tbag_skywalker

I hope some clutch gurus read this because I'm totally stumped.

I finished installing a new Spec stage 2 clutch last week because my old Spec stage 1 had worn out. For the past week I've been trying to figure out why the new Stage 2 won't fully disengage yet the Stage 1 had worked fine for several years.

I knew the clutchfork wasnt the culprit but I replaced that anyways since the tips at the t.o. bearing had been worn down quite a bit over the years. The next idea I tried after I put the car back together was to bleed the clutch-- first the standard way by unbolting the slave cylinder and slowly pumping it. Not a single air bubble came out. Then I figured I'd try using a MityVac at the reservoir and the same thing- no air whatsoever.

The master and slave cylinders are both stock, no leaks at all. The slave was replaced about a year ago because I accidently destroyed the old one. I literaly blew it up because I didnt engage the clutchfork completely upon reassembly after I had my transmission rebuilt. The clutch pedal was hard as a rock yet I felt the need to push it as hard as I can... then it exploded. I'm still wondering what the hell I was thinking when I did that. Anyways, needless to say I'm sure there's no problem with the current slave cylinder since its practically brand new. I still however wonder if I may have ruined a seal inside the master cylinder?

The pedal seems to feel normal- typical throw with just a little free play on top, except the fact that the clutch enages completely as soon as my foot comes of the floor. Its actually failing to disengage to the point where if the car is on flat ground and in first gear it will actually creep forward slowly before I even let the clutch pedal out. I figured this has gotta be bad for a brand new clutch break-in so I only drove it a couple miles till I determined what the problem was and its been on jackstands ever since.

Sooo now I'm lost. I took some measurements- first how far the pedal is pushing the rod into the master cylinder when it hits the floorboard, about 7/8". Then I got under the car and removed the little slave cylinder housing and bolted the slave cylinder back on so I could watch the end of the fork move, this was 3/8". I figure if someone knows how far the fork needs to be pushed to fully disengage the clutch I could confirm that maybe my master cylinder isnt functioning properly and replace it with another oem or a mcleod adjustable.

I'm freaking stumped and I wanna be able to drive my car. Any input would be greatly appreciated. Thanks guys.

wrd1972

iTrader: (12)

I posted several useful comments on this in a another similar post in the last week.
Try a search.

BALLSS

if you TQ the pressure plate bolts more than 22 ft lbs....you will have disengagement issues....if this is a LT1 pull clutch car.

tbag_skywalker

****** - I torqued the pressure plate bolts in 2 stages- 15 ft lbs in a star pattern and then around again at 35 ft lbs in a star pattern because thats exactly what the SPEC representative that I talked to said to do.

Think about this logically, why would torquing more than 22 ft lbs give me disengagment issues? Having disengagement issues at over 22 ft lbs makes absolutely no sense. The pressure plate must be torqued till it touches the flywheel, which only takes about 10 ft lbs, then tightened evenly. It can't possibley get any closer than that- I could torque those 6 bolts as tight as I want as long as I don't damage the pressure plate and not have any disenagement issues whatsoever. I appreciate your input but I'm sure that's not whats causing my problem.

wrd1972 - I did a search, couldn't find anything. Maybe post a link?

tbag_skywalker

wrd1972 - Nevermind I found the thread you were talking about it it makes perfect sense. I dont doubt you but I just don't understand why Spec/Ram would make a clutch that wont work properly in the specific car it was designed for???

The cars all put together and sitting on jackstands now, i've taken it apart and put it back together 3 times in the past 2 weeks and I dont even wanna look at the POS let alone pull the tranny out again. So unfortunately I won't be able to give you an numbers regarding the compressed and uncompressed thickness of the friction disk. But I will keep your advice in mind.

My problem isn't quite as bad as the guy with the RAM clutch, 1st, 3rd, 4th, and 5th are kind of difficult to get into but if im gentle they'll go in smoothly and 2nd and 6th feel nearly normal. I just dont want to frive the car and risk ruining the clutch because of improper break-in.

If the problem you and the guy with the RAM clutch had is the same problem that I'm having (which there's a good chance it is), would buying an adjustable master cylinder give me the tiny bit of extra range I need to get my clutch to fully disengage?

wrd1972

iTrader: (12)

Like I said before. The "critical release spec" is very narrow and less forgiving for these pull clutches as compared to the more standard push clutches. If the marcels are even .005" over spec (too springy, too thick) meaning too much distance between compressed and NON compressed, the disk will drag because the clutch simply cant fully release like it should.

