I was surfing the net checking out websites when I stumbled accross the RAM Clutch web site. For anyone who has eveer had clutch problems (like me) There was a nice peice of info regarding the not-so-strong clutch fork.
If this breaks, you will feel like you lost your hydrolics and the clutch goes away. Pontiac was nice enough to address the situation and produced a NEW and IMPROVED fork and shaft.

The clutch fork on my wife's 1984 has already been replaced once and now it feels like a hydraulic failure. Can this system be bled? I can't see a bleeder screw.
Any advise would be appreciated.
Thanks

should be on top of the slave cylender...

There is a bleeder on the top of the slave cylinder. But bleeding will only pressurize the system back to factory spec. Since Pontiac saw fit not to allow any adjustment in the clutch, so when you burn the tires, you burn the clutch also. I am having the RAM racing clutch installed to check its reliability.

Man talking about clutch problems, the slave on my car is in a state of constant leakage. I replaced the entire unit once and rebuilt it several times, after about a yr it would always start leaking again. The key to making it last is the rubber dust boot covering the rod. Once this boot is cracked or torn, dirt gets in and the slave starts leaking. I got sick of this so I thought up my own unorthodox fix. I use 2 slave cyclinder pistons. I had lots of extras from all the times I rebuilt the slave. On one of them I cut off the skinny piece that the spring attaches to, the rest is shoved into the slave after the 1st piston is inserted. Having 2 rubber seals helps to keep the fluid in and air out

that is unothodox, but a good idea. You could also probably find some urathane tube and make a better boot.

Actually in no car that I've ever seen is clutch presure adjustable. Only a few racing packages I've seen can do this, and that is acomplished by changing the springs in the preasure plate. The mech clutch link adjustment is only to adjust pedal travel, and throw out clearance.

The main diferance between hydraulic, and mechanical, is that Hydraulic systems are "zero Freeplay" in most applications. What little return spring there may be usually isn't enough to pull the bearing off the plate. Mech link's have no way to self adjust, so Zero Freeplay isn't posible with them.

Fiero hydraulic clutch is no differant from any other I've ever seen. Pretty much all of them GM, Ford, etc, use a "zero freeplay" setup. This eliminates any adjustments over the life of the clutch, keepig the car with a full pedal. (80's ford trucks had a horrible problem with clutch slave life. like killing as many as 3 a year.)

The problem in Fiero is that the stock clutch, like most small cars uses a diapram type presure plate spring. (At least the factory one I saw was) These plates don't have the ability to tighten as RPM's rise.

Multi arm, and "loaded" diaphrams can do this. Both of these employ a series of weights that load up more on the clutch disk as RPMs increase. A stiffer diaphram only p plate is an improvement, but it will be signifigantly stiffer to keep depressed at a stop light too.

I'm "glad" to see that I'm not the only one who has clutch problems with their Fiero.:)

I have a question. Is it possible for air to be drawn into the system at the slave end without any evidence of fluid leaking from the slave cylinder? I continually have a problem with air in the system, but I've been reluctant to replace the slave because I haven't noticed any leakage of fluid. However, every couple of months when I can no longer disengage the clutch enough, out comes the bleeding kit.

I'm getting awfully tired of bleeding this damn thing though. We could probably start a new thread containing just the methods that everyone has individually developed to bleed the clutch hydraulics on the Fiero. My experience has taught me that it is NOT an easy skill to acquire.

-Patrick

yeah, it could be doing that. It's unusual, but posible. Air will go thru a smaller opening than fuild.

Check all the fitings and lines too. you could have a rubber line starting to fail.

Thanks Ogre. Sometimes when I'm bleeding this system for the upteenth time I almost wish I had an automatic, but then I slap myself a couple of times and remember how much more FUN it is driving a 5-speed.

I don't miss stick too much. delaware valley traffic is horrid just about 24/7. stick gets really old fast in it. clutches don't last long either. I've never gotten more than a couple years out of one around here.

For an auto it performs rather well. It's do better if it was an AOD, but I'm not up to the amount of time to change it.

Patrick, you should try my unorthodox fix. It really works, the few inches of extra length make the clutch release high, but now I know its completely releasing because it shifts so much better. I guess you could cut the rod down the same amount, but I like my clutch like this, before even with a brand new slave, it released quite low.

Hi Paul,

It sounds like you and I have the same problem but have tried to cope with it in two different ways.

I also felt that the clutch was never fully disengaging, even immediately after bleeding the system, so what I did (out of desperation) was to move the entire slave cylinder closer to the clutch fork. This was done by removing the cylinder from the mounting bracket, pounding the studs out of the cylinder's mounting flange, pounding the studs back into the cylinder's mounting flange from the other direction, and then mounting the cylinder onto the other side of the mounting bracket. Originally, the cylinder was attached to the far side of the bracket, away from the clutch fork. The way I reinstalled it, the cylinder was closer to the clutch fork by about ½ inch. Did it help? That's debatable.

