39 Tranny troubles

[Bored&Stroked]

While the grease may cause an issue with the syncro "biting" into the cone on the input shaft, it doesn't explain the weird "grinding" noise you mentioned . . . so my guess is that there is still something else going on.

BTW: I'm not very good at driving gently, so I have no clue as to if that will help anyway! LOL. I've always found that when something makes a weird noise more than once, it is going to happen again . . . and maybe when I'm far away from home at night!

[Shoovel]

Solidaxle,
I’ll share my experience with you. I rebuilt the trans in my 39 Coupe shortly after I purchased it. It would grind always going into 2nd. I bought VanPelts book, great info. I spoke to several people in the know. I used parts from VanPelts and a supplier here in Canada. I replaced the input and output shaft bearings with sealed bearings. (Some folks remove the inside trans sealing, I did not.) I replaced the syncro assembly with an updated one and both brass blocker rings. I found a NOS 2nd gear and a good used reverse idler. (Reverse idler was badly pitted) If you replace the 2 main bearings, MAKE SURE you use the original snap rings or the proper thickness ones from VanPelts. If you use the snap rings that comes on the new main bearings, you’ll be in a heap of trouble. Ask me how I know. These trans are over 80 years old, so they leak a bit. I use 140 GL4 oil and shift it gently.
Hope this may help you. Good luck.

[solidaxle]

Originally Posted by Bored&Stroked

While the grease may cause an issue with the syncro "biting" into the cone on the input shaft, it doesn't explain the weird "grinding" noise you mentioned . . . so my guess is that there is still something else going on.

BTW: I'm not very good at driving gently, so I have no clue as to if that will help anyway! LOL. I've always found that when something makes a weird noise more than once, it is going to happen again . . . and maybe when I'm far away from home at night!

I here ya! I usually go a little overboard rebuilding things so I can avoid breaking down on the road.

[solidaxle]

Originally Posted by Shoovel

Solidaxle,
I’ll share my experience with you. I rebuilt the trans in my 39 Coupe shortly after I purchased it. It would grind always going into 2nd. I bought VanPelts book, great info. I spoke to several people in the know. I used parts from VanPelts and a supplier here in Canada. I replaced the input and output shaft bearings with sealed bearings. (Some folks remove the inside trans sealing, I did not.) I replaced the syncro assembly with an updated one and both brass blocker rings. I found a NOS 2nd gear and a good used reverse idler. (Reverse idler was badly pitted) If you replace the 2 main bearings, MAKE SURE you use the original snap rings or the proper thickness ones from VanPelts. If you use the snap rings that comes on the new main bearings, you’ll be in a heap of trouble. Ask me how I know. These trans are over 80 years old, so they leak a bit. I use 140 GL4 oil and shift it gently.
Hope this may help you. Good luck.

I also replaced the clips under Van Pelts advise.

[solidaxle]

Originally Posted by Bored&Stroked

While the grease may cause an issue with the syncro "biting" into the cone on the input shaft, it doesn't explain the weird "grinding" noise you mentioned . . . so my guess is that there is still something else going on.

BTW: I'm not very good at driving gently, so I have no clue as to if that will help anyway! LOL. I've always found that when something makes a weird noise more than once, it is going to happen again . . . and maybe when I'm far away from home at night!

Maybe I'll button it up and give it a good pounding. Sink or Swim. HaHa.

[Mart]

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Originally Posted by solidaxle

The rake is not too radical. I do not have a dropped axle. The front spring is lowered, but so is the rear, I have Biggie/ little tires.

I just wanted to point out that lowering the rear does not offset lowering the front with regards to oil migration.

Lowering the rear adds to the problem because in lowering the rear you lower the middle also by a lesser amount. The lower the clamshell area the worse the potential problem.

This might not be what the problem is in your case, but I just wanted to mention it, as when reading your statement it sort of implies that lowering the rear makes it better.

[cadillac512]

You've probably already ruled it out, but if not, might check the output shaft for end play due to the bolt/nut at the u-joint loosening. When I purchased my Merc that bolt had backed out into the u-joint and was causing noise and shifting problems. The output shaft was moving front to rear of course.

[rotorwrench]

Two important items have had recent history of problems on new reproduction parts. The short caged roller that fits inside the input shaft & pilots the main shaft has been failing. There have also been problems with the blocker rings not fitting correctly.

Mac VP is the guy to talk to about these items and how to recognize the possible problems.

The U-joint cavity only needs to be about half full using the JD corn header gearbox grease. I would use SAE-90 GL-4 Stay-Lube unless there is a seepage problem. Straight SAE-140 is pretty heavy stuff unless the climate is high temperature. I still use SAE-50 Aircraft grade motor oil with no Lycoming additive in my old overdrive transmissions. It's equivalent to SAE-90 gear lube.

[solidaxle]

Originally Posted by Mart

I just wanted to point out that lowering the rear does not offset lowering the front with regards to oil migration.

Lowering the rear adds to the problem because in lowering the rear you lower the middle also by a lesser amount. The lower the clamshell area the worse the potential problem.

