33 replies to this topic

[Dan]

When you said the inside of the slave was dry, what did you mean? Is the fluid getting there properly?

The only solution may be an alloy billet slave from Fast Carl....

Edited by Dan, 15 September 2007 - 11:14 PM.

[Jammy]

I'm liking that solution!

No, I mean with the dust seal off, the inside was bone dry. The slave cylinder bled beautifully with the EZ bleed.

[Dan]

The orange spring is a lot heavier than the Metro was ever designed for, I suppose there is a chance that the pedal design simply doesn't have enough advantage to do it but I don't think it's likely.

Watch the crank pulley while someone presses the clutch to make sure it's not a thrust washer failure...

I reckon it's got to be down to wear. Is it the right type of CRB? There are several.

[Jammy]

Well I've tried two CRBs, but they've been of the same type. Will watch the pulley, but had a poke around there earlier and there wasn't much play.

Its not actually still in a Metro, its in the Minus, as far as I know its using a Mini pedal box, but I couldn't say for sure.... If it pushes the M/C piston all the way up into the cylinder surely the pedal has enough travel?

How important is having level drive straps? I have spacered them, but they are off very slightly, like by 0.5mm!

[Sprocket]

Masters are the same, slaves very much aren't.

As Ethel says the hydraulics are self adjusting by virtue of a non return valve in the master. This can all be caused by the system needing to settle in and you can use the self adjustment to force it all together. Wind the return stop out and then pump the pedal and you will see the point the arm returns to moves. Do this until there is almost no travel and it is keeping the clutch open all the time, then reset it back to where it has the required gap from being relaxed and no more. That should have settled all the parts into each other and get it working.

If there is a non return valve in the master, what hapens when you release the clutch pedal? where does the fluid go?

The slave cylinder works the same way as the brake wheel cylinders, the springs return the piston and pudh the fluid back to the resevoir. If there is no spring tension, the piston will stay where it is as does the fluid behind it, the next time you press the pedal, more fluid is pushed into the cylinder pushing it further untill such a time that the piston meets the push rod and is then under spring tension.

If the push rod is not located how i described it, the system is out of adjustment for wich ever reason, mostly due to wear, but in different components. The slave cylinder piston would be at mid way therefore, if the friction surfaces were to wear, you would adjust the return stop and the system would still work without the piston bottoming, too much wear and the bolts on the pressure plate will catch the wok. Same the other way, as the mechanical components wear the piston would move towards the end of its travel, too much wear and the piston might reach its max travel before the clutch is dissengaged.

[Ethel]

One plus with the pre verto is that you can easily extend the lever with a bit of pipe or similar - operate it by hand and so eliminate the hydraulics to help decide where the fault is.

Can't see uneven drive straps causing anything more than judder.

Was the friction plate sliding freely on the primary gear splines?

[jonny d]

I had the same problem with my rebuilt clutch tried all what you did and nothing,put the clutch back in and get a pry bar and pry it out at the arm if it works then it will be
as mine was slave cylinder or master cyl I had a pattern slave part that let air back in i also had a master cylinder problem renewed them both with genuine parts then instant result clutch again. I also noticed that the pin that goes into the slave was a different length from theverto to the non verto so replaced it with the longer one which was the non verto one hope this helps.

Edited by jonny d, 16 September 2007 - 12:38 AM.

[Sprocket]

Refrained from posting this as the auther is an 'EX' contributor of this forum, however, this is good advice from some one who really does know what he is doing with clutches.

http://www.mancheste...bleshooter1.htm

[Jammy]

Thanks for that MS, this bit interested me:

If none of the above sorts it however, it is likely to be a problem with the primary gear - either one or both of the bushes has 'gummed up' and is not allowing the primary gear to rotate freely on the crank. It could also be that one of the bushes (usually the inner one) has 'walked out' and has taken up the end float in the primary gear. I've had both of these happen regularly on my Turbo before fitting the MINTEC (Calver) fully floating bush, which has proved 100% reliable

I have this morning put a piece of rollcage tubing on the clutch arm, and tried to disengage the clutch, thus bypassing the hydraulics. Even with a good 2 foot of leverage I couldn't get the plunger to move in move, if at all. The plunger doesn't even move in enough so that the threaded portion is inside the cover!

[Ethel]

Thanks for that MS, this bit interested me:

If none of the above sorts it however, it is likely to be a problem with the primary gear - either one or both of the bushes has 'gummed up' and is not allowing the primary gear to rotate freely on the crank. It could also be that one of the bushes (usually the inner one) has 'walked out' and has taken up the end float in the primary gear. I've had both of these happen regularly on my Turbo before fitting the MINTEC (Calver) fully floating bush, which has proved 100% reliable

I have this morning put a piece of rollcage tubing on the clutch arm, and tried to disengage the clutch, thus bypassing the hydraulics. Even with a good 2 foot of leverage I couldn't get the plunger to move in move, if at all. The plunger doesn't even move in enough so that the threaded portion is inside the cover!

did you try it with the engine running? think you'd hear the clutch picking up drive if it did

Odd if the pedal goes down and the arm is solid ???

[Jammy]

Hmmm, no, I'll try again with the engine running. Didn't have much time to try it this morning...

[Dan]

If there is a non return valve in the master, what hapens when you release the clutch pedal? where does the fluid go?

All non return valves have a working pressure range, this one is there to make sure the fluid has to be forced back into the master past it. That's why the pre-Verto has a return spring (not sure how the Verto handles it but I think it's to do with flex in the top hat). It's to stop the innertia of the travelling piston forcing all the oil back into the master if you drop the clutch (because the clutch spring is so strong and the assembly travels fast if you dump it) and to slow the clutch engagement a little. Does mean it needs the return spring to bring the lever fully off the CRB but it keeps the cluth nicely primed. This valve is the only difference between the bean tin (or equivalent plastic replacement) clutch and brake masters.

Jammy, have you greased the plunger up properly with Graphogen? It should move if you're using a big old lever.

[Jammy]

Ok, I've just taken the diaphragm spring housing off, and I can feel behind the flywheel. The friction plate can move back enough to spin freely (whilst the flywheel stays still). This means that everything is sat on the crank correctly, yes, and therefore there is no need for me to remove the flwheel?

[Se7enS1ns]

This is a bit of a stab in the dark at this stage really, but did you have the primary gear off at all? Im thinking that if the inner thrust washer was put on the wrong way round (Chamfer flywheel side as opposed to crank flange side) this would cause clutch disengagement issues.

Just a thought.

[Jammy]

I dunno, I haven't had the primary gear off, but its sexond hand and it was running before I bought it, so I don't think that would be the problem.

Anyway, I've added another slim spacer to the diaphragm bolts, as the drive straps weren't lever by a fraction. Bolted it back together and it seems to be a better pedal, still hard to feel the bite though if there is one. Just waiting for the car to charge before I try it with the engine started.

Just one question. If the horns on the backplate had been machined down, so you could use 3 or 4 drivestraps instead of the usual two, but I used two anyway, what problems would this cause? I did think about this when I put it together, and phoned Bill (from whom i bought the assy) but he said use two straps.

Oh, and I checked the push rod against the imaginary line between the slave cylinder bolts, and its ever so slight beyond the line (engine side, not inner wing side), so I don't think the arm is worn.