Clutch bleeding

[jellytott]

Hi

Is it just me....

Having repeated spongy clutch operation over the past year and having very black contaminated fluid coming out I've decided to replace the slave and master cylinders today (FTE parts from EuroCarparts), I've heard that 944's are a bit of a pig to do but I never realised the statement its been very time consuming and frustrating to get almost 90% pedal operation, so has any one else got any experience and best and reliable method that works please.
it lack pressure the top 10% and you need to put you toe behind the pedal to ping it up fully back to the clutch pedal rest position.

1) So I started with the time and trusted pump,pump the clutch pedal inside and me below to release the bleed when I could get someone to help....nope
2) a power bleed a single man operation, used in connection with pressure from a road wheel....well almost worked lacks the final 10% to return to rest state on the clutch pedal.
3) back feeding fluid from the slave bleed valve (the theory is that this assists the getting air out as it wants to travel up)...again lack the final 10% return to rest state on the pedal.
4) Jack the front of the car with option 1 (two people pump,pump the pedal and me below the car) this is by far the best I've got in pedal pressure.

As mentioned I've got almost all the air out, will probably have another bash at it waiting for the system to settle for another attempt.....

So any suggestions would be so warmly accepted

Regards

John

 

[Waylander]

you want to get the back of the car as high as possible, as the bleed nipple is at the rear of the cylinder.

did you also set the length of the push rod and return spring. i would also replace the nylon bushes in the pedal and the clevis of the push rod.

take a look here, http://www.clarks-garage.com/shop-manual/clutch-04.htm getting a measure up there is a real pain, so i cut two bits of thin bamboo to the right length

 

[vitesse]

Tell me about it-my wife's 924S suddenly got a bout of pedal going right down & staying there-previously I had adjusted both pedal travel & helper spring & I know that the clutch is worn after 106K miles but still no slippage .
So I've bled it several times after fitting a new slave cylinder, with just the the front wheels on ramps -eventually got a good pedal ,then when she drives it,bingo pedal down to the floor again.

So bit the bullet this last Monday -reversed onto the ramps,then jacked up both sides & inserted stands leaving the rear higher-& using a non return bleed tube with Irene's expertise on the pedal eventually got it-I hope -air bubble free.
Never needed to do this way before so here's hoping.
Why Porsche didn't allow more room behind the bleed nipple is a mystery to me but have used quite a lot of Dot 4 fluid.
Incidentally,the cylinder-FTE brand cost me £41 from ECP,compared to £72 (Fagg brand)over 4 years ago when I last changed it-wife's car seems hard on the clutch system whereas the red trackday one has never blinked

 

[jellytott]

Waylander, I'll try the back up higher method, the collet on the push rod is fine but I only fitted the new push to the same lenght to the one that came off,,,I'll probably check the throw lenght.

Vitesse I'm pleased in a odd way its not just me but like you I've got through quite a quantity of DOT 4 already,,,, this method looked good here I don't normally suggest Utubes and American accent
telling you how too but it makes sense to me doing it this way. To make access easier I remove the starter motor.

https://www.youtube.com/watch?v=wdf--suwqw0

 

[Waylander]

The blue feed hose can get porous and allow air to be drawn in

i would replace that too

 

[bmnelsc]

The blue feed hose can get porous and allow air to be drawn in

i would replace that too

I was wondering about the pressure hose from the master to the slave cyl. Do they get spongy with age and expand when the clutch is depressed reducing travel at the slave cylinder?

 

[jellytott]

The blue cotten coated pipe has been changed too, the feed pipe is part flexible out of the master cylinder about 20cms long it become rigid pipe at the back of the cylinder head then all rigid pipe all the way down to the slave (this on a 944S)

 

[Waylander]

The pressure hose, if it's getting spongie I would get it replaced soon as, if they burst when the exhaust is nice and hot you will have a fireball on your hands.

brake fluid is quite flammable!

 

[jellytott]

good call,, my flexible hose presently looks fine but probably will change it and enter the "bleeding process again" joy !!!

 

[vitesse]

I have always removed the starter motor-even more pain (or joy) otherwise.I even have a little loop of blue rope to hold the starter out of the way in the brake /clutch bleeding thingies box.After so much bleeding effort, I can now remember that the correct bleed nipple spanner size is 7mm!

 

[jellytott]

Yes, its 7mm and I keep it under my pillow now

 

[vitesse]

More pain & grief in my ongoing saga-once completed as above,I drove the car over to our local trading estate to pick up some fuses for the car alarm feed(another story) ,changing up & down the box as much as possible-clutch hydraulics absolutely fine.

Left overnight -wife said she'd use for it shopping to try it out(basically to regain her confidence) got off the drive 1st gear change-pedal went down to the carpet,so back on the ramps & axle stands for plan B mark 3!
1st task was to exchange the master cylinder bought in September last year still under warranty from EPC whilst I could.The new one actually cost me £10 less.
Then removed the oil reservoir,blue feed pipe & the hybrid steel /rubber connection pipe from master cylinder to steel downpipe to slave cylinder.
Fitted new piece of blue feed pipe-although existing is fine-
Irritated to find rubber /steel section looking pretty knackered underneath (out of normal view) where suffers exhaust manifold heat(could be the original item fitted 30 years ago!-so ordered new pipe & picked it up yesterday form Chester Porsche together with new white plastic bush & a rubber bung to cover the operating access hole(was missing).
Slightly amazed at the cost -pipe alone £55.60 less PCGB discount of 10% (compared to £31 5 years ago for one for my red trackday car)
Also pleasantly surprised to find that the design has now been changed with a longer steel multibent steel section which preceeds a longer rubber section thus effectively moving the rubber part away from the exhaust manifold heat area.
I did query this at the parts counter-a totally different part no-but assured it was the only one for the job although the PET drawing still shows the original style.
All refitted today (before the rain) & fingers again crossed & superglued for trial Friday.
What I found necessary was to bend the steel pipe section as required to avoid a too tight return bend in the rubber pipe -maybe this a requirement but no knowledge about fitting correctly at the OPC