VCCA Home Forums TECHNICAL - 1945 AND NEWER 1946-1948 Transmission noisy

I recently got my ”˜46 coupe up and driving. It is stock except for the later model 235. I drove it around the neighborhood with open headers for a time or two, but have since installed exhaust pipes coming out just before the rear wheel wells. Now I can hear the transmission which sounds like you threw a hand full of gravel in it. The sound is in every gear and worse when you let off the throttle. Any ideas on causes? Most likely to least likely.

I would start with the U joint. If it is OK pull the transmission. First make sure the transssion is full of gear oil
If it is the transmission it is probably the cluster gear and more.

I agree with Gene,

There isn't much moving around in the transmission case when in high owing that it's a straight shot from input shaft to U-joint. So if it is making noise in hight as well as low and second then most likely is the U-joint. Just 14 little bearing pieces in from and a roller bearing in the rear. Not likely either of those.

Forget Gene's advice on checking for oil before taking the transmission out. I would take the transmission out before checking for oil. That way if there indeed oil in in the transmission then you already have it out. See? Clever is what we are down here in NC. Oh, yeah.

Best,

Charlie

There is definitely oil in the transmission. I’m using a GL-4 . Unfortunately it had a GL-5 in it when it sat idle for a few years , never circulated through it. I didn’t know any better. I’m hoping that the brass wasn’t corroded badly.

The brass is only in the synchronizers. Even if there was deterioration of them due to GL-5 (which I really doubt) I do not think they would be the source of noise.

It just is NOT the gear oil.............GL-5 never caused a problem.

Ditto what Gene said.
We have several transmissions that have had GL-5 in them for over 45 years now.
NO problems.

I was under the impression that brass components would corrode from a GL-5 fluid if it doesn’t state that it is safe for brass. This info has come from sources in car forums. I hope the noise is from a U-joint and not transmission. Much easier and cheaper.

Re read the 2 previous posts... then contact every single supplier of GL-5 you can think of and ask them if their oil harms non ferrous transmission parts.

Trans is probably just worn a bit,when I got my 37 on the road the trans was noisy so I found another and it was a little quieter so I went back to where I got the trans and picked up the rear end and it was much quieter after it got installed.

I believe that I may have found the source of the transmission problem. I pulled the speedometer driven gear, and it is ground down on one side. Apparently it was seized. That would certainly sound like a hand full of gravel while being ground down. I haven’t taken the car for a spin, but hopefully this is the problem and now I can drive it. Anyone think I should pull the cover off the U-joint and flush out any material from the gear? I’m kidding. Of course I will. I’m keeping my fingers crossed that I can go for the cruise in this Saturday. My question is, Is the speedometer drive gear of a more hardened steel than the driven gear? I hope so. I have a transmission from a ”˜50 and can rob the driven gear from it, but would hate to trash it if the drive gear is damaged, too. Besides, a speedometer is highly overrated anyway!

I agree that the need for speedometers in these classic cars is over-rated!

I suggest 2 things to do before you simply install a new driven gear. One is what you suggest. Try to examine the driving gear. If it is damaged I would not sacrifice another driven gear.

The other is to determine why the driven gear failed. My best guess is that something in the housing that bolts into the transmission bound up or the cable stuck in the housing. Once again, until you have an idea about what caused the failure I would not just replace the driven gear.

Speeedometer gears were sold only in matched sets. I am sure you will find the 1950 gears are not the same or will not match-up with your originals.

Oh happy day! I pulled the driven gear and it’s identical to the one from the ”˜46 trans. I haven’t had a chance to look at the drive gear in either transmission, but I’ll inspect the one that is in the car and go from there. Looking at the manuals, it looks like the drive gear may be the same also, just different spacers. I’m hoping for a chance to take the car to the cruise in for it’s debut this Saturday before the season ends. I’ll plug the hole for the cable and go if no other problems.Keep your fingers crossed. I need it , the’50 isn’t running well. It acts like the accelerator pump is not working right. This on a rebuilt carburetor.