I had an issue with the MS a few weeks ago, but it was changed and it fixed the problem. The problem was creeping and not coming out of gear. The car is an 04 Goat with T56 and I replaced the MS with a new Delco unit.

But, that was then, and now I have a new problem. The tranny grinds a little when cold and shifting into 2nd or 3rd. It has done this for 2 years or about 10k miles. The rest of the gears do not grind. But two days ago I wound out 2nd to just over 6k and shifted into 3rd. I then wound out 3rd to just over 6k and when I shifted into 4th the linkage hung up between gears.

I could not get it to go into 4th and it also would not go back into 3rd. The car motored to over 90. I pushed in the clutch and coasted off speed. When I slowed to about 50 it went back into 3rd. I thought no big deal since I've had hang ups before and nothing jerked or sounded broken. I drove it the rest of the day and it was OK.

Yesterday, I had the street to open it up and decided to take it to 100. I never made it, the same thing happened. In addition, it felt like the tranny skewed to the side, like a broken or tired tranny mount. I checked the mount today and it does not appear broken, but it could be tired especially on a 15 yr old car.

But, I've had broken mounts before and they move around at all speeds. The car shifts great in all gears except when I wind out 3rd and go to 4th. I know the T56 uses an aluminum fork for 3-4. But, as I mentioned above the car shifts well until you hit 6k. If you stay below 5k it shifts well into 4th. I know high RPM hang ups usually mean the clutch is won't fully disengage. But, I fixed that when I changed the MS, and the trany shifts well in all other gears.

Also, the problem occurs when hot, after say a 20 minute drive. It also did not hang up for the 1st three weeks or so after the MS change.

Any help is appreciated.

 

Id look into getting a tick adjustable MC, either that or it might be time to consider a new clutch (with a non adjustable pressure plate).

 

Yea, those are some good thoughts. But 1st the has car an LS7 clutch which is adjustable. Second, the OE MS worked well for years with it. The tranny during those years had the usual T56 quirks such as: sometimes hard to put into first and reverse when hot. It shifted well until this Spring when the MS rolled over and I replaced it three weeks ago.

It shifted well until Friday when it started to hang up between 3rd and 4th. I thought about getting a Tick but had good success before with the OE MS. If I had installed the Tick, I could have ruled it out as the trouble.

Also, the only gear shift it does it in is 3-4. Could the 3-4 fork work at lower RPMs but hang up under full power shifts?? I'd hate to buy a new Tick and find out its an internal problem. Help!

 

Im betting this is your problem. The LS7 pressure plate is known to stick and ends up not letting you shift sometimes. Mine was great for years and then all of a sudden I was getting locked out of gear above ~4000rpms. Mostly noticed it in 3rd gear for some reason, but 4th was also an occasional issue and never had it going fast enough with that clutch to shift into 5th at high rpms. I don't remember 2nd being really an issue for some reason, just notchy sometimes. I was afraid it was an internal issue too, I pulled the clutch though and everything looked ok, not damaged, but I got a monster stage 2 anyway. Haven't had the problem since and the shifts feel smoother and less notchy. Do a search for the LS7 clutch, you will see many members here and on other forums have had issues with the pressure plate.

 

Ok, thanks I will consider it but will run a few more tests. You would think as the clutch adjusts tighter to take in slack caused by wear that such an adjustment would prevent the disc from sticking and hanging the shift and not the opposite. Also, I have a high pedal. One inch of slack and then after an inch or so further disengagement. Then another 3 inches or so of free pedal before hitting the floor. I have to release the pedal 1/2 way from the floor to start engagement. I thought it was fine.

What was the release point for you on the old LS7 clutch? Why now after many years and about 30K miles? I wonder if the new MS install altered the adjustment?

 

Sounds like your clutch is going over center and sticking under high RPM. Try adjusting the clutch/Tick MC with release point closer to the floor.

 

Yea maybe, but I have the non adjustable OE MS.

 

Yea theoretically that is how its supposed to work...until the adjustable PP gets stuck and doesn't work at all.

Mine was the same, felt like the oem LS6 clutch, had the same travel.

Mine was the same as yours, near the top. Mine had less than 30K miles before I started getting issues and Im assuming that is when the PP just starting acting up and getting stuck or whatever.

 

Here is an update. Being the sort of guy who tries to figure out the problem instead of throwing money at it, I continued to check things. After checking the tranny mount I found the rubber half torn away from the steel. i could not see it until I jacked up the tranny and removed some exhaust pieces and dropped the x-member. The mount wasn't mangled, but it was 1/2 separated. It also felt solid when I wiggled the tranny before dropping the x-member.

