Nearly Non existant clutch

[craigieeb]

bit of a head scratcher going on here,

I was running the ZF type gearbox (removed from an E36)
that died and I have replaced it with another ZF box from an E46,

Ive used the exact same equipment from the old set up,
slave, release bearing, clutch fork,

and now the clutch biting point is on the floor..? where as before it was perfect,

i.e hardly any pedal travel before, and now there is a good few inches before there seems to be any pressure..?

the weird thing is, the part numbers on both gearboxes are exactly the same,

the slave was only unbolted from the box and not undone from any pipework, so no air has got into the system.

anyone got any suggestions?

[craigieeb]

Well,
came out this morning to find a nice pool of clutch fluid under the car,
and an empty reservoir but all the pipes are bone dry,

so i'm thinking the slave might be leaking from the seal...?
I'll pull it out later on and investigate

[DanThe]

Sounds like it, change the master too while your on

[craigieeb]

But why? Lol
There's no fluid or evidence there is any leaking from it
and the pool of fluid was on the slave side dude.

[DanThe]

Have you changed it recently? Ever?

[craigieeb]

No and no

[DanThe]

Change it then

[jmc330i]

As Dan said, change them both. If you only change one, chances are you will be changing the other within a month - the master on mine lasted almost a week after I changed the slave!

[craigieeb]

EH!!!!

Just pulled the slave off, and there's no trace of fluid anywhere, nothing at all

so I'v changed it anyway, filled the reservoir bled it, bled it and bled it, and is back to normal

that's got me baffled like!!

even when i was pushing the slave rod in and out, there was no fluid coming from anywhere

fook it, if it's working then it's fooking working

[HairyScreech]

How olds the clutch hose? I thought I had a cylinder on the way out the other week, one nice new braided hose later and no more clutch slop.

I think a lot of these cars have had new slaves etc but no ones touched the lines since they were built.

[maxfield]

I've had it a couple of times on BMWs where doing the gearbox I've caught the slave cylinder and it's caught the seal and leaked after.

[craigieeb]

How olds the clutch hose? I thought I had a cylinder on the way out the other week, one nice new braided hose later and no more clutch slop.

I think a lot of these cars have had new slaves etc but no ones touched the lines since they were built.

It's still the standard hose for the moment,
I was going to change it for a nice shiny braided one, but wasnt sure which to get,

I was under the car while i had the missus pumping the peddle
and there was no leakage or "ballooning"

but what I have noticed..
when you pop the slave rod out of the outer rubber, I can see fluid, inside,
are you supposed too? or is there in inner seal also??

[craigieeb]

I've had it a couple of times on BMWs where doing the gearbox I've caught the slave cylinder and it's caught the seal and leaked after.

There's no "nicks" or anything in the outer rubber, but see above lol

[HairyScreech]

cant really advise the hel one, good quality but the length/bend is a bit off so it leads to the cylinder being upside down and a bit hard to bleed, when bled its nice though.

[Brianmoooore]

Seal you can see is just to keep muck out. The real seal is at the inner end of the piston, and all fluid should be behind it.
In normal use, a ridge of debris builds up at the limits of piston travel in both the master and slave cylinders. If for any reason, such as a fluid leak, dismantling of parts, or even bleeding, the pistons move past their normal limits, the seal gets pushed into this debris, and if the rubber is in anyway past its best, it's likely to be damaged. Dislodged debris from the master can also find its way down into the slave and wreck the seal there.
These are the reasons that it's recommended to change both cylinders at the same time.

[craigieeb]

Yeah, I seem to remember buying a goodridge hose years ago for the M20, and found it was too short,
so that put me off a little, and with me now having the ZFbox and E46 slave in the E30 I wouldn't know what length to get

anywhoo, to answer my own question

when you pop the slave rod out of the outer rubber, I can see fluid, inside,
are you supposed too? or is there in inner seal also??

I've just dissected the slave on the com desk, and the outer rubber seal seems to be just a dust boot,
as there is a rubber sealing ring on the piston inside the cylinder,
so I shouldn't of been seeing fluids just inside the dust boot

(if that makes sense

[craigieeb]

Seal you can see is just to keep muck out. The real seal is at the inner end of the piston, and all fluid should be behind it.
In normal use, a ridge of debris builds up at the limits of piston travel in both the master and slave cylinders. If for any reason, such as a fluid leak, dismantling of parts, or even bleeding, the pistons move past their normal limits, the seal gets pushed into this debris, and if the rubber is in anyway past its best, it's likely to be damaged. Dislodged debris from the master can also find its way down into the slave and wreck the seal there.
These are the reasons that it's recommended to change both cylinders at the same time.

[HairyScreech]

[quote="craigieeb"]Yeah, I seem to remember buying a goodridge hose years ago for the M20, and found it was too short,
so that put me off a little, and with me now having the ZFbox and E46 slave in the E30 I wouldn't know what length to get

If you are using the stock E30 hose then I would assume that's the length you want.

Otherwise I might be able to let you know soon, Iv got one with a leggy box and possibly a grumpy diff so my thinking is to go to a newer ZF box and a medium case z3 diff.