Clutch master cylinder - replace or not?

[trikey]

That’s as good as access gets I’m afraid!


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[Blink]

Originally Posted by trikey

That’s as good as access gets I’m afraid!

That's what I thought.

[trikey]

I use a syringe with a pipe attached to fill the pot up.


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[Blink]

Ok, just to make sure I haven't missed anything, this is the plan.

1) Get the cap off the master cylinder (one way or the other!).

2) Suck out as much old fluid as possible with a syringe.

3) Fit the cap from the Sealey VS820 or the Gunson Eezibleed to the MC.

4) Fill the Sealey or Gunson with new DOT4 fluid.

5) Connect my 'contraption' to the gold quick release connector.





6) Pressurise the Sealey VS820 or Gunson Eezibleed (25psi if the Sealey).

7) Open the nipple on my contraption and allow 1 litre of brake fluid out.

8) Close nipple.

9) Unscrew the Sealey/Gunson cap and refit the MC's own cap.

10) Disconnect my contraption from the gold quick release connector.


QUESTIONS

A) Is step 2 necessary?

B) If it is, how much fluid does the MC itself hold?

C) Do I put a hole in the rubber condom or not?

D) Why can't I ditch the rubber condom altogether?

E) What's the best new fluid to use? (I've already got some of this)


TIA

[Mike Noc]

The rubber condom allows for the level to rise and fall in the reservoir whilst keeping air out of the system - the idea being clutch fluid is hygroscopic and will pick up moisture if exposed to atmosphere over time.

If you ditch it and fill the reservoir up then the excess fluid will leak out of the bleed hole in the cap when you press the pedal down the first few times.

When I fit new clutches I always replace the condom and don't cut any holes in it, but the choice is yours.

[Blink]

Originally Posted by Mike Noc

The rubber condom allows for the level to rise and fall in the reservoir whilst keeping air out of the system - the idea being clutch fluid is hygroscopic and will pick up moisture if exposed to atmosphere over time.

If you ditch it and fill the reservoir up then the excess fluid will leak out of the bleed hole in the cap when you press the pedal down the first few times.

When I fit new clutches I always replace the condom and don't cut any holes in it, but the choice is yours.

Ok, thanks Mike.

[Blink]

Questions remaining from post 54 after Mike answered C & D.

QUESTIONS

A) Is step 2 necessary?

B) If it is, how much fluid does the MC itself hold?

E) What's the best new fluid to use? (I've already got some of this)


Post 54:

Originally Posted by Blink

Ok, just to make sure I haven't missed anything, this is the plan.

1) Get the cap off the master cylinder (one way or the other!).
2) Suck out as much old fluid as possible with a syringe.
3) Fit the cap from the Sealey VS820 or the Gunson Eezibleed to the MC.
4) Fill the Sealey or Gunson with new DOT4 fluid.
5) Connect my 'contraption' to the gold quick release connector.
6) Pressurise the Sealey VS820 or Gunson Eezibleed (25psi if the Sealey).
7) Open the nipple on my contraption and allow 1 litre of brake fluid out.
8) Close nipple.
9) Unscrew the Sealey/Gunson cap and refit the MC's own cap.
10) Disconnect my contraption from the gold quick release connector.

[HarryM1BYT]

Originally Posted by Mike Noc

The rubber condom allows for the level to rise and fall in the reservoir whilst keeping air out of the system - the idea being clutch fluid is hygroscopic and will pick up moisture if exposed to atmosphere over time.

If you ditch it and fill the reservoir up then the excess fluid will leak out of the bleed hole in the cap when you press the pedal down the first few times.

When I fit new clutches I always replace the condom and don't cut any holes in it, but the choice is yours.

That works fine from the factory, where the MC is filled under pressure to push the condom up, but without that, the capacity of the MC is quite limited.

I appreciate the fluid is hygroscopic, but is it really a problem for the clutch system? The moisture absorbed can certainly be a problem in the braking system, where the fluid can become hot and boil, yet the braking MC is vented to air.

The whole point of the condom in the clutch MC was one of making it a quick change item, with no need to bleed, which would not leak fluid out when on the parts shelf. Once the system is tampered with, with to flush fluid, the condom serves little purpose, other than to serve as a seal around the lip of the lid.

[Mike Noc]

The reservoir capacity is pretty limited with or without the condom Harry, but I agree in the great scheme of things it doesn't make much difference whether you replace it or not. As I said the choice is yours.

[Blink]

Rain has stopped play again.

PS. I still have questions A, B, E in post 57.