at 1:36PM
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Sorry to post to and old thread but ... My problem is that I can not engage the transmission by pulling the bar lever, it just will not go into gear. Any advise?

    Bookmark   September 30, 2011 at 1:30PM
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Best remove the cover so you can see if the belt is turning the transmission pulley.

    Bookmark   September 30, 2011 at 8:57PM
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rmui(ZONE 7 Northeast USA)

I know this is an old thread, but hopefully this information will help someone, just as I've found some old threads here, including this one, have been helpful to me. A few asked about replacing the drive belt. Sorry I don't remember the details now, but a few years ago I did replace the belt of my 1996 14sb mower without removing the engine. It was a tight fit, but after looking at the routing I found a way to squeeze it in without damaging anything.

    Bookmark   May 22, 2013 at 8:59PM
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Wonder which way the spring loaded key goes into the shaft, round side down or up. Fell
out while I was taking it apart and am not sure. this is also the JD14SB. thanks..

    Bookmark   March 17, 2015 at 2:53PM
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