Clutch shudder

[Baker7888]

Probably. Use a magnet based dial indicator, mount it to the block, with the tip on the flywheel. Pry the flywheel back and forth. Any movement is your end play. Compare to stock specs. Was the engine originally an automatic, or manual? An auto would have virtually no thrust wear, while a manual is indeed suspect.

Thanks. I bought a dial indicator kit. I will be busy the next few days unfortunately. Luckilly it was an auto with supposed low miles. It was all stock, seemed clean. Indoors. Fingers crossed

 

[Baker7888]

Probably.

Well i did it quick, here’s my setup. I am measuring .007 with a 24” 2x3 between the crank and timing cover pulling parallel to the crank. I dont really like prying on the timing cover. Although it is a pretty stout unit. Not sure where else to get a bite. Does anyone know the tolerance? I had the wife push the clutch as well. This results in about .001

 

[Bonnewagon]

You said LT1 right? This one? read this articlel about the thrust surface. https://www.motortrend.com/how-to/ccrp-0909-lt1-engine-build/ Go to 18:10 minutes.

 

[Baker7888]

You said LT1 right? This one? read this articlel about the thrust surface. https://www.motortrend.com/how-to/ccrp-0909-lt1-engine-build/ Go to 18:10 minutes.

View attachment 230265

Thanks, yes 96 LT1. I guess that would fall under SBC. So my .007 should be good? About how hard should i be prying on the crank pulley? I *think* i am getting all the play but its a tight spot .. also i guess my next move is to pull the transmission. Hopefully i find something obvious in the bell housing area.

 

[Baker7888]

Z so

Since no one has brought this up, is that '87 flywheel balanced to match the LT1?

I should dig into the parts bible to see what the p/n is for the fork ballstud for our cars just to post a reference.

Everything that i can find, suggests Gen 1 one piece rear main seal and Gen 2 Lt1 flywheels are interchangeable and weighted the same. I am not positive that this is accurate but it’s all i’ve got. I am running an LT1 specific crank pulley so i know that that’s correct.

If you know the right ball stud. That would be awesome information to share.

When i get a chance i am going to pull the transmission and then clutch but am worried i won’t find any reason for the noise.

 

[Baker7888]

Any chance the knocking you are hearing is the throwout bearing contacting the pressure plate forks when the clutch is disengaged?

I am reading multiple lt1 / t56 guys saying the noise is the throwout bearing clanking off the input shaft and that it’s “normal” nothing you can do about it. Same exact description. Goes away when clutch pedal pushed in. Some say car’s done it since new. That said. When I had my fork adjusted on the tight side, technically the TOB should have had pressure on it (seated on fingers) Cant confirm due to no inspection window. I think the noise was still there.

There is also a TSB 03-08-29-004C “neutral rattle” that describes angular acceleration, i cant really wrap my head around it. Says a dual mass flywheel can help in some cases. Doesnt seem to be any solution.