Look at the fire wall. Make sure that it isn't cracked. There have been some cases of that happening

 

Describe how you bled the clutch, did you crack the bleeder on the slave?

 

It's probably the slave, had same symptoms as you but around 80k miles.

Since you have to pull the transmission, I went ahead and replaced the clutch assembly. After looking at the clutch disk, I probably could've waited another 3 or 4 years or 30k miles.

If it were me, I would replace the slave. Might be a good time to put an aftermarket shifter in it. At least you would get some improvement for your efforts.

 

For symptoms like that, it is almost always the slave. If a good bleeding of the clutch didn't resolve the issues, then you need a new slave. Regardless of the miles, it is still 12 years old and they were pretty weak even when new.

 

Thanks for the ideas.

@BertsGTO I checked the firewall for anything that would indicate a crack or fatigue, and i couldn't find anything in that area. That is a weird one for sure.

@greenmtn, Yesterday, I used the help of two other people. First i basted out as much fluid from the reservoir as possible (refilled fresh). Then i had someone push the clutch and i cracked the valve and closed it. person #3 would fill the reservoir every 2nd bleed. I ran the fluid completely clear. Had the person in the car pump it for 30 seconds or so, then did the same thing again another 10 times or so. I would say that i emptied about a pint of Napa DOT4 into and through the system.

@mlformula95, when you say same symptoms, what do you mean? does that notch sound familiar, or just the general sponginess? I was hoping that notch that came and went would be a tell-tale or something... What bothers me the most is that it 'felt' perfect and then it was completely out of whack no degrade whatsoever. And yeah, It's just disappointing i need to open it without a 2nd reason. I dont really have plans to add much power if any, i never found the shifing to be unsettling, but maybe ill look into other shifters it to make it worth while.

@Rich-Tripower, I agree about the age, vs mileage. I can totally see a seal going, but i really want to see a leak before i'm excited to tear out the transmission. I'm thinking of clamping the clutch to see if it leaks down over night or something...

*shrug*
Ultimately i think i'm in for dropping the transmission. I haven't a clue what i'm doing, but i have time (this place is awesome) . I would love to get it back on the road before summer is over...

 

Clutch pedal didn't return to top after shifting, had to actually get my toe under the pedal and "pull" it back up. If I was super gentle and slow with the pedal, it would do ok, but you could tell it felt weaker.

The sudden notch you are noticing could be a few things. Could be slave related, I'd also check trans and and motor mounts.

 

I think i have a different problem. I finally dropped the transmission (I'm slow, no mechanic, and pretty much don't know what i'm doing), i noticed that two of the fingers on the diaphragm spring are pushed in about 1/4 inch (Maybe less). I believe this is bad. I can't figure out a way that those should be stuck like that unless they are broken.

I'm looking for a second opinion, can someone confirm or suggest this is normal? Do they unstick? Can i unstick them? Do i have to buy a clutch now? I'm in there so its just parts at this point...
The Stuck fingers are at the 9:00 position. Right above that green marked metal piece.

 

If you've ever installed a clutch, those fingers move when you torque down the pressure plate. I guess it's like preloading a spring. Anyhow, it could be whoever installed the clutch didn't torque the bolts down correct, or some of the bolts loosened, or you have some weird uneven clutch wear or a bad pressure plate

doesn't matter now, might as well change everything now that its apart

I also concur. You might as well, as everything is worn and you would hate to have to go back in there and replace stuff later on... just make it all new.

 

doesn't matter now, might as well change everything now that its apart

 

Nope, I have never installed a clutch. Again, i'm the original owner and i have never had anyone do any work. Thank GM? maybe?
Just FYI, it engaged smooth as silk always. No shudder, very linear feel, it was the clutch i measured all other clutches against.

Yeah, I'm all in favor of replacing it - I do not drive hard at all, so this is disappointing, but hey- things break. I was happy with the feel of the stock clutch, do i go stock, or find something else?
I think the hardest part of working on my car is doing all the research...

 

I'm about to replace my clutch at 63K miles on a bone stock car because of a failing slave and have researched my choices until my eyes bled it seemed. I ended up going with a LUK clutch kit from RockAuto with an F-body slave. I decided I didn't need a performance or heavy duty clutch because my car will rarely see a track and will probably remain mostly stock it's whole life. I drive it hard on the street occasionally but felt like the LUK was the best choice for performance/price, they make the OEM clutches. I went with the F-body slave, it seems to be popular because it's more sturdy than our OEM's and you just need to swap a couple of things from the stock slave to the F-Body one.

No feedback on how it all works yet, I haven't had it installed. I'm curious to see where you go with this and how you like what you ended up with so please keep us updated.

