Transmission gears questions

[Bruce_MO]

10 minutes after I started up my '30 tudor after a years-long restoration, I heard a loud "bang" and I immediately realized that something bad happened in the transmission. I pulled the top off to discover that some small metal object (screw, nut, ???)that had fallen in when things were open went thru between the main drive gear and the cluster gear. One or two teeth on each were slightly damaged but not broken. I dressed them down lightly with a die grinder (only the top edges of a couple teeth were burred, maybe 1/16" to 1/32" in length) and decided to drive it to see what I had. It was pretty noisy in 1st and 2nd, so I decided to pull it apart this winter, assuming I now had some bearing problems as well (I have another unrestored A as a baseline, so I know this transmission is extremely noisy). With it all apart, there was no other obvious bearing damage (they were all new 30 miles ago), and now I'm looking for advice...

1) with all parts out, I see that I left a few burrs on 2 teeth; they have small bright spots. I can do more dressing with a Dremel grinder and can easily leave 95+% of the tooth are intact. The damage is very slight on the teeth and I've seen much worse gears come out of "A" transmissions. After grinding, the top edges of a couple teeth will have an area about the size of the head of a pin dressed down. The main drive gear was new repro and the cluster was used but in excellent condition. Any advice on the merits of grinding on teeth? The gears are too nice to pitch and I want to minimize cost.
2) I can't feel any roughness in bearings, but I'll replace them all. As noisy as the box was afterward, is it likely that I did indeed damage one?
3) The low/reverse sliding gear is pretty loose on the main shaft (2nd sliding gear is a lot better). The shaft is 1.250" OD (it was a new repro) and the gear is 1.2503" ID. The looseness at the splines is noticeable; it almost seems like the gear can "rock" fore and aft on the shaft a small amount. I know there's supposed to be a very snug fit that may require slight pressure to slide the gear down the main shaft. The gear is also an excellent used one, and none of my spare gear and main shaft combinations are better. Is that a major source of noise?

Thanks for any advise you might have.

 

[Jason in TX]

Did you look at the case? Is there a crack where the shafts come out the back? a nut forced between the teeth could have pushed the rods that run through the cluster gear and the sliding gear apart, causing the case to crack and perhaps the case is flexing or the shafts the gears ride on are not tight anymore. Just a guess...

 

[Bruce_MO]

I'll look again...didn't see anything the first time and I don't have any dye penetrant stuff...

Thanks

 

[rotorwrench]

Another thing to check, if you have a way, is the runout or slight bend in any of the affected shaft components. If the mainshaft front tip gets bent, it could potentially make a lot of noise. Same for the countershaft that the cluster rides on. You can roll the coutershaft on a surface plate and check it that way pretty easy. The mainshaft might be better to use live centers or a lathe to check it.

Kerby

 

[glenn in camino]

I once put a trans together with a mix of repo and original gears. I drove it noisily once around the block and took it out. I now believe in good used gears that have been together for a while and new bearings.

 

[Milton]

I once thought I lost one of the clutch inspection plate screws into the opened trans. I fished around with a magnet looked with a dental mirror. Examined the dirt under the car and never found that screw. Many days later I was pulling forward in the driveway and the rear wheels locked and then freed up. As I moved the car there was a massive clunking sound. I pulled the trans cover and moved the car and, lo and behold, I had found the missing screw crammed between the gear teeth in the second/high gear slider. I hammered it out and put the top plate back on and drove on with no future problems. God bless the ignorance of youth and 600W trans oil.

 

[RonC]

your better off finding another good used transmission with good gears and replace the bearings.

 

[Tom Wesenberg]

This picture shows the cover I made to keep junk out of the ****** while I work on it, and the handle to help lift the ****** in and out of the car.

This third picture shows an easy to make stand to be used while working on the transmission. The flange plate isn't really needed, and I've made other stands by just inserting the pipe into a piece of 2 x 12, or 2 x 10.

When I first tried to drive my Model A the ****** sounded like a broken down threshing machine as soon as I let out the clutch, so I pulled the ****** and took it apart. Everything inside looked like NOS, except the small bearing between the input and output shafts. It had a couple of ground up rollers. You'd never think such a racket could have come from that little bit of damage. I replaced the bearing and now it's quiet as can be. Had I put the rear end up on jack stands and shifted to high gear and released the clutch, the ****** wouldn't have made any noise, since the bearing wouldn't be turning. Just another check for the next time I have to diagnose a ****** noise.

I would be suspect of that loose gear you mentioned, where it can rock on the shaft. Also look inside the cluster gear for any pits or roughness where the 3 roller bearings ride.

When you used the Dremel to dress the gear teeth did the grindings go inside the ******? Or, was the ****** apart?

Was the flywheel cover dialed in?

 

[BRENT in 10-uh-C]

First off, what gear lube was in the transmission? With too thin of lube, transmissions are indeed somewhat noisy just because of the gear design.

The next thing I think you should be hearing is a clicking or pronounced sound as the "off-center" gear comes around if there is an issue with a bent shaft.

Since you claim that money is an issue, inspect the bearings closely with a magnifying lamp. If the rollers do not show signs of damage and are not loose in the cage, consider re-use for the immediate time. As far as the gear(s) is/are concerned, it is possible you did not fully debur them. A flat file will possibly be a better option since I am sensing none of these gears were "new" (i.e.: NOS, NORS, --but not old repro.) when installed.

My only reason for suggesting you disassemble, inspect and then reassemble is you have the capability to make the repairs yourself if indeed there is an issue. It is very possible that if you not find any obvious damage to the bearings, shafts or case, then upon reassembly and installing proper 600wt, you will find after driving it for a few hundred miles that the gears become "friendly with themselves" and the noise all but goes away. If it decides to disintergrate after a few miles, it sounds like you have not lost anything other than some of your time.

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