Excessive Clutch Chattering in a 1969 z/28 Camaro - Team Camaro Tech
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post #1 of 37 (permalink) Old Oct 13th, 00, 05:15 PM Thread Starter
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I recently purchased a 1969 Z/28 Camaro. It has a very smooth running 350 small block, original equipment engine in it, and a 4-speed transmission with Hurst shifter. It had the clutch replaced once awhile ago, however the car had moderate chattering in the clutch when starting from a dead stop, enough to shake the hood. I had the pressure plate, disc, and throwout bearing all replaced with new parts of good quality. The fork appears to be in good condition. I also had the flywheel resurfaced at a machine shop. The chatter was worse. I had the auto shop grind the flywheel again, and put another brand new heavy duty clutch kit in. The chatter has become even worse yet, much worse than when the old clutch was installed. It now shakes the entire car when trying to start from a dead stop in first gear or reverse, and when downshifting. I am at a standstill with this problem, I do not know where to go or what to do next. Anyone with suggestions, please feel free to e-mail me, or post a reply. Thank-you!!!!! Please help!!!
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post #2 of 37 (permalink) Old Oct 13th, 00, 05:35 PM
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When the clutch job was done, they forgot the most important part - the pilot bushing in the back of the crank. This crummy little bronze bushing, when it wears, causes exactly the symptoms you describe. I ALWAYS remove them and replace with the Torrington needle roller bearing, available at your friendly Chevy dealer or Moroso/Summit/Jeg's for about $12.00. They last forever and solve all manner of driveline chatter and vibration problems.

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post #3 of 37 (permalink) Old Oct 14th, 00, 11:52 AM Thread Starter
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Thank-you for the quick reply. I am posting this for a friend who does not have a computer. I checked with him, and they did replace that bushing, in both clutch jobs. Would you, or anyone else have any other suggestions? Would you think perhaps replacing the flywheel might help? As mentioned before, I had it cut twice on a lathe, perhaps a replacement might recitfy the problem. Also, the both the motor mounts and the tranny mounts are fine, and all bolts are tight. The univeral joints are brand new as well. Any further info that anyone can provide me will be greatly appreciated. Thank-you.
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post #4 of 37 (permalink) Old Oct 14th, 00, 02:00 PM
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Have your friend check the input bearing of the transmission.

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post #5 of 37 (permalink) Old Oct 14th, 00, 03:35 PM Thread Starter
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Thanks for the tip, Jody, however I neglected to mention that was ok as well, there was minimal play in that shaft. Would anyone think it could be anything to do with the bellcrank, or anything? The fork itself appeared to be in good condition, so I'm inclined to believe it is not that. Any further suggestions anyone has will be greatly appreciated.

Thank-you for your time.
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post #6 of 37 (permalink) Old Oct 15th, 00, 01:19 PM
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Didn't know the flywheel was cut on a lathe - that won't produce the correct surface for the disc. Correct surfacing procedure for a flywheel is to have it ground, preferably on a Blanchard surface grinder; this produces the correct surface pattern and roughness to be compatible with the clutch disc (similar to the smaller machine used to produce the surfaces on a brake rotor with the overlapping circular cross-hatch effect). I'd have the flywheel re-done (or replace it if it's too thin for another cut); everything else appears to have been done, assuming the bellhousing is centered within .007" or less to the crankshaft.
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post #7 of 37 (permalink) Old Oct 15th, 00, 05:05 PM Thread Starter
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Thanks for the reply, Johnz. I will have him check on the bellhousing centering, that is something new to me. I also plan on replacing the flywheel as well. Thank-you to all who have taken the time to post replies, and if anyone else thinks of anything that could be causing this, please post (just in case a new flywheel does not correct the problem). Thanks!!!
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post #8 of 37 (permalink) Old Oct 16th, 00, 02:12 AM
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One Quick question:

Is the car is a factory Z-28? If so it did not originally come with a 350...someone swapped the motor (was the DZ302). If they did not use the proper motor mounts, and several different ones will appear to bolt up properly, the drive angle can be too low or too high and cause the problem you are describing.

Just a thought...

