Slave Adjustment

Dang! Things are not going that great yet with the slave. I now have the new one in the car, and trying to bleed from the slave with a hand vacume pump. For some reason I am not getting fluid to flow. I build up the vacume on the bleed screw to high vacume, then slowly turn the nut and keep pumping as vacume is lowering, but no fluid is coming through. I thought maybe something got in the main line, so I disconnected the main line from the slave, and bled from the main line, and flow is fine from there. I am wondering if I am getting air from somewhere? Only place I can think is the main line where it connects to the slave (see photo of old slave connected). I have all that real tight though. I could maybe wrench it more, but I laid on it pretty good already. Maybe the main line where it connects to the slave is supposed to have some small rubber piece between the main line and the slave screw, and maybe fell out when I was replacing them? Right now it is a metal to metal fit where I tighten the main line on the slave (called flange fit?).

Thanks for the lesson in hydraulics. I had mistakenly thought that increasing the bore size of one or both cylinders would ease the pressure

Anyone got ideas why I can't get fluid through my slave? Only thing I can think of is an air leak somewhere, that's all that makes sense to me. For those interested in seeing the difference in slaves, here is a photo showing my prior aluminum slave on the left (probably regular bore) and new (long throw with smaller bore) on the right. Once I get the frekin thing working I can report if there is any change in pedal pressure for those wondering from regular to long throw.

Remove the bleeder screw and see if the hole is obstructed. Maybe it didn't get drilled??! If that's clear, then check the passage that is drilled into the cylinder bore. If that's clear, then remove the hard line fitting and check its' passage. If that's clear, then remove the piston from the cylinder and check the end of the bore. There may have been a washer (or similar part) installed that is blocking the flow between the inlet port and the bleeder screw port.

You should be able to gravity bleed the slave. Fill the master cyl and open the bleeder screw. Brake fluid will soon begin to flow out of the bleeder screw. This is how I did mine. Didn't even need to connect the bleeder.

As I recall, the stock slave cyl bore is 1", and the stock clutch master bore is 11/16" or .6875" (early cars)

Well I was never able to bleed through the bleed screw with the vacume pump, but yes fluid will come out of the bleed screw if I push in the slave a little, so to me that means it is full. It all worked fine when I hooked up the return spring and shifts excellent now. The pressure on the clutch pedal when beginning to pres it in is much stiffer right at the top, and the pedal seems stiffer too with the long throw. However, it is obvious to me now that the old aliminum slave was shot, and maybe with that unit with it being shot the pedal was just soft anyway due to the bad slave. It seems it all got even stiffer the more I drove it. Thanks for all the advise, it all helped understand this stuff more.

quote:

The pressure on the clutch pedal when beginning to pres it in is much stiffer right at the top, and the pedal seems stiffer too with the long throw.

That makes sense because for each portion of travel of the clutch pedal (Master cylinder) the slave is moving further (i.e. doing more work) against the resistance of the pressure plate.

I'm glad you got it all worked out.

Julian

Well I am not sure if I am done with this or not. I saw the other post about the spring and actuating rod, and now I am wondering if I have my actuating rod adjusted correctly. This is what I experience: When I had the bleed screw open, I could push in the slave cylendar acuating rod by a little over 1/4" by pushing in on the cluthch arm, so to me, it seems I have a little too much play but I didn't mess with it. However, when I closed the bleed screw and drove the car around everything at the clutch arm is now real tight (I can't push it back in like before and the return spring won't pull it back further either like when the bleed screw was open). This makes me wonder if when adjusting the acuating rod, if this adjustment should be made when there is no presure in the system such as with the bleed screw open. Only then I can really feel the free play by pushing on the arm.

Only reason why it may have worked great yesterday is because it tightend itself on the small adjusting screw when I drove it because I didn't have that small screw tightened on the arm with the nut.

When you push the piston into the cylinder with the bleeder open, you are just displacing the fluid out of the bleeder screw and not back into the system. The return spring should push the piston back into the slave cylinder until the adjustment screw "bottoms out". If the pin were removed from the push rod, you should be able to push the piston (with some effort) all the way into the slave cylinder until it bottoms. The brake fluid would be displaced back into the master cylinder reservoir. There could be something blocking the fluid flow from properly returning to the master cyl. The master cyl push rod might be adjusted too long, or there could be something inside the bottom of the slave cyl.

