Clutch bleeding question?

[Geoff Deakin]

Seems almost too stupid to ask - I've been doing this for years, but this has got me completely stumped.

I have changed to an AP Racing 0.812" master cylinder for the clutch together with the original remote reservoir.

I first fitted the Girling pushrod from the original master cylinder. Then discovered this was the wrong thing to do, as the piston and pushrod in the AP cylinder are shimmed to suit each cylinder and we were therefore unable to draw the fluid through, as the inlet port was not uncovered by the stroke of the piston.

Then fitted the correct pushrod, but still unable to bleed the clutch.

When the outlet pipe on the master cylinder is removed, fluid flows from the reservoir, through the cylinder and leaks out freely.

With both inlet and outlet pipes tightened, and trying to bleed the system, no fluid or air is expelled, other than a very small amount on the first thrust of the pedal.

Has anybody got any ideas?

I'm hoping to borrow a Mityvac and try and draw the fluid through.

All ideas very, very gratefully received.

Cheers,

Geoff.

 

[René]

don't know much about this, but I had once when I replaced most fluid, no more pressure under my pedal(from my Hartge Z3 V8)...and I was all alone and thought aaaaaaaaargh
then I thought what can I do? tried some things but no result...
then I thought I try it by hand (because the pedal did not get pressure under it.
then after say 20 or so up and down the pedal with my hand as fast as I could with no pressure at once I felt some pressure so i did went on this way and say 5 more attempts I've got my pressure back and kept working after that.
thats my story of my clutch pedal fluid...you can try that?

 

[SteveB]

Hi Geoff

It may be worth checking that you have free play in the pushrod.
It can affect the pumping action if the internal ports / piston are not in the correct fully back position thus preventing an intake of fluid from the reservoir.
If you have remote reservoirs check for any kinked or soft feed pipes that be 'sucked' closed on the down stroke of the pedal, these may pass under gravity but not on suction.

Steve

 

[Geoff Deakin]

Thanks Rene and Steve for your suggestions.

I'm back on the car tomorrow night, and I'll check everything again and try your suggestions.

Cheers,

Geoff.

 

[Geoff Deakin]

Right - All sorted!

The original master cylinders were Girling.

In fitting the new AP CP2623-93PRT160 master cylinder, I made an obvious mistake (Found last night!).

The AP m/cyl has a seperate blue anodised adaptor for the inlet supply.

I found that the fluid hole drilled in this adaptor is offset, not central.

As a result, using the original pipe and union for the inlet, although fitting perfectly, I was blocking the hole off with the flare on the end of the pipe.

Using a male-male adaptor solved the problem, and the system bled perfectly.

Hope this may help somebody else in the future.

Cheers,

Geoff.

 

[René]

good find, no wonder when you think its the same but isn't completely, you could scratch your head on things like that ;-)

 

[Thomas Rouw]

till there's no more hair left I might ad.

will check on my slave aswell since the box is still out of the car.

grtz Thomas