Z421KW 54" Drive disengage not working

MBoyle

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Equipment
Kubota L3301, with LA525 bucket, an 5' Land Pride Bush Hog
May 5, 2025
7
1
3
Alabama
Hey I've got a 2017 Z421 and the right drive tow lever moves freely but will not disengage the HST drive. Anyone know why?
 

Mowbizz

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Equipment
Bx25d
Aug 19, 2021
634
358
63
New Hampshire
Do you mean the “bars” that you push forward to go and pull back for reverse?
never heard them called “tow levers”?
Also do you mean the mower will not go into “neutral” when the bars are in the neutral position?
 

Mowbizz

Well-known member

Equipment
Bx25d
Aug 19, 2021
634
358
63
New Hampshire
Hey I've got a 2017 Z421 and the right drive tow lever moves freely but will not disengage the HST drive. Anyone know why?
Oh wait! Now I know what you mean! The lever in the rear to push or tow the mower…I have a Z422 and I’ve never figured this out either!
Waiting for answers
 

Mowbizz

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Bx25d
Aug 19, 2021
634
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New Hampshire
Who the heck has an owner’s manual??🤣
Guess that “right hand lever” was hiding in a totally different place…no wonder I couldn’t find it!😜
 
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MBoyle

New member

Equipment
Kubota L3301, with LA525 bucket, an 5' Land Pride Bush Hog
May 5, 2025
7
1
3
Alabama
Do you mean the “bars” that you push forward to go and pull back for reverse?
never heard them called “tow levers”?
Also do you mean the mower will not go into “neutral” when the bars are in the neutral position?
No,
Do you mean the “bars” that you push forward to go and pull back for reverse?
never heard them called “tow levers”?
Also do you mean the mower will not go into “neutral” when the bars are in the neutral position?
No, those are the motion control levers, I'm talking about two, small rods, located behind the seat in the engine area. They disengage the HST so the mower can be safely towed. Both of them are moving when I pull them, but only the left one works.
 
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MBoyle

New member

Equipment
Kubota L3301, with LA525 bucket, an 5' Land Pride Bush Hog
May 5, 2025
7
1
3
Alabama
The diagrams I posted are from Kubota Illustrated Parts (K-Pad) for the Z421KW.
Take a picture of what you do have and post if you can so we can see what's what.
i see the cotter pin now that I pulled the tire, the linkage is intact, it turns a square shaft on top of the HST. Looks like the problem is inside the HST.
 

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Bee-Positive

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Equipment
BX1880, Cab, FEL, Tooth Bar, MMM, QH, Ballast Box
Nov 16, 2022
1,180
1,088
113
Amsterdam, NY
i see the cotter pin now that I pulled the tire, the linkage is intact, it turns a square shaft on top of the HST. Looks like the problem is inside the HST.
Put a mark on the lever and shaft, move the lever and see if the shaft moves also. Do this on both the right and left sides.


Lever.jpeg
 

Mowbizz

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Equipment
Bx25d
Aug 19, 2021
634
358
63
New Hampshire
Lousy setup! On My cheapo (well not so cheapo anymore) Craftsman T210 that I bought for my daughter, that function works perfectly! Go figure!🤔
 

Bee-Positive

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Equipment
BX1880, Cab, FEL, Tooth Bar, MMM, QH, Ballast Box
Nov 16, 2022
1,180
1,088
113
Amsterdam, NY
The shaft is definitely turning.
THE shaft is definitely turning or BOTH shafts, left and right, are definitely turning?

If both are rotating with absolutely no play then it's above my pay grade. I've never worked on the HST and defer to those with deeper knowledge of the system. Sorry I can't be more helpful.
 

MBoyle

New member

Equipment
Kubota L3301, with LA525 bucket, an 5' Land Pride Bush Hog
May 5, 2025
7
1
3
Alabama
THE shaft is definitely turning or BOTH shafts, left and right, are definitely turning?

If both are rotating with absolutely no play then it's above my pay grade. I've never worked on the HST and defer to those with deeper knowledge of the system. Sorry I can't be more helpful.
Yes, both shafts turn when their individual levers are moved. Not sure why the left (working) tow switch matters what the right one is doing. Are they linked somehow? Sorry if I'm being dense, but aside from brakes and one horrible hydraulic clutch on an '89 Datsun, I've no experience with hydraulics.
 

Bee-Positive

Well-known member

Equipment
BX1880, Cab, FEL, Tooth Bar, MMM, QH, Ballast Box
Nov 16, 2022
1,180
1,088
113
Amsterdam, NY
The instructions state you should stand at the rear of the tractor and first pull the LEFT side lever and push it down to the by-pass position thus holding it in place. Then pull the RIGHT side lever and hold it (no locking position) while you move the tractor.

To me - BOTH must be used at the same time to free up the transmission. Each side must lock into the transmission, so if you only unlock one side the other will still be locked and it won't budge.

As I said above if you are "unlocking" both sides properly and it still won't roll I have no other ideas since I've never taken one apart.
 
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Mowbizz

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Equipment
Bx25d
Aug 19, 2021
634
358
63
New Hampshire
The instructions state you should stand at the rear of the tractor and first pull the LEFT side lever and push it down to the by-pass position thus holding it in place. Then pull the RIGHT side lever and hold it (no locking position) while you move the tractor.

To me - BOTH must be used at the same time to free up the transmission. Each side must lock into the transmission, so if you only unlock one side the other will still be locked and it won't budge.

As I said above if you are "unlocking" both sides properly and it still won't roll I have no other ideas since I've never taken one apart.
That’s the way I understood it…have to hold the “right one” standing behind the mower while the other side is pulled out…🤔