JD 1020 brake failure?

I've been cleaning metal out of the rear of my 1020 that my grandfather got repo probably in the early 70's. I assumed all the fine metal that was in the rear came from spider gear failure about 20 years ago and just not cleaned out properly. I removed both axle housings to clean them out and replace the brake seals and clean them out too. Upon looking closer, I found that brake piston on the right side was updated and the left side was still original style. Looking closer the right side has deep grooves and wear in the rear end housing where the brake disc friction material rides against. Near as I can tell, the rear housing has been chewed out about .250" deep comparing to the other side. If I measure where the groove begins, it measures exactly the same depth as the other side. So I guess this was where the metal came from about 45 years ago and never cleaned out. It isn't any wonder all 3 pumps were trashed. Guess my question is what happened to caused this? I guess since it's been that way this long it shouldn't hurt to put it back together this way. I assume probably the only way to fix it properly would be another rear end housing? Sorry for the long post and thanks for any input. And by the way Merry Christmas!

What happened is the brake disk lining came off and they kept operating it with metal to metal. That ground the housing out over time. All the while putting metal filings into the hydraulic system.

A donor housing would be the best fix. A used housing should not be hard to find. I have had a similar damaged housing repair at a machine shop. machined the housing flat and then made an insert/sleeve then they pinned the sleeve to the housing. It was not cheap and we only did it because it was a rare housing that was near impossible to find a good used housing. It might be cheaper to buy a JD 1020 with a bad motor/transmission just for parts. I have seen non running JD 1020s not bring $750-1000.

If your not going to be using it much then I would just put it back together with a new disk and see how it goes.

I do not envy you the work in cleaning out the rest of the hydraulic system. That metal will be every single hydraulic compote on that tractor. I do mean everywhere too.

I did a JD 2020 a few years ago top to bottom. $10k in parts and half that in labor. So it would only work if your doing a "family" heirloom tractor.

The brake disc that is in it now is fine other than the grooves and was that way 20 years ago when it was apart then. I was young them and never noticed the wear. From what I know is that the tractor hasn't been apart since my grandfather got it in the late 60's early 70's with about 900 hours on it. So it was most likely that way when he got it then and has been this many years later with no issues. Someone was also in the transmission around that time too. You're right about the metal. I have hours of just cleaning. The reserve tank in front of the radiator was lined about 3/8" thick with metal. I'm on the downhill side of cleaning. Got the rear mated with the clutch housing today, and both axle housings off. I had to tear on apart because of a bad outer bearing, but got the other one back one. I also got the brake valve apart, cleaned and back together. My biggest issue will be with the loader cylinders. I guess the right think to do is tear them apart. Seems like there's only metal laying where oil wasn't flowing, so I don't really expect much to be there. I only put about 20 hours on it a year. It should be fine the way it is for my lifetime.

Your bigger items to clean are the main pump, brake valve, and the power steering valve. That is after cleaning the rear end housing out. Then checking the transmission/charge pump out for wear. If you have the hydraulic hi-lo then that needs cleaned out too. I am not sure if your JD 1020 could have had the independent hydraulic PTO or not. The Later Mannheim tractors usually did.

These things are terrible when they have the hydraulics get contaminated. Who ever thought a bypass valve on the filter was a good idea should be shot. May the system shut down so you do not destroy the entire system with junk!!!!

Well all 3 pumps are trashed. I repaired the power steering pump, replaced transmission pump, and main hydraulic pump. The main hydraulic filter over the years, the cone went missing that had the filter against the transmission case. The transmission suction screen also had a hole in it also. The filter may as well had not been there. My tractor has the continuous PTO and no hi/lo in it. It was time for a clutch also, so I guess it's getting a few Christmas presents too! Figured I may as get it all done at the same time.