Resolving a Inconsistent Differential Lock Pedal on a 455
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Thread: Resolving a Inconsistent Differential Lock Pedal on a 455

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    SulleyBear's Avatar
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    Resolving a Inconsistent Differential Lock Pedal on a 455

    Hope those of you who have ever had issues with your differential lock pedal find this helpful.

    I Spent Saturday disassembling my 455 because of a differential lock pedal which I would bump and accidentally engage and it was causing the rear differential lock to engage occasionally, even when I didn't want it to. After rebuilding my rear differential unit this summer with new seals, gaskets, etc. (no bearings or hard parts required) and reinstalling it in the tractor, I would encounter sporadic times when the rear differential pedal would be engaging the differential. So, not having time to bother with it during the mowing season, I simply unhooked the pedal rod from the pivot bracket mounted on the rear case by removing the spacer #16 and cotter pin #15 shown in the lower illustration. While this disabled the Differential Lock, during the summer I didn't miss it as I rarely use it.

    I knew I would need to address this before winter but just kept putting it off because I knew this was going to be a small project. In order to get to this particular assembly, you must remove the tractor rear fender platform assembly with seat, remove the fuel tank and re position all of the fuel lines and rear wiring harness as well as removing the rock shaft cylinder, rear pivot assembly and some other components (rear weight brackets, etc) to really be able to get in between the inner frame rail and the drivers side of the rear differential.

    I was concerned that perhaps I had bent either the bracket shown at the spacer numbered #16 in the lower illustration I have attached. On the upper illustration, the bracket is the one held on by bolt #12 and has a 90 degree bend. But once I got in there, another bracket, which pivots on a pin on top of the bracket held in by bolt #12 which serves as a rear and forward stop for the rod movement, which is part of the entire rear assembly looked like it was functioning normally. My tractor uses the solid, non adjustable rod shown as 13b below.

    Most of the linkage components are tucked up inside of the C shaped frame rail on the drivers side of the tractor and difficult to see in it's entirety. For those of you who have worked on these tractors, you know precisely what I am talking about. Not wanting to drop the entire rear end assembly out of the tractor as I did when I rebuilt it, I did the best I could to see the various components in an area which is busy with lots of other lines, brackets, hydraulic hoses, driveshaft, brake components not to mention the drive pedal linkages, etc. on the opposite frame rail.

    The spring shown in the lower illustration as #9 on the front pivot shaft is actually designed to create pressure on the pivot rod and it puts downward pressure on the pedal giving it a consistent feel when you push the Differential Lock Pedal instead of simply up and down. The pivot bushing shown as #10 and #11 in the lower illustration were both knocked out of position due to wearing their retaining lips off over time. I replaced both of those bushings, which restored some "smoothness" to the pedal but still appeared that it did nothing to resolve the issue. Once I had the long rod #13b removed, I checked it so see if it cleared all of the things which it runs through, over and around and the rod was not hanging up on any of the other parts nor were they any rub marks where it was making contact.

    Turns out that when I reinstalled the entire rear differential assembly this summer, apparently the bracket shown in the upper illustration held on by bolt #12 and the flat "L" shaped bracket which pivots on the pin retained by washer #3 and spring clip #2 in the upper illustration had been slightly bent downward on the rear of the bracket (perhaps while jacking the complete rear axle and differential assembly in place). I removed the bracket and straightened it in a vice and reinstalled it (very limited work area between frame and rear assembly) but I couldn't tell if this would entirely resolve the front of the pivot bracket from engaging the shaft on the rear differential which causes the locking to occur.

    I don't recall how much clearance there was before between the end of the pivot bracket and the shaft engaging mechanism in the rear assembly. It appears that the front of the pivot bracket actually rides on the end of the Differential locking shaft inside of the rear end making contact at all times, just not enough to engage the differential.

    Not wanting to have to disassemble this again for this issue, Instead of a simple cotter pin or a spring clip, I installed a round spring loaded clip (like a small key chain ) through the end of the rod #13b and attached a pull spring which has a solid loop through the retaining round spring clip. This way, the new spring I added can't fall off the retaining clip and the long rod can't come unhooked. Then I made a 90 degree bracket which is mounted through one of the rear cover assembly bolts and created a spring pull on the activation rod #13b towards the rear of the tractor. This causes the differential pedal, #5 in the lower illustration, to fully return to it's maximum upright position through the pedal floor board.

