2020 Brakes

[WangoTango]

I'm pretty sure I know where this is headed, but thought I'd get other opinions first. The left brake on my 2020 requires several pumps before it has any braking action. I plugged the LH port at the brake valve and it was rock solid. I swapped the lines left to right, and the problem went to the RH brake (so the problem stayed with the wheel). I swapped the brake lines back to the way they should be. I bled the LH brake and it works fine for a little while. However after letting it set for only a few minutes, it will get spongy again and require bleeding. If I let it set overnight it takes about 7-8 pumps before I get all the air out. If it's only a few minutes it takes maybe 1 pump. All signs seem to point to the problem being in the disk, which will involve pulling the wheel/final drive assembly. I'm hoping someone has another idea to try first. I'm really not looking forward to doing that. When you press both pedals at the same time the brake seems to work better. I know the equalizing valve can cause this problem sometimes, but since the brake gets solid when plugging the port it makes me think the problem lies elsewhere? Thanks in advance.

 

[Tx Jim]

Sounds typical for rear axle brake piston seals(R50703 & R50704) are leaking. One needs to R&R rear axle housing to R&R seals, https://partscatalog.deere.com/jdrc/sidebyside/equipment/60191/referrer/navigation/pgId/231915

 

[WangoTango]

Thanks. I was hoping it wouldn't come to that. Does that suck as much as it looks like it does?

 

[Tx Jim]

You're welcome. R&R of rear axle housing/brake piston isn't very difficult if one has good mechanical abilities.

 

[Jim.ME]

Thanks. I was hoping it wouldn't come to that. Does that suck as much as it looks like it does?

It is certainly not as bad as some jobs. The worst part will be handling the tires and axle housing, and how bad that is depends on what you have for a shop or lifting equipment. Beware you may find you need brake discs as well as seals when you get in there. Check the transmission sump screen when you drain the transmission. If it has a bunch of fibrous material on it that is likely brake material.

The 2020 Service Manual (SM2072) has a good write up on removing the final drives from the transmission and another on the brake system.

Be safe, use good blocking.

 

[WTW]

I'm pretty sure I know where this is headed, but thought I'd get other opinions first. The left brake on my 2020 requires several pumps before it has any braking action. I plugged the LH port at the brake valve and it was rock solid. I swapped the lines left to right, and the problem went to the RH brake (so the problem stayed with the wheel). I swapped the brake lines back to the way they should be. I bled the LH brake and it works fine for a little while. However after letting it set for only a few minutes, it will get spongy again and require bleeding. If I let it set overnight it takes about 7-8 pumps before I get all the air out. If it's only a few minutes it takes maybe 1 pump. All signs seem to point to the problem being in the disk, which will involve pulling the wheel/final drive assembly. I'm hoping someone has another idea to try first. I'm really not looking forward to doing that. When you press both pedals at the same time the brake seems to work better. I know the equalizing valve can cause this problem sometimes, but since the brake gets solid when plugging the port it makes me think the problem lies elsewhere? Thanks in advance.

If pedal does not settle once you get it pumped up / brake applied and hold it, it not likely piston seals are leaking rather the brake disk is warped like a dinner plate, which will return brake piston too far back into piston bore when setting. Think of the warped disk being like a big bevel spring. To get brake applied after warped disk returns piston too deep, you have to pump brake to flatten disk before you can pinch it to apply brake. Problem is too much piston travel. Pretty common on tractors that have been run with frozen pedals.

 

[Fixingfarmer]

If you have or can borrow a forklift it’s not a bad job at all. It all lines up pretty easy going together with some rotation and a bit of wiggling. Even a cherry picker will do in a pinch but you have to be more careful or get a spreader bar. 4 longer bolts thread them in finger tight only to align it than rotate and push it will slide in nice when lined up. It’s easiest to do without the tire on but I have seen it done as one with a 2 trolley overhead hoist it worked pretty slick but I’ve only seen one of those bridge cranes with the double trolley. The last one I pulled the weight and the tire and rim off left the inside hub as something to keep the forks on since you won’t want to move it anyway then a block of wood 6x6 I think under the axle on the front of the fork tipped back aways worked great.