Paul, I think what you and I have done is treat the symptom, but not addressed the real problem. The real problem as I see it is that it is near impossible to get all of the air out of the system. And it's this air being compressed when we step on the clutch pedal that's not allowing the clutch to cleanly disengage. I'd love to hear from a seasoned pro (Ogre?) or two and find out what their opinions are on the Fiero's clutch hydraulics and the bleeding of these systems.

-Patrick

but Patrick, what you did was the same as changing to a longer rod. With my method, you get an additional rubber seal as well as more length. If what you say is true, and there still is air in the slave, thats ok as long as the amount of air remains constant. The problem is when more and more air gets in. 2 rubber seals is better than 1 in my opinion to keep it out.

Hi Paul,

((I have removed the "joke" that had originally appeared in this spot.))

I agree that there may be some merit in having two seals instead of one in order to help keep the air out and the fluid in. Two seals shouldn't be necessary, but if it helps, great, good idea.

However, I still think that having ANY air at all in the system compromises the operation of a hydraulic clutch (or brake for that matter). Because there is no manual adjustment to be made, the clutch will always only be moved a certain distance when the clutch pedal is put to the floor. If air is being compressed, that distance becomes less. This results in the clutch not cleanly disengaging. Whether you or I move the slave cylinder closer or install a longer rod, I don't think it actually makes any difference. It doesn't make a difference because the hydraulic clutch automatically compensates for what we've done. I believe the only way to make the clutch actually travel a greater difference when activated would be to have the rod make contact at a lower point on the clutch release lever. This would change the geometry of the setup. Clutch pressure required would be higher, but the positive tradeoff would be greater clutch travel. I hope you can picture what I'm trying to describe. In practical terms, this idea would probably be difficult to implement (or maybe not), but in theory I think it's sound.

Paul, you've mentioned that the longer rod, etc. has given you cleaner clutch disengagements. My fear is that in doing so, you have done something that is possibly preventing the clutch from fully engaging.

Feedback?

-Patrick

[This message has been edited by Patrick (edited 09-07-1999).]

The Fiero uses a cable system to shift its gears. This is an extremely inefficiant link between driver and gearbox. From the day I drove my '84 off the lot,back in '84, I felt like the clutch was never fully disengaging. High shifter input along with vague gating made the car a challenge to drive in traffic. Unfortunately I'm afraid this is the nature of the beast that will never be remedied with bleeding. After crawling back into the car 15 years later I've found that the problem didn't go away by itself. It's kinda' like drivng a VW Beetle with a shorter shift lever! As much as I love my car, the shifting will allways be a problem due to designe, not air!

well.... having an extra seal isn't a bad thing. tho adding anything to the length of the rod really won't change the amount of travel.

there are 2 ways to change clutch travel. the first, as you mentioned, is to change/alter the fork. The second is to alter the master/slave volume ratio. Making the master bigger, or slave smaller, would increase the travel of the slave for the same amount of pedal motion. Of the 2 the second is prefered. It prevents adding to any side loading of the slave piston that could cause binding.

Bleeding: Bleeding clutch slave is a big pain. Part of the trick is to make sure the bleeder end of the slave is the highest point. Jack the car on the drivers side, or park across a slope with the drivers side high, may help air bubbles in the slave move toward the bleeder. If you haven't done it in some time, replace ALL the fluid in the system as well. Moisture can retain air and other gasses.

All I can add is that if the slave is working and then its not, it must be because air is getting in or fluid is being forced out. Now that I think about, I also agree that changing the rod length will not change the travel, but I put the extra piston in for the extra seal not the length. As I said before, the key to making it last is the rubber dust boot. I molded one out of hi temp silicon, not very pretty but seems to be working.

OK, a couple of comments.

First of all, it seems nobody appreciated my slightly off-color joke. My apologies, I won't do it again. Now, down to business...

Sorry Motorhead, I don't agree with you at all on this one. The problem that Paul and I are discussing has NOTHING to do with "high shifter input along with vague gating". The reason the damn thing won't go into gear is because the engine is still spinning the input shaft of the transmission. How do I know for sure? Simple. When the system is in dire need of being bled, but I don't feel like doing it in the pouring rain, I simply put the car in first gear BEFORE I start it. When the motor's NOT running, I can put that baby into any gear I want, no problem. That's the proof right there. Once the car is moving, you can actually change gears using no clutch at all. So using a "partial" clutch works fine. Kinda hard I imagine, on the synchros in the tranny though. Before I come to a complete stop I double-clutch and put it into first gear and leave it there with the clutch depressed while I'm at the stoplight. This probably helps to shorten the life of the throwout bearing, but you gotta do what ya gotta do sometimes. I don't recommend driving any car like this for a multitude of reasons. But I mention all this only to explain that the difficulty in shifting, especially into first or reverse, is because the clutch isn't disengaging properly, not because of an "inefficient link between driver and gearbox". And finally, I also disagree with your comment, "this is the nature of the beast that will never be remedied with bleeding". I disagree because immediately after I bleed that sucker, she works like a charm. However, much to my distress, the honeymoon only lasts for a short while and then it's back to me cursing the day I ever heard of a Fiero. So Motorhead, please don't feel like I'm picking on you. It's nothing of the sort. It's just that discussing this subject has caused me to focus on almost two and a half years of total frustration trying to deal with this problem.

