jjbs7

Hi. So I am having a hard time finding information on my particular symptoms. Hoping someone here can help?

I have a 2001 Z06 that had several performance upgrades before I bought it. I can't say for sure if the clutch is stock, but I know the rear end is a 4/10. May or may not matter for my problem.

So here is what has started happening. A couple of days ago I went to reverse and felt grinding with the clutch down...thought maybe I was not in gear all the way. Did the typical third then reverse, etc...thinking maybe synchros but it still grinded. Happened when I went I went to shift to 2nd I believe as well....again with the clutch down. In both of these cases I know the shifter was fully in gear.

I thought maybe I needed to re-align the shifter with the Pin & 3 Torx bolts...but decided to do more research and testing first.

I found that my clutch slave reservoir had pretty black fluid so I did the ranger method on it and have fresh fluid in now....but this did not help.

What I have realized now from further testing is that I don't have to be in any gear to replicate this. The shifter can be in neutral, and if I give it some throttle with the clutch in, I get the same grinding noise. With the clutch out...I can't get that noise to happen at all....either in gear or in neutral.

So clutch in, and in neutral with some throttle is how I get the grind.

I'd like to fix this myself as I honestly do not have a relationship with any performance shops that I trust.

seahawkfan

Hi,sounds like a throw out bearing or twin disc clutches also make this noise too , have a mcleod rst in my 02 z06 and it makes the noise you describe from time to time , I would bet you have a twin disc in that car making noise , but hard to diagnose with out actually hearing it .... hope this helps !

Bill Curlee

You may have more than ONE issue but, here is where I would start.

When you have the clutch FULLY depressed the engine/flywheel & pressure plate are disconnected from the clutch disk. The clutch disk is connected to the Torque Tube input shaft.

SO, when the car is stationary, the clutch disk, TT prop shaft and trans input shaft are NOT rotating.

If,,, you grind or have a difficult gear engagement, the clutch disk may not be fully releasing and is still being rotated by the flywheel/pressure plate.

This can be caused by a defective clutch master cylinder, air in the clutch hydraulics or mechanical issues with the clutch.

Do you have an aftermarket master cylinder (TICK or any other adjustable master) or is it an OEM Stock master???

If its adjustable, you may just need to LENGTHEN the adjustment rod a little. That allows the slave to push deeper on the pressure plate springs and release the disk.

TRY THIS:

Jack the rear wheels off the ground (Jack stands and wheel chocks for safety) and with the engine running (idling), clutch fully depressed by an assistant, trans in first gear, see if the rear wheels are being DRIVEN by the engine. They should NOT be turning with a lot of torque.

The rear wheels may turn a little and you should easily be able to stop them from turning by hand and hold them stationary. IF, they are being driven and you cant easily stop them, the clutch is NOT fully releasing.

Check that issue first and report the results.

Bill

jjbs7

Thanks for your feedback. I will get a better look this weekend when I remove the lower bell housing to see if the clutch is stock or not...and to see if there is anything obvious.

jjbs7

Thanks Bill. I will perform these tasks this evening if I can. I will also look to see if that clutch master cylinder is aftermarket. Definitely by this weekend to see the results.

jjbs7

Hi again Bill. Ok, so I ran through the lifted test. With the clutch in and car lifted and ebrake off, the tires do not move. Clutch engages about half way up as usual. Wheels then spin and stop when I depress the clutch. If I go to neutral and clutch down, some throttle causes the grind noise.

As for the master cyl, it looks to be adjustable. The eyelet that clips to the clutch pedal is threaded on the rod from the master cyl. Not sure how much it would adjust. Couldn't say if it's stock or not at this point.

Thanks Again,
Jim

huesmann

So I believe that tells us that the pressure plate is releasing fully. Are you saying the car makes the noise when you have the shifter in neutral and release the clutch, but it doesn't when it's in 1st? Is the "some throttle" important? It doesn't make the noise with "some throttle" in 1st? Does it make the noise with no throttle in neutral?

Can you tell where the noise is coming from, outside the car? Is the noise constant, or just transient, e.g. at certain pedal (gas or clutch) positions?

jjbs7

Hi. Thanks for the feedback.

"So I believe that tells us that the pressure plate is releasing fully."
->I believe that is the case, that engagement and disengagement is working correctly.


"Are you saying the car makes the noise when you have the shifter in neutral and release the clutch, but it doesn't when it's in 1st?"
->no. I'm saying it happens with the clutch fully depressed and held there while increasing the RPMs to 1800 or so. When the RPMs decrease, so does the grind noise.


