Need help with 2001 hitachi ex35u drive motor

[RPF207]

I removed my drive motor to replace the large O ring I suspected was leaking. Replaced the o ring and now as I’m trying to tighten the 7 Alan head bolts that hold the motor to the final drive I get them tight with my small dewalt 20v impact but there is still an 1/8” gap between the motor and final drive. There are 8 springs on the inside face of the motor that obviously open some type of something in the motor.

It feels like those are all the way compressed and what ever they open is what is causing the gap, as in I need to hand tighten them really tight to get that valve?/clutch? To open to seat the motor all the way, or maybe I don’t have the springs compressed yet and they are just that strong. This is just an around the property machine, I’m not a business owner and this is my first excavator although I am very mechanically inclined. I don’t want to tighten the bolts any more without knowing that is what has to be done to seat it all the way. I have put an Alan wrench on the bolts and a wrench on the alan to turn them but it is very rugged.

I have removed the motor multiple times to check the alignment of everything… the dowel is aligned, the center shaft is aligned and so on. I can grab the center of the final drive and with force rotate it and move the track. I guess I’m just assuming there is some crazy torque spec to get it to seat and looking for help. The 7 alan bolts were VERY tight when I removed them as the popped like a cap gun when they broke loose.

 

[RPF207]

So I’ve found the torque spec for the alan head bolts. 47 ft lbs. I must be doing something wrong if it won’t seat all the way

 

[RPF207]

The service manual I downloaded actually doesn’t show the 8 springs at all.

 

[mg2361]

 

[RPF207]

The rotating group did slide out until something stopped it. Maybe only 1/2” and then it’s held in. I can push the he rotating group in by hand until the springs inside that overpower me. I can actually push the rotating group in to the point that it’s flush with the center shafts shoulder that contacts the face of the bearing at the motor. And the bearing at the motor is flush with the plate that contacts the roaring assembly

 

[RPF207]

Rotating** not roaring

 

[RPF207]

Ok. I’m working on it again and I’ve now changed my opinion on what is fetching up and it seems to be that rotation group that has the plungers in it that ride on the swash plate. That rotating group hub is bottomed out on one of the plungers as if the swash plate or something between has moved

 

[Vetech63]

The rotating group has a piston plate that floats on pins. One or more of those may have fallen out when the assembly pulled out a bit.

 

[RPF207]

I got it. After studying my service manual many times over, specifically the diagram of the final drive and motor I concluded that something behind the rotating group had fallen out of place. I place my air nozzle on on of the small holes located on the final drive mounting face and blew out the ring with the seals on it that held back the brake clutch and rotating assembly. Pulled that all out and saw that the swash plate had come out of its home and fallen down which made up for the extra that the rotating group stuck out. Placed it all back in its correct position and the drive motor now bolts back on all the way easily.

What I also learned is that these final drives and motor are best worked on when in a vertical position unlike my situation as it was horizontal still on the machine

 

[RPF207]

Well guys. The new o rings didn’t fix anything. Had it all together, degreased and left over night. Came back to more fluid. It originally looked like gear oil but I couldn’t believe gear oil would find its way into the drive motor housing so I changed the motor O rings but here I am now.

I pulled the drain plug on the outside of the final drive and put my air nozzle in it to compress the final drive case. And sure enough a bunch of air was coming out from the inside diameter of the final drive mounting bolt circle. removed the the whole final drive, put it on the bench and found that there is a 4” crack!!!!!!

my buddy is an ace welder, think it could be tig welded or are the bearings not running true now or maybe some other problem. Again this is only a “farm rig” but I don’t mind doing things right if necessary. Maybe I can buy just that casing, idk. Time will tell.