Pc50uu-1 mini excavator final drive cover plate removal

[Russ T Shackleford]

In trying to service my komatsu pc50uu-1 final drive. It started to feel weak on the one side and then abruptly stopped working.

I sourced a complete final drive for around $2k but would like to just replace the drive shaft if that's all that's destroyed in there. The oil was very glittery... so I know something is ground to a nub in there.

I pulled the snap ring from the face plate but can't get the plate to pop off. I put longer pipe plugs in there to see if I could remove the plate by rotating or prying it but no luck.

I will try a slide hammer tomorrow. I don't believe there is an internal ring like the kyb drives. This is a hydash brand.

Landamachinery.com lists the individual parts I would need to rebuild the drive. Let me know if you've found better websites for pc50 parts. Thanks!

 

[Russ T Shackleford]

Can confirm: slide hammer worked great.
O-ring looked extremely gross. Apparently they glued it in place?


The planetary gears have a many missing teeth as a trailer park queen. Well mystery solved I'll pull the rest apart and get quotes on parts needed

 

[BluewaterLa]

Where you ordering your parts from ?

 

[Joe H]

https://www.alibaba.com/trade/search?spm=a2700.product_home_newuser.home_new_user_first_screen_fy23_pc_search_bar.keydown__Enter&tab=all&SearchText=komatsu+pc+50-uu+final+drive

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[laidback01]

wow, hope that's all, but the idea of all that metal being ground up, those teeth getting crushed to small enough pieces that get between ball and race, and that finally gets turned to powder... hmm... I'm pretty sure you're going to find excessive wear in the second planetary too, but you typically need the motor out and in a press to get to that set - unless they vary by manufacturer. I've only read about the tear down, not actually done it, and from a Deere shop manual.

I probably need to spend a night in a Holiday Inn for a night or so before I'm willing to take one of those fully apart.

 

[Vetech63]

wow, hope that's all, but the idea of all that metal being ground up, those teeth getting crushed to small enough pieces that get between ball and race, and that finally gets turned to powder... hmm... I'm pretty sure you're going to find excessive wear in the second planetary too, but you typically need the motor out and in a press to get to that set - unless they vary by manufacturer. I've only read about the tear down, not actually done it, and from a Deere shop manual.

I probably need to spend a night in a Holiday Inn for a night or so before I'm willing to take one of those fully apart.

Don’t forget the continental breakfast with the imitation eggs and days old biscuits

 

[Russ T Shackleford]

Where you ordering your parts from ?

777.parts.com, and supply.parts have a quoting service. landamachinery.com in China has parts too. I located planetary gears for around $200 for the set, I'm still looking for a reasonable price on a reduction gear. Some places are charging $500-$1000 for just the reduction gear.

 

[Russ T Shackleford]

wow, hope that's all, but the idea of all that metal being ground up, those teeth getting crushed to small enough pieces that get between ball and race, and that finally gets turned to powder... hmm... I'm pretty sure you're going to find excessive wear in the second planetary too, but you typically need the motor out and in a press to get to that set - unless they vary by manufacturer. I've only read about the tear down, not actually done it, and from a Deere shop manual.

I probably need to spend a night in a Holiday Inn for a night or so before I'm willing to take one of those fully apart.

I didn't take really good pictures of the inside but found very little particulate or damage further inside the case. The central shaft and reduction gear teeth looked perfect with very tight lockup. I figure it's worth trying to rebuild.

I'll wash everything out. Use a super magnet to collect any more particulate and drain the oil and refill it several times in the first few hours of service. If all else fails I know I can part out the old motor on ebay to recoup losses then buy a new rebuilt travel motor.

I just know that people DO rebuild these and that is is possible. I've never been the kind of guy who's scared of wrenches but I appreciate your perspective as it tempers my optimism.

 

[HarleyHappy]

When you have it that far apart, you’re gonna know what you need to replace.

 

[John V]

I tried rebuilding one of these on my ihi 55j2. Bought parts from alibaba, dirt cheap for the big bearings, reamer bolts, etc. Never quite ran right. Opted for whole new final drives. 2 finals were $1160, shipping was $1520 for DHL 3-4 day service. Could have had them sea freighted for about 1/3 the cost. Unbolted the old ones and bolted the new ones right up. Gear ratio is slightly different is why I opted to replace both.

 

[laidback01]

hey, when you were using it, what alerted you to the idea that something was wrong in the finals? did it lurch or slip or anything? or was draining the oil your first indication something was wrong? I'm just curious is all. Mine seems fine, but I do see slightly sparkly oil - I change my final oil when I change my engine oil.

 

[Russ T Shackleford]

hey, when you were using it, what alerted you to the idea that something was wrong in the finals? did it lurch or slip or anything? or was draining the oil your first indication something was wrong? I'm just curious is all. Mine seems fine, but I do see slightly sparkly oil - I change my final oil when I change my engine oil.

I had a slightly weak left track from the time I bought it. There was a revolving click for about 100' then it spontaneously deconstructed itself and the left track stopped dead. Luckily I reached the flat area I was traveling to before the teeth jammed the gears.

Clicking was probably a missing tooth or two, then the stoppage was broken teeth jammed in the gears. This was visible when I pulled the cover. I used old gas in a spray bottle to flush out the old oil and to wash everything down for inspection. I'll be washing and inspecting all parts I removed and totally repacking all of the bearings as I go. My breakdown was pretty abrupt. So I'm fairly confident the damage was limited to the planetary gears and a little superficial damage to the plastic ring on the bearings.

If you have glitter in the oil, change it after letting it completely drain and refill then monitor it. I'm learning rapidly to really watch the oil and grease levels on heavy equipment.