Weekend Freedom Machines banner
1 - 2 of 2 Posts

512 Posts
Discussion Starter · #1 · (Edited)
Hello All. Like many others, I too have rear PTO noises that I'm trying to figure out. I read through all of the threads in the Hydrostatic Drive Tractors Forum, and I can't quite find an end-all-be-all root cause. I'll try to be as thorough as possible, as I know that there are probably more than several of you out there that know exactly the issue, and what the root cause is, and the solution to the problem.

Model - '88 332 (no SN). Rev4 hydro damper + pending 430 diff/linkages swap taking up real estate on the right hand side. Rear PTO + MCS pulley stuff purchased together from Craigslist.

The short story
Rear PTO makes a grindy/rattly sound as long as the engine is running below 1700RPM. It changes in tone and intensity with the PTO on/off, but is always present at low RPM. Bearings and keyway in the clutch and in the MCS pulley bracket are new. I've read that the problem could be a warped armature, warped or worn oddly rotor, warped field winding coil, badly worn shaft key, badly worn shaft key slot, or bad bearings. I've also read that some people just live with the noise, and some say no way, it shouldn't do that. I've read that the anti-rotation bracket should be loose attached to the field coil winding, and I've read it can be hard mounted, or hard mounted with rubber isolators. It makes the noise regardless of my anti-rotation mounting, or even not having it attached at all and holding the coil in place by hand. I have replaced all the bearings and keys. I just don't want to have a catastrophic failure of something that costs a ton of money to fix down the line. If I can fix it right the first time, I'd rather do so. How do I further diagnose?

Additionally, after running the PTO on the machine testing it and recording the noises, I removed it to inspect. It now makes a grindy/squeaky noise when you rotate the input shaft by hand, and the output shaft has a wobble like it did before. The noise goes away when the clutch is engaged with a battery, and spinning it by hand.

The long story, and all of the supporting background information
When I got the PTO, it had a nasty wobble to it. I attempted to adjust the air gap to the prescribed 0.018", but was unable to get it to be consistent. Rotating the shaft would cause it to go tight-loose-tight-loose, as it spins. Also, when I stuck it in a vise and hand turned the drive shaft, the output shaft would wobble, or sort of wallow around in an ovoid shape if viewed in line with the splines. You can see it from the side too. Very difficult to get that in a video, more on that later. So I decided this was bad...

I carefully disassembled the whole thing. Finding that the small bearing on the coil side was wicked grindy, that the big bearing on the opposite side was OK-ish, and that the keyway was worn really bad. I replaced the keyway and large bearing, both purchased from Deere (noting that the keyway is not the same size as the one used on the MCS pulley end, all of that hardware I also replaced with Deere parts). I ordered and replaced the small bearing on the coil side from SKF. The anti-rotation hole was blown out completely, so a nice thick machining washer was welded in its place. Everything was lubed to death, and carefully reassembled nice and snug. I then adjusted the gap, which worked out good this time. I can now spin the shaft by hand, and it makes no noise at all, and no perceptible wobble/wallow. I felt good about all this.

Fast forward a few days worth of fabricating up an anti-rotation bracket that fits the left hand side under the rockshaft cylinder, and install the whole bit.

Once everything was installed nice and tight, I fired up the engine to try it out. First thing I noticed was the new rattle/grindy sound at low rpm, PTO off. This noise goes away above 1700RPM (TinyTach). There is a slightly different, and louder grindy sound when the PTO is engaged. This sound correlates perfectly with the disengage noise, as far as intensity, and abruptly going away above 1700RPM. I also noticed that the whole assembly slides fore/aft when engaged/disengaged. There seems to be a significant amount of slop fore/aft in the splines. They are otherwise tight. I do not have the little spring that goes in the female side at the trans end. The shaft has the grease fitting. Also, as purchased from Craigslist, there were 2 odd looking washers assembled between the output shaft, and the input to the MCS pulley shaft (see images below). They take up some of the fore/aft slop. I have never seen them in any parts diagrams, or otherwise mentioned in any forum post.

Additionally, after running the PTO on the machine testing it and recording the noises, I removed it for inspection. It now makes a grindy/squeaky noise when you rotate the input shaft by hand, and the output shaft has a wobble like it did before. The noise goes away when the clutch is engaged with a battery, and spinning it by hand.

My anti-rotation bracket doesn't change whether or not the sound occurs.

I feel like there is more than one issue, but I'm not 100% sure, or where to start really.

Here is a link to the first time trying it out. I didn't have the anti-rotation bracket at the time, just a pair of vise grips preventing it from banging around. You can kind of hear it making noise, but not that much. I honestly didn't realize there was a problem at this point.

Here is a link of it isolator-mounted to the anti-rotation bracket making a God-awful noise. This is when I found that there was a problem. Worth noting that mounted to the bracket, it will not move fore/aft hardly at all now. I thought that the bracket was the culprit until I tried again like in the video above, and it makes no difference.

Here is a link of it making a noise as I hand rotate it in a vise. You've got to turn the volume up for this one to hear it. Also, I can feel it chunking for each time it makes the sound. If feels similar to a bad bearing. The sound goes away when the clutch is engaged. I'm planning on taking it apart again to investigate.

Here are the two odd looking washers. The second one is laying flat.

Chocolate Cake Dessert

Thanks in advance.


512 Posts
Discussion Starter · #2 ·
No ideas anyone? I'm still at a loss. I replaced the shaft and the small bearing which took care of the grindy noise and wobble when turning by hand. The new *** bearing doesn't wobble relative to inner and outer races. The old shaft was 0.010" smaller diameter than the new one. I also added the little spring on the trans end of the shaft. But the noise with engine running is no different. The sound isn't like the bell ringing noise. It is clearly coming from the clutch, as you can feel it and hear it rather easily. My only other thought is that it could be some kind of resonance. But even that can't understand why it'd be different from other people's machines, and it doesn't occur at other engine speeds.
1 - 2 of 2 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.