The correct length for the stock slave cyl push rod is 3.07" to 3.09" (~ 3-1/16" to 3-3/32"). It is measured from the center of the eye to the end that contacts the piston. I don't know if it is the same dimension for the long throw slave.

quote:

Originally posted by jb1490:
When you push the piston into the cylinder with the bleeder open, you are just displacing the fluid out of the bleeder screw and not back into the system. The return spring should push the piston back into the slave cylinder until the adjustment screw "bottoms out". If the pin were removed from the push rod, you should be able to push the piston (with some effort) all the way into the slave cylinder until it bottoms. The brake fluid would be displaced back into the master cylinder reservoir. There could be something blocking the fluid flow from properly returning to the master cyl. The master cyl push rod might be adjusted too long, or there could be something inside the bottom of the slave cyl.

The correct length for the stock slave cyl push rod is 3.07" to 3.09" (~ 3-1/16" to 3-3/32"). It is measured from the center of the eye to the end that contacts the piston. I don't know if it is the same dimension for the long throw slave.

jb1490, I think you may be right, fluid is not returning to the master for some reason. This is making some sense now, because remember I could not vacume bleed the system at the bleed screw like I could on my other cars. Which to me could mean there is no opening at the master for fluid to flow freely back into the slave when the clutch pedal is released all the way. So maybe the rod at the master is adjusted too long like you say. I tried pulling on the pedal some and I get maybe 1/4" where I can pull it back and I see the master cyl bolt come out just slightly, but maybe it isn't enough. But I wonder what is making the pedal stop at it's highest point, whether it is the pedal mechanism itself reaching some max setting within the pedal mechanism or if the master itself is already all the way out or not. I suppose the only way to tell is disconnect the master cyl rod bolt by the pedal and turn the bolt so that it gives less rod length. Geez you gots to be a freakin engineer to figure some of this stuff out. At least I am learning something (maybe).

If to try this, it seems I need to free up two spots by the pedal in order to allow space to trun that nut coupling on the master cyl rod (see photo with blue arrows). I hate this part, those areas are so hard to get at!

But there must be some fluid moving back to the master, otherwise the clutch arm would never return back at all, no?

Here is a photo looking down into the master (left side of photo represents front of car). I am not sure what these holes do, but the one on the top seems to be set a little further back toward the rear of the car than the hole at the bottom. It appears that the top hole does have part of the master cylener plunger showing, appears maybe half open? Maybe that is the return hole? Can you tell, I would rather take photos than get under that dash like a praying manthis with arms bent to my chin trying to adjust things.

Before you crawl under the dash (and hurt yourself...my neck hurts just thinking about it), loosen the B nut on the slave cyl hard line and see if the slave return spring allows the slave piston to retract into the slave cyl (until the adjusting stop screw bottoms) . If nothing happens, then open the bleeder on the slave and the piston should retract into the slave cyl.

quote:

I need to free up two spots by the pedal in order to allow space to trun that nut coupling on the master cyl rod

You only need to loosen the jam nut on the clevis. Then turn the push rod with a pair of pliers (or what ever works). Rotate the push rod counter clockwise as viewed from the driver's seat. This will effectively shorten the push rod. You could take the pin out of the clevis. This would let the push rod move slightly away from the master cyl, but there isn't much room between the clevis slot and the cast bellcrank.

Thanks jb. Lucky I saw your post before getting under the master and breaking my spine. I took out the all the nuts on the top of the slave (B nut and the bleed screw), and the freaking thing still won't push in to releave the final pressure. When I put in the slave, I had about 1/4 inch or so of play with no fluid in the slave (I could push the arm back and forth about 1/4 inch). Only thing I can now think is that something seemed to occur when fluid got in there, and now it won't return all the way even with all the screws out, odd as hell. I now even got the wife involved. She pushed in the clutch and I tried to adjust the bolt down some more on the slave rod. I already had it bottomed out to the rear toward the eye, but I cranked on it real hard to losten it toward the eye some more. I got maybe 1/4 turn of that bolt and the rod too downward. Then I measured the arm distance and that action allowed the arm to go in a little more very slightly. So to me that shows that rod will go in more, but something seems to have changed within the slave, as I could have never gotten that slave on the clutch arm with the pressure it has now. Now I wonder how to get that slave off with the pressure on it from the clutch arm pushing against it. Maybe I could loosen the clutch arm where it is attached to the trans and try and pry open that gap to make it large enough for it to spin free, and then just adjust the arm further to the rear of the car and tighten that nut again. Damn, one or two hour project is taking about 3 weekends so far for the weekend warrior!

