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Discussion Starter · #1 ·
I’m new here and new owner of a 420 with 1007 hrs.
To get it to move forward you have to push the lever more than half way to maximum. Then it goes too fast after it starts moving until it starts to climb or needs to pull, then it will stall, you then have to push the lever 100% to make it pull. The engine runs great and never stalls. Reverse behaves normal.
Second, the man I bought it from threw in a 54” blade. The blade came off a 318. My JD dealer says the mounting bracket for my 420 is no longer available.
Any suggestions?
Thanks
David
 

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Did you check the hydro fluid level? There should be a clear vinyl line with a clear plastics sight tube in the back of the tractor on the right side. If the fluid is below the sight tube then add accordingly. Could also be a hydro lever linkage issue. Start with hydro fluid level. Easiest repair to make by simply adding fluid.

Edit: Oh another thing those are 2 speed transmissions. Not sure if this will effect anything but just in case, make sure the speed selector is in either high or low and not floating somewhere in between.
 
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I think you need either a "frame squeezer" or a blade made for the 420, IIRC. The "frame squeezers" are out there, but you'll have to do some searching.

Or if you're handy with fabrication, you could make one. (I cut the front off a 210 frame for such a project, but that's as far as I got). After looking at it, the frame of the 210 is a little thinner than a 140 or a 300/400 series. Not sure how it would hold up with a 420/430 and a 54, depending on what you used it for.
 

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Discussion Starter · #4 ·
I’m new here and new owner of a 420 with 1007 hrs.
To get it to move forward you have to push the lever more than half way to maximum. Then it goes too fast after it starts moving until it starts to climb or needs to pull, then it will stall, you then have to push the lever 100% to make it pull. The engine runs great and never stalls. Reverse behaves normal.
Second, the man I bought it from threw in a 54” blade. The blade came off a 318. My JD dealer says the mounting bracket for my 420 is no longer
Did you check the hydro fluid level? There should be a clear vinyl line with a clear plastics sight tube in the back of the tractor on the right side. If the fluid is below the sight tube then add accordingly. Could also be a hydro lever linkage issue. Start with hydro fluid level. Easiest repair to make by simply adding fluid.

Edit: Oh another thing those are 2 speed transmissions. Not sure if this will effect anything but just in case, make sure the speed selector is in either high or low and not floating somewhere in between.
available.
Any suggestions?
Thanks
David
I think you need either a "frame squeezer" or a blade made for the 420, IIRC. The "frame squeezers" are out there, but you'll have to do some searching.

Or if you're handy with fabrication, you could make one. (I cut the front off a 210 frame for such a project, but that's as far as I got). After looking at it, the frame of the 210 is a little thinner than a 140 or a 300/400 series. Not sure how it would hold up with a 420/430 and a 54, depending on what you used it for.
I replaced the filter and fluid before I
Did you check the hydro fluid level? There should be a clear vinyl line with a clear plastics sight tube in the back of the tractor on the right side. If the fluid is below the sight tube then add accordingly. Could also be a hydro lever linkage issue. Start with hydro fluid level. Easiest repair to make by simply adding fluid.

Edit: Oh another thing those are 2 speed transmissions. Not sure if this will effect anything but just in case, make sure the speed selector is in either high or low and not floating somewhere in between.
l changed the filter and fluid and adjusted the linkage before I asked for help.
Did you check the hydro fluid level? There should be a clear vinyl line with a clear plastics sight tube in the back of the tractor on the right side. If the fluid is below the sight tube then add accordingly. Could also be a hydro lever linkage issue. Start with hydro fluid level. Easiest repair to make by simply adding fluid.

Edit: Oh another thing those are 2 speed transmissions. Not sure if this will effect anything but just in case, make sure the speed selector is in either high or low and not floating somewhere in between.
I changed the filter and fluid and adjusted the linkage before I asked for help. The tractor doesn’t creep when it’s in neutral, I’d there more to the adjustment than that?
 

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I replaced the filter and fluid before I

l changed the filter and fluid and adjusted the linkage before I asked for help.

I changed the filter and fluid and adjusted the linkage before I asked for help. The tractor doesn’t creep when it’s in neutral, I’d there more to the adjustment than that?
Is there any linkage that could be worn? Check the tranny-to-flange bolts and also your crossmember bolt (should only be one going to the tranny). Good luck, and let us know!
 

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If you adjusted the linkage to remove creep from the system, you are familiar with the linkage from the dash tower back to the hydro. With over 1000 hours on your tractor, it is very likely that there is some play in that linkage, maybe a worn bolt, or a hole in a linkage member that has become elongated. It does not take much extra play to cause a problem like you mention. Also, the linkage connection (roll pin) to the round input shaft of the hydro can be loose and something that is easy to overlook.
 

