Dan Baldwin Posted November 18, 2004 Share Posted November 18, 2004 (just posted this on the IZCC list, too) Don't wanna drop the tranny just yet, want to get opinions/thoughts/guesses. From a stop, I put it in 1st, as I begin to lift off the clutch pedal I hear and feel (at the gear shift and clutch pedal) a buzz/light vibration in the clutch/tranny area. Doesn't make the noise with the clutch pedal to the floor, and only does it for a small range of pedal travel near the bottom of pedal travel (maybe 15% of range of motion, starting ~10% off the floor) . With the clutch near the floor, the buzz is a lower frequency, as pedal comes up and clamping force increases the frequency goes up slightly. Not a huge range of frequency, though. At a certain level of clamping force the noise ceases (though clutch is still slipping). It does this with the car motionless (foot on brake) or if the car is allowed to inch forward. The buzz/vibration frequency does not vary with engine revs much. And sometimes it doesn't do it (maybe 15% of the time). I don't think it's the throwout bearing because it seems to me it would be noisy with the pedal to the floor instead of when I start to engage the clutch. I'm feeling a little reluctant to drive 150 miles to Lime Rock for a two-day track event with it doing this. I have in the past had flywheel bolts back out, ultimately hanging up on the clutch disk and locking the clutch up (wouldn't slip). I don't know if that's what's happening now, though. Ideas? P.S.: I'm *NOT* dropping the tranny tonight! Quote Link to comment Share on other sites More sharing options...
BrandonsZ Posted November 22, 2004 Share Posted November 22, 2004 You could have a bad aftermarket clutch, or your flywheel could be warped slightly (it gets warped when you wait too long to replace the clutch and end up slipping it which of course dumps tonnes of heat in the flywheel. Same reason why the rebuilt clutch could be warped slightly. I got a really bad clutch job on my first ricer, 'cause the car was so light it shook the whole car. I replaced the clutch but had to have the flywheel ground again, beacuse it was chattering so bad it scored the flywheel. I blame the clutch 1st then the flywheel second (especially if it has been ground before because they are usually case hardened like disc brakes, once you start grinding off the surface it will just get weaker and weaker and more suseptable to warpage. Don't know specifically about yours though. I would say IMHO that you could go 150 miles on it as long as it's not slipping (the rpm is steady going up a hil). Quote Link to comment Share on other sites More sharing options...
johnc Posted November 22, 2004 Share Posted November 22, 2004 With the clutch near the floor, the buzz is a lower frequency, as pedal comes up and clamping force increases the frequency goes up slightly. Does the sound change (frequency increase) when revving the engine with the clutch in? Could be a pilot bearing problem. Are you running the bronze or the roller pilot bearing? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted November 22, 2004 Share Posted November 22, 2004 The few pilots that I've seen with problems never made audible noise, but they all had trouble getting into 1st gear from neutral, because the input shaft didn't want to disengage from the flywheel even with the clutch pedal depressed. FWIW, I've never seen the bronze bushing fail, but I've seen several pilot bearings fail in this manner. I don't know what perceived benefit the bearing is supposed to provide over the bushing, but I don't run a bearing for that reason. Sounds like stuff coming loose to me Dan. Maybe its time to safety wire the crank bolts or get one of those high dollar harmonic dampeners. Quote Link to comment Share on other sites More sharing options...
CarJway Posted November 23, 2004 Share Posted November 23, 2004 It could possible be the Throw out bearing. I have replaced it in my mustang twice only to figure out it is the self adjusting mechanism on the clutch pedal. It's keeping the bearing engaged just enough to keep it spining all day. And by making it spin all day it's taking a crap again. It does have vibration on the pedal also when I let out 35% of the clutch pedal. But this buzz noise it makes does go up as the revs do. Just a thought. Could be way off...... Quote Link to comment Share on other sites More sharing options...
wheelman Posted November 23, 2004 Share Posted November 23, 2004 I think the center section of your clutch disk is starting to fail. If it were the throw-out bearing, pressure plate, flywheel or pilot bearing it would vary with revs. The clutch disk will rub on the flywheel even when the pressure is released and I think part of the center hub is vibrating because of this. Could be a damper spring has come loose. Wheelman Quote Link to comment Share on other sites More sharing options...
Guest norm[T12SDSUD] Posted November 27, 2004 Share Posted November 27, 2004 Hey Dan, does it vibrate above 4000 rpm if you nail the throttle and rev up to 6000 rpm and let fall back down? When my flywheel started coming loose that was the first thing I noticed. Also it's possible the transmission front countershaft bearing is starting to go out but that's probably not the case here. Later,Norm Quote Link to comment Share on other sites More sharing options...
Dan Baldwin Posted November 30, 2004 Author Share Posted November 30, 2004 Thanks, all. I missed Lime Rock, I had work work to do anyway:( I'm sure it woulda made it OK, but no reason to tempt karma... I'm running the plain bronze bushing. The noise doesn't seem to vary much with rpm. Does it vibrate? All the time! I don't drive the car much, so it's hard to make a relative comparison. No prob engaging all gears. Stupid thing is, when I had the engine rebuilt last year I had the bolts safety-wired, but when I had to do an emergency clutch swap at Watkins Glen last year, and had the flywheel surfaced also, I didn't re-safety-wire. Having had the bolts back out on me a coupla times, I think I'm gonna have to have a look in there (groan). ttfn, Quote Link to comment Share on other sites More sharing options...
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