M37 PTO On Early & Late Model Transmissions

[SasquatchSanta]

I got around to installing a late model NOS transmission in one of my M37s (The Woogie) today.

I picked up some rollover noise that I believe to be coming from the PTO. Given the Tannsmission is NOS I can't imagine it being in anything but the PTO. I've always been under the assumption that there is only one PTO and it fits both the old style and late model transmissions. Can anyone confirm this.

When the PTO was installed we could only use one gasket/shim and it "felt" right. Any more than one gasket/shim would have made the fit too loose.

I discovered when changing from old style to the new style transmission the winch "out-of-gear" safety catch in the floorboard tunnel has to be moved. Evidently the transmissions are different???

I also rewound my cable spool today. I don't ever recall unwinding the cable under power, (with the pto engaged and in reverse) so I don't know if the ticking noise at every revolution is normal. Always before I simply free-spooled the cable.

The noise went away when the PTO was in forward (winding in the cable) but there was a definate click and hesitation in the drum on every revolution when the drum was paying out under power.

If there are any winch gurus out there I'd appreciate your insight.

 

[Capt.Marion]

I know the transmissions are different, and I didn't know you could put a PTO on the earlier ones. So I would reckon there'd be some difference, although I truly have no clue. Good luck with this, I need to get my winch working too...

 

[m376x6]

That's a good one. The transmissions (US style) are interchangeable. The cases as far as styles are different slightly. The internals are completely different between them. Its possible the PTO mounting location is shifted slightly between them, although I have in working on both styles these many years have never noticed it. You shouldn't hear clicking in either direction. You mention one gasket. Gaskets are used to set up the gear backlash between the pto drive gear and the cluster gear it uses. Very important it is done correctly. Try disengaging the clutch on the winch, place the pto back in reverse direction and see if there is still clicking. Also, you should be able to unwind your winch by hand (sometimes it takes a heavy tug) with its clutch or drive collar in the disengaged position. If you have to power it out to unwind your winch you have issues with your winch. There is a brake in the clutch, but it is on the pto drive input shaft. There is also a wiper that contacts the outside of the winch drum and that shouldn't place that much pressure on the drum as a rule. See if you can locate closely the source of the clicking if it is still making that noise while the pto is engaged with winch clutch out. This way the pto, driveshaft, and worm and gear will be moving as well as the internal drum shaft, but the drum will be unpowered. I have a rebuilt early style tranny in the shop and have just brought in a new style for rebuilding. I'll measure them both on the pto opening as I am now curious. There were actually two different input gears on the pto's, one was originally designed for the old style and a different one for the new style. Not to worry though, there was only about 15 thousandths difference between them on the diameter and that was easilly dealt with using pto gaskets. Do some investigating and let us know what you are finding out.

Regards,
M376X6

 

[SasquatchSanta]

Thanks for the insight M376x6.

The actual positioning of the winch lever boot is the same. What's different is the lever is tilted forward further than with the old style transmission therefore the little clasp that mounts to the transmission tunnel and normally holds the winch handle in neutral now needs to be moved forward for the winch handle to fit into the neutral slot.

When I put the winch out of gear and run the PTO in reverse there is no clicking. What I've got is when I'm uwinding under power the drum hesitates for a second at the same place on each rotation, makes a noise and then starts moving again. I marked the cable drum --- it always happens in the same spot. It doesn't happen when the drum is running the other direction. One would think that if there is a gear problem within the winch proper that the hesitation and clicking of the drum would happen in both directions. I'm wondering if it doesn't have someting to do with the brake. Always before I simply put the winch out of gear and unwound the cable by hand therefore I don't know what is normal when you unwind under power.

The guy that installed the PTO is an old experienced mechanic that has installed PTOs before. He felt there was already sufficient clearance with just one gasket. I figured we would have to use several gaskets to get the desired clearance but he said if anything it is a little loose. Since we only used one gasket there is no way to tighten up the slack.

 

[m376x6]

No clicking unless the drum is in motion, and only unwinding. I'll bet that little wiper is catching on something. The shift lever goes over a 90 degree angled pin that can be adjusted in and out on the shift shift shaft going into the pto. The shift lever should have a short oblong groove running up and down cut into the end of the lever. This allows for the change in distance between the pin itself and where the lever attaches to the rear cover tower on the pto. If there is just a round hole the diameter of this pin the lever will bind and be diificult to shift either in or out. On this 90 degree pin that threads into the selector shaft there should be a locking nut.


Regards,
M376X6

 

[Bill W]

As mentioned The idler gear on the pto is always turning when your rolling so clicking would not be intermitent. There is a spool brake ( not the little band brake on the worm shaft ) on the LU-4 that is suppose to catch/lock the spool if it free spins to fast ( little square piece mounted behind the drum flange),that might be hitting??. Also My 54 m-37 had a 1958 (NP420) in it and my winch equipt parts truck had a 1954 ( early model) tranny in it, I interchanged the pto and had it in the truck for about 2500 miles and had no prolems with it BUT there is a TB out that states not to interchange the pto between the early tranny and the later NP420, theres speculation that there was a early/early tranny that was in the first prodution run 37's ( no proof) this TB might be refering to as the part# of the (early) tranny listed in the TB doesn't match up to the part # of the NP trannys that were in the 51-54, M-37s ( does that make sense?)

 

[m376x6]

When you mention early early, I' guessing you mean something like a prototype transmission or a shelf transmission that would have been used for the intial vehicle submissions for approval. Very possible, maybe even a spur gear type as used in the Power Wagons and WC's. I'll look through Zenthmeyers book, maybe he mentions something and I've just forgotten it. I've put old on new and new on old and mixed them every which way and as long as you get good backlash there has never been a problem that I'm aware of.

Regards,
M376X6

 

[Bill W]

Yeah Bryan
Like the first 200+ - ,M-37s off the production line had 6v gauges with resisters on them., I'm thinking ( no proof of course) that there was left over stock at the factory that got used up first. As mentioned I did not have a problem either but there is a TB on the matter., just can't figure where it applies??

 

[SasquatchSanta]

Thanks for all the insight guys.

I'm certain the clicking was caused by a sheared winch pin that would hanging up and intermittently causing the drive shaft to slip in the winch. Sometimes the most simple solutions are the least obvious.

The PTO was removed today. With it's removal, the rollover noise went away. At least I know it wasn't in the n NOS late model transmission. That was a relief.

The PTO looks good and turns freely. Whatever the problem is, it can't be anything serious. I also can see now where/how the winch lever can be adjusted back and forth.

I know it's a real "no-brainer" but it's worth remembering to always be certain to adjust the winch lever to insure it's in neutral when installing a new PTO or a complete winch assembly. Should the winch happen to be in gear and the truck is started with the PTO unknowingly in gear some serious damage could result. If nothing else it could deform some perfectly good cable.

Yesterday when I was operating the winch I was reminded of how handy a little "redneck engineered" add on that I made to my winch several years ago is. These winches are DANGEROUS. In my opinion they are really two-man operation machines --- one man in the cab operating the truck clutch and forward/reverse lever and the other man in front of the truck operating the Engage / Disengage lever. If you've ever operated one of these winches you know that as soon as you get the slightest tention on the cable it's almost impossible to move the Engage/Disengage lever to disengage. Several years ago I bought a rubber hammer, bolted a lite chain to the handle and welded the other end of the chain to the truck. The rubber hammer works quite nicely to slap a stubborn shift lever out of gear. It's no guarantee --- it's still dangerous but it helps.


Thanks once again for the insight.