This might not be what the problem is in your case, but I just wanted to mention it, as when reading your statement it sort of implies that lowering the rear makes it better.

I see your point, the rear spring only effects the body the front spring effects the frame and body in relationship to frame rake.

[solidaxle]

Originally Posted by cadillac512

You've probably already ruled it out, but if not, might check the output shaft for end play due to the bolt/nut at the u-joint loosening. When I purchased my Merc that bolt had backed out into the u-joint and was causing noise and shifting problems. The output shaft was moving front to rear of course.

It crossed my mind to check it. Figures, I just had the torque tube off to replace a bad shaft/pinion coupler pin. It would have been the time to check it. Oh well!

[solidaxle]

Update:
I filled the transmission with fresh oil and test drove. Went 5 miles and stared hearing the same old noise. It sounds more like a bearing growling then a grinding. Much to my disappointment, the U-joint grease in the case is not the problem. On to pulling the torque tube and checking the U-joint bolt for tightness.

[Mart]

Ok lets try and think this through.
Does the noise happen at a certain engine speed or at a specific road speed?
Does the frequency go up and down with road speed?
Does it happen in First? If so at what speed (engine or road).
Does it happen in Second? If so at what speed (engine or road).
Does it happen in Third? If so at what speed (engine or road).

What happens if you are driving along (lets assume in top gear) and the noise starts, what happens if you select neutral and coast. Does the noise continue?

This may be a long shot but do you have a mechanical speedo hooked up? What happens if you disconnect the cable at the torque tube end?

Can you make a recording and post it up on youtube?

Come back with some answers and we might be able to home in on it.

Mart.

[solidaxle]

Mart,


It happened 5 miles into the test run, while in third gear. Sounds like growling, then it stops.
I turned it around at that point and it went through the gears just fine, no noises.
The final 1/2 mile back home I left a traffic light and turned up a hill and it started in first then shifted to 2nd, still had the growling, then third, still growled. Finally it straightened out and I was back at the garage.


It does it in neutral also and when I push in the clutch. There doesn't seem to be a specific RPM or a change to make it happen or stop.


I do have a mechanical speedo. The noise sounds more aggressive then anything the speedometer gear would make. The speedo gear doesn't lock in place, it's free to move up and down the shaft within the limits of the clip and bearing.



When I last installed the torque tube there was an extra washer/shim between the speedo gear and bearing that I removed. So the order of things now on the torque tube is


Clip
Speedo gear
Washer or call it retainer.
Bearing
As shown in the Green book.




I'm going to pull the torque tube and make sure the u- joint is bolted up tight.

[Mart]

Before you pull anything disconnect the speedo cable at the torque tube and try it.
I had a dry bearing on the speedo on my Model A Roadster (Old Rusty) and the noise was so loud I thought it was the gearbox. I just happened to touch the speedo face and it was buzzing at the same frequency as the noise. I was just at the point of pulling the engine and box or the axle. The speedo is still disconnected now!
Fingers crossed it is something that simple.

[rotorwrench]

From that last test drive going up a hill was mentioned at start of noise. If load sensitive then it could be a thrust issue or just strain. The harder the pull on helical gears the more the trust load but everything in there receives more loading including bearings. If the speedo checks out OK, I'd be wondering about a bad bearing in there somewhere. With a bad bearing, the noise will just get worse over time.

[solidaxle]

Originally Posted by Mart

Before you pull anything disconnect the speedo cable at the torque tube and try it.
I had a dry bearing on the speedo on my Model A Roadster (Old Rusty) and the noise was so loud I thought it was the gearbox. I just happened to touch the speedo face and it was buzzing at the same frequency as the noise. I was just at the point of pulling the engine and box or the axle. The speedo is still disconnected now!
Fingers crossed it is something that simple.

I'll give it a try. Maybe pop off the speedo gear on top of the torque tube and put tape over the opening.

[Lawson Cox]

With things being like they are today, I would be hesitant to use the slang term "TRANNY" any more and just call it a transmission. I never liked the terms Tranny, dizzy etc. anyhow. My 2¢.

[solidaxle]

Update:


Dropped the rear end and removed the torque tube, sure enough the universal joint bolt and washer were loose. Cleaned it up and put lock-tight on it. Should be good to go now.


Just to make things a little easier next time. I looked for 7/16 fine thread coupler nut for the two top cup bolts that are a PITA to get a wrench on. No such luck finding them locally. I'm going to weld two nuts together to get the extension I need.

[Tim Ayers]

Originally Posted by solidaxle

Update:


Dropped the rear end and removed the torque tube, sure enough the universal joint bolt and washer were loose. Cleaned it up and put lock-tight on it. Should be good to go now.


Just to make things a little easier next time. I looked for 7/16 fine thread coupler nut for the two top cup bolts that are a PITA to get a wrench on. No such luck finding them locally. I'm going to weld two nuts together to get the extension I need.

Great news and good idea about the nuts. Even with the "correct" reduced size Ford nuts, it's a tight fit.

[Mart]

Glad you found the issue. having the nut loose can cause damage in the transmission.