Ra40 Clutch drama.

[maurice c]

HI,
I recently got a dose of enthusiasm for preventative maintenance. The clutch slave was weeping so I got a new PBR one and bleed the system. The clutch was a little spongy so I bleed it again, and then again. It was still spongy so I looked at the flexible line, it was perished, surely that was the problem. One flexible line later, its still spongy. I rang a highly regarded member of the CCG (Chuck) and his advice was to inspect the master cylinder. It was only a year old so I didn't expect any problems but lo and behold it was leaking fluid. One PBR master cylinder was purchased and fitted today. I bleed the system a couple of times and WTF, its still spongy. Now the next thing to try is the hard line, which I will have to get made up. There are no visible leaks from the system. Everything is pretty tight, when I'm bleeding it, i press the pedal to the floor and open the nipple to let the pressure out. The clutch feels good for a few minutes and then starts to become intermittently spongy, I have to pump it to keep driving. I don't mind spending the money as these parts obviously needed changing. Questions

1 Is it possible that I have a faulty slave as this is where all these problems began. Maybe its letting in air as it goes through it range of motion?

2 My next move is to replace the hard line, if I still have a problem after this has anybody ever had issues with trapped air in the clutch system?

Glad to hear any input at this point, thanks Maurice.

[thechuckster]

peel back the rubber boot on the salve cyl and see if there's gunk in there - will let you know if the slave cyl seals/bore is munted.


edit: hard line wouldn't need replacing unless you've crushed it. Only problem i had with my old ra40 was the slave pushrod not retracting enough leaving the throwout bearing always spinning and up against the pressure plate fingers), so i fitted a fairly weak spring from slave cyl to arm (in parallel to the pushrod)

[allencr]

I bleed the system a couple of times
1 Is it possible that I have a faulty slave as this is where all these problems began. Maybe its letting in air as it goes through it range of motion?
2 My next move is to replace the hard line, if I still have a problem after this has anybody ever had issues with trapped air in the clutch system?

Slaves don't let in air only leak IMO, they would let in air if the passage to the MC isn't clear when its at rest.
No reason to suspect the hard line. Not many, if any, places to trap air.

Fix the MC.

[maurice c]

Thanks guys, the slave is only about a week old and the MC is a day old so they are both good, running out of ideas at this point, all thats left is the hard line.

[vpatrol]

maybe worth noting but just because the parts are new doesn't mean they can't be faulty. I've had new parts be faulty right out of the box before.

[kriso]

when bleeding the system what order are you doing it in? did you hand prime the master cylinder before fitment?

[maurice c]

What do you mean by the order I bleed it in? I filled the master with fluid and then pumped it through by bleeding at the slave. I got somebody to press the pedal down and I released the bleed nipple and repeated until all air had been expelled. Hand Primeing the master cylinder is not something that I'm familiar with, if you could tell me some more about it. The symptoms have remained the same before and after the master cylinder so I'm not really placing blame there.

[kriso]

best way to bleed it is to bled the MC first on its own then bleed the slave cylinder, you can also just gravity bleed the system by just cracking the nipple on the slave and let gravity do its thing to force the air out, just need to keep the MC topped up so it can help force the fluid through. if air is getting into the system it can only be the MC that is doing so and yeah i have got rooted ones new out of the box before too .

[Willofan]

What a dilema, to be sure there is no air in the system and as suggested, undo the pipe to the MC and let is bleed out with gravity, undo the flex pipe to the SC and blow it out with compressed air to make sure it is clear, do the pipe up on the MC and let the fluid drain down till it is running freely from the flex pipe then do it back up, the undo the bleed nipple on the SC then let it bleed out with gravity. Do not pump the pedal during this time. Once the fluid through the bleed nipple is running freely (no bubbles) lock it up and try the pedal.

If it is still spoingy, you will need to check the SC to see if the seals are correctly fitted or bore damaged, but as stated, this will leak not drag in air.

[maurice c]

Yeah this one is really doing my head in, its a small job not an epic sage.

[maurice c]

Right o,
Problem is solved sort of. When I remove the spring that goes from the end of the clutch fork to the slave cylinder the problem disappears. What was happening was that the spring was pulling the slave cylinder in a bit causing there to be a bit of slack before the pedal engaged the clutch when you pushed the pedal, giving me the impression of some air in the line.

Now I've found out that the slave cylinder rod is the right length, I don't know if the spring I am using is the right strength.

Questions:
1 All the cars at the wreckers I've seen, have no spring on the arm, is this a problem?

2 Is there supposed to be some movement on the clutch arm, can it be pushed back towards the slave cylinder for about 10mm. The pivot point in the gearbox may be out of adjustment, and no I wont be taking out the box to adjust it.

Thanks Maurice.

[thechuckster]

1. works without them but as the slave cyl finds a resting state position and the arm starts to get floppy on the pivot point/throw-out bearing it can result in the throw-out bearing resting against the pressure-plate fingers (and both of them wearing a bit more).

Also helps keep the clutch arm locate on the slave pushrod.

I just found the weakest spring that would fit and applied only a miniscule of tension when your foot is off the pedal.

[maurice c]

I think that somebody has put a much stronger spring on there and that I when I cleaned it up with degreaser when I changed the slave it became a lot more efficient. Thanks Chuckster.

[crowncustom]

Have you checked the free play between the clutch rod and the master cyl?Has it got an adjustable slave rod also?If it does then check the free play as well.
Cheers Brett.

[allencr]

1 All the cars at the wreckers I've seen, have no spring on the arm, is this a problem?
2 Is there supposed to be some movement on the clutch arm, can it be pushed back towards the slave cylinder for about 10mm.

1. No. If there is a spring, THEN there also has to be an adjustable stop or pushrod, if not, then no spring can be used.
2. Yes. It needs to move to allow for future wear of the clutch & flywheel.

Light contact on the throwout/release bearing is supposed to happen & no problem at all.