I am about to install a new brake master cylinder. It is part of a CPP kit, originally from a Corvette.

I've installed a few master cylinders in my time, but have never bench bled one.

The kit came with little plastic tubes that screw into the fluid output ports and re-direct brake fluid straight back up into the MC reservoir. Instructions say to use these on the work bench, with fluid in the MC, and work the piston back and forth. Of course they showed a master cylinder with a push-rod protruding from the body that you could grab to push in and pull out. The MC I got from the kit does not have this, so I would only be able to push inwards and let it come out on it's own.

I could also do this on the truck, using the pedal to actuate the MC.

Just wondering what has been the experince of others with performing, or skipping, this pre-bleeding process.

Thanks,

Gustave

 

Go ahead and bench bleed it. It makes bleeding the system much easier.
Use a screwdriