Harmonic tone (S) Pilot bearing??? (1 Viewer)

[Eric Ellis]

Posted this kind of question before, but:

For a year plus I had this odd harmonic tone (sometimes tones) that seemed to come from the driveline somewhere. Played with the clutch and it was independent of the clutch. You would begin to hear it above say, 10 mph getting louder and changing tone with speed. I would go out on a smooth road speed up and throw it into nuetral and coast to listen. Finally I put it up on stands and we seemed to track the sound to near the output in the case. Just couldn't figure it out, but there was no driving problem no gear scratching etc...no problem and at all...just the damn tone.

Move forward to 4 months ago and and replacing some seals and the main seal and inspecting the clutch; drop the transmission and plink plink plink some bearings fall on the ground:

Whoa...the pilot bearing is melted down and most of the bearings are long gone. fix it up, new clutch, new throw out (old one was still good), resurface the plate. Clean up the shaft after cutting the pilot bearing remenants off. button up and hit the road. tones gone Theory was the melting bearings were translating a harmonic tone down to the output?

Now 3 days ago...what am I getting? the harmonic tones again.

Was it the pilot bearing... is there something that would be causing my pilot bearings to fail??? Or what else may be causing the sound?

Any input would be greatly appreciated

 

[Pin_Head]

Was it the pilot bearing... Or what else may be causing the sound?

No. It is not the pilot bearing because it doesn't rotate when the clutch is out.

Anything that rotates when it is running is suspect.

Sorry I couldn't be more helpful, but for noises, you have to be there and use your ears.

 

[cruiserbrett]

Drivetrain? Stock, or aftermarket? I'd imagine if a v8 bellhousing(or a damaged stock one) is out of spec and there is more than say .01" offset in axial centers you could be causing the pilot bearing to wear prematurely and eventually fail.

Put it up on a lift again, and use a cheapo stethescope(sp?) to see if you can determine the location of the noise?

 

[Eric Ellis]

Drivetrain? Stock, or aftermarket? I'd imagine if a v8 bellhousing(or a damaged stock one) is out of spec and there is more than say .01" offset in axial centers you could be causing the pilot bearing to wear prematurely and eventually fail.

Put it up on a lift again, and use a cheapo stethescope(sp?) to see if you can determine the location of the noise?

Stock. Off on vacation this week so, I will hope to get to it.