Stuck brake on D2 5U

Pull the brake pedal assembly and squirt some of your favorite penetrant onto the linkages from there. Its the only place that there are linkages. I would go underneath and take the drain plug out to check for condensation before I dump anything in like Diesel.
If its the brake truly dragging you should be able to fix it all up when you remove the brake bearing assembly. Don't forget the set screw in the bottom that you need to adjust to lift the brake band off from the drum.

I checked the drain plugs. All 4 were absent. 🙄
On the outer pairs I could stick my finger up and feel the brakes. On the inner I could reach in and feel plenty of grease.

I loosened the brake bearing assembly. The linkage is still attached so I can't say I "removed" it. I can see a cotter pin inside but fear pulling and not being able to get it back together. I did fish out some of the grease in there and spray in penetrant. I'm able to work the pedal over the full range at this point but it still needs more effort than the right side pedal. I'm not even sure if the progress was made inside the bearing assy or closer to the pad.

I'll let it sit for a day with the penetrant sprayed in there and see if it starts freeing up some more. Haven't seen any obvious (to me) problems yet.

putsplut - The drain plugs are normally left out at all times, and are only installed if you're working in deep mud or water, to prevent the mud or water filling the steering clutch compartment. What a lot of people do, is drill the plugs with say, a 1/4" or 5/16" hole, and then insert a 1/8" split pin in the hole, and open the ends .. then screw the plug in. This then allows drainage of any oil weepage, but prevents the ingress of mud. It won't prevent ingress of muddy water, but it slows it up enormously.

The brake problem is best attacked by disconnecting external linkages and checking for free movement at every component that rotates in a bushing or bearing. It's quite common for Cat brake linkages to seize at bushings or bearings. Once you've determined that the linkages are rotating freely, you can then advance your investigation to further down the line, inside the clutch compartment.

mine was seized when I did the steering clutches.I found the lever4B4939 seized onto the shaft4B6691. It took a lot of heating and cooling and penatrating oil to free it but it is good now.The end of the shaft is held in place by a bolt and flat steel keeper in the slot.If you look at the end of the shaft where it comes through the final drive housing you should be able to see if it is trying to turn or not.

Here is a picture of the end of the shaft-It should not move when you move the brake pedal.If it does then the lever is seized on the shaft

I am able to see shaft 4B6691 rotating as I work the pedal. At this point I seem to have full range of motion with the pedal but it is not moving easy like it should. I've loosened the brake adjustments up significantly and am able to move the brake with my fingers either through the access hole on top or the drain hole underneath. With the 4 bolts holding the bearing assy housing removed I can look in from the bottom side and see (and feel) the linkage rod (4B4694) going toward the 4B4939 lever. I can feel a cotter pin at the end of the rod up inside the bearing assy housing. I'm not sure there if there is enough space to remove the pin even if I'm able to pull the cotter. Since I have only minimalistic tools I'm afraid to do anything that might require pulling the tracks, roller frame, and final drive case. 😮 Should I be able to remove the linkage without major disassembly? What kind of tools/equipment is needed to get in there the "right" way?

When I reach into the opening of the bearing assy and reach downward I can feel grease. Should that area be able to drain back to the drain by the bottom brake set screw?

there are two plugs on each side .If the shaft is moving it may be your best bet to pull the final drive off and use heat to free it.

I think everything is free at this point. Are you saying that shaft shouldn't be turning? 😕 (Looking back, yup, thats what your email said!)

I've poured diesel through (no plugs so it runs through) and sprayed penetrant all over the place in there. I've worked the petal back and forth and it seems to have gradually loosened up fairly well. At this point, everything works except the return spring isn't always strong enough to pull the brake pedal all the way back up. The return spring looks different than the spring on the other side and different than the spring in the parts book so it may be slightly undersized. I'll keep working the lever more but its working well enough that I could turn the wife's compost pile and only needed to hook the pedal with my boot a few times.

I'll look at the shaft some more and see if it is still turning or whether it has come free. The service manual makes pulling the final look hard. Am I just being a chicken?

keep oiling it and keep using it.no harm done