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As I now know, the 420s have several different gyrations of speed control linkages. The engineers couldn't make up their minds as to how to make it work properly. I don't think they ever did. You'll have to determine which you have as they all adjust differently. I would suggest obtaining a service manual. A guy on eBay sells them in a digital format (PDF) for around $10 bucks. You can download it immediately. It will be your best investment. Although I must say the writers weren't all that helpful in explaining this particular issue. Lots of "assemble parts", then they leave it to you to figure out. But there are enough photos and explanations to figure it out. Be patient!
 

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For the blade you will need a frame squeezer or a 420-430 mount like others have said. A 400 mount will work with some mods.
 

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To get it to move forward you have to push the lever more than half way to maximum. Then it goes too fast after it starts moving until it starts to climb or needs to pull, then it will stall, you then have to push the lever 100% to make it pull.
I have a 318 - the linkage on a 420 will be different, but if it includes a dampener ('shock absorber'), check it. The dampener may have weakened to a point where it cannot stabilize the linkage once the hydro is engaged. This would allow the linkage to move, even when all of the nuts n bolts holding it together, are tight.
 

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Discussion Starter · #10 ·
I’m new here and new owner of a 420 with 1007 hrs.
To get it to move forward you have to push the lever more than half way to maximum. Then it goes too fast after it starts moving until it starts to climb or needs to pull, then it will stall, you then have to push the lever 100% to make it pull. The engine runs great and never stalls. Reverse behaves normal.
Second, the man I bought it from threw in a 54” blade. The blade came off a 318. My JD dealer says the mounting bracket for my 420 is no longer available.
Any suggestions?
Thanks
David
As I now know, the 420s have several different gyrations of speed control linkages. The engineers couldn't make up their minds as to how to make it work properly. I don't think they ever did. You'll have to determine which you have as they all adjust differently. I would suggest obtaining a service manual. A guy on eBay sells them in a digital format (PDF) for around $10 bucks. You can download it immediately. It will be your best investment. Although I must say the writers weren't all that helpful in explaining this particular issue. Lots of "assemble parts", then they leave it to you to figure out. But there are enough photos and explanations to figure it out. Be patient!
[/QUOT
As I now know, the 420s have several different gyrations of speed control linkages. The engineers couldn't make up their minds as to how to make it work properly. I don't think they ever did. You'll have to determine which you have as they all adjust differently. I would suggest obtaining a service manual. A guy on eBay sells them in a digital format (PDF) for around $10 bucks. You can download it immediately. It will be your best investment. Although I must say the writers weren't all that helpful in explaining this particular issue. Lots of "assemble parts", then they leave it to you to figure out. But there are enough photos and explanations to figure it out. Be patient!
Thanks, jetjoe,
I said earlier that I had adjusted and changed oil and filter. I also bought hard copies of the owner’s manuals for the tractor, mower deck, and blade. I even bought a hard copy tech manual. I didn’t find the solution or maybe I’m too stupid to understand the tech manual. I was hoping someone on this site might have experienced the same problem and give me the magic answer. I didn’t notice any slack in the linkage, but I’m going to double check every point that moves.
I still have a torch and will cut the pieces to modify the 318 bracket to fit the 420. I will have to go to a welder or machine shop to have it finished. I had to get rid of my welder when I got the pacemaker. I hoped someone on this site might have a better solution or even a salvage part.
Thanks again
David
 

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Did you check the hydro fluid level? There should be a clear vinyl line with a clear plastics sight tube in the back of the tractor on the right side. If the fluid is below the sight tube then add accordingly. Could also be a hydro lever linkage issue. Start with hydro fluid level. Easiest repair to make by simply adding fluid.

Edit: Oh another thing those are 2 speed transmissions. Not sure if this will effect anything but just in case, make sure the speed selector is in either high or low and not floating somewhere in between.
Just an FYI. The two-speed differential is either high, low, or neutral. There is no in-between. If not in high or low the tractor won't move at all. As it happens, I'm right now working on re-assembling this very system on a 420.

Can you ask the previous owner if he/she had done any work on this system recently? If so, check that first.

On some versions of the 420 linkages, there are two holes in the arm that attaches the linkage to the transmission swash plate shaft. (The shaft that controls the speed and direction) If the linkage is attached to the wrong hole, it could cause a condition like this as the control would move much faster than intended.

A possibility I can offer is, the control shaft on the transmission is very sensitive and only moves a few degrees of full travel. From your description, I would look closely at the condition of this transmission control arm. Make sure the roll pin connecting it to the shaft is still in place and not sheared. If the linkage is in good condition, I'm afraid a transmission change may be necessary. The pump/transmission is easy enough to replace, but working on the innards is another story. Best to simply buy another used pump/transmission. There are usually several on eBay for a few hundred bucks.

Unfortunately, the fender pan will have to come off to check all of this. Not that hard, but might seem so the first time you do it.
 

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Discussion Starter · #12 ·
You all have been very generous. When I get back from a two week motorcycle trip I will attack this project. I haven’t been on a ride since the COVID hit. I normally put 10 to 15 thousand miles a year on my bike, but since COVID it’s been in storage. I’m going back to riding, at my age I don’t know how much longer I can hold the damn thing up.
Thanks
David
 
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