Here's something else that added to my frustration level. The following is an email that I sent to Raybestos two years ago.

"I'm having a problem trying to find the correct clutch slave cylinder for my car. It's a 1987 Pontiac Fiero with a 4 cyl. 2.5L engine and the 5 speed manual transmission made for Pontiac by Isuzu. The part number in the Raybestos catalog is NPN SC37794. As soon as I saw the Raybestos cylinder I could see that it wouldn't work. Right off the bat it was obvious that the rod that reaches to the clutch lever was too short. (It was about three inches long instead of six.) When the dealer insisted that it was the correct slave cylinder, I simply used the rod from the old unit. Unfortunately this did not help. It turned out that the bore size of this new unit was 15/16 inches whereas the original GM slave cylinder has a bore size of 3/4 inches. As you can appreciate, this makes a difference when dealing with hydraulics. The larger bore size of the new cylinder prevented the clutch lever from being moved as much when the clutch pedal was depressed. This of course led to the clutch not fully disengaging. The dealer took back the cylinder but still insisted that it was the correct one and that I had the WRONG TRANSMISSION in the car. Anything to save face I guess. So at this point I'm still limping along with the old slave cylinder. I had no trouble replacing the clutch master cylinder in this car with a Raybestos unit, so I'm hopeful that you can steer me in the right direction."

Well, Raybestos never bothered to respond. In another thread here I mentioned that the Raybestos parking brake cable I bought two years ago has already started to seize up. You might be able to deduce from this what I think of Raybestos and their products.

Anyway, what I probably should have done two years ago was to simply have bitten the bullet and bought the GM replacement slave cylinder. What I think I might do now though is buy a rebuild kit and try Paul's idea. I don't know, maybe I'm just a glutton for punishment. :)

-Patrick

now for something compleatly differant, and really annoying..... As old as there cars all are...... have you replaced the pilot bearing? a worn or gummed bearing will also cause these problems.

Sounds like a two minute job... :)

i ain't an ogre for nothin'. hehehehehehehe.

Patrick, you sound really frustrated, I know that feeling. After years of bleeding and rebuilding that damn slave, I just about tried everything I could think of to keep it working. I decided not spend anymore money on it and try to figure out a no cost solution. The double piston idea was the last of a long line of brilliant but ineffective ideas.

Hi Paul,

Looks like we're discussing this in "real" time.

The slave on my car must be "stamped" because it is quite smooth. The piece of crap that Raybestos was pawning off two years ago that I took back was definitely "cast" because it was very rough.

I'd be interested if anyone else is aware of the bore size of their slaves. If we could find a unit that had a smaller bore size, we could get some more clutch travel. It's a long shot, I know, but hey, I'm desperate!

You're right Paul, I have been very frustrated with this car. Unless someone has gone through what we've been through, they just don't appreciate how nice it is to drive a vehicle that shifts properly.

Ahhhh.... I used to love driving my Z28 with a 4-speed and a clutch that worked....

the slave seems simple enough for any machine shop to fabricate. Just use a billet about the same length and machine a hole in it, then tap threads for the bleeder and hose.

What about the mounting flange?

I'm not sure what a billet is?

here we go...... you're realy gonna hate this.

I spent the last couple days examining Fiero clutch system to see just what it has.(Mine is auto, so I hadn't a real reason to look at clutches.) There are a number of things that will cause premature slave failure. The mose obvious, the slave itself, isn't the whole picture.

1. Slave cyl alignment. The slave must be carefully algined or it will experiance excesive side loading of the piston. this chews up the bore, which then chews the seal. Alignment of the slave seems simple, it's not. I'm not even going to try to explain a procedure. Check your dead slave bore, and see if it's got allot of wear on one side.

2. If the clutch fork, or throw out bearing are not free moving, you will also get excesive side loads in the slave cyl. (There is always some side load, the trick is to minimize it.) Also the clutch is binding at this point, wasting energy, and requiring more slave preasure to compensate.

3. The Pilot Bearing, as mentioned earlier, can bind on the input shaft which keeps the shaft turning enough to make shifting hard.

