EX120 - Swing motor gear oil leak (Pictures)

[jonno634]

If I had the time, I’d just do it.

 

[Egetebee]

Yeah huh?
I'm still waiting on parts (bolts, o-ring, and a torque tool with extensions and socket, etc.)
I've just finished up classes and have some time off for the Christmas holiday so, yeah maybe just get it done and then it'll be available on those days that warm up and I can keep going on the project periodically throughout the winter.

Thanks again,
E

 

[mg2361]

You shouldn't wait to repair that. If enough water gets in there and freezes it can bend the bottom of the cavity creating other issues, like a rotary manifold that is no longer vertical. I have seen this many times so I wouldn't take the chance. Make sure to replace the rubber boot around the rotary manifold. That could be a source for water entry.

 

[Egetebee]

Hi Everyone,
As you've advised, I've started on the Swing Motor swap.

At present, the fuel tank is drained and removed for easier access as we don't have another machine to help do the lifting so it'll be done manually.

Hopefully today I'll get the old unit out, clean & degrease the area and be able to remove the remaining stud of one of the M20 swing motor bolts that broke earlier in the season.

Question: Should I use loctite on the new bolts when tightening down the new motor assembly?

Thank you,
E

 

[Egetebee]

Ok,
Removed the old swing motor and was also able to remove the broken stud.

The bolt holes were in rough shape so I cleaned & chased them out however 1 of the mounting holes will not thread properly when starting from the top. I'm able to thread a bolt from the bottom up but from the top down it just won't start smoothly.

It just so happens that this particular bolt is directly in line with the pinion channel so I'm wondering if I can simply use a longer bolt, thread from the bottom up and use a nut on the top side?

Whaddy think?
E

 

[Welder Dave]

If you can thread it all the way threw from the bottom, I think you should be able to clean it up to thread from the top. Put a rag under it and maybe a small round file or light touch with a die grinder would let the bolt thread properly. Even a slightly bigger drill bit turned by hand might take off a slight burr and allow the bolt to start from the top.

 

[Ronsii]

I would find a tap of that size and run it through the top and the threads will work, make sure you try to start that bolt first when you're putting it together.

 

[Egetebee]

If you can thread it all the way threw from the bottom, I think you should be able to clean it up to thread from the top. Put a rag under it and maybe a small round file or light touch with a die grinder would let the bolt thread properly. Even a slightly bigger drill bit turned by hand might take off a slight burr and allow the bolt to start from the top.

Hi Dave,
That's exactly what we did and several times too, in fact, it threads from the bottom all the way out of the top and pretty smoothly, but still just not starting from the top properly. The top hole was no longer round but oval and even after chamfering the top to get to 'good' threads the new bolt refuses to catch properly. At this point, the only known good threads are the bottom half. Tried working it for literally hours till the thought of simply using a longer bolt from the bottom came to mind.
Figured to ask about that as a possible solution.
The bolt is in line with the pinion channel and I don't think the bolt head on the bottom will run into anything.
Can you confirm this Dave?

Thank you,
E

 

[Egetebee]

I would find a tap of that size and run it through the top and the threads will work, make sure you try to start that bolt first when you're putting it together.

I did actually use one of the old hardened bolts and cut flutes into it to make a 'tap' and that's how I was able to cut from the bottom up, worked very well too. Seems like a new bolt just doesn't want to go in from the top no matter what.
As mentioned to Dave in the previous post, the only known good threads are at the bottom half of the hole. The first 3/4" from the top are so ragged that they're pretty much gone.

So the thinking is that either I drill out the entire hole and retap with the next size or go with the nut & bolt solution which will definitely work as Thankfully this particular bolt is exactly in line with the pinion channel.

Do you see a big problem with this as a solution Ronsii?

Thanks again,
E

 

[Ronsii]

When you start upsizing things you run into issues trying to keep the holes exactly on center and drilled perpendicular to the face which will lead to the same problems you are up against now unfortunately. As a first choice I would still try to locate a real tap and chase those threads out from the top.... You may have a burr or bent in hole on the swingbox... it won't take much because of the tolerances involved with that thing... so you my need to go in and file/burr it out... but first try and find a piece of hot rolled or good fitting drill bit and fit in the bore and bores next to it just as a check for size and angles.

 

[Welder Dave]

A Heli-coil or other type of thread repair might be a good idea if only half the threads are good. I agree with trying a real tap from the top. Maybe a slight taper on the bolt would help it thread in?

 

[Egetebee]

When you start upsizing things you run into issues trying to keep the holes exactly on center and drilled perpendicular to the face which will lead to the same problems you are up against now unfortunately. As a first choice I would still try to locate a real tap and chase those threads out from the top.... You may have a burr or bent in hole on the swingbox... it won't take much because of the tolerances involved with that thing... so you my need to go in and file/burr it out... but first try and find a piece of hot rolled or good fitting drill bit and fit in the bore and bores next to it just as a check for size and angles.

Understood, we do have a local company which supplies industrial tools and will check for the M20x2.50 tap.
My concern is that with the top half of the threads compromised it may be that applying 400lbs torque will strip the rest of the hole threads.

Thank you for taking the time to help,
E

 

[Egetebee]

A Heli-coil or other type of thread repair might be a good idea if only half the threads are good. I agree with trying a real tap from the top. Maybe a slight taper on the bolt would help it thread in?

I'll look for the correct tap.
Can't seem to find the M20x2.50 Helicoil for less than $100 and wonder if they would support the 400lb torque load.

Thought the 'bottom-up' bolt would take care of the cross-thread / strip issue while also able to handle the torque.

Thank you for helping,
E

 

[Ronsii]

Helicoils are generally stronger than the parent material given it's mild steel... I forget how deep the threads are in the frame... maybe 1 inch... and don't know how long a helicoil of that size is although I have stacked them before on deep 3/8th holes.... but much different use.

 

[jonno634]

I haven’t worked on this particular excavator, but I’d assume if the bolt head is clear, it would be clear all the way around. Make sure you get a HD nut if you do it that way.

 

[Egetebee]

Helicoils are generally stronger than the parent material given it's mild steel... I forget how deep the threads are in the frame... maybe 1 inch... and don't know how long a helicoil of that size is although I have stacked them before on deep 3/8th holes.... but much different use.

Thank you Ronsii, didn't know Helicoils could be stacked.

E

 

[Egetebee]

I haven’t worked on this particular excavator, but I’d assume if the bolt head is clear, it would be clear all the way around. Make sure you get a HD nut if you do it that way.

Hi Jonno,
Yeah, figured if would be clear too but wasn't 100% sure.
I'll be sure to get the same 10.9 nut for the bolt if it goes that way.

Thank you,
E

 

[Ronsii]

Aren't those high shouldered bolts holding the swing box down?

 

[Egetebee]

Aren't those high shouldered bolts holding the swing box down?

Maybe the originals were but the 10.9 replacements are fully threaded.

E.

 

[Egetebee]

Update:
Purchased the M20x2.5 tap but could not get it to start from the top and it was too long to start from the bottom. Oh well.
Finally, began trying every single one of the new bolts and found one that actually started from the top. Kept working it in & out and now have a bolt that I feel confident should start smoothly once the motor is in.

Question: Should I use Loctite? Red or Blue?

Thank you again for all of your help,
E