 

[WangoTango]

I got the wheel and axle off without much of an issue. The brake linings were broken it at least 4 pieces. It looks like now the brake disk and linings come as one part instead of 2 like in the manual? When I pulled the axle, the pressure plate and disk fell to the floor so I'm not sure of the order they were in. I think the pressure plate sits on the sealing ring, and then the splined disk/lining assembly sits on top of that? I was somewhat surprised that the pressure plate-to-disk contact point is metal on metal? Then the linings press on the tractor side of the final drive mating surface for stopping power? Is that correct? It's not quite what I expected to see I guess.

 

[Fixingfarmer]

Based on where you piston is in that picture you should be able to stack them in that order that should be a left axle right is opposite. I’m curious why there’s more holes in the disk perhaps someone else with a 2020 can chime in is that the right parts diagram? I don’t see a serial number breakdown. I also don’t see a number for all of the parts in the stack like a drawn box usually shows?

 

[wore out]

I got the wheel and axle off without much of an issue. The brake linings were broken it at least 4 pieces. It looks like now the brake disk and linings come as one part instead of 2 like in the manual? When I pulled the axle, the pressure plate and disk fell to the floor so I'm not sure of the order they were in. I think the pressure plate sits on the sealing ring, and then the splined disk/lining assembly sits on top of that? I was somewhat surprised that the pressure plate-to-disk contact point is metal on metal? Then the linings press on the tractor side of the final drive mating surface for stopping power? Is that correct? It's not quite what I expected to see I guess.

"I was somewhat surprised that the pressure plate-to-disk contact point is metal on metal?"

Disc should have linings on both sides, IIRC, so NO metal-to-metal.

 

[WangoTango]

I didn't see any evidence of linings on both sides. There has definitely been metal to metal between the piston and one side of the disk. I guess I'll get a whole new disk assembly and see what it looks like when it shows up.

 

[Jim.ME]

I didn't see any evidence of linings on both sides. There has definitely been metal to metal between the piston and one side of the disk. I guess I'll get a whole new disk assembly and see what it looks like when it shows up.

It should have linings on both sides of the disc. Lined brake disc goes next to the differential housing, pressure plate on the axle side.

Not to be a downer but you might want to consider doing the other side as well, given the condition of this one.

The broken-up lining can plug the suction screen in the transmission so you will want to clean that if you haven't. If screen that plugs you will see reduced, if not complete loss of hydraulics.

Tx Jim or someone may have a better answer on the parts, however I think it is because all the parts in that box have been substituted, if you read the descriptions, and the parts are replaced individually now not as a kit. I believe originally you could get just linings to put on your brake disc, so they also offered the bare disc. And there were changes to the ring, so 1 thru 3 get replaced by 4 and 5 as I read it.

 

[Tx Jim]

Jim
Your statement concerning parts being substituted in the last 58+ yrs makes it difficult for a person that hasn't recently personally viewed brake parts know exactly how new parts should appear.

 

[Jim.ME]

Jim
Your statement concerning parts being substituted in the last 58+ yrs makes it difficult for a person that hasn't recently personally viewed brake parts know exactly how new parts should appear.

It appears the replacements are the same ones used in the 2030s s/n 187300 and before. It looks like they are phasing out the loose linings and bare discs, you get the disc with the linings bonded on now. And for some reason the pressure plate changes to the same one as those 2030s.

 

[WangoTango]

Update and closure. This job really kinda sucked. On the surface it wasn't bad. But it made a huge mess, and I caused myself a couple of problems because I got in a hurry. Something still had oil in it that I couldn't seem to stop weeping. It overflowed my catch pan and ran all over my shop. Wheel and axle came off ok. Getting the seals back in was a bit of a problem. I took a file to bevel the sharp edges as the piston seals went back in the bore. I had it all together once and as I was torquing the axle bolts back down I heard the pressure plate crack. I'm not sure what caused it, but I suspect the piston wasn't all the way in the bore and it got a little cock eyed, and cracked (even though I was cross torquing). The pressure plate has been superseded to a one piece piston/pressure plate part. It took awhile for me to verify that I was getting the correct thing. Also, the disk and pads are now one part as well. I think that was discussed previously. Once I got the one piece piston/pressure plate in place it all went back together with almost no problem. Brakes now work as they should. Now on to the next disaster. Whatever that may be...but I have feeling what's coming up. More to come on that later. Thank you all for the insight!