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post #9 of 37 (permalink) Old Oct 16th, 00, 06:00 AM
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Hey Camaro 350, if you find the problem let me in on it. I've had the same problem, only not as bad as you are describing. Also went through the same steps as you, with no solution. I also had a friend that had the same problem... he got so disgusted with replacing everything and not curing the problem that he put an automatic in it. What type of 4-speed is it by the way??? Mines a p.o.s. Saginaw.

Mark
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post #10 of 37 (permalink) Old Oct 16th, 00, 01:20 PM Thread Starter
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HI. Thanks for the replies. As far as the motor goes, all the numbers check out, the engine was made the 1st week of feb, in '69, and the car was made the 2nd week. The numbers on the block and tranny check with several different Chevy books I have, so I'd be inclined to think they are the proper motor mounts.

Do you know if the flywheel was replaced for the person that wrote stating they had the same problem? I am thinking of replacing it myself, however do not want to go this route if it yields no success. I'd rather put an automatic in as your friend did. Please let me know on that, and anything else you might think of. I really appreciate your time to post. Right now it is so bad the car is not driveable, it is shaking itself apart when trying to shift and pull away from a red light. Anyone else with suggestions please feel free to post, or e-mail me if you are not registered. All the info I can get is greatly appreciated. Hopefully we will be able to figure this out, and if and when I do, I will post the cause and solution prior to closing this thread.

Thanks to all who have posted so far, and to any who will post in the future!!
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post #11 of 37 (permalink) Old Oct 16th, 00, 01:23 PM Thread Starter
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Oops, I forgot to mention, the tranny is also a Saginaw 4 speed, p.o.s. I'm beginning to wonder if there is a problem with the tranny itself, possibly there is a problem with the Saginaw ones. Thanks again for the replies.
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post #12 of 37 (permalink) Old Oct 16th, 00, 06:27 PM
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Oil is your clutch's enemy. Clutch disk,pressure plate,and flywheel need to be extra clean!!!! If shop is not cleaning parts with brake clean,and then keeping their fingers off surfaces chatter will result.Also, if they are putting grease on input shaft,they may be using to much.When the input spins, there goes all that lube all over your nice cleanclutch parts WOOPS chatter time! Try cleaning the clutch with brake clean,with engine running,and buddy pushing in clutch pedal.Spray cleaner directly on both sides of clutch disk.If problem is better you know the problem is greasy parts. Be very careful when cleaning, it can be dangerous,(spinning parts,flammable chemicals) Good luck
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post #13 of 37 (permalink) Old Oct 17th, 00, 05:51 AM
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camaro350

Have not replaced the flywheel. Resurfaced it, with a grindstone as someone stated. Replaced disc, pressure plate, pilot bushing etc. Mine just chatters a little if you take off really slow. Not bad enough to tear everything out and get an automatic yet! My friends tranny was a Saginaw too. Maybe there is something wrong with them...

Mark
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post #14 of 37 (permalink) Old Oct 17th, 00, 07:43 AM
 
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The problem is in the Marceling in the driven disk. The disk has a bit of compression built into it, and the ones you are probably getting are made off-shore.

Also, there are coil springs in the spline to facing part of the disk, and if they aren't the correct tension, the clutch will chatter like a tropper.

I have heard of a few people changing just the driven disk to a dual friction Centerforce part, and that seemed to fix those chattering woes very well on vehicles that didn't have linkage, bearing/bushing or ratio issues.
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post #15 of 37 (permalink) Old Oct 17th, 00, 12:16 PM Thread Starter
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Thanks to all who have replied so far. I know it is not an oil problem, as I watched the shop assemble everything, everything was kept clean. My rear engine seal is not leaking, and when the old clutches are removed they are "dry", no evidance of any types of oils or greases on them.

IgnitionMan, could you provide more detail on the ratio/bushing thing, and on what a dual friction disk is? I am about to install a new flywheel, and new Borg-Warner stock clutch, with a standard organic disk. Perhaps I should cancel this and install this dual friction disk instead. Let me know what you think on that.

Once again, thank-you for all your suggestions, hopefully we will nail this problem soon!!!!

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