Jan,

This is indeed strange, I think we shoudl step back and analyze the situation prior to changing too much more. To help me understand a little better I have some questions;

1. What were the symptoms that caused you to change to the long throw slave?
2. Even though you couldn't vacuum bleed, you managed to manually bleed the new slave correct?
3. You drove the car, how did the clutch feel, did it slip at all?
4. With the bleeder open/removed do you get fluid when the clutch pedal is depressed (like a manual bleed)

In your MC photo it looks like the MC plunger is all the way back against the circlip. The easiest way I find to tell is to loosen the two bolts in the front trunk bulkhead that hold the MC to the bulkhead, if the MC is forced off the bulkhead by residual pressure the rod is set too long. But if this wasn't an issue previously changing the slave would not affect it.

Julian

quote:

Originally posted by Joules5:
Jan,

This is indeed strange, I think we shoudl step back and analyze the situation prior to changing too much more. To help me understand a little better I have some questions;

1. What were the symptoms that caused you to change to the long throw slave?
2. Even though you couldn't vacuum bleed, you managed to manually bleed the new slave correct?
3. You drove the car, how did the clutch feel, did it slip at all?
4. With the bleeder open/removed do you get fluid when the clutch pedal is depressed (like a manual bleed)

In your MC photo it looks like the MC plunger is all the way back against the circlip. The easiest way I find to tell is to loosen the two bolts in the front trunk bulkhead that hold the MC to the bulkhead, if the MC is forced off the bulkhead by residual pressure the rod is set too long. But if this wasn't an issue previously changing the slave would not affect it.

Julian

Yes, this is all pretty strange. I decided to change the slave because it was leaking slightly and shifting was a little difficult, and I saw the throw was pretty small. So, time to change and I figured go with the long throw. On the new slave I was finally able to bleed somewhat by pushing in on the slave rod with the bleed screw open, then closed the bleed screw and returned rod to normal. I did this a few times and I suppose it drew some fluid in. (I had about 1/4 inch play there, and I suppose that did it). By the way I can now bleed excellent from the bleed screw with the vacuume pump on the bleed screw (go figure!). When I first drove the car around with the new slave, I didn't have that much throw, although it shifted ok. The more I drove it the stiffer the pedal became (now real stiff, especially at the top of the pedal movemnet - da wife could hardly press it). But I figure that is probably how a long throw is supposed to be, although maybe not that strong at the top. I figure it is real hard now at the top because the slave rod is partially initiated and won't return all the way. That slave is freakin awsome though for throw distance, it seems it is at least 2 inches throw distacne from start to stop position after I drove it around, but I have to measure. When the wife pressed the pedal and I looked at the slave, the throw distance is just excellent. Right now I am ruling out any issues with the master, because with both screws out of the top of the slave, I figure that should release the clutch arm back into position, so that is nothing with the master as it isn't even hooked up. Remember I had play before I put fluid in there and drove around. So tonight I may try and measure where the top of the piston is on the slave by sticking a toothpick or ice pick down into the bleeder screw, with the assumption that the piston (or something) should be toped out.

Here is the other odd thing that I just now recall. When I had the old slave hooked up, it also was somewhat tight against the arm (no play). But when I opened the screws at the top of the old slave in order to release pressure to remove it, I was only then able to push it in more ("then" I had play). Now I wonder if something is adjusting within the trans itself to keep tension right at this beginning of motion position on the clutch arm. I suppose only way I will know is to somehow remove the slave and see if the rod moves further into the slave when it is out of the car, and then also see if the clutch arm is free to move then. The clutch arm was free when I took out the old slave so I would assume it would return again. So now I wonder how to remove it. Only thing I can think is to try and force the bottom clip ring loose on the slave bracket but I don't think I will have luck there with the amount of pressure. Other option may be to somehow spread the clutch arm at the transmission arm gear area and allow the arm to then travel free toward the rear of the car. But I don't know if I could get something to spread that clutch arm apart enough.