For the sake of discussion, lets say the clutch release spec is .030" or so. If the compressed measurement is .250" and the NON compressed measurement is .285" then there is no way the disk can fully release. You can push the pedal all the way down and still no go. If you could in theory push the pedal another inch or so into the floorboard, then you would most likely get full release.

By contrast, on a NON marcel disk like my Spec 3+, the distance between compressed and NON compresses is less than .005" which means there is no possibility of having a disk dragging release issue.

Again, for the sake of discussion, lets say the clutch release spec is .030" or so. If the compressed measurement is .250" and the NON compressed measurement is .255" then there is plenty of room for full release to occur, and then some. This disk would release quickly by only having to push the pedal a few inches leaving better than 2/3 of the pedal travel totally dead and useless.

Marcel disks (stock disks) require near full pedal travel because the marcels must release in conjunction with the disk facings grabbing the flywheel and pressure plate.

If you got an adjustable master cylinder, it may fix it, it might not. You would have to try it. I do know that the cylinder bores are different in some of the MC's. A MC with a bigger bore would push the clutch fork further that a similar MC with a smaller bore using the same stroke for both.

Simply what you and the other guy need is a tad more fork movement or clutch release. You will not get that with stock hydros. But IMHO, the heart of the problem is the disk being a tad out of specification.

If you want to test something while its together and on the stands, have someone sit in the car, push the clutch pedal to the floor. While doing this, try turning the rear wheels by hand. I will bet money there is some drag there when there should not be. Compare this "feel" to that with the tranny in neutral which will turn with the least resistance. it only takes a little bit of disk drag to load the tranny gears/syncros and make the shifting difficult.

This thing drove me completely nuts for weeks and I will bet dollars to doughnuts that what I am telling you, is your problem.

BALLSS

tbag

I assume we are talking about a LT1 "pull" type clutch here.....forgive me but if the PP bolts are over TQ you will have disengagement issues. 22 ft lbs is spec.

Not saying you don't have issues with the clutch itself as suggested or hydraulic issues but I can tell you for a fact over TQ on the LT1 pull clutch will cause disengagement issues...been there done that when i got careless on a clutch swap and used my air gun on PP bolts....car on jack stands and would not go into gear....had friend hold in clutch while in gear and I tried to spin rear tire...no go....pulled tranny and retorqued to 22 ft lbs and good to go.
BTW use red lock tite on PP bolts

I to was like WTF when I was told to confirm PP TQ and found the 22 ft lbs TQ is there for a reason.

Good luck and certainly address the other concerns given

tbag_skywalker

****** - I could see what you mean now by overtightening the pressure plate bolts. Especially with an impact gun since its pretty easy to accidently torque to 60 ft lbs or more with one of those. The tech guy at SPEC told me about how the blue housing part of the pressure plate that contains the diaphram on the LT1 clutches are aluminum and can be easily damaged if overtightened, which I imagine would cause all kinds of engagement/disengagement problems. I'm also sure that he talks to guys with clutch issues all day, so I still dont think there's a problem with the torque specs (15ft lbs, then 35 ft lbs, with red thread lock) he gave me but I will definately keep your advice in mind.

I've just got a few more possible solutions I wanna try first before I go pulling the tranny again, on my back in my garage, with my cheap-*** Harbor Freight tranny jack lol. I didn't mean to come off harsh either-- in a way I reacted like you when I first read "no more than 22 ft lbs or you'll have disengagement issues," I was like WTF is he talking about? but now I gotcha, and thank you. And if the solution ends up being pulling the tranny and retorqueing the bolts, I'm calling up SPEC bitching.

wrd1972 - I see what your saying now about the friction plate being slightly out of specification and how little room for error there is with a pull-clutch. Thanks for the clarification-- I get frustrated and sometimes I don't see something from someone else's point of view right away.

