keithb7

Symptoms Of Clutch Pilot Bushing Wear

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Posted (edited)

For the sake of my own curiosity, I am interested in learning what some symptoms are of a worn pilot bushing. I am going ahead to replace mine now,  as I chase an odd little rattle noise in the drivetrain of my 1938 Plymouth P6 Deluxe sedan. Someone got me onto the idea about tranny alignment. I hear a little rattle only under certain driving conditions. I also get an odd little rattle when I brake hard. U-joints are good. Tranny rebuilt and feels tight. Clutch gear (synchromesh) does not appear worn excessively. I have it apart right now re-checking things again. I rebuilt it 300 miles ago. Yet, I feel a slight quick little grind when I engage the synchromesh while shifting. Slight gear misalignment with the pinion could be an issue maybe? I suspect the pilot bushing could be the culprit.  Do these sound like worn pilot bushing symptoms?

 

Pic of synchromesh. Typical of both sides.

 

 

IMG_6170.jpg

 

 

IMG_6169.jpg

Edited by keithb7 (see edit history)

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Posted (edited)

A bad pilot bushing can cause clutch chatter, and front bearing failure, and sometimes a third gear (direct) synchro that doesn't want to work.

 

A misaligned bellhousing may cause repeated failures of the pilot bushing and front bearing if it is bad enough.

 

If the transmission is out of the car, always check bellhousing alignment. It is annoying to do, but worth it.

 

If transmission is disassembled, check a synchro by oiling it and the cone it normally engages, then push the synchro into the cone while twisting. It should grab the cone and stop it cold. If it wont, investigate why (probably a worn out synchro).

 

Avoid super slippery gear oil for a synchromesh transmission. There are many oils available that are made to work with synchromesh today. Synchros want oil, not gear oil. Tractor oil or even motor oil would be a better choice than typical gear oil from the parts store.

 

The rear axle on the other hand would probably appreciate the slipperiest gear oil available.

 

I can only guess about the rattle. In some transmissions the reverse gear idler rattles when there is nothing wrong.

 

Edited by Bloo (see edit history)

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Posted (edited)

Thanks @Bloo. I ordered  new clutch gear (synchromesh) today.  I spent a little more time understanding how it works. The square brass pieces seen in my synchro pic above are wearing thin. They engage the cone. The thinner brass I suspect is not lining up the two gears to the right speeds. Won't hurt to change it. It is 82 years old I figure. 

 

I do want to change the pilot bushing while I have it apart. I have a spare 218 crank here with the pilot bushing still in it. I decided to take a practice run with it today. I tried packing the hole with grease and inserting a tight fitting drift. Hitting it with a hammer, hoping hydraulic pressure would push the pilot bearing out from behind. Not so. It would not work. Had the drift turned on a lathe. Cut a groove for a tight fitting o-ring as well to help maintain pressure of the grease. No go. The bushing would not come out. I resorted to my set if mini files. I cut through the bushing. Then the "grease and drift method" was able to get the bushing out. I'm not sure I want to do that to my crank in the car. Hoping I can get a smaller pilot bearing puller in there, as the engine & bell housing sit in the car, with the tranny & clutch out.

Edited by keithb7 (see edit history)
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Additionally, I did some research on bell housing alignment. I think I have a spare input pinion that I can insert into the pilot hole. Then attach my dial indicator to it. Then I can measure the pinion alignment to the bell housing. Maybe. We'll see what I can mock up. The car does have a 1953 228 engine in it, so mis-alignment could really be a possibility.  I did use a telescopic bore gauge and a 0-1" micrometer to measure pilot bushing bore wear on the bushing in my crank now.  Compared to a brand new bushing I measured about .005 to .007 of wear. Not sure that's an issue, or enough to warrant replacing the bushing.  I'll replace it anyway so I now it's good.

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I purchased a pilot bushing removal tool to change the one on my 52 Plymouth. They can be a challenge.  Worth it even though I never expect to change a clutch again.

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3 hours ago, keithb7 said:

Compared to a brand new bushing I measured about .005 to .007 of wear. Not sure that's an issue, or enough to warrant replacing the bushing.  I'll replace it anyway so I now it's good.

 

I would. The tighter and straighter you can get it the better it will work. I don't know for sure what is called for for clearance on your car. .005-.007 compared to a new one sounds like a lot. Also, I believe the new one will tighten slightly when you drive it in, so it could be a thousandth or 2 worse than it looks. Use only an sintered bronze (Oilite or equivalent) bushing. Get one a magnet won't stick to. Allegedly the ones with steel in them last longer, but they will also tear the hell out of the shaft when they run out of oil. Speaking of oil, soak it in light oil overnight before you put it in.

 

I have successfully removed bushings with the grease method, but I really don't recommend. Finding something that fits tight enough for it to work is a challenge, the hammer needs to be heavy, and grease goes everywhere. Where I live you can "rent-loan" a slide hammer with a hook or hooks at the auto parts store. Much cleaner, and better if you have room (and you probably do have room). Last time I did one the hook was to big, but there was a 3 hook puller in the kit that I assembled with only one hook. It worked great.

 

To check alignment, attach something to the flywheel itself (I used a magnetic base last time I did it), and run the dial indicator around the inside of the bore the transmission registers on. That will show you misalignment. Correct for half the dial reading. If it is misaligned, offset alignment pins exist for musclecar era Mopar/Chevy/Ford in various ODs, hopefully something will be available off the shelf to correct it.

 

Also run the dial indicator around the face the transmission mounts to. That shows you whether the crankshaft runs perpendicular to the transmission mounting face. If it is way off, a piece of shim stock between the engine and bellhousing on the low side should fix it.

 

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I bought the small threaded puller this morning and got the pilot bushing out in minutes. The right tool....All the difference.

 

Yes, there is some wear. I can feel it when I put it on the pinion, and compare it to the new bushing.  Glad I went head and did this.

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