Date: 12 Jun 2006 14:16:50 GMT
From: Dave Hinz <>
Subject: Re: bad drivetrain sounds (c900)

On 12 Jun 2006 12:27:04 GMT, John B <> wrote: > On 10 Jun 2006 13:16:42 GMT, Dave Hinz <> wrote: >> >> Excellent. (You're an engineer and/or technician, by the way, right?) > Close enough - biochemist/cell biologist. I do experiments in a lab all day. Biomedical engineer by training, working IT as a designer/project guy. I like your approach. >> Is the noise there when the clutch pedal is out and you're in gear, >> moving forward? > Yep, that's the only time it's audible. Most audible when the wheels are > driving the engine, but this may be because the engine is quieter under this > circumstance. Sounds gearbox-ish at this point then, input shaft area. There are circular springs in the synchro hub area, if one of those were somewhat peeled out that could explain the noise. Time to look for swarf in the gearbox oil, I think. Should have a magnetic drain plug. You want to see if there's chunks - filings are, surprisingly enough, pretty common and not a huge deal. But any piece-parts or chunkies would be bad. >> If so then it's not the pilot bearing; the only thing >> moving relative to it's surroundings then, that's at engine speed, is >> that shaft itself, the drive chain and sprockets, and the input shaft of >> the tranny and the things attached to it. > Ok, I guess we can rule out the pilot bearing then... Right, which I think puts us into concerning territory. Just on a swag, though - is the speedometer doing any strange jumps or anyting? That shaft goes around at about that rate, but it'd be road-speed dependant rather than engine speed. But it sounds input shaft-ish from here. Are you comfortable pulling the side hatch off of the tranny to visualize the synchro hardare and shift forks? Dave Hinz

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