1939 tramsmission CLank sound

G

guy1unico

Well-known member
This just started happening today. For over 10,000 miles this transmission has shifted like butter. I will check fluids tomorrow in the meantime there is a continuous clanking sound in 1st and 2nd but not third and the car still shifts fine. Can you think of anything causing this noise other than the fluid level?
Also what type of grease would I use in the transmission case?

Thank you,
Guy
 
In first and second gear the power comes in the input shaft, goes down to the cluster and then back up to either first or second gear, which ever one is coupled to the main shaft and cluster at the time and then out the output shaft. In third gear, the input shaft and output shafts are locked together by the third gear synchronizer, so the power goes straight in through the input and out the output shaft. It's like one solid shaft in third gear. The cluster gear is still being turned by the input shaft but since the cluster gear is only turning gears not driving the main shaft there is no load on any of the gears, so they are quiet. No power is being directed though the cluster or first and second gears. Being quiet in third gear tells you that most likely the cluster, first or second gear broke a tooth. Especially if this noise just abruptly started. If it was a clunking U-joint, it would probably be noisy in all gears. You can take it further and say that if it was only noisy in second gear and not in first than either second gear or the cluster gear that drives second gear broke. Same for first gear. But if its noisy in both first and second gear than possibly the cluster broke at the front where it's driven by the input shaft or the input shaft tenth that drive the cluster broke. I'd drain it and see if any teeth come out.

Here is good video of a 4-speed that shows the power flow so you can visualize it. Same basic concept as your 3-speed. Choose which gears are noisy and then which gears they share in common that would be under a load. That might not be your problem but it's where I would start.

https://www.youtube.com/watch?v=K2IfBlea9cc
 
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My dad had a '32 3-window with a stock 265 Chevy coupled to a '39 trans. One day he just accelerated hard, no revving and dumping the clutch (so he claimed) and second gear vanished like it wasn't there anymore. He drove it that way for a while. If I had not driven it before I would have sworn somebody forgot to install it. Here are a couple photos of it. That was neat '32 3-window, except for no second gear, not even the slightest click out of it. All Ford sheet metal, stock '32 frame. I should have bought it from him. One of my top three all-time collector car mistakes.
 

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Flathead Fever said:
My dad had a '32 3-window with a stock 265 Chevy coupled to a '39 trans. One day he just accelerated hard, no revving and dumping the clutch (so he claimed) and second gear vanished like it wasn't there anymore. He drove it that way for a while. If I had not driven it before I would have sworn somebody forgot to install it. Here are a couple photos of it. That was neat '32 3-window, except for no second gear, not even the slightest click out of it. All Ford sheet metal, stock '32 frame. I should have bought it from him. One of my top three all-time collector car mistakes.
Click to expand...
509387

509388
 
The addition of a lot of sawdust has been tried to minimize gear noise as a short term fix
Drain the oil and see what comes out, had it happen to a MG I was driving, drained the smaller pieces out, soon after I just had 4 th gear, drove with just 4th for 6 months
 
Flathead Fever said:
My dad had a '32 3-window with a stock 265 Chevy coupled to a '39 trans. One day he just accelerated hard, no revving and dumping the clutch (so he claimed) and second gear vanished like it wasn't there anymore. That was neat '32 3-window, except for no second gear, not even the slightest click out of it.
Click to expand...

Man, I'd be proud to own that 3-Winder even WITH NO 2nd gear! That's a sweetheart.... perfect chop!

Coop

509387
 
Got under car drained the oil. actually the trani case looked super nice not all greasy and beat up. The oil looked clean and no metal parts came out. I put all the oil back in and we still have that wire rib sounding clank.
 
It is good news that you didn’t find any metal chunks come out with the oil. You might check the bolt that holds the u-joint to the output shaft, if it is loose you will have excessive endplay in the trans. I had one come loose back in the sixties, which was probably due to my inexperience. I don’t remember if it made a noticeable noise. It beat the crap out of the washer.
 
How loud is this sound? A broken tooth is pretty noticeable. I would think some metal would have come out of there when you drained it if a tooth broke but it could still be laying in the case. You might try pulling the top off and draining it (again) and see if you can spot anything wrong. Drop a magnet down in there and do some magnet fishing. If you don't find anything you might try jacking up the rear end and jack stands. Slide it into first gear by hand and see what it sounds like with the shifter top off. You can run the trans for a little while with it drained Cover the trans with something, so it doesn't fling gear oil all over the place. Just don't lock it into two gears at the same time, that could break something, it locks the trans up solid so it cannot turn.

Right now, I have three 1948 Ford 8N tractor projects. I buy good ones cheap with problems. I'm going to help each grandkid restore one, there just little guys but they love tractors. Why not brain wash them into being vintage Ford guys at the same time. I have one that the guy was discing in second gear. All he did was come to a stop and put it in first gear and the trans locked up and it will not move. Stalls the engine the second you engage the clutch. He pulled the trans cover and tried prying the gears back into neutral and they won't move. I paid $500.00 for it, good tires, new battery, alternator conversion, runs great as long as the clutch is held in. I have not researched it yet. Th owner said there is something that breaks in there requiring the tractor to be split into two halves to repair it which isn't that bad of a job. I've replaced some clutched on those 8Ns before. I bought another one for $700 that is a real good tractor. The guy replaced a leaking head gasket and then it wouldn't start afterwards. He replaced everything trying to figure it out and then got so mad he bought a new $40,000.00 Kubota. It has a distributer like an Early Ford with the coil on top of it. When he put the coil back on, he bent that wound wire coming out of the bottom coil and grounded it out. That was an easy fix.
 
The rebuilt transmission may have some of those substandard roller bearings that have been failing as of late. One is inside the input pinion mating with the main shaft and the other two are inside the cluster gear mating with the counter shaft. If one fails it starts making noise due to the abnormal movement of the parts associated with them. It will get worse over time is that's the case.

A person can also have a problem with the pilot shaft bearing in the flywheel.
 
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rotorwrench said:
The rebuilt transmission may have some of those substandard roller bearings that have been failing as of late. One is inside the input pinion mating with the main shaft and the other two are inside the cluster gear mating with the counter shaft. If one fails it starts making noise due to the abnormal movement of the parts associated with them. It will get worse over time is that's the case.

A person can also have a problem with the pilot shaft bearing in the flywheel.
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That's a good point. That would be another reason it would make noise in first and second and not third. I don't think of these things, because when I was rebuilding transmissions and rearends at the phone company it was still all USA parts.
 
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