    The result is a much firmer and consistent Differential lock Pedal which cleanly engages and disengages as it should. Now the pedal has a nice feel when pushed and it releases to unlock the differential fully. I reassembled everything and tried the tractor in snow plowing situations and it worked great. Over the years, I have found it was easy to "bump" the differential locking pedal when just re-positioning my size 14 feet and occasionally engaging the differential lock even when I didn't intend to. Now the pedal has a nice firm push required and releases to a full upright position. The pedal is actually higher than it was by about 1" to 1.5" or more so "bumping it" when simply shifting my feet should be less of an issue.

    It appears the problem is resolved and the pedal actually functions better than when new.

    Looking at the lower illustration, I am wondering if John Deere actually accomplished the rear spring pressure with the revised rod with the clevis pin and internal spring, which they are showing in 13a on the lower linkage illustration. It appears that the later built tractors use the rear differential lock pedal rod with the clevis and internal spring, perhaps to achieve the same result as I did with the rear pulling spring, to provide that pressure which releases the rod fully. Otherwise, It's not clear why they would have used that style rod shown. Depending upon the tractors serial number either the differential rods shown in the lower illustration as 13a or 13b are used.



    Last edited by SulleyBear; 01-11-2016 at 11:41 AM. Reason: Added content

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    techie1961's Avatar
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    That's good of you Sulleybear for putting that to a thread. I had a similar issue with my 455 but it was something different. When I picked up the tractor from its PO, the back end would kick and buck when going around corners due the diff lock being stuck on. I checked the linkage that you mentioned and determined the issue was with it and not an internal transmission problem since when I disconnected it like you did, the problem went away.

    What mine ended up being was a stuck bushing on the brake pedal cross shaft. It was seized under the foot pan on the right side where it passes through the frame. I don't use the brake and didn't notice that it was seized since the bushing was a D shaped piece and there was enough slop in the frame rail that it still moved. It just wouldn't come up high enough and the way these are built, the diff lock comes on when you push the brake pedal.




    Lorne
    My century barn redo

    1999 John Deere 455 AWS
    1997 John Deere 455 AWS
    2001 John Deere 445 AWS
    1994 John Deere 425 (Sold)
    60" mower, 60" mower, 60" mower with JD Mulch Kit, 54" Mower, MC519 and Powerflow, 47" Snow Blower, 54" blade with bucket add-on (Plucket), 54" blade, 54" blade, 51" Broom, and garden cart
    John Deere 314 Sold
    Grew up with a John Deere 140 and all the goodies

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    I done a rebuild the same as you did, I didn't think it was that difficult to uninstall or reinstall. When I 1st look at the project; I thought it was the only way to do it by removing the trans axle assembly. I'm glad that you found a great improvement. Its my favorite things to read about in here.
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    Seems like a good fix Sulley. Does your diff lock still engage when the parking brake is engaged? The diff lock pedal should go down when the park brake is set.
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    Quote Originally Posted by techie1961 View Post
    That's good of you Sulleybear for putting that to a thread. I had a similar issue with my 455 but it was something different. When I picked up the tractor from its PO, the back end would kick and buck when going around corners due the diff lock being stuck on. I checked the linkage that you mentioned and determined the issue was with it and not an internal transmission problem since when I disconnected it like you did, the problem went away.

    What mine ended up being was a stuck bushing on the brake pedal cross shaft. It was seized under the foot pan on the right side where it passes through the frame. I don't use the brake and didn't notice that it was seized since the bushing was a D shaped piece and there was enough slop in the frame rail that it still moved. It just wouldn't come up high enough and the way these are built, the diff lock comes on when you push the brake pedal.
    Techie 1961,
    When I posted this, I was HOPING you would see it and comment on it as I know you also have extensive personal experience with the 445 / 455, not to mention that you own a whole herd of them.

    I checked my brake linkage as well and it is actually surprising how busy that tractor is under the center section with all of the components which run between the frame rails. I use my brake religiously when I get off the tractor to keep it running and my brakes have always functioned extremely well.

