Transmission Issues

1942 Pattern 13

C60S

Transmission Update after 5 more years of running the transmission lost a tooth in the lower cluster. See 3 Ton Transmission for information on searching for parts and repair.

Recently I posted the following thread to the MLU Forum

C60S Transmission Question
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I have notice a new vibration or catch in the transmission on my C60 (which I just installed a new engine). The problem only occurs during deceleration in 3rd gear on steep hills. It takes the form of a intermittent catch felt through the gear shift lever. As anybody else noticed a similar occurrence, if so did you discover a cause.

When I had the transmission out I did disassemble it to check for wear (it has been 18 years since the truck was restored) there was no metal chips in the case I strained the gear oil and ran it through fine filter with strong magnet to see if there was an unusual amount of metal particles which there were not. The only part showing wear was the pilot bearing area of the main shaft. I'm wondering if it is just bearing chatter on the pilot bearing. See picture.

I sort of expect the response - of course that is the problem, I'm already looking for new main shaft and bearing, but I looking for input so I can fix it once.


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Phil Waterman

#2 Yesterday, 11:59
cletrac
David Pope Join Date: Jul 2003

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Phil, the only time you get any movement in the pilot bearing is when the clutch is pressed so that's not your problem. The problem would have to lie either with the 3rd gear on the main shaft or in the cluster gear bearings or the center bearings on the main shaft.
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#3 Yesterday, 12:47
Phil Waterman


Terminology Difference

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Quote:
Originally Posted by cletrac
Phil, the only time you get any movement in the pilot bearing is when the clutch is pressed so that's not your problem. The problem would have to lie either with the 3rd gear on the main shaft or in the cluster gear bearings or the center bearings on the main shaft.

Hi David

Thanks for the response, my picture choice was poor resulting in a difference in part terminology, I was referring to the Pilot Bearing 4.352 the picture I posted is unclear it is of the Main Shaft 4.403 and not the Main Drive Gear 4.351. (see exploded view picture) Good point though the I did replace the pilot bearing in the flywheel of the new engine so that it would mate correctly with the original transmission.

The pilot bearing on the main shaft is turning in all gears accept 4th, which adds to the confusion because I only have noticed the "catch" or single chatter in 3rd gear when going down fairly steep grades 6-8% (steep for on road).
Attached Thumbnails

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Phil Waterman

#4 Yesterday, 14:12
Alex Blair
Registered User Join Date: Feb 2003
Location: Ottawa ,Canada
Posts: 1,931

Wear...

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Quote:
Originally Posted by cletrac
Phil, the only time you get any movement in the pilot bearing is when the clutch is pressed so that's not your problem. The problem would have to lie either with the 3rd gear on the main shaft or in the cluster gear bearings or the center bearings on the main shaft.

Hi Phil..
I agree with David..some good close up's of third gear and the cluster may tell the story better..sounds like wear on the gear faces..straight cut gears will show this wear and are more susceptible to this than angular cut gears,although all gears wear..prolonged usage of third gear would would induce wear that would only show on those gear faces..
And unfortunately the wear is can not be adjusted ,as shimming the crown and pinion to adjust for proper load clearances..
But it is measurable..put in the old bearings and reassemble the transmission..
Then turn the transmission slowly by hand and feed a length of plastigage through the teeth of third gear...record your clearances..
Then replace the bearings and do the same thing and the difference in clearances should be measurable..If there is no difference it will be the gears..
The consistency of the clearances,which will show up on the plasticgage will also tell you if a shaft is bent or a gear is warped
Enjoy..

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Alex Blair

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Last edited by Alex Blair : Yesterday at 14:16. Reason: Left out a line..

Alex Blair


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Or wear on the splines in the bore of the third sliding gear and/or on the splines on the splines on the mainshaft in that area. I see that the reflection on the mainshaft appears different in that area of the spline. This will cause the gear to cant over or twist and decrease clearances, thus binding up, or else radial backlash will cause the crown of one gear to mesh higher up the face of another gear rather than centrally in the valley. Is there any signs of galling on the faces of the teeth?.
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This thread is useless without Pictures!

I totally agree with Tony this thread without good pictures is useless

To post pictures large enough to see wear on the gear assemblies I brought the thread pictures over to this my website so not to use MLU bandwidth unnecessarily.

 


Look to the right of the pictures for notes on the pictures

 

 

This pictures shows the rigging I use to remove the transmission form the truck. As I work alone I have to modify the way that you might use if you were working in a normal shop.

I have a steel box tube cut to fit between the rear of the cab and the windshield frame. This allows me by removing the floor plate over top the transmission to lower the entire transmission out through the bottom. This is also useful in servicing the clutch as you can remove the clutch without taking out the engine.

Here you see the transmission lowered to the floor. Cardboard is just to keep trash from falling into the transmission during the process.

This is the picture 2008 shows the condition of the gears. First thing to note is the rust marks on the gears. This CMP like many others had water in the transmission when it was first restored in 1990. The picture below shows the condition of the transmission in 1990.

 

Despite the rust damage the transmission has operated without problems for 12,000 miles.

When I drained the transmission I ran it through a coffee filter with a strong magnet to attract metal particle, not much showed up and there were no steel bits.

 

Note rear of transmission is to the left

Picture taken 1990 shows water damage at that time. At that time the transmission was completely disassemble and all the gear faces were buffed with a mild abrasive to remove as much of the rust as possible, but with out trying to grind out any of the pitting.

 

Note rear of transmission is to the right

1990 In this picture you can see that the transfer case shift tower shows evidence of water having gotten in.
2008
2008
2008 Lower cluster front bearing
2008 Lower cluster
2008 Lower Cluster rear bearing
2008 Lower Cluster Rear Bearing

2008 Main Drive Gear # 4.351

 

These pictures are repeated with different section of the shaft brought into focus

2008 Main Drive Gear # 4.351

 

These pictures are repeated with different section of the shaft brought into focus

2008 Main Shaft 4.403

 

Note the bearing surface on the front shaft which rides in the roller cage bearing inside the Main Drive Gear.

Wear in the area of the first reverse gear and third gear slide gears is visible but does not seem excessive.

2008 Main Shaft 4.403

Close up #1

Note the bearing surface on the front shaft which rides in the roller cage bearing inside the Main Drive Gear.

2008 Main Shaft 4.403

Close up #2

Note the bearing surface on the front shaft which rides in the roller cage bearing inside the Main Drive Gear.

2008 Main Shaft 4.403

Close up #3

Note the bearing surface on the front shaft which rides in the roller cage bearing inside the Main Drive Gear.

2008 Close up of the Main Shaft Pilot Bearing 4.352

Note the bearing surface on the front shaft which rides in the roller cage bearing inside the Main Drive Gear.

2008 First and Reverse Gear 4.417
2008 High Speed Gear and Counter Shaft Drive Gear (?) 4.415
2008 Revers Lower Cluster Idler Gear 4.430

2008 Revers Lower Cluster Idler Gear 4.430 Bushing 4.431

2008 Inside of transmission case
2008 Outside of the transmission case rear

2008 Outside of Counter shaft Bearing 4.22