4200XL Pump Motor Problem

[A1 Dirt]

On my RC4WD 4200XL Excavator, the outer motor housing spins up the motor shaft. I've torqued the set screws as much as I can and used threadlock, but the housing still spins free. The only thing I can think off is to try cone point set screws. Any solutions or other suggestions?

[woodhog]

Try drilling a shallow hole for the setscrew to go in to.

[Espeefan]

You could also try filing or grinding a small flat on the shaft, where the setscrew would make contact. Or maybe do that, and drill a small dimple on the flat as well.

[A1 Dirt]

Thanks for the suggestions. The problem has been solved. Just after I ordered set screws, etc., RC4WD decided to send me a new motor. Hopefully, I can get it all back together so it doesn't come apart. Lots of threadlock!

[cdm]

threadlock wont do anything for that. once you overcome the grip power of the set screw the only solution is a wedge/flat spot.

its a good practice to flatten all shafts anyway. saves future complications

[A1 Dirt]

I installed the new motor. Same problem - housing slid on the shaft. Checked the set screws - both had backed out 1-2 turns. Currently waiting on a response from RC4WD.

[cdm]

so did u notch it and put the screws against the notch? rc4 is prenotched i believe to begin with

[A1 Dirt]

No - This is a NEW replacement motor. It should have been ready to roll as received. I expected it to be OE (guess it was, it failed).

The motor shaft is smooth. I took the original motor apart and there are no notches or flat spots. I don't intend to take this one apart.

Depending on what I hear from RC4WD, I'll probably try knurled cove point set screws, then cone point, then cone point after drilling a detent.

As a last resort, I'll try a retaining compound. I called Loctite and the lady said that Loctite 290 is a wicking threadlock that can be used as a retaining compound. The only problem might be the shaft/housing tolerance - too tight, too loose, or just right.

There are a few warm, sunny days forecast and I'm anxious to get this digger outside in the dirt

[Espeefan]

Loc-tite 680 is some very strong retaining compound. I've used it before at work, on bearings that are just a little to loose of a fit on shafts tightly, and trying to remove an old bearing with this stuff on is very difficult. You have to use some heat, or else you'll destroy the bearing in the process of pressing it off. 680 might be worth a shot. Just keep it out of the bearings themselves, and do a good job cleaning off the oil from the shaft and mating parts.

290 is another great product. It definitely wicks into anything! It will work as a retaining compound too, but not nearly as well as 680.

[cdm]

Originally Posted by A1 Dirt

No - This is a NEW replacement motor. It should have been ready to roll as received. I expected it to be OE (guess it was, it failed).

The motor shaft is smooth. I took the original motor apart and there are no notches or flat spots. I don't intend to take this one apart.

Depending on what I hear from RC4WD, I'll probably try knurled cove point set screws, then cone point, then cone point after drilling a detent.

As a last resort, I'll try a retaining compound. I called Loctite and the lady said that Loctite 290 is a wicking threadlock that can be used as a retaining compound. The only problem might be the shaft/housing tolerance - too tight, too loose, or just right.

There are a few warm, sunny days forecast and I'm anxious to get this digger outside in the dirt

you are complicating things for yourself and im not sure why.

take a small file or a dremel and notch the shaft where the grub screw digs in. problem solved.

why would there be notches inside the motor?!



see that slot/notch? thats what gets the grub screw to bite..

as you see their motor IS notched.



maybe the new versions of the bager don't have that but it should. the pump is cross drilled like their (vehicle) shafts and thats where the screw has to be alligned to bite pump side.

[Espeefan]

Originally Posted by cdm

you are complicating things for yourself and im not sure why.

take a small file or a dremel and notch the shaft where the grub screw digs in. problem solved.

why would there be notches inside the motor?!



see that slot/notch? thats what gets the grub screw to bite..

as you see their motor IS notched.



maybe the new versions of the bager don't have that but it should. the pump is cross drilled like their (vehicle) shafts and thats where the screw has to be alligned to bite pump side.

Chris, I think you are mis-understanding the original poster's problem here. His out-runner's bell housing, which has the magnets inside of it, is slipping on the central motor shaft. He isn't saying the motor doesn't have a flat on it, on the stub end, where a gear, or pulley would mount.

[A1 Dirt]

That's right - other end of the motor. In the Pic - one set screw in - one out.

[cdm]

seriously guys? it is the exact same thing. if he got the other one apart already, it takes a second to notch it where the screw(s) sit. in his case 2 of them. rc4 likely had a bad batch or a cheap/newer one. i have had issues with them too with various parts.

here i just took apart one of my brushless to show you



you can locktite it all day long and it wont hold. you need an ident for the screw to grab. else it will spin 9 out of 10 times especially on these high torque motors.

now im surprised you dont see the marks of the screws grinding against the shaft, right? any of those there?

if not, there could be a thread issue on the housing and it isnt deep enough to allow the screws to go all the way down to grip.

[A1 Dirt]

For those of you who didn't understand what I was trying to explain, I posted a video.

http://www.youtube.com/watch?v=34Hnd6FftW4

RC4WD sent a second replacement motor. It ran fine for a few minutes, then began to slip. Some where along the line the set screws were kicked out. I did a little drilling and used some cone point set screws. The problem seems to be fixed, so far.
The bell housing seems to be press fit on the shaft. The set screws do little more than fill the holes. It's not an easy task to disassemble the motor.

Thank you all for your suggestions and comments.

[ihbuilder]

you did the right thing with a cone point set screw . I highly doubt a flat will keep it from running off the shaft like that . that motor does seem to have excess vibration . could be crap bearings a batch of bad mag cases (running out )

[A1 Dirt]

The cone points did not hold.

As a last resort, I used Loctite 290 as a retaining compound. So far, it's held through four batteries. Hopefully that was the fix.

There is still some intermittent noise when the motor/pump is under load. You do not hear this noise in the video. It's much louder. Since the motor is running OK, I now believe the source of the noise is the hydraulic pump.

There is no air in the system so that's not the problem. It's probably bearings going out.