 

The advantage of the F-Body slave is that it is less expensive than the GTO slave. They are exactly the same aside from the fitting on the outside which you can swap from your original GTO slave onto the new one.

Replace the clutch now while you have it apart. I don't really see much of an issue with your pressure plate, but the OEM clutches aren't known for their strength so you might as well replace it with something better. The issues you've been having are likely due to the slave, but a better clutch would prevent you from having to tear into this again before long.

How does the flywheel look? If it needs attention, be sure to have the flywheel resurfaced or buy a clutch package that includes a new flywheel.

 

Several of us have used the LS7 clutch kit + F-Body slave cylinder (seperate part) to replace the stock clutch parts. I'm 10 months in on mine and it works fine.

Google "LUK 04-905" and "GTO" and you should find lots of older threads to get you specifics.

Also, much respect for you doing this on your own - Doing the clutch is one of the tougher jobs, at least on your back and by yourself, even for me who does all of my own work for the last 25 yrs.

 

I started to untorque the pressure plate and the two stuck fingers sprung back. So i stopped. I'm still pretty certian i'm going to replace the whole rotating assembly. What i haven't got a feel for is how forgiving the assembly is. I can't really see screwing up the slave cylinder install, but if i somehow don't torque the flywheel properly, or get the wrong bolts, or buy one that hasn't been balanced properly, my car and clutch has a death wobble until i feel like working on it again. Call it "first time apprehension".

@Rich-Tripower
The stuck fingers dont really indicate anything? I dont know clutches, so that's an honest question. They were stuck, two fingers about 1/4 inch further in than the others. Sorry the picture doesn't show much.

@Blue Dream
I was looking at that same LUK clutch kit. What is steering me in that direction is the "%We supply 98% of north American passenger vehicle clutches"

@Logan71
-I will look again into the LS7 clutch. I read something about shimming and not getting things spaced correctly, or poor pedal engagement - kinda scared me off initially.

Also, much respect for you doing this on your own - Doing the clutch is one of the tougher jobs, at least on your back and by yourself, even for me who does all of my own work for the last 25 yrs.

Appreciate that. I have to say, i live in the rust belt, so working on a 12 year old car usually means hitting things with hammers to un-seize things and using the angle grinder to cut off bolts. This, in comparison, is nice. The bolts just come loose with one grunt. And with the exception of one exhaust bolt, i haven't stripped or broken anything yet. -now that stupid exhaust bolt on the other hand- i dont know what to do yet.

 

You'll be fine. There's a guide for it, google search for it.

 

Get LT1-S clutch, rejoice in shifting again.

 

Your wallet won't be doing any rejoicing.

 

@Rich-Tripower
The stuck fingers dont really indicate anything? I dont know clutches, so that's an honest question. They were stuck, two fingers about 1/4 inch further in than the others. Sorry the picture doesn't show much.

My point was that I don't see any fingers out of place.

Monster Clutch has nice packages complete with a new flywheel, pressure plate and disc along with all the bolts you need for the clutch and flywheel along with a new pilot bearing. I think it also includes a clutch disc alignment tool.

As far as the slave install goes, you do need to measure things and shim as needed but 98 times out of 100 you don't need to shim it. But you do need to check it before you bolt it all together. Monster really helped me work through that part of the process when I was doing my clutch and slave install.

 

Get the best clutch you can afford. It's one of the most important parts of the M6 driving experience so don't cheap out if you don't have to. Also think about the shifter and clutch master. Definitely upgrade the line with a remote bleeder.

 

JMO but it seems that slave failures happen a bit more often than clutch failures. I'd still be on the stock clutch if it wasn't for the slave.

 

Stock clutch is ok, it just seems to glaze pretty easy when you drive it hard.

 

I installed the LUK clutch a few years back, maybe 40k miles ago, and it feels great. It was also my first time ever replacing a clutch. The slave was also replaced with just a regular oem unit from Rock Auto. I have the Tick Clutch Master Cylinder which is nice to have but at just about the same amount for the clutch pack, it's not a bargain upgrade.

 

If you don't like glazing, looking at an LS7 is a bad idea.

 

Seeing as you'll be replacing the slave anyways you should definitely get a speed bleeder from monster or tick as well. They're like $50 and totally worth it to avoid the headache of bleeding the slave normally. Also seeing as how you're stock definitely stick to a LUK LS7 clutch, they're surprisingly stout.

 

Just a few things to add:

I agree on the speed bleeder. I added one when I did mine and tied it off under the hood when I was done.

There's lots of talk about shims, and I almost ordered some, but dismissed the idea and I've been OK. I believe GTO44 did shim his, though. YMMV.

