'76 c30 BAD clutch chatter and issues - The 1947 - Present Chevrolet & GMC Truck Message Board Network

kamel · 08-07-2009, 03:32 AM

So, having driven several trucks with the same trans, sm465, this one seems to have a characteristic unlike any others. The clutch only seems to work in two positions, in and out. Any in between finessing causes horrid chatter and clunking. It still grabs a little, but is not smooth by any means, I know it's a mechanical clutch, but it shouldn't be doing this. My thoughts are flywheel bolts are loose, flywheel is out of true and needs resurfacing, and clutch parts are loose or a combination of these. It also has a gnarly clunk rattle that is RPM related, noneffective of speed, but does not do it nearly as bad free reving.

Any help or advice is appreciated.

Igotachevyor2 · 08-07-2009, 07:44 AM

sounds like its time for a new clutch kit and fly wheel resurface. i think you can get a clutch and flywheel kit from autozone for around 200.00.

James McClure · 08-07-2009, 07:57 AM

Kamel: In all likelyhood, nothing is loose. Usually a chatter is from foreign material on the disc, the disc is worn down to the rivits, weak disc damper springs OR, weak pressure plate springs. Foreign material on the disc is usually engine oil. Whatever it is, your going to have to take it appart and do a visual inspection of all the parts. When the trans is out look at the fingers on the pressure plate before you unbolt it. Make sure they are all flush with each other. If they aren't some of the apply springs are weak. Look at the disc and see if any damper springs are broken or if the spring pockets are heavily worn and if the hub is very sloppy. Replace the pilot bearing with the solid sleve type NOT the roller bearing type as they tear up the trans input shaft nose if they fail and the solid ones won't, Jim.

kamel · 08-10-2009, 02:14 AM

Alright thanks. I'll drop it and see whats goin on in there. I don't think it would be engine oil, this motors supposed to have <5K on it, but I am very skeptical of the ability and brain capacity of any one that worked on this truck prior to buying it. The hood was bent, drivers side window crank handles busted, and parking brake mysteriously stopped working (it WILL not budge from the released position) after the P/O picked it up from some goons in a burbank garage for an oil change.

Anyone got an idea what the rattle may be?

08-07-2009, 03:32 AM	#1
kamel Registered User Join Date: Oct 2007 Location: SoCal Posts: 20	'76 c30 BAD clutch chatter and issues So, having driven several trucks with the same trans, sm465, this one seems to have a characteristic unlike any others. The clutch only seems to work in two positions, in and out. Any in between finessing causes horrid chatter and clunking. It still grabs a little, but is not smooth by any means, I know it's a mechanical clutch, but it shouldn't be doing this. My thoughts are flywheel bolts are loose, flywheel is out of true and needs resurfacing, and clutch parts are loose or a combination of these. It also has a gnarly clunk rattle that is RPM related, noneffective of speed, but does not do it nearly as bad free reving. Any help or advice is appreciated.

08-07-2009, 07:44 AM	#2
Igotachevyor2 Apache Club Join Date: Jan 2006 Location: Goodlettsville,Tn. Posts: 1,294	Re: '76 c30 BAD clutch chatter and issues sounds like its time for a new clutch kit and fly wheel resurface. i think you can get a clutch and flywheel kit from autozone for around 200.00. __________________ 58 CHEVY APACHE I 74 CHEVY C-10 I 78 K-10 donor truck I 89 SONOMA My Trucks Apache Sitting Idle MySpace Project Dad's Truck (74 C-10 to K-10 conversion) .

08-07-2009, 07:57 AM	#3
James McClure One shot, one kill. Join Date: Dec 2007 Location: Saratoga Springs NY Posts: 859	Re: '76 c30 BAD clutch chatter and issues Kamel: In all likelyhood, nothing is loose. Usually a chatter is from foreign material on the disc, the disc is worn down to the rivits, weak disc damper springs OR, weak pressure plate springs. Foreign material on the disc is usually engine oil. Whatever it is, your going to have to take it appart and do a visual inspection of all the parts. When the trans is out look at the fingers on the pressure plate before you unbolt it. Make sure they are all flush with each other. If they aren't some of the apply springs are weak. Look at the disc and see if any damper springs are broken or if the spring pockets are heavily worn and if the hub is very sloppy. Replace the pilot bearing with the solid sleve type NOT the roller bearing type as they tear up the trans input shaft nose if they fail and the solid ones won't, Jim. __________________ 1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shotJim or Paladin whichever you choose.

08-10-2009, 02:14 AM	#4
kamel Registered User Join Date: Oct 2007 Location: SoCal Posts: 20	Re: '76 c30 BAD clutch chatter and issues Alright thanks. I'll drop it and see whats goin on in there. I don't think it would be engine oil, this motors supposed to have <5K on it, but I am very skeptical of the ability and brain capacity of any one that worked on this truck prior to buying it. The hood was bent, drivers side window crank handles busted, and parking brake mysteriously stopped working (it WILL not budge from the released position) after the P/O picked it up from some goons in a burbank garage for an oil change. Anyone got an idea what the rattle may be? Last edited by kamel; 08-10-2009 at 02:16 AM.



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