    I didn't take any pictures of this project as #1, I totally forgot, #2, I was wearing 2 pairs of surgeons gloves and #3, I still forgot. But I think it would be hard to differentiate between all of the various lines, rods and linkage under there in a picture so I chose to instead post the parts pictorials, which depict it's layout. After all, everything is black paint and it is surrounded by tall black frame rails and the hefty black rear end assembly. And of course, this summer when I had it all apart, I power washed everything really well and then I painted everything black again.

    Techie 1961, do you happen to know if any of your tractors use the differential lock rod with the clevis and spring setup shown as 13a in the parts diagram I posted? At first I thought maybe they were doing that revised design to make the rod adjustable but in looking at the pictures, I am not sure it really has any adjustment to it. Instead I am wondering if there goal was to put the spring pressure so there isn't always contact between the pivot bracket and the differential rod which is inside of the transmission that actually locks the rear when the pedal is pushed.

    Thanks for adding your information about the brake bearings. All of this information just helps those of us with these tractors should we encounter the need to work on these issues as they arise.

    By the way, your shop project is very impressive and you have done an incredible job. You have used that classic barn in a way which is ideal as you maintained the classic appearance from the outside but certainly have a wonderful modern shop to work from. Congratulations on a job extremely well done!
    Last edited by SulleyBear; 01-11-2016 at 06:35 PM. Reason: repair damage I caused with too much editing
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    Quote Originally Posted by xcopterdoc View Post
    Seems like a good fix Sulley. Does your diff lock still engage when the parking brake is engaged? The diff lock pedal should go down when the park brake is set.
    Sure does, functions just like brand new. In the end, all I did was create a system to provide back pull on the pedal to provide just a slight clearance on the Differential pivot bracket but the added benefit was getting the pedal up higher so I could minimize hitting it with my giant clod hopper feet. Some of the pedal height was restored by replacing the bushing which had worn on the cross pivot bar I mentioned in the posting. How much came from the new bushings and how much from the spring I am not sure as I just measured the total finished project.

    We are supposed to get 6" to 9" more of snow tonight and snow for the next several days so I will surely get to try it out some more. One of the driveways I plow for an older couple rises 10' in elevation from the road in only 50 feet of length so it is a serious grade and I always park on the grade and lock the brakes to run my hand held salt spreader on their driveway and entrance area. Of course their driveway is on the center of the curve in the road as well making it even tougher.

    It held like a champ this morning just like it always has. I have to push all of the snow UP this driveway as there is no place to pile it at the bottom without blocking the mailbox or fire hydrant so I always push all of the snow up the drive and at the top of the hill, the drive turns 120 degrees left. I pile all of the snow at 90 degrees to the right. It is a rough one to plow and nearly impossible for a pick up because of the design. My tractor does a great job and it allows me to pile snow out of the way.

    I don't like to use the blower on this driveway as the house is J shaped around the driveway and the neighbors house and driveway are in close proximity on both sides so there isn't a lot of places to throw the snow without irritating one of the neighbors.
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    xcopterdoc's Avatar
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    Nice job!

    Sent from my XT1080 using Tapatalk
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    techie1961's Avatar
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    Quote Originally Posted by SulleyBear View Post

    By the way, your shop project is very impressive and you have done an incredible job. You have used that classic barn in a way which is ideal as you maintained the classic appearance from the outside but certainly have a wonderful modern shop to work from. Congratulations on a job extremely well done!
    Thanks SulleyBear! Much appreciated.

    I'll have a look at the underpinnings once it warms up a bit. That part of the shop is a bit cold right now. Remind me if I forget.
    Lorne
    My century barn redo

    1999 John Deere 455 AWS
    1997 John Deere 455 AWS
    2001 John Deere 445 AWS
    1994 John Deere 425 (Sold)
    60" mower, 60" mower, 60" mower with JD Mulch Kit, 54" Mower, MC519 and Powerflow, 47" Snow Blower, 54" blade with bucket add-on (Plucket), 54" blade, 54" blade, 51" Broom, and garden cart
    John Deere 314 Sold
    Grew up with a John Deere 140 and all the goodies

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    SulleyBear (01-13-2016)

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