Lastly, I found this regarding the 'clutch fingers' issue. Can't say for certain that this is the cause, though. https://www.exedy.com.au/ediagnose/problem/c3c0d7e4-f15b-cab7-12e3-299f5ad3f7fb

 

I didn't shim mine, nor my buddies clutch.

If you're stock and don't beat on the car, then sure go with the LS7 clutch.

However if neither of those are true or will become false in the future, you should look into something a little better.

 

Success!

I got my car back together today and took it for a ride. :gears: The clutch grabs lower off the floor, but not unsettling so. It feels very strong, and i think i did something right as i dont feel any rumbling through the pedal. It sounds like it may self adjust, but if it doesn't it's perfectly fine grabbing where it does. Its a lot push-backy-ier. I haven't decided if its significatly heavier than stock. It definitely pushes back harder at you, but for me (and this is the weird part) it may be easier to push in than stock. Almost Like my stock setup would bind 'normally', and just not have a ton of force to push back... This clutch is a more springy feel. All goodness IMO.

For anyone searching this in the future, ill add the following:
I ended up installing a Rhinopac "brand" slave cylinder and a LUK 04-905 Clutch kit. When the OEM one and the Rhinopac one were side by side, they are identical in casting marks and everything. It was $65 shipped.
I got the Clutch from RockAuto $230
The clutch kit comes with a Flywheel, Pressure plate, clutch, pilot bearing, alignment tool, and a tiny grease packet. It also came with a pack of 6 bolts, which were not actually flywheel bolts!
I didn't shim the slave.

The guide that gets linked to on the forum is exactly what is needed to do the job.
I bought the Harbor Freight transmission jack. It really is worth it.
I also bought some 6 ton jack stands for the front - I just like how large they are so i can get the front tires 4 inches off the ground without even extending the arms. Makes me feel 'safer'. I tried to do it without lifting the back end of the car, but truthfully it just gets too tight back there, and rotating the driveshaft is needed eventually when working on those e18 bolts.

The rear driveshaft coupler donut is hard to get off. I couldn't pry it off using the pry-bar method. I used a drill blank to feed into the inserts, and then hit them sideways to kinda' wobble them out.

Back to the bolts:
I reused the Flywheel bolts, i torqued to spec and used blue loctite. The bolts that were in the flywheel originally had Blue loctite on them already so i figured it would be adequate.
I really thought the kit came with flywheel bolts. I started to thread them in and they went in too easy. The head sizes are the same as the flywheel bolts, but the threads are pressure plate bolt. The bolts are labeled "Clutch mounting bolt" so i dont know.
Does the LS7 crank have a smaller bolt hole?
Blue loctite and torqued the pressure plate bolts.
Also, reused and loctited the e18 driveshaft bolts.

A second person to hold a screwdriver in the flywheel teeth while tightening the bolts on the flywheel or PP would have been great, but it's not necessary, just exhausting to do it with one arm, on your back...

There was a green dot on the pressure plate and a green paint stripe on flywheel. I dont think i saw this mentioned anywhere but i aligned them thinking maybe it was balanced as an assembly. This one kinda sucked, because if i didn't install the flywheel the way that i did, i wouldn't have noticed the stripe, and i could have messed up this whole thing if it was important :shrug:
One thing that i did well, but probably spent too much time on was aligning the clutch disc. I played with the tool for about 45 minutes trying to get it centered. The trick is to allign it to what you think is center, and then clamp down the plate a little and then feed the alignment tool in and out in different orientations. If it doesn't bind in any position, its good. I had 0 issues putting the transmission back, it took maybe 5 minutes to get back together starting from the floor.

I did not replace the pilot bearing. A friend recommended that i just inspect the transmission pilot shaft for scoring and there was none. Same with the splines, The splines where the clutch rides were in perfect condition.

I changed the trans fluid, but i may have underfilled it. While the transmission feels quicker now, it does clank and click a little louder than it did before. (i filled using the fill hole, and not the 4.6 quarts recomended). I have the Valvoline Dex3 synthetic stuff. Time will tell. I may give it a few more drive cycles before i make any changes.

All in, it took probably 16 hours over the course of 3 weekends. Again, first clutch and most of that time was just me crawling under the car, realizing i forgot something, crawling back out, and repeat. I think i could do another one in under 8 with a buddy.
Not sure i saved much money either. I think i bought about $200 worth of tools and equipment (not all of it was needed, but i had an excuse to buy tools). Add about $300 for Clutch and slave, so im in $500 given my labor was free...

I did crack a stud on the output 'collector?' of the exhaust manifold, i bolted it together with one bolt, but now i'm looking for an upgrade of some type i suppose. The good thing is it's the top stud that cracked so gravity will tend to keep the joint in compression.

Thanks to the responses here and special thanks to Logan71 for that last nod of confidence that i was indeed ordering the right stuff.