I've done a good bit of searching but have yet to find an resolution of my problem that isn't an expensive shot in the dark. Also, I'm putting this thread in the LT1 section because I don't think pull type clutches pertain to anyone else here.

I've been getting a loud rattle from the bell housing/trans area after starting off in first gear for quite some time now. The noise occurs immediately after the clutch is fully engaged (foot fully off of the pedal) at low RPM in 1st gear and only occurs under 1500 RPM. The noise goes away if I apply the slightest amount of pressure to the pedal or doesn't sound at all if I never completely release the pedal under 1.5K. I can also hear it rattle in most gears under 1500 RPM when under load (silent when coasting but sounds with the slightest bit of throttle).

Things you should know:
-Throw out bearing was recently replaced after the old one grenaded
-Noise was always faintly present but became much more audible recently
-Rattle is loud enough to hear over the engine
-Also rattles a bit at idle but is MUCH less noticeable... the engagement rattle is loud enough to hear from several car lengths away
-Hydraulic clutch system was replaced a year ago with a new sealed OEM unit
-Clutch components are roughly a year old with about 5,000 miles (except new TOB with < 1,000 mi)
-The pilot bushing was replaced at the time of the TOB swap because my input shaft ingested the old one and caused a ton of nasty chatter and hard shifting

My initial thought was that the T bolt on the trans that holds the clutch fork in place had become loose. This would have moved the fork away from the slave cylinder just enough to cause a rattle when the clutch pedal is fully released. I thought the fork was rattling around on the TOB because the slave cylinder wasn't applying enough pressure to compensate for the added gap.

I slid my trans about an inch away from the bell housing and had a peek inside. The T bolt for the fork was fully torqued down and everything appeared to be in working order. Now I'm really confused.

Possible causes...
-TOB is not seated properly in the pressure plate.
The 3 tabs on the TOB are held in place with the circular clip, I don't see how I could have screwed that up.
-Damaged trans?
I did mention that my input shaft ate/enlarged the year old pilot bushing and created a bunch of dust in the process. This was probably from using the wrong type of grease because the bushing was toast. The car would chatter like crazy in first and second gear. After pulling the trans, I found that the input shaft was fine with little wear and axial play so I replaced the bushing (making sure to leave 1/4" out of the crank this time thanks to wrd1972) and gave it a liberal coating of marine grease. Engagement has been butter smooth ever since but this rattle worries me.

Any ideas? The fact that it only rattles in gear and not in neutral is confusing.

Or could it be those pesky DAMPER SPRINGS?

 

Well I will say I do not think your fork is bent, they just generally break...... From the way you described, it sounds like your T/O bearing is the culprit and is VERY common.

 

I vote for broken/weak clutch damper springs

 

make sure its not just an exhaust rattle first. i thought my TOB was rattling until i looked around under the car and noticed the exhaust pipe was hitting the cross member/ skid plate located hlfway between the transmission and rearend


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BTW I have never seen a bent Clutch fork on an LTx in real life

 

This is what happened to my fork!

 

I don't think it's an exhaust rattle because I removed the crossmember after installing long tubes. I also inspcted the TOB and it looks/spins fine.

 

They will usually do that before they bend much I have seen broken I have seen worn out I have seen the "T" broken I have seen the "T" Worn through the fork I have seen the tips of the fork missing but I have yet to see a bent one

 

The clutch kit that's in there now is a $200 Autozone special that was installed 7/2011. It had the MIC pressure plate with the C70043 stamp, an organic disc, and circular throw out bearing. The Autozone TOB flange bent and was replaced with another TOB under warranty about 2 months ago.

I was planning on replacing the clutch disc soon because I plan on installing my DIY 8.8 and a CC503, so if it is the damper springs then I can wait.

 

Probably a reman disk and they like to make noise for sure

 

Could be a tranny issue?

Maybe grab a dial indicator and check the endplay on the input shaft if you've got the tranny out right now.

Can't remember what the numbers should be but someone in the Manual Trans forum should know.

 

The trans had to go back in because I needed my DD back on the road. I didn't find anything unusual.

Wouldn't a bad input shaft bearing cause it to rattle at idle as well? I'm starting to think it's the damper springs.

 

Bearing will make a whirring noise and when you push the clutch in it will go away

 

The trans had to go back in because I needed my DD back on the road.

 

If anyone needs a clutch fork I has a brand new GM one 4 sale!

 

This is a true statement if you're talking about a pilot bushing/bearing. I was just bringing up the possibility of there being a problem inside the transmission.

It was just a shot in the dark, as I know LT1 clutches like the back of my hand, however I've never torn into a T56 with the exception of changing an input shaft seal.

You can use a dial indicator to check the endplay of the transmission's input shaft when its not in the car. Don't know if it would create rattling noise if its too loose, but I guess its a good place to start investigating once you've ruled the clutch out. There's some guys with a lot of good info about the T56 in the manual trans section as the only major difference between LT1 and LS1 f-bodies trannys is the midplate and input shaft.

 

Not true. If the clutch is pushed in the input shaft is not spinning the same speed as the pilot bushing/bearing therefore that is when they will be prone to make noise. Let the clutch out the input shaft is then spinning with the crank.

 

I'm re purposing this thread. I'm trying to sort out every kink so my car will fly through inspection next week.

I pulled the trans today to check things out and didn't see anything out of the ordinary. The new pilot bushing was in good shape, the input shaft had minimal play, the pressure plate teeth were fine, the fork was straight and the t-bolt was torqued.

The only thing I can think of being the source of my problem is the clutch friction disc itself. It's a sprung hub with 5 dual springs that all appear to be in good shape.

Is there something I'm overlooking?