If my friction plate is too thick when uncompressed, I'm gonna be calling SPEC up and ripping new ******** until I get a clutch from them that I know will work lol. Until then I've gotta confirm that my master cylinder isnt shot someway or another. I wish I knew what the throw is supposed to be for the slave cylinder so I could confirm that the master is pushing enough fluid when I push the clutch pedal. I'm getting almost exactly 3/8" travel from enaged to 'almost' disengaged.

I'm gonna either have to find some kind of GM reference book which will have technical data like that, or see if I could buy a new stock master cylinder from the dealership with assurance that I could return it if it doesn't solve the problem. Also I may call McLeod and talk to them about their adjustable master cylinders. A friend of mine with an LS1 camaro was having similar problems as me, he ended up buying an adjustable master which corrected the problem all together, even got the engagment point right where it should be in the pedal movement.

I greatly appreciate your help, but I think I need to confirm that my hydralics are functioning properly before I go pulling the tranny, again. And like I said, SPEC is gonna get a freakin earful if my friction disk is out of specifications like youre saying.

wrd1972

iTrader: (12)

I doubt you will find a specification for the slave cylinder stroke when you push the pedal. If you could figure out the specification for the full release window, you could measure the disk, do the math and determine if the disk is bad real quick like how I described above.

There is one other thing that can be done, in theory, however I have never tried it. You could slightly shim the PP away from the flywheel. This would force more overall release when the pedal is pressed. If one were wanting to try this, I would go in .020" increments. Not sure what you could make shims out of that would do the trick. But I am sure you see what I am getting at here.

As far as dealing with Spec. They have in the past had a bad rap. However from reading comments in the clutch board, they seem to be very active in helping their customers.

BALLSS

tbag

when i put my PP on with the electric impact gun I just "slightly" used it not full on knowing the TQ spec was low....but found it was to much. It took about 45 ft lbs to remove the bolts. I am sure there is a strong reason why the spec is 22 ft lbs.....christ I used to tighten the crap out of my PP bolts on my 57 chevy I put a 3 finger clutch in.

Certainly hydraulic issues could be your problem but if I understand you did not break into them and did bleed by hand and MV...so I am thinking problem is elsewhere.

Disc thickness....I understand that idea but have not experienced it with the SPEC 2+ I ran before my ZOOM HP.

If I could throw another thing to check in the mix...

The clutch fork may be bent or loose

I know this is a PIA...I went through quite a learning curve when i did A4-M6 swap and pulled the tranny more times than I care to admit.

tbag_skywalker

wrd1972 - well you were right about finding technical data like what the throw of the slave cylinder should be. I searched threw a bunch of books, including my haynes manual which has been damn near useless.

Your theory of shimming the pressure plate slightly off the flywheel is a good concept, heck id probably try it if I had another f-body that I could toy around with. They only thing I'd be concerned about is how much of the pressure plate's ability to clamp the friction disk to the flywheel youre going to be taking away. I know it'd only be a few thousanths away from the flywheel, which one would logically think that wouldn't affect that, but with these clutches who freakin knows lol.

I have been in touch with the SPEC tech guy and he sounds pretty stumped. He said to check and make sure nothing is stuck between the mating surfaces of the transmission/bellhousing/block which would throw the inputshaft off to an angle-- which in turn would cause the pilot bearing to get hung up on the inputshaft. I'm a total neat and clean freak when it comes to this stuff, plus being an electrical apprentice I'm always paying attention to wires and making sure they dont get pinched, so I know that no junk from the garage floor or wires are stuck in between any of those components. The next thing he said to do it make sure the hydraulics are working properly too, and he gave me a few pointers on that. If the hydraulics are working properly, which hopefully I'll be able to determine by this weekend then your theory on the friction plate is right, which would mean that I'd get a new (free) friction disk from Spec.

Another interesting piece of information he told me is that the thickness of my old stage 1 when it was new is .310" which is exactly the same as my new stage 2. What is still leading me to believe its hydraulic problems is that since I accidently destroyed my old slave cylinder last year the stage 1 had been acting funny, and now the stage 2 is really giving me trouble since its thicker (more hydraulic movement need to fully disengage it).

****** - Basically most of what I said to wrd1972 would be what I was gonna say to you too. I also wanted to add that I'm still keeping the torque thing in mind-- I more than likely will retorque to 22 ft lbs once I confirm my hydraulics are alright, before I exchange for a new friction disk.