4. The clutch disk is warped/bent. Over time the clutch disk, preasure plate, and flywheel, can warp from age, heat, etc. A disk can easily be bent if not properly installed.

The only way to fix problems 2-4 is to pull the tranny. problem one can only be examined after you're totaly sure 2-4 are fixed.

The reasons I think the double piston setup works are these:

1. I agree that the second seal protects the working seal from dirt. This is never a bad thing. Most hydraulic systems have multiple piston/ram seals. (inluding youre shocks & struts.)

2. The second piston keeps damage to the bore caused by excess piston side loads away from the main piston. the main piston can more easily float sideways, keeping the working section of the bore from wearing. As near as I can tell, the Slave cyl only actually uses about 1-1.5 inch of the total bore length. The rest is room for the keeper spring, and clutch disk wear compensation.

In addition to all this, you could have some actual tranny problems, but since you all indicate that it works fine after bleeding, I'd say you tranny is probably ok. (tho if you haven't puller the console apart lately you should. the shifter does need some periodic cleaning etc.

Thanks Ogre, I appreciate the time you've put into this, especially considering you own an automatic!

Paul and I were going on about this as you can see above. (Misery loves company.) One thing that both you and I have mentioned before is cylinder bore size. The smaller the slave bore size, the greater the clutch fork travel. Many GM parts are transferable between makes and applications. Do you know of a similar shaped slave (GM or otherwise) with a smaller bore that could be mounted in place of the original Fiero one? I mentioned in an earlier post that my stock slave has a bore size of 3/4 inch. If we could just find a slave with a bore size of 5/8 or maybe even 1/2 inch, this might be enough to overcome the problem of the clutch not disengaging cleanly.

I suppose the same could be accomplished if we could find a master cylinder with a larger bore size.

What do you think? Is there a chance that a different sized cylinder (slave or master) could be adapted to fit on the Fiero?

it might help to use a longer throw, but don't count on it. A hydraulic clutch starts to release nearly as soon as it presurizes. It really doesn't take allot of travel to operate. Don't compair it to a mech linkage which has to take up freeplay before the bearing even contacts the clutch.

It this point in the game, I'd be very suspicous of the Pilot bearing, and clutch disk. if the disk is binding on the input shaft, it will drag the fly wheel.

With this many repeated falures of slaves, I'd reaaly recomend pulling the tranny, and doing a complete clutch job. including getting the fly wheel cut(resurfaced). I would not, even on my own car, continue to find modifications untill I knew the clutch was 100%. I strongly doubt either of yours are right now.

while it's out pull the clutch fork apart, and clean, & grease, it. check it's bushings, they are just little sleeve bearings that do wear out. replace them if at all posible. (they may be hard to find anyplace but a tranny shop.)

you might as well aslo replace the input shaft seal, and axil seals.

Thanks Ogre. Once again you have stated some very valid points. The problem is that the vast majority of us DON'T want to have to pull the entire engine/transaxle assembly out of the car, especially if it's "just" a clutch problem (and the car is still usable). I understand completely what you're driving at in your last post, but like a lot of other people, I want to make sure there isn't some "easier" fix before I resort to pulling the guts out of my Fiero.

I still think that there is a possibility (in my Fiero's case anyway) that being able to move the clutch fork a bit more would help. It seems to me that the stock Fiero hydraulic clutch system is only just barely capable of disengaging the clutch at the "best" of times. By that I mean when everything is brand new and absolutely properly aligned, and not a single molecule of AIR in the system. If any one of a hundred things happen to reduce this perfect "harmony", then the problems begin and the clutch fork is not capable of moving far enough to cleanly disengage the clutch.

True, as you pointed out, there can't be major mechanical faults for the clutch to perform properly, but mine appears to work alright immediately after it's been bled. This is why I'm still desperately clinging to the hope that "simply" changing the master/slave hydraulic ratio would produce a superior clutch action.

Ogre, I would pull the tranny but I cant stand doing this. The first time the slave started acting up, I pulled the entire tranny thinking something was wrong inside which happened to me before. (rivets in clutch disk popped out another story) When I realized it was the slave, it made me sick to my stomach. I dont feel like going through that again.

Geez, Paul, I don't feel so bad now. :)

all of this makes me glad that i also own an automatic....:o)

Wow! I go away for a couple days and miss everything.

After reading all these posts,I like the idea of finding a different master-slave ratio, but it would be a trial and error procedure, right? And what about possibble damage caused by too much travel?

You guys are vastly more experienced with this car than I, but I gotta' agree with Ogres point of insuring that other components are in proper operating condition before trying mods.

By the way,in my nature of the beast remark I was comparing our cars to the mechanical shift linkage set ups. I think some of my shifting preblems are a result of worn cables and slave cylinder, which I'll fix when money and time permit.

Educational discussion ya'll, keep up the good work!