Clutch hydraulic issues

[GTVeloce]

Some background: the clutch in my 75 TS was taking up very close to the floor, but it was still working fine. I then had to replace the tailshaft centre bearing, so while I was there I replaced the clutch flexible hose and checked and regreased the clutch TO bearing and fork. Reassembled and bled. Quite a lot of black particles came out with the fluid.

Clutch seemed to be working (the fork was being moved by the slave cylinder) however, when it came time to test drive, I couldn't get enough movement to allow gear engagement. So, I replaced the flexible hose between the reservoir and the MC with whatever I could find that would fit (it looks like fuel hose maybe). Bleeding and pressure bleeding did not work and now I had no pedal at all (i.e. it won't return by itself). I decided to replace the MC as I had a spare new one on me. Always a fun job. In the end I had to remove the complete intake up to the manifold; the steering column down to the intermediate shaft and other random bits. I bench bled the MC after install; reconnected everything and bled and pressure bled again but still to no avail - I cannot get any clutch pressure at all.

The pressure system I have used was initially a bike pump on an adaptor into the reservoir but then I just started pumping nitrogen into it instead.

What am I missing? There doesn't seem to be any fluid leaks in the system so should be any air leaks. The slave cylinder was rebuilt about two years ago. I have raised the rear of the car substantially - it is on a downwards slope to begin with and then I have jacked up the rear only.

My next task is to rebuild the slave again but if there is some other step I am missing I would love to know.

Thanks

[teambee75]

Make sure pressure plate is not stuck.  I found this out the hard way after going through a similar exercise.  Symptoms were not being able to engage any gear when clutch pedal was depressed.  Immediately leaping to the wrong conclusion I first replaced slave cylinder (which had slight weep anyway),  then master cyl when that did not succeed.  Was then still unable to get any pedal effort.  Not sure why now but for some reason ended up starting car in gear (with wheels on ground).  It lurched forward & then there was a loud crack as plate released and pedal came back.  Don't know if there is a good way to diagnose whether this is the issue but greater minds than mine on here will probably have one.  If you are going to try this make sure you have plenty of room in front of the car with no children, small animals etc. in the way.

[GTVeloce]

I don't think the pressure plate should be stuck as I was driving the car only a few ago and I was also able to move the car just last week after the initial work was done. Albeit only a metre on the driveway as the clutch take-up was so low to the ground I was not comfortable to drive it any further.

Also, currently depressing the pedal results in no movement of the clutch fork (i.e. the slave cylinder is not moving) which is my first issue to fix and I suspect my only issue...hopefully!

[Mick A]

G'day.

Try to bleed the air out at the hard line from the master cylinder.
Pump it up by hand then crack the 12mm fitting. Hopefully the air pocket goes and you get your pedal back.

Mick.

[GTVeloce]

I have tried many different methods and so far the only one that has been of (limited) success was to reverse pressure bleed. I pumped fluid backwards through the slave cylinder nipple using nitrogen to provide the pressure. It has enable me to get the fork to move about 9mm when pressing the pedal and the pedal self returns now.

However, it is still not enough to disengage the clutch and hence I can't select gears while the engine is running. The book saids I need 11-12.7mm but I just can't get the extra few mm.

Next step is to rebuild the slave cylinder. I have replaced everything else...

Question: I replaced the hose between the reservoir and the MC with some spare hose that I believe to be fuel hose. Is this going to be a problem? It had no markings on it and it seemed to be too hard for vacuum hose. What if it is vacuum hose?

[GTVeloce]

This clutch is going to be the death of me! What should be a fairly straight forward job is proving to be far harder than it should be.

I was going to remove the slave cylinder to rebuild it but couldn't get it out. Is there a system to retract the clutch fork enough to allow the S/C to be with drawn. Otherwise it will be easy enough. Two bolts and the flexible connection. Or is there some other approach required to remove the S/C?

I don't believe it is a bleeding issue now as I get no benefit to pumping the pedal a la pumping the brake pedal when there is just a little air in the line. This makes me believe it must be the slave cylinder on its way out as a process of elimination there is nothing else left!

[Mick A]

Crack the bleed nipple.
Push the fork toward the cylinder and it will push the piston in.
That should give you a second or so to remove the pushrod from between the piston and the fork.

Cheers.
Mick.

[Mick A]

Actually you shouldn't even need to open the bleed nipple. It should just push back now that I think about it.

Cheers.

[Divano Veloce]

Hi Julian,

sorry for chiming in late on this one. If theres a bubble of air downstream of the bleeder, ie on the slave piston face it wont be bled out. Try cracking the bleeder and pushing the slave piston all the way in and tighten the bleeder before letting it out.

[Divano Veloce]

Do that a couple of times

[LukeC]

Notoriously hard to bleed on Alfettas! Master outlet is in the wrong direction to facilitate easy bleeding.

I always used to bench bleed vertically (out port up), but those cars without their own master revervoir need a remote setup on the bench, then plug the inlet and outlet, mount and pressure bleed. This works best IMO.

The TS is worse again because the master points downwards to clear the plenum. Took me about four sessions with a dry system last time I did this with (a) a not so patient wife and (b) a two mates with no real practical car knowledge... to get mine bled good enough to drive, and then I have to drive the car around until it came perfect.

Use all the tricks:
- One person pumps the crapper out of the pedal (fast, making sure the pedal reaches the top of its stroke), then holds it down. Other person cracks the bleeder. Repeat lots. This one usually works the best to get you well on your way.
- The usual down with nipple open, up with closed.
- Plain old pressure bleeding.
- Use the slave to pump it through: push in (open nipple), out (nipple closed) etc

Once you get it good enough to drive, do that! Don't ask me why, but they get better.

[Divano Veloce]

Good to know what I'm in for when I put mine back together...

[GTVeloce]

Success! Finally. Well, I tried plenty of things and eventually took the slave out (thanks Mick (choderboy)). Rebuilding it was easy and putting it back was ok too. The only thing I struggled with a little was getting the pushrod back in. I found the best way was to remove the bolts and twist the slave almost 90 degrees. Because of the way the mounting is this gives a little more room to get everything back together. Then just rotate back and bolt.

The slave had quite a bit of sludge and was quite dirty inside. Once cleaned up though it looked fine in the bore.

Then I started bleeding, again. Once again, the best pedal I could get was with a reverse pressure bleed using Nitrogen to push fluid up and out the reservoir. But it still wasn't enough. Tried the pump up and crack the hardline to flex line joint. Tried pushing the piston as far back as possible and then cracking the bleed nipple but all to no avail.

The final thing that got me over the line was just a simple old school bleed but pumping the pedal down very slowly. So, simple hose from bleed nipple into a jar of fluid and closing the nipple at the bottom of every stroke.

The clutch works fine now albeit a little lower to the floor than is perfect but as Luke said I have found they get better as you drive them so I will just give it a good drive over the weekend and see.

What I have discovered now is that there is some vibrations there that should be there but I will start a new post for that.