Clutch Chatter?
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Senior User
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Clutch Chatter?
I have a 76 f-250, 390 backed by a np435/np205TC. I think I am experiencing clutch chatter, I am wondering how to correctly diagnose this without pulling the clutch out. I have a "knocking" sound when acc. I can double clutch sometimes and it will quit, and it will stay quiet not matter how hard I acc/dec, but when I switch gears it may start again. This is a pain to diagnose because it is intermitant. I have all new u-joints and my drive shafts are freshly re-balanced. The clamps aren't too tight, and my yokes are all tight. Anybody have some ideas/opinions?
Post Fiend
Joined: Jan 2005
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Then have you got a tach? These are pretty well damped but you may notice it fluctuating if you have clutch chatter. Also during chatter there should be rapid shock loads on the transmission input shaft so can you feel it on the shifter?
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Yea you feel it like crazy on the shifter, Im also thinking maybe its my input shaft causing this. When I put it in neutral sometimes it also makes this wierd vibration, but it isn't as loud...no fluctuation in the tach and the engine increases rpm nice and smooth, also there is no jerking motion while in the cab just a bad vibration through the shifter and the loud knocking noise.
Methanoholic
Joined: Mar 2009
Posts: 6,442
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From: Maine (NorCal Native)
The following is my personal opinion and is just that, My opinion!
When setting idling in neutral, listen to the sound... Push the clutch in, Listen to the sound. What's the change, The key is, does it change the same every time you push and release the clutch.
You might have a pilot bearing/bushing gone or an input shaft.
When a pilot bearing/bushing is gone, It may chatter when taking off, it may lockup off center causing vibration (chatter). If the pilot bearing/bushing is bad it will also damage the inputshaft & bearings. If it's a pilot bearing, You'll know right off, they typically squeal, Bushings do not.
-Enjoy
fh : )_~
When setting idling in neutral, listen to the sound... Push the clutch in, Listen to the sound. What's the change, The key is, does it change the same every time you push and release the clutch.
You might have a pilot bearing/bushing gone or an input shaft.
When a pilot bearing/bushing is gone, It may chatter when taking off, it may lockup off center causing vibration (chatter). If the pilot bearing/bushing is bad it will also damage the inputshaft & bearings. If it's a pilot bearing, You'll know right off, they typically squeal, Bushings do not.
-Enjoy
fh : )_~
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Senior User
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Thanks thats what I think too... yes when its making the sound in neutral it changes the moment i start to put pressure on the clutch pedal
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Methanoholic
Joined: Mar 2009
Posts: 6,442
Likes: 8
From: Maine (NorCal Native)
The moment you put pressure on the clutch ... That tells all!
That would be a throwout bearing!
That doesn't fit with the rest of your description though. that won't cause chatter, just get noisy when you push the clutch. It might vibrate some, but not chatter.
Clutch Chatter is when your dash shakes, typically on take off.
And is caused by one or more of, bad flywheel, clutch disk, pressure plate, pilot bearing, input shaft.
[edit]
And bad crank bearings (thrust).
[/edit]
What I was trying to get you to listen to is the input shaft noise, you would need to disengage the clutch for what I was looking for.
But it's all a moot point now if you have a throwout bearing gone it'll need to come apart.
Replacement of all related clutch parts is advisable at that point.
-Enjoy
fh : )_~
That would be a throwout bearing!
That doesn't fit with the rest of your description though. that won't cause chatter, just get noisy when you push the clutch. It might vibrate some, but not chatter.
Clutch Chatter is when your dash shakes, typically on take off.
And is caused by one or more of, bad flywheel, clutch disk, pressure plate, pilot bearing, input shaft.
[edit]
And bad crank bearings (thrust).
[/edit]
What I was trying to get you to listen to is the input shaft noise, you would need to disengage the clutch for what I was looking for.
But it's all a moot point now if you have a throwout bearing gone it'll need to come apart.
Replacement of all related clutch parts is advisable at that point.
- Throwout Bearing
- Pressure Plate
- Clutch Disk
- Flywheel (or resurfaced)
- Pilot Bearing/Bushing
-Enjoy
fh : )_~
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