Maybe I am fretting over nothing though. The car runs great, with exceptional throw and shifting ability is at it's best (with super hard pedal I suppose mostly from the long-throw unit). This is why I thought I was done with it, but it just doesn't seem right from what I understand to not have any freeplay. Maybe someone built something into this trans that takes up the freeplay in a safe manner?

I measured down into the slave through the bleed screw and it is about 1 & 3/4 inch untill I hit something, maybe that means nothing. Now I am wondering if whatever pushes back against the trans arm within the trans is not pushing back hard enough to push in the final motion of the slave rod further. I suppose I could put a rubber piece on the trans arm and see if I can hammer it back more to see if I get any little motion out of it.

Definitely do not try to rotate the clutch arm on the shaft!! You will either break the arm or damage the splines.

It sounds like there is something in the slave cyl that is acting like a check valve and not letting the fluid return to the master cyl.

I suggest to remove the clutch slave actuating rod pin and see if you can push the slave cylinder back by hand to establish whether it is truly a slave problem or more likely a clutch problem.

I hate to say but I have a feeling you may have over extended the clutch fork and it has popped out of the retainer on the throwout bearing and not seated back correctly. This may explain both the non return fully and hard clutch pedal. I'm not sure whether you'd be able to see with a flashlight in the sight hole of the bell housing.

quote:

Originally posted by Joules5:
I suggest to remove the clutch slave actuating rod pin and see if you can push the slave cylinder back by hand to establish whether it is truly a slave problem or more likely a clutch problem.

I hate to say but I have a feeling you may have over extended the clutch fork and it has popped out of the retainer on the throwout bearing and not seated back correctly. This may explain both the non return fully and hard clutch pedal. I'm not sure whether you'd be able to see with a flashlight in the sight hole of the bell housing.

Yeah, maybe there are potential downsides to a long-throw slave, we will see. Only problem to remove is that actuating rod pin that goes through the slave eye bold attached to the trans arm is in there pretty solid to try and hammer it through in such a small space. Today I bought a small 1/2" bold with a small sliding rod on it with nut behind it, and I may be able to place it bewteen a good solid part of the clutch arm and the slave bracket to turn it slightly enough to remove pressure and then remove the pin that goes through the slave/trans arm, and then remove the slave. Things are so close together in that area that I don't think I have much room to play with the slave unless I remove it, but we will see.

I may look in the bellhousing hole and try a photo through the bellhousig too, but I have no clue what I am looking at...at least my camera gets in places that sometimes my face/flashlight can't.

Well that went over like a lead balloon. I fabricated the bolt/spreader device, but the area to work in is just too small next to the slave bottom where I was hoping to push open the clutch arm by placing it between the clutch arm and trans. My next thought is to just place a thick bolt under the salve between the clutch arm and trans as the wife pushes the clutch pedal slightly. Then when she lets go of the pedal slowly, pressure from the trans arm will be on that inserted bolt and it should free up pressure on the slave so that at least I can see if I can push the rod into the slave further than it is now. If the rod pushes in further by hand, then I would guess the slave is ok and something is preventing the trans arm from returning further. Funny thing is that it all runs great, shifts perfect with no strange noises with clutch pedal in or clutch pedal out. It is just at this final end of clutch arm release that it doesn't seem to want to return further to give play at the arm. Maybe I just drive it and fagetaboutit. Or maybe I just drive it up to Byars to take a look see before I loose a finger messing in that small clutch arm area while da wife presses the pedal. I would need a nice secure large diameter bolt or some type of good metal piece to temporarily hold that clutch arm open.

Maybe whilst the wife presses the clutch you could put a block behind the arm for safety and have her let the pressure off, then you should be able to reduce the length of the actuating rod, which may be enough to remove the preload you appear to have on the clutch.