BoostAddct

I'm at a loss on this one so hopefully someone here can help; Last night I was practicing my launching from a stop and after the 4th time when I went to shift to second it would not go in and then it would not go back into any gear. The clutch pedal still felt normal, but the clutch was not disengaging. I was able to get the car home by just driving without the clutch and it still goes in to every gear. I started investigating and here is what I cam up with:
-Clutch master fluid is full
-Slave cylinder is pushing fork, but only about 1/2" so from the access holes it doesn't seem to be enough to disengage
-Clutch Fork seems to be fine and not cracked
-I re-bled the master in case their was air and that didn't do anything

Car Details:
'94 SC300
BL67 Turbo Kit
R154 Trans
RPS 6-Puck Sprung Clutch (less than 5k on it)

What else can I do to troubleshoot before having to remove the trans? From what I see it looks like the slave isn't pushing the fork far enough to disengage, but I can't say for sure since I don't know how far it should be pushing. Please give me any other ideas it could be so I can check them.

RyanV

iTrader: (9)

How many miles on the motor, and is it an RPS pressure plate too?

You can slip it into gear, but you can't use the clutch.

Another guy has the exact same issue as you in the perf forum.

I think it's because when you push on the clutch pedal the crank is moving backwards along with the clutch, and it isn't releasing anymore.

The problem is just too fishy..and I've troubleshot this exact issue for a month before.

One thing to check is if the clutch rubber hose is expanding(taken from the other thread).

BoostAddct

Motor has 65K on it; I'll trace the rubber clutch hose and see if it's possible somewhere that it is expanding. I'm leaning towards the following diagnosis;
-Bad slave cylinder
-Bad clutch master cylinder
-Cracked/Bent clutch fork
-Worn clutch disc
-Clutch disc spring broken

The thing that still throws me off is that from watching the slave push on the fork it doesn't seem to be going far enough in to release it.

SpiderN9NE

iTrader: (8)

i havent read the other guys problem but you probably shattered your disk. happened to me with my 240sx. the fork and everything else still works but pressing against the pressure plate doesnt work right because of the disc all messed up. when i took my trans out the teeth on the pressure plate looked like they were all messed up but it was just from the disc being broke in certain places so the teeth on the pressure plate wasnt even all the way around. so i think without the disc the pressure plate teeth are collasped to far to disengage the from the flywheel.

cant guarantee this is your problem but symptoms seem to be right on.

edit:i just noticed you have 6 puck, dont know much how they operate or fail but i shattered oem disk and got your problems.

BoostAddct

Well I fabricated a 1/4" and 1/2" longer slave rod and that didn't solve the problem; I hate to throw a clutch master cylinder and slave cylinder at it if that won't solve the problem and it doesn't seem like the rubber line is really expanding. I'm worried that I am going to have to pull the trans to get to the bottom of this one....

lemmiewink

Ok, so the slave is pushing the fork. So I'm assuming that the release bearing hub is attached to the pp. When you push on the clutch does the diaphram "breath"?

Also replace the hydraulics one at a time. You can't rule them out with visual inspection because sometimes they fail internally.

Do the slave cyl first. Then bleed and try again. Then do the master cyl if the slave doesn't fix the problem.

I assume you can bleed it properlly, but just incase you don't.

Push the pedal down SLOWLY. Don't mash or pump it. Hold it down (use a friend for this) then crack open the bleeder screw. Close it while the pedal is held down. Then raise the clutch pedal SLOWLY.

I would rule the hydraulics out before taking apart the transmission. Also what fluid do you have in there? This could effect engagement also.

SpiderN9NE

iTrader: (8)

if the slave is moving, how could you think that it could be the slave or the master cylinder. even if bleed half way you could still disengage a clutch. try to look through your fork hole at the pressure plate teeth. if the they arent all at the same height then there is some type of disk failure. enough disk there for engagement but the the teeth on the pressure plate are out of wack where the proper function for disengagement isnt there. or throw out bearing. im mean the extending would compenstate on the loss of movement and it didnt work. im not telling you to tear your trans apart but fixing the easy's wont fix the hard if its your problem.

BoostAddct

The slave is pushing the fork, but it is not going that far and that appears to be why the clutch isn't disengaging; How far movement wise should the rod be moving?

What do you mean by "breath"

Thanks for the bleeding tips; I was bleeding it similar to how I have bled brakes so that could have a small effect too. For fluid I'll have to look again at what we used when we did the trans swap, but I'm definitely looking at adding Redline MT90 if that's what people would recommend. How would the trans fluid effect the engagement though?

BoostAddct

The slave is moving the rod and fork, but it's only moving it like 1/2" or so and it doesn't move the teeth of the pressure plate very far. The teeth are all at the same height and I didn't notice any damage from what I can see through the viewing holes.

lemmiewink

Breath as in the diaphragm of the pressure plate expands then retracts. Fluid doesn't effect clutch engagement per se, but it does affect how hard it is to throw into gear. The countershaft has to slow down enough so that your synchros can line up.

This means that the fluid has to have the right amount of friction (called the coefficient of friction) to effectively throw into gear. If not, it could be incredibly hard to put in gear.

Also check my update...

BoostAddct

The fluid we used was Synthetic 75W-90 GL-5; It was from a local Auto Parts store since we were in a bind for some when we did the swap.

Brownmagic

iTrader: (1)

Did anyone check the pressure plate to see if any of the fingers went bad?

SpiderN9NE

iTrader: (8)

Did anyone check the pressure plate to see if any of the fingers went bad?
brownmagic quote

he said they were all the same as far them being in the correct alignment so i guess he didnt see nothing wrong with them. but im like you the way it sounds it sounds more clutch components, practicing launches. but if its only moving 1/2 inch, thats not sounding right how did you bleed the master cyl?

BoostAddct

UPDATE! I kept the 1/2" extended rod in and re-bled the system; The clutch started working again, but engagement was literally all the way at the top now. I took it out for a test drive and the slave cylinder literally ripped itself out of the trans and started dragging on the ground so I lost all pedal pressure; Upon inspection somehow the cast housing cracked around each bolt....it didn't seem like I overtightened them though.

lemmiewink

Holy crap.... Well time to get a new slave. Also. Check the pp bolts for tightness.. just in case...