I have been having an issue with shifting my car for a while now. I can not speed shift it at all...my NV4500 trans in my dodge cummins truck shifts better than the vette does. So far I have measured the slave cylinder travel and it is what McLeod told me it should be, can't remember spec but .420 rings a bell. The air gap between each disk is .025 on the disk closest to the engine and .008 on the disk to the torque tube. The instructions said .025 on each side. I have had the transmission rebuilt, new master and slave. I have also checked the air gap and it was .140; spec is .125-.250. It is hard to get into reverse and the shop replaced the reverse assy and it's still hard to go in. I know this is an odd description, but at idle shifting into all the gears it is hard to go into reverse and 4th. I have issues about every time I try and shift it into 4th at the track. I have also had the clutch out and it looks good, no issues. I have done shifter alignment multiple times as well as new c6 shifter and still nothing. Torque tube looks good, rubbers look brand new, bearings feel good, pilot bearing new as well. I noticed the input shaft going into the clutch has some wear and think this is it, but curious what others have to say.

Recap of parts replaced:
-New GM slave and master cylinder
-transmission has been rebuilt by me with all the goodies and rebuilt again by a transmission shop
-checked air gap it's good (.140)
-c6 shifter and alignment
-bled air out slave and master 50-60 times no kidding!

Thanks,
Bryan

 

Sounds like you need a slave cylinder shim, all singe disk aftermarket clutches suck with the stock pos mc cylinder. Without a shim your clutch isnt going to disengage properly, you could upgrade to a tick mc or shim the slave. Have you done the rev test and seen if the car moves forward with the clutch pedal down, rev to redline in 1st gear on a level surface and see if the car crawls forward.

 

I have done the test with it in 1st with going to redline that test passed. Mcleod clutchs are designed around the stock HYD's. I have talked with them and that states the same. I have checked the Air Gap and it was .140 or so I have it wrote under the drivers floor under car to remind me. I had shims in my hand and didn't need to install per Ticks measurements. I have a lot of local guys that run the same clutch and none of them needed the shims either and run factory hyd. I am not basing my info off that, but I measured and it was good. Oh and I am running the Mcleod RXT clutch which is a TWIN disk. that is the reason I posted the picture of the marks on the shaft in two spots thinking that it was hanging up on the worn area's. The slave cylinder moves the correct travel also. I am going crazy trying to figure this out.

Thanks,
Bryan

 

Bryan

Way back when I got my SPEC Twin Disk Clutch under a group purchase, I procrastinated on installing it because 6 out of the 12 people who installed the clutch had shifting issues, air gap issues ect...

Man Oh Man,, what did I get my self into. SPEC stepped up and had the people send back the clutch for a diagnosis.

CONCLUSION: When the clutch was being installed, people were installing the ENTIRE (TT/TRANSMISSION/DIFFERENTIAL ) into the bell housing and during the process, allowed the weight of the drivetrain to rest while the TT Input shaft was inside the two disk. That caused the disk (HUB) to bend and warp.

OVERVIEW: When you installed your drive train, was there a chance that you could have allowed the weight of the drive train to bend the hubs of the clutch disk. If so, you will still have air gap BUT, not in every part of the disk surface.

If it were me, I would pull the lower inspection cover and check the disk 360 deg and see if there is a part that is less than the required air gap.

PS... I Installed just the TT into the clutch and onto the bell housing and then assembled the trans and diff onto the TT after the TT was fully bolted on the bell housing. 100% perfect clutch operation!

Bill

 

Yeah with the twin disk you shouldn't be having any problems, twin disk clutches in general("and single disk oems") are the only ones that work great with the shi**y GM clutch hydraulics and remedy any high rpm lockout, the twin disk design and engineering of adequate spring tension needed and increased surface area achieve great results.

Yeah I'm with you shouldn't be having any problems, I would probably be losing my mind too if I were in your shoes.

I would follow Bills advice, I have followed Bills advice in numerous instances relating to many of the c5s quirks, especially in the past when it came down to properly installing the rear drivetrain in a c5 corvette. When it came down to installing everything back into the car, The TT goes in first, which it should easily slide into the bellhousing and into the alignment pins, no c clamp should be needed, then the diff/transmission etc. Zero problems afterwards.

if you ever take out the drivetrain again I would examine the propshaft for any bend and where it enters the pilot bearing for any damage make sure their isnt any grooves.

 

Answers in RED

 

Let's bump this up!! Here is the pictures of the clutch as I removed it from the car. I have been talking with McLeod clutches and they say this is normal. The fiber disc that mounts to the flywheel and floater has a grove of .020 then goes out. The opposite side is worn from the outer edge in. So that disc is like a belleville washer if you may! The floater disc looks good and the fiber disc to the pressure plate looks to be wearing even! That is the harsh grove in the input shaft from the first post. I am curious if anyone else is having this issue. That just tells me the first disc is bent but they tell me that my "clutch looks textbook"!!















Here is a picture of the fiber disc that is I between the flywheel and floater





The grove towards the inside of the disc is .020 thick. They want the disc that goes I between the flywheel and floater per there site it needs to have .020-.025 and I am getting numbers all over, like it is bent you can see in this picture.



I hope this helps some, I have already ordered new input shaft

 

https://www.mcleodracing.com/content...street-clutch/

 

To answer this with a question if you will, IF the weight was to be on the hubs wouldn't it be on both hubs and not one? My disc that is warped/bent is the bottom disc that is sandwiched between the flywheel and floater. The top disc that is sandwiched between the floater and pressure plate is flat no issues. IF the weight was there I sure would have thought it would have gotten the top one more than the bottom one or both would be damaged correct? I am just trying to see if I am seeing this correct! Only thing I can see is that it was damaged from the day one, and has gotten worse as the miles got on it. I even took a picture showing that the fingers are not touching when on a flat surface. From what I can tell is that the input shaft is damaged due to the clutch was transmitting the load on the disc that is between the floater and pressure plate (top disc), and since the bottom disc being like a Belleville washer it was only contacting half the discs surface. You can relate that to the input shaft picture in post #1.






This picture is showing the bottom disc measurements between each puck and floater. It is as low as .011 to .020 I think that it shows it is bent as well.

 

Bump it up. Anyone have/had this issue?