I put a new clutch fork in there last time I had it apart last week- the old one wasn't bent or anyhting, theyre pretty freakin solid, but it was worn down about 1/32" at the tips that pull the throwout bearing. I figured it wouldnt really help my problem since the hydraulic setups in our cars are self adjusting, but I also figured it couldn't hurt to replace it anyways while I was in there just in case. And youre right this all is a pain right in the *** lol. I'll keep you guys updated this weekend when I can work on it again.

wrd1972

iTrader: (12)

Stock disk thickness (uncompressed) is around .320". This spec really is not critical since the hydros can adapt. At one point I knew the measurement of the same disk compressed but I dont remember it. My Spec is .360 IIRC but of course it does not compress.

If you do some searching, you my find where I posted the compressed thickness measurement. It would have been about 3-4 years ago.

DANS93TA

bleed the clutch again by hand, unbolt it and point the rod down. just because air doesnt come out everytime doesnt mean their isnt air in it. mine would make bubble sometimes and sometimes i could pump it a couple of times and there wouldnt be any bubble, but the next few times there would be. and get a new slave its only like 40 bucks it'll be worth it. oh yea after bleeding pump it one more time and hold it and have a friend put the rubber diaphram and cap on.

tbag_skywalker

wrd1972 - Yea that's whats boggling my mind about this screwey ordeal, the Spec clutches with pucks that don't compress like what you have are .360" and the uncompressed thickness of my stage2 is supposed to be .310" yet my clutch still wont fully disengage lol. I didnt ask for thicknesses on any of the other clutches like yours but the rep told me that the stage1 and stage2 clutches had the thinnest friction disks out of most of SPECs clutch line. Come to think of it, imagine how screwed id be with a stage3 6-puck with a thickness of .360" lol.

Oh I forgot to ask you in my last post-- with the car shut off and up on jackstands, should the rear wheels spin by hand as freely with the clutch pedal pushed in and in gear as they do when the shifters just in neutral? Obviously mine almost dont budge with the clutch pedal pushed in and the shifter in gear right now. I just wanted to know what its supposed to feel like for when I actually fix this car.

DANS93TA - Well I guess it coulnd't hurt to give bleeding one more try lol. That is a little different at the end than what I've done. When youre done bleeding and you pump it one more time and hold it, how far do you hold the slave in while you put the diaphram and cap back on the reservoir? Just an inch or do you push the slave all the way in?

Same with the normal bleeding- I've been pushing the slave rod all the way in during bleeding, should I maybe just push it in short 1" movements when I'm trying to bleed it?

Spartan7

iTrader: (7)

You should have replaced the master first if you doubted it. Get all the small stuff out of the way before you start worrying about a faulty disc. My first guess when I read your thread was hydraulics. I would say replace the master (or the entire pre-bled assembly if you feel like paying for it), bleed them using GM's recommended procedure, and see if that helps. If not, then you can worry about the disc and the PP bolt torque specs.

Counted Out

iTrader: (6)

Hahahahahhaha. I did that EXACT same thing.

But I hope you found my thread (Wrd1972 was talking about it), as I am having the same problem - more or less. I can't shift at all once the car is started but I can't figure it out to save my life.

I'm starting to think the disc is at fault.

Counted Out

iTrader: (6)

To the OP, can you shift gears? You said your car starts to take off with the clutch pedal to the floor, that is one problem I wasn't having. I could let up off the clutch and give it no gas (while in first gear) and I would slowly take off but, to my understanding, that is normal. I just could not shift into gears once the car was started, except for being able to jam it into first.

Speedracer2j

iTrader: (8)

When I was in Iraq my dad and buddy put my car together- motor/tranny swap. I run a spec stage 3, with their aluminum flywheel, and mcleod hydraulics. My first problem, was spec didn't state their flywheel was not for internal balanced motors... my dad and buddy couldn't find out why it vibrated. But also, I noticed the same you spoke of, it was dragging, and reverse was SOMETHING else to get into. But mine, was intermittent. Sometimes worse than othertimes. Well I tore the tranny out, fixed flywheel balance, inspected everything, good to go and reinstalled it. Still had it a little bit, off and on, but less. My buddy has drove it a bit since I have been gone, and put it on the dyno, and the issue kind of went away. Im assuming something with air in my hydraulics or so... at any rate now everything is ok. Don't think I helped to much, but you know your not alone, and there is hope. From my experience SPEC tech line was terrible, a little rude, and I ended up answering my own questions.

wrd1972

iTrader: (12)

This is good discussion guys. Just hang in there.

