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Clutch Slave Cylinder and Bleeding

Started by december2016, October 21, 2016, 12:21:01 PM

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I have a 1977 MGB and the clutch pedal goes to the floor with no pressure needed and no shifting.

I have questions on the following regarding the slave cylinder and the bleeding procedure:

1- is the bleeder in correct position on the slave?
2- the three copper washers? One used flex hose to slave! How about the other two?
3- correct fluid to use - "silicone "  or regular?
4- some tips on bleeding please.
5- any other tips and hints you may have.

Safety Fast!!!
Don Boudwin
Clayton, Delaware


The kit in the photo looks to have everything you'll need.  Answers to your questions:
1 - Bleeder - Your bleeder appears to be correctly placed.  I checked the catalog, which shows it in the wrong place in their photo of the kit, but correctly on the sketch of the original system. This is for both Moss and Victoria British (obviously a photo supplied by the kit source, which they both are using the same).  It has to be at the highest point to let all the air out with the line (flex hose) coming in at center back. Just to be sure, I checked both my car and an old trans pulled from a wreck with the slave and arm still in place.  They are the same as your photo.
2 - Copper Washers - One at the slave cylinder end of the Flex Hose.  One at the other end of the Flex Hose (connection to hard pipe under the lock nut).  One at the hard pipe connection to the master cylinder. 
3 - Silicon Fluid - The fluid provided is correct, but silicon helps prevent the seals from deteriorating longer. It is your choice.  You are replacing the entire system and there's not much fluid in this application, so the silicon fluid cost is minimal, even with already owning this fluid.
4 - Bleeding - This can be tricky.  As I've said before, the lines trap air at high points that are difficult to clear.  I prefer to fill from the bottom (slave cylinder), pushing fluid into a dry system through the bleeder.  Though designed to be a one-man bleed down operation, this system can be used to do a feed-up as well.  I've sent you the pictures earlier of my rig using a Mighty Vac in reverse or compressed air.  This one can be set-up similarly.  You will also be changing the hard pipe with the master, so have the opportunity to eliminate those air catches. Try it as intended, though I warn you, it may not work that well.
5 -  Other - The master cylinder in the kit is different than the original, so that's why they provide the copper tube and fittings.  The original has a banjo type connector at the front of  the master cylinder while the new one has a threaded connector.  I've never installed the new replacement type, but do know it is pretty tight in front of the master cylinder to the firewall as it is.  I would think it might be wise to consider using  a male-to-female threaded elbow at the front of the master cylinder.  Also, as mentioned earlier, getting rid of the high-point air catches in running the new tubing will make it much easier to bleed in the future.  See if there's any way to do that.
I took a photo of the slave cylinder on the spare gearbox from the wreck.  Not a great photo, but you can see the bleeder at the top side and what's left of the Flex Hose connected center back of the cylinder.
Hope it helps.  Let me know if you need anything else.
Safety Fast!
Art Isaacs
Art Isaacs
AMGBA Tech Staff

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