Posted by Mike (Montreal, Quebec) on Wednesday, August 10, 2005 at 10:35PM :
In Reply to: Help needed: Driveline noise posted by Mike (Montreal, Quebec) on Tuesday, August 09, 2005 at 3:36PM :
Thanks for all that replied on possible cause sand positive comments on my truck.
I have also received e-mails from Charles Talbert of M Series Rebuild and he indeed points towards the main shaft snap. Quotes from his messages: "...sounds like the snap ring has come off the front end of the trans. main shaft. This is a very common problem in the early series transmission, see it occasionally in a 420. From your description, I'd say it's in the later stages of damage caused when this happens. The early stages are jumping out of 3rd gear, later stages are gear clashing, hard shifts of gears 3 & 4, the final stages are not being able to shift at all. This usually ruins the main shaft, input shaft, 3rd gear, synchronizer assembly, & some small parts, bearings will be history too..."
and when I asked if this is something I can diagnose myself by taking the shifter tower off (must have been a Yankee in a past life!): "You could pull the top cover & have a look, however if it's what I suspect, you won't be able to see the real shaft damage because it is hidden till the shaft is pulled from the case. This fact is why so many people believe they don't have a real problem till lots of damage has been done, it's hidden & they feel all looks good. You will be able to see easily synchronizer damage, it's in open plain view once you pull the top off... The clanking noise is likely broken synchronizer components, the rapid grinding noise would be from the 3rd gear sliding back & forth on the main shaft outside its normal travel distance because of the snap ring failure. I would almost bet this is what has happened." Mr. Talbert seems to me like a real gentleman!
I have conducted a test with my TC in neutral to see if I could isolate the noise and the tranny seems to be quiet but this may be due to the light load on it.
What I plan to do next to rule out the TC not being fully engaged is to disconnect the shift levers and manually check when it engages (feel the ball stops). I also plan to make a run on low range. If low is fully engaged, the noise (if made by the tranny) should be the same.
I am on vacation with familly this week but next week, I'll be able to run more tests and report back.
Regards,
Mike