Just to clarify. Lets assume you have two NON marcle disks. This means that the two facings do NOT compress when clamped.

Disk 1 is .360" total thickness.
Disk 2 is .300" total thickness.

Both of these disks will work perfectly and will not drag period. Overall thickness is not really an issue. Also lets say you have either of the above disks installed. With the disk being fully clamped, the pressure plate can open up as little as .010" and you would have full release and no drag.

With the marcel disk that you have now that is giving you fits, lets assume that when its clamped, it compresses .030". This means that at the very least, the pressure plate must open .030" (plus a tad more) to get full release and avoid drag. Again, you guys cant get your pressure plates to open wide enough. Air in the hydros would do this and a marcel disk with too much range between compressed and NON copressed. Thats about it.

With the car on jackstands and the clutch pedal fully pressed, the rear wheels should easily turn over by hand REGARDLESS of whether the tranny is gear or in neutral.

Another way to bleed it is to remove the slave and SLOWLY push the piston in and out several times. You may need catch rags around the master cause fluid may get pushed out. Again, bleeding these LT1 slaves is gravy next to the LS1 slave. They are very forgiving.

tbag_skywalker

Ok guys just a little update here, no bad news but nothing really good either-

I decided to spend time more time bleeding the clutch because I never really had before, and from DANS93TA's post I think he was implying that it takes a while. I unbolted the slave, hooked the mityvac up to the reservoir, and started pumping the slave while holding it straight up and down in short strokes. No air came out for the first 5-10 minutes but then suddenly air bubbles finally started coming up and some were really big too. This literaly went on for a half hour, more and more slowly rose up and then it started slowing down. So I figured maybe my problem was solved and this was all there was to it. I bolted the slave back up, capped the reservoir, and had my friend get in the car while still on jackstands anbd throw it into first with the clutch pedal held pushed in. I finally was actually able to spin the back wheels but there's still a lot of resistance. Before that if I held on with both hands and pulled with everything I had the wheels would barely budge, but now I can turn the wheel with one hand but still with some difficulty.

I figured well lets keep goin with this bleeding and hooked everything back up the way it was before and restarted bleeding, another half hour goes by and plenty more bubbles slowly rise like before. towards the end of that half hour I thought the problem was finally solved since no more air was coming up. Did the same thing- capped the reservoir and bolted the slave up. This time around I was pretty dissappointed, the car didnt get worse but it didnt get better either. There's still a lot of resistance while I try to turn the wheel, but its definately a lot better than it was before we started working on it last night.

This is showing me that I really think there's issues with the hydraulics, whether its the master or slave I dont know. Eventually I'm sure I'll end up doing what Spartan7 said and buying a prebled master&slave assembly. For now I'd like to expirement with the master to temporary solve the problem before I go spending more money-
I found this link: https://ls1tech.com/forums/manual-tr...r-writeup.html
It'll allow the master cylinder to be able to push just a little more fluid which would temporarly solve my problem (until I buy a new prebled stock hydraulic setup). Its a bit unconventional, but it'll be a good learning expirience and probably a quick fix so I'm plannin on workin on it tomorrow.

Counted Out - Yes the cars very driveable as long as I'm very careful. I still choose not to drive it because I'm affraid of ruining a brand new $450 clutch because of improper break-in. 2nd and 6th gear feel nearly normal when shifting. But 3rd, 4th, and 5th are hard to get into. If I push too hard or throw the shifter too fast while driving I'll get a grind or the car just wont let me to in at all, like there's a wall preventing me form getting into gear. And with 1st gear like I said before, I've gotta push it a little harder than usual to get it in, and if I'm stopped and on flat ground the car will start slowly creeping forward before I start letting the clutch out. As for reverse I'm not sure, I havent tried that yet, I only drove the car maybe 5 miles. But yes the clutch also feels like it fully engages as soon as my foot comes off the floorboard whereas when it was working properly the engagement point would be right in the middle of the throw of the pedal.

That's all for now guys. Thanks again eveyone for your input, and I'll keep updating this whenever new things pop up.