Is the "some throttle" important?
->some throttle is very important...it does not do it at idle


It doesn't make the noise with "some throttle" in 1st?
->no, unless the clutch is down.


Does it make the noise with no throttle in neutral?
->no, must have throttle

"Can you tell where the noise is coming from, outside the car? "
->This is very difficult to find. From inside the car, you can feel it dominantly in the shifter. Pulling the shifter boot you can hear it loudly from the opening. From outside the car, it sounds more like a rattle than a grind. This is actually making me rethink if it is a grind at all to be honest and rattle instead. Using a metal bar, I tried to feel where the vibration is. I can feel it in the exhaust, and the bell housing dominantly. I do not see anywhere in the exhaust where a rattle could be coming from, & don't believe the clutch would impact the noise if it was exhaust related. I really don't feel it in the trans or the diff. So I would have to say front half of vehicle center.

Is the noise constant, or just transient, e.g. at certain pedal (gas or clutch) positions?
->The noise is there around 1800 with the clutch down or up enough not to be engaged, regardless of what gear position the shifter is in.

Bill Curlee

If the wheels dont drive YES, the clutch is releasing properly.

The noise cant be properly diagnosed (pin pointed) until you break down the drivetrain and examine all of the parts. Most likely a PILOT BRG, THROW OUT BRG or TT Input Shaft Brg issue.

If you can live with the noise until it gets worse or a good time to pull it apart, I would just live with it.

Bill

jjbs7

Thanks Bill - I appreciate the help. I'm hoping once I break it down that the culprit is obvious.

seahawkfan

Im telling you guys again I have a twin disk mcleod rst and makes the same noise and while annoying its not uncommon, while I have no problem shifting I think you have two or more things causing you symtoms , the noise is one shifting is another .

jjbs7

Hello Again. Can you tell me how shifting is a problem in this scenario? it does it in neutral position with the clutch down. Look forward to your feedback...Jim

jjbs7

Hi Bill. So I got around to working on the car this week.



The clutch looks to be in pretty good shape....I think this is an LS7 clutch? Would you happen to know?






Once Once I got the clutch removed, I was able to get my finger in to what is left of the pilot bearing. Stuck a magnet in and pulled out a clump of needle bearings.



I'm unsure of the condition of the throw out bearing. The inner portion of the bearing can rotate within the sleeve without side to side play but it does not spin. Also up and down play is almost half the depth. Not sure if these conditions is normal or not? I'm thinking I will just replace the slave cylinder & throw out Bearing to be safe anyway.

I'll break down the TT assembly in the coming days and inspect those bearings as well for wear. I would assume that something would have caused that pilot bearing failure & I don't want it to happen again. I'm 24 hours of labor into this to get it this far being in my garage.

SaberD

It wouldn't be much more work at all to take a look into the torque tube. I'd give it a spin and listen to how the bearings sound once you take it off the trans. Even if it sounds good, I'd still take it apart to check the couplers.

Not all torque tubes are exactly the same though depending on year and auto/manual. You can see a lot of the internals in this thread.

https://www.corvetteforum.com/forums...dies-pics.html

jjbs7

I like the write up! I separated the TT, Trans/Diff, and cradle over the weekend. I plan to pull apart the TT this week. I also have a leak on the front of the trans where the spindle comes out of the trans. So I need to find a write up for replacing that seal as well. This was quite a bit of work, but learned a lot about my care in the process.

how does that clutch look to you?

Bill Curlee

The disk doesn't look that bad but, its difficult to tell just by looking. You have to measure the thickness of the linings and know what new vs minimum thickness is.

That pressure plate is TRASHED!!! The wear on the ends of the fingers is bad and you have three that are whacked out.

Throw out bearing is trashed as well as the Pilot Brg.

What does the end if the input shaft look like??

jjbs7

Hi Bill. This is an LS7 clutch setup, I believe three are supposed to be inward like this. I measured the linings by putting a dept gauge in between the the sections and found that depth to be 1mm. From a rivet to the top of the lining is 3mm. Total thickness of the clutch plate is 9mm.

Frame77

The LS7 pressure plate definetely has three fingers located inward like that.

Replace the slave. And check the input shaft as Bill recommended. That shaft is f***ing expensive!
While you're in there take a measure to make sure the slave is shimmed correctly.

huesmann

jjbs7, what is that rusty frame thing around your transaxle?

Frame77

https://www.rpmoutlet.com/dte-differential-brace.htm