Howdy,

Looking for advice from folks with more experience. I've been chasing an oil leak for a bit on my '91. Left the rear main until the last and it appears that was the culprit. I pulled it all apart and replaced the rear main last week and started putting things back together. My problem is I can't get the trans to seat all the way...its going into to where its got about a 1/4" gap.

As a disclaimer, this is the first clutch I've removed...watched some but never was hands on. The dual mass set up is gone and I'm putting in all the same parts, they look like they should give me a few more miles from what I can see. I've got two different alignment tools to be sure one of them wasn't messed up and both seem to be fitting the same way. I've taken the clutch off and reinstalled it to try and get a better alignment but still had the same issue.

My gut is I've got either one of two things, or a combo of two things going on. Either the clutch plate is off alignment just enough to hold things out or I'm ending up with the trans on too much of an angle some direction to allow it to slip in. Each time I've had the clutch in I've tried to get the trans in multiple times with multiple angles, etc. Same result every single time.

Pilot bearing looks ok and the alignment tools slip in without any issue, verified when I had the clutch apart yesterday. As the clutch is installed right now, if I put my metal alignment tool in it will slide right through and seat all the way in. If I just start the splines and put a little pressure up, I can feel a snag as it goes in which I'm assuming is the edge of the pilot bearing, but no issues if I put that same amount of pressure in any other direction.

Am I missing anything other than pulling the clutch apart again and redoing the alignment until I get it absolutely perfect?

thanks

 

Verify that the pilot on the input shaft will fit properly within the pilot bearing. Measurements are good, but a test-fit of the bearing on the shaft prior to installation of the bearing into the crank is best. Now that you have the bearing in the crank, you can test-fit it by removing the clutch temporarily, if you care to try that. But, before going to that trouble, first try releasing the clutch while shoving the gearbox forward. Whatever you do, do NOT force the trans forward by cranking down on the bolts to draw it up to the bellhousing.

Live well,

SJW

 

do you have the disk in the correct way? one face mates to the flywheel and the other side is towards the transmission. or are you using the dual mass disk in a single mass flywheel?

 

I'll see if I can finagle it around to check the fit. Everything I'm putting in is what came out (nothing new at this point) so it did fit and was working until it came apart. On the forcing, yep fully aware of that one.

thanks

 

Everything in there and being put in (pilot bearing, flywheel, clutch plate, and pressure plate) are all what come out of it to replace the seal. They all fit and were working until they came out.

On the clutch plate, since it was working my assumption is its all part of what was put in at the last clutch replacement before my ownership. On the direction, drew a complete blank on how it was when it came out (major duh moment) so I'm going by the images in the FSM at this point even though its for the dual mass system and mine has since been switched. The 'fat' side is facing the pressure plate. In looking around for info on how to tell other than a marking or label on the disk I've come up with no info on that front. There's no markings on the clutch plate at all...no words, letters, numbers, etc. If you have any idea on a source for that sort of info I'm all ears.

The flywheel is a Spec (SC05S-2) and the pressure plate as what looks to be a AC Delco number on it (C70043) but no other markings.

 

The "C70043" marking is a replacement LuK pressure plate assembly that was installed to replace the OEM original Valeo pressure plate (which have a non-"C" part casting number such as "382109-DO" and the word "Valeo" stamped into the casting).

The LuK replacement kit number for this clutch assembly is #04-113. LuK sells the replacement pressure plates to replace the OEM Valeo made ones when they wear out, but the "C70043" indicates a China-manufactured pressure plate casting. They can be flaky to begin with, or other times they work fine - your mileage may vary.

If you still have the original (springless) clutch disk in your car, this is the Flywheel Side. It has the longer splined nose piece which goes toward the flywheel:



The Gearbox Side of the disk is flatter:

 

Oh, and by the way -

 

Dayum 1/4" so close. Although it wasn't a ZF6 and thinking I was going to man handle this trans in, after wrestling with it for more hours than I care to admit, next morning ran down to the local hardware store and got me some bolts. I was going to cut the heads off of them and cut the screwdriver slot into them but they were long enough to thread in to bridge the gap. Slid in like butter with no fuss and the hindsight thought..."should've bought those bolts/guide pins in the first place!"
https://www.chevydiy.com/wp-content/...015/11/113.jpg

 

Word of caution. The tranny mounting bolts show up as M12 thread in my parts listing, so those Summit pegs may not work since they're not metric according to their website.

 

Great info and I'm learning...like I said, this is the first time I've messed with the clutch flying solo. The clutch disk has been replaced (assuming whenever the clutch was replaced) and now has the springs. This tells me the FSM images I'm going by may or may not be right. Its splined nose piece is longer on one side of the disk and currently I've got it facing away from the flywheel. Would the longer nose piece still go toward the flywheel even if everything has been changed from the dual mass set-up? Or does it vary based on the components. I'm still kicking myself for not paying closer attention pulling it apart...but will likely never miss noting the orientation on a clutch ever again.

I had the trans out last winter in a prior attempt at chasing the leak, but did not touch the clutch at all, and it all went back together smooth as you please so I know the pieces parts were good then. Only difference is the weekend hack being obviously clutch challenged.

This is my last day of vacation before going back to work and I'm planning on pulling the clutch all out again today and checking to be sure the input shaft easily fits into the pilot bearing. Pretty sure there are no issues there, but will make me feel better to be sure. Also, being lucky enough to have a lift and trans jack its not that big of a deal...I've got a lot of respect for all you folks doing this off jackstands. Definitely doable (many years doing all my work that way) but way more wrestling and finagling.

thanks

 

My feeling based on what you write is that Yes, your clutch disk is in backwards. The longer nosepiece side, if facing towards the transmission, means less space remains for the throwout bearing and clutch plate fingers. If you swap the disk so that the longer snout splines are towards the flywheel, and it fits no problem, then that's a pretty good sign.

 

Pretty sure you were spot on. Pulled the clutch out today and double checked the input shaft and pilot bearing...no issues at all. Put the clutch plate in the other way around with the longer nose in and everything went together without any issue. Got the trans in, new U-joints in the driveshaft, the driveshaft and the C beam all in today which is way further than I expected to get. Final test will be when I have it ready to run and making sure everything works but I'll be surprised if there are any clutch problems at this point.

So, if anyone is wondering, you can put a clutch plate in backward on a 1991 Corvette. I'm pretty sure I'll never make this mistake again since experience truly is the best teacher.

Really appreciate all the insight.

thanks

 

Good thing you caught it and also that it didn't go back together. Can be tough to do but it can happen with some clutches. My father bought a 77 Chevy truck from a friend when I was about 12 years old. It needed a clutch so the friend installed a new one prior to the handover. Well his mechanic put the disc in backwards. It worked for a whole year and then one day, the first time my dad pulled a trailer with it, it started acting up. We had to drive from E of Dallas back to Ft. Worth stuck in 3rd gear. I don't know how it worked, the sprung center was like an inch thick on that side. What killed it was the springs finally ground through. Seems crazy that the disc could flex that much and not break sooner. I learned a lot of new words and sayings the next day when we pulled it apart. Haha. Fun times though for me. I got to witness my first rounded off bolt removal scenario. Pop's welded a large nut on one of the crank bolts that was thrashed. I also learned I didn't like the smell of or being covered in 90w gear lube. 😀

 

A rather unique smell

 

Eau de Hypoid cologne. It's a scent you'll never forget.

Congrats to the OP for solving your problem.

Live well,

SJW