3rd gear knock Updated 6-5-12

[Kevin - Illinois]

This weekend I worked with the stethoscope with the rear wheels off the ground and rear end connected...found the following...

Knock is not detected at the differential, torque tube, u-joint, transmission or clutch housing with the car in reverse, first or second gear

Knock is there and very loud in 3rd gear at the rear end, torque tube, and u-joint. It's loud but not "as loud" at the transmission and clutch housing.

So today I pulled the rear end, disconnected the u-joint and ran it. Attached is the video. You can hear a rattle in second and 3rd gears. Not sure if it's the same one since it's in two gears, and it does not go away when the clutch is pushed in...

https://www.youtube.com/watch?v=cNUNG...ature=youtu.be



Kevin

[d.j. moordigian]

I wonder if the out put shaft stops turning, in 2nd and 3rd, with the clutch depressed?

[1931 flamingo]

Knock does not seem to be as bad as previous videos. Backing up, was the pilot brg replaced/ck'd?? Did you try running the engine WITHOUT the tranny installed??
Paul in CT

[TinCup]

I don't hear it as much either.

[bogdonj]

Seems less noisier????

[H. L. Chauvin]

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Kevin,


Home laptop does not handle Youtube well -- sporadic sound not matching video -- agree with above comments. Will try video at office tomorrow.


Running out of suggestions; however, sometimes the impossible can possibly happen with Model A's. Page 43, Tom Moller's Green Handbook, Volume 2, his diagrams indicate differences in early & late transmissions; hence, the mixing & matching of early & late used gears, main shaft bearings, & transmission cases can cause problems, for example:



1. The very early transmission cases used thrust washers at both ends of the cluster gear, & the later cases were machined to eliminate thrust washers.



2. Also, the early transmission gear had the countershaft spacer machined into the inside of the gear, & the later cluster gear requires a spacer between the bearings as he indicates in his diagram.


3. Can incorrect mixing & matching possibly happen twice; i.e., with (2) transmissions?


We all started out trying to educate you -- then, the pendulum stopped & changed directions whereby you are now educating us, including your educating your engine builder. You have the Hotel Room Door Keys. Outstanding Room by Room investigation thus far.

[Tom Endy]

If you run the engine with the rear end removed and the U-joint removed the rear bearing in the transmission is not captured correctly and it can slide back and pour oil all over the place.

I rebuild Model A transmissions for a shop and years ago the owner tried to run the engine and transmission on a lift with the rear end removed. He also removed the U-joint so it would not flail around and batter the rear bearing retainer. He called me and said the transmission was pouring oil from the back. I explaned that the U-joint keeps the rear bearing tight up against the stop in the housing and against the stop on the main shaft. Since then he has modified a U-joint by removing the back section and just bolts the front section to the transmission.

Tom Endy

[H. L. Chauvin]

Kevin,

For the apparent reduction in mechanical noise -- could it be that:

a) Your audible volume was adjusted differently in this particular video? -- or,

b) If something is rubbing on a crankshaft bolt which is too long, it is wearing down whereby the tapping noise is slowly going away? -- or,

c) Could it be a protruding weld on a welded counterweight wearing away & making less noise? -- or,

d) Could it be any other moving metal to metal item just wearing away & making less noise?

Appears that if a particular condition is effecting audible sound & noise, there has to be a logical cause for same.

Not much help, but just thinking out loud.

[James Rogers]

Check the pilot bearing. I want to be proved wrong because, I think that's what it is.

[MrTube]

James, wouldn't the pilot bearing only make noise when the clutch is disengaged / slipping?

[Kohnke Rebabbitting]

Originally Posted by MrTube

James, wouldn't the pilot bearing only make noise when the clutch is disengaged / slipping?

You are right Mr. Tube!

[James Rogers]

Originally Posted by MrTube

James, wouldn't the pilot bearing only make noise when the clutch is disengaged / slipping?

Probably but it is such an easy check and eliminates that part. If someone suspects the flywheel housing, why not the pilot.

[d.j. moordigian]

James

In the flywheel?

[Patrick L.]

Are the flywheel to crankshaft bolts protruding too far ?? Was the flywheel dowel cover installed ??

[H. L. Chauvin]

Kevin,

1. You probably already have determined that:

A. The reason that the 3rd gear noise is louder on the other far end, (at the differential), is because the forward noise around the transmission is much louder in 3rd; & also,

B. If the 3rd gear noise is not eliminated when the differential is disconnected, the differential "alone" cannot be the source of the noise.

2. In carefully reading your above message #1, something to think about is:

A. Now that the differential is disconnected, & the U-joint has been removed, something "different" is happening such as:

(1) The noise does not subside when the clutch is depressed; &,

(2) The noise also now appears in 2nd gear, & now, also like in 3rd, the 2nd gear noise does not subside when the clutch is depressed.

3. There has to be a mechanical reason why noise conditions are different with this most recent test -- maybe somebody can chime in with a similar experience.

[H. L. Chauvin]

Kevin,

On second thought, the noise differences noted in your last message #1 appears to possibly be related to Mr. Tom Endy's message #7 above, noting that the main drive gear can move back & forth with the U-joint removed.

[Kevin - Illinois]

I've been asked to pull the flywheel housing. Can this be done with the engine in the car? I'm assuming to do this I have to pull the pressure plate, clutch and flywheel. Not sure what to think since this was a long block rebuild I paid for.

[CarlG]

The flywheel housing also contains the rear engine mounts. You'd have to support it somehow, and at the same time, all the rear-end stuff and the transmission would have to come out, including the flywheel itself in order to get at it.

[d.j. moordigian]

Kevin,

Why the housing? What is suspected with it? Was it checked for alignment when it was
installed on the engine?

[Kevin - Illinois]

Can I even do this with the engine in the car?