1939 transmission noise
 

Anyone have thoughts on how to diagnosis this transmission noise? Noise goes away when clutch is depressed. The clutch, pressure plate, pilot and throw out bearings are new and seem very good. Throw out bearing slides smoothly on the shaft, no hang up, no wobble. I pulled engine today, my feeling is the trans input shaft is the problem, it feels a little sloppy, not sure if it should be tight, but I can wiggle it up and down a little. Also twisting left and right, there’s some slop, again not sure what’s an acceptable tolerance? I have video, but for some reason, I can’t attach to this message.

Re: 1939 transmission noise
 

I think your video needs to be posted on the web, like on You Tube, and then the link to the video can be posted on this forum.

Re: 1939 transmission noise
 

It is normal for an INPUT Shaft to be able to wiggle up, down, left & right like that because it's being mounted in that big bearing is the only thing keeping it straight - WHEN the trans is not mounted to the engine. That is why the PILOT BEARING or Bushing is important. The snout on the input shaft fits snugly enough to just allow rotation in the center of the pilot bushing/bearing, which also holds the shaft concentric with a line drawn through the crankshaft's rotational centerline. Coop

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Re: 1939 transmission noise
 

When you depress the clutch the rotating parts in the transmission slow. I would think the problem is in the transmission.

Re: 1939 transmission noise
 

Noise that goes away when the clutch is depressed in most times the transmission input shaft bearing. The input shaft should only have a very small amount of movement if the bearing is good.

Re: 1939 transmission noise
 

It can also be the throwout bearing. New does NOT mean "good". I'd suggest you place just a bit of pressure on the pedal and see if the noise subsides. If it does, my money is on a poor quality throwout bearing.

Re: 1939 transmission noise
 

When the clutch is engaged, the whole input assembly is turning the same speed as the engine crankshaft. When the transmission is in neutral and clutch is engaged, the input and the cluster gear continue to turn right along with the engine so any bearings involved there can make noise if there is a problem.

When the clutch is disengaged and held that way, the throw out bearing and the pilot bearing are the only things turning along with the engine. Both quit turning right away when the clutch is re-engaged.

If this is all happening while the transmission is in neutral and the clutch is still engaged then it could be the main input bearing or the internal bearing between the input and the main shaft. Folks have been having problems with that roller that fits inside the main input shaft. The rollers on the cluster could also have a problem. Some of these caged rollers have been suspect as well but the longer ones don't seem to fail as easy as the short ones. Some counter shaft clusters use the free rollers and they don't seem to be problematic.

Used caged rollers are better than some of the new junk that has hit the parts sources over the past several years. NOS Ford stuff or old NORS aftermarket stuff is good. A person should contact Mac VanPelt for information concerning good caged rollers for the shafting. Some have mentioned that there are some good new parts available but I don't know myself.

Re: 1939 transmission noise
 

Occasionally the pilot nose on the main drive gear is worn undersize or the pilot brg is faulty. A snug fit is required between the nose and brg or the main drive gear will
squirrel around since as mentioned the main drive gear brg has some inherit wow to
it. The roller skate roller bearings readily available are a joke. Used are the best I cer-
tainly agree.Each roller should measure at least .1870 and cage should not rack.

An insanity job a while back had a similar issue, turned out the bearing bore in the gear end of the main drive gear was worn over size and the roller just slopped
around and of course tore up the pilot on the outp0ut shaft.
Charlie ny
PS or I just call Mac VanPelt

Re: 1939 transmission noise
 

Curious, the French flatheads used a bronze bushing for the pilot instead of bearing. Any pros/cons to a bushing vs. a bearing?

Re: 1939 transmission noise
 

There is normally some play in a transmission input shaft before it slips into the pilot bushing.

This is hard without hearing it in person. First off, just because the parts are all new does not mean they are not defective. I have had to go back in and replace many defective "rebuilt" clutches as a fleet mechanic. They get boxed wrong; you name it and I have had it happen to me. Never-ever-ever turn your core parts in on anything your working on until the job is done, just incase you need to go back and figure out what went wrong you still have the original parts. Take the new clutch disc and pressure plate and sit them on a bench and compare their heights to the originals. Not the same height than you have a problem. Next take the clutch disc and stick in on the input shaft. It's a lot easier to find out now the splines don't fit instead of when you are putting the trans in. I learned that one the hard way on a wrongly boxed disc. Next make sure the Throw-out bearing fits on the bearing retainer. Make sure the pilot bushing fits on the input shaft and it spin easily. I also learned that one the hardway, I got a brass pilot bushing that was either boxed wrong or machined wrong. I kept trying to put the trans in and it would not go that last little bit. I never again put a pilot bearing in without first sticking it on the input shaft first. Make sure the disc is not backwards, some cars you can put them in backwards and some you can't. Don't trust the decal that says flywheel side. You really should have the flywheel surfaced, especially if it has blue hot spots, grooves or a dial indicator says its not flat. It's not always necessary, especially on the fleet vehicles I worked on but on my personal car I would definitely have it ground. I would buy a quality "new clutch and not a rebuild. Once you bolt down the pressure plate measure the fingers to make sure they are adjusted evenly. Lastly, don't put floor mats, trans covers and stuff like that back on until you have test driven it.


Normally the throw-out bearing would be the noisy culprit when you push the clutch in but its new. Just to make just take your fingers and push the clutch pedal until you feel the throw-out bearing make contact. That's the only thing spinning at that point. It should feel nice and smooth.

When you push the clutch all the way down, and while stopped, and while in neutral, nothing in the trans should be turning but it can happen. If the pilot bushing/bearing is too tight on the input shaft. It will grab onto the input shaft which will it and the cluster gear. That would make it hard to shift and If the front bearing, input shaft needle bearings, cluster gear bearings or shaft were worn you might hear them while parked. They might only make noise while driving when there is a load on them, just depends on how worn they are. If you were to shift it into 3rd-gear that would lock the input shaft to the main shaft and prevent the input from spinning if the pilot bearing was too tight Then there would be no way for anything to spin in the trans and you could eliminate the trans as the cause of your noise.

I'll trade you problems. My daughter's 150K mile Scion just broke a clutch. Something let loose inside there, and it won't disengage. Definitely the clutch itself and not its hydraulics. Not bad for getting that many miles out of the original clutch that was girls first car. I bought her a brand new stick shift Scion back in 2006 because I told her your going to inherit all these cars in the garage someday and not one of them is an automatic. I have a nice hoist to do it on and a trans jack. I just need to move a bunch of engines, roll out a '32 roadster from under the hoist. Put a frontend under the '34 pickup that is up in the air so I can roll it out of there and then I can get the Scion up in the air, sit on a stool and install a "new" factory Toyota clutch. I'm never crawling on the ground again to put a clutch in, I'm too old for that!!!

Re: 1939 transmission noise
 

Excellent comments and advice given by Flathead Fever above……..

Re: 1939 transmission noise
 

I love Flathead Fever's Comment:

"I'm never crawling on the ground again to put a clutch in, I'm too old for that!!!"

I second that opinion. I remember all the clutches and manual transmissions I removed while on my back in the dirt or on the concrete. How many times did I drop the tranny right onto my chest (seemed the best place for it) - and manhandle it back into place from back on my chest.

Now, it would have to drop on my "belly" . . . as my chest seems to have disappeared! LOL. I think I'd need taller jack stands . . .

Re: 1939 transmission noise
 

A lot of us have the furniture disease! Our chest fell into our drawers!