Anyway before changing the mount, the shifter would start to hang up at about 5500 and would lock up so that it would not move at 6000. The new mount helps but did not eliminate the problem. Now it shifts OK at 6000 and locks out at 6500. Its a lot better and is good for normal spirited driving, but it still locks out the shifter at high RPM.

JD AMG you maybe onto something. After changing the mount, the car shifts smoothly until you really hit it. The smooth shifting is due to the new mount, but the high RPM hang up is still there although much better than before.
I understand the centrifical force is too much at high RPMs to disengage the clutch completely. When this happens, the pedal is stiff and will not depress. I guess the clutch springs get tired over time and wear to the point that they wouldn't allow the clutch to release.

Does it hang up because of the adjuster or do the springs warp as the clutch ages?? Can it be fixed by resetting the adjuster?

 

Final upshot. This crazy clutch started readjusting itself. After I changed the tranny mount, the drive line tightened, and I started hearing a strange racketing type noise coming from somewhere in the drive line. It did it two or three times one day. I noticed then that the clutch would not hang up until about 6500. The clutch seems to have tried readjusting itself.

While I realize a new clutch is necessary, it is good enough for the rest of the season. I will replace the clutch this winter. No more adjustable clutches for me. Thanks for the help.

 

Sorry forgot about this thread.

Don't know if the PP can be "fixed" or adjusted, I haven't seen anyone say that it could. If you search here and mostly the Corvette Forum you will see a ton of posts with this same issue with the LS7 clutch.

Also check your clutch fluid, I bet its dirty. Mine got dirty real quick with the LS7 clutch due to how dusty that clutch was. The monster clutch so far isn't like that.

 

[QUOTE=JD_AMG;20124582]Sorry forgot about this thread.

Don't know if the PP can be "fixed" or adjusted, I haven't seen anyone say that it could. If you search here and mostly the Corvette Forum you will see a ton of posts with this same issue with the LS7 clutch.

Also check your clutch fluid, I bet its dirty. Mine got dirty real quick with the LS7 clutch due to how dusty that clutch was. The monster clutch so far isn't like that.[/QUOTE\

First thanks for taking the time to respond. Second, the MS was replaced a month ago so the fluid is fine. Third, and not least, I had the time to take out the tranny yesterday. One of the bolts from the SC worked its way out while the second bolt was half way out. This in itself did not affect clutch performance since the SC continued to open and close although it was loose. The second half out bolt kept the SC from turning and breaking the clutch line when the pedal was depressed.

When the trans came out, I noticed hundreds of speckles and mar marks on the PP. I have not found the bolt. The FD and PP face are perfect and so is the flywheel, so no metal entered there. I have a Fidanza aluminum flywheel and ordered a new insert disc. I do not want to spend 700 or more for a clutch, so I am looking at the Ram and ACT clutches. I have heard of too many fitment issues with Spec products.

Any suggestions for a reasonably priced clutch is appreciated. Thanks, and you can be sure that the SC bolts are getting two coatings of locktite. :-) And this explains why the clutch was good for years and then one day it wasn't.

 

Finished putting the tranny in yesterday. Replaced the pilot, rear main seal, and the barbell. Loctited the SC and checked the adjustment before installing. I have a great pedal and the clutch is smooth. Took the car upto 6500 in third and it shifted well into fourth. Also installed the bronze shifter bushing. It made a difference. The shifts are more positive and click in more so like a rifle bolt.

So, let it be said again that at some point in the life of a self adjusting clutch, it will hang up at high RPM and not allow you to shift. The tranny is fine.

I did a little reseach concerning tranny fluid. I found interesting Vids on Redline's site and on Leno's garage. The Tremec speaker stated that ATF is used because it flows well. The Redline speaker stated that many competitive drivers add a quart of MTL (80-90) to the fluid. This slows down the synchros, which makes them engage better and the tranny shift smoother.

Not having a quart of Redline MTL handy, I put in a 24 ounce bottle of Lucas transmission treatment and topped it off with Dexron VI. It shifts a lot smoother. The grinding into 2nd and third when cold is gone, although I attribute this to the new clutch. But, I can now hear the synchos winding up doing there job, and the shifts are much smoother. I'm glad I found the info. I searched T-56 on You Tube and found many good tips from the manufactures and not from some guy talking in his garage.

Thanks to all who contributed. This has been another LS world learning experience. :-)