Farmall A transmission question

I have a 1945 Farmall A that has a transmission problem and I’d like some ideas on exactly what I should look for and how to correct it. It seems to occur primarily in reverse. When I back it up it tends to growl initially and then it has a slight lurch as it backs up depending on the amount of incline. It has a slight growl when the clutch is released going forward but otherwise operates smoothly after that in all forward gears. The shift lever changes gears easily and other than a little whine going forward, it works great in all forward gears. While I don’t think this is part of this issue, I do keep the pto in gear because it slows the input shaft from turning so I can shift it easily. If I don’t have the pto engaged, it takes several seconds for it to be shifted without grinding gears. If anyone has experienced this with their Farmall A, I would appreciate any specifics on what the likely source of the problem may be. Thanks in advance, Jerry

An odd combination of things there, Jerry.

First off, it does take some time for the input shaft to slow to a stop to give you a grind-free shift. Two or three seconds on the clutch would be the outside limit when everything is working and moving properly, but two would be about normal. It's a little surprising to hear that your PTO with no load on it should be sticky enough to stop the shaft any faster, or at least noticably.

But about the growling . . . it's a pretty good sign of a rough bearing somewhere in the train. Could be at the very front, the throwout bearing starting to go. Could also be on any of the shafts in the transmission. It's hard to nail it down, but if you can locate it to either side, it could be also be any of the bearings on the diff shafts or the axle.

The lurch . . . does it happen only at the beginning or can you notice it as you move along in reverse? Wondering if you might have a tooth out on the gear if the latter.

Jerry
Had those same problem on super c except for the lurch, found out it was the pilot bearing.
Jim

I took it for a short ride again this evening. The lurch and growl is just as it begins to move. They are both more pronounced in reverse than going forward. After it's moving, even going up hill backward, the lurch disappears. I probably just need to start with the throwout bearing and then if that does not have any slop or roughness, go further. Thanks for your advise. I appreciate it. Jerry

I experience the same phenomenom as you when putting it in gear. It takes several seconds to get in gear after engaging the clutch. I haven"t tried the pto trick but will do so. Also, every bad throwout bearing I"ve experienced has been noisy until applying a slight pressure to the clutch, then it goes silent.

Jerry: I don't have an A, but I have a Super A - so this may or may not totally apply to your situation....

As far as the "lurch" in reverse, these tractors have a pretty fast reverse gear - much faster than 1st gear forward - and it is very easy to get a lurch in reverse while letting out the clutch. That may, or may not pertain to what you are experiencing.

The A/SA/100/130/140 series of Farmall tractors are notoriously famous for emitting growls from the final drives. However, they generally growl all the time if they growl at all. If your growl occurs ONLY as you are letting out the clutch, then I'm with Scotty. But, if it growls pretty much all the time, it may be the nature of the beast. In addition, they may growl on the "coast" side of a gear, but not on the "drive" side. Mine for example, is quiet in reverse as I'm backing, but when I begin to stop in reverse ("coast"), it is more noisy. If you haven't already done so, I suggest you check your final drives for gear lube being up to "full".

Finally, I have owned more than a couple of these models and I have had to wait several seconds on all of them to keep from grinding when going into a gear. I consider that perfectly normal. The gears are not synchronized and therefore, there is no blocking ring on a slider to grab a gear and hold it from spinning while engaging the gear. Hence, the grind unless you wait.... An M and an H will do it too, although the A series seems more in need of a pause. Let us know if you find something.

mike

If you're going to open it up for the throwout bearing, satsop's idea on the pilot bushing is worth considering. IIRC, it's asimple bronze or maybe even an Oilite bushing in the center of the flywheel. It's intended to run without any additional lube, but if it gets crud into it (like dust in oil leaking from a rear main seal) it will get sticky instead of turning freely and cause the main shaft to keep turning, causeing the input shaft to turn even when clutched. One way to check that CAREFULLY without tearing down is to leave your PTO engaged and have a helper depress the clutch pedal with the motor running at a low to medium speed. If the PTO shaft is turning, it's likely the pilot bushing is gummed up. The CAREFUL part comes in when you try to see if slight resistance will stop the PTO shaft. Tractor off and in neutral, ignition OFF, either hold the shaft with your hand or hang a heavy pipe wrench off the PTO shaft and have your helper crank the motor on the starter only (Ignition OFF, no running!) and see if the shaft turns. Be prepared to let loose of the shaft or the wrench IMMEDIATELY if it starts to turn.

If it doesn't try to turn, it's likely a sticky pilot bushing making for the noisy shift. If it affirmatively turns, it may be that your freeplay is out of adjusment and the clutch is not completely disengaging when you press the pedal. If it's out far enough that the throwout bearing stays in contact with the clutch fingers, the growl could be what I described before, the throwout bearing beginning to go.

Normally, the bearing only turns when in contact with the fingers. When the clutch pedal is released, it should pull back to about 1/4" away from the fingers, not turning and therefore making no noise. A thoroughly bad throwout bearing will be noisy when pressure is applied. They will go out in different ways, but it is possible in the early stages for it to be quiet when away from the fingers, and quiet when taking the full pressure of the clutch fingers, but to growl and rattle some under intermediate pressures as the pedal is pushed and released.

Thinking on the lurching some more, though, and it being worse in reverse, it sounds more like one of the big ball bearings on the diff shaft or the axle. They can be a bugger to track down, as the noise runs all through the iron making it hard to pinpoint. Do you hear any kind of snapping or chunking sound when first changing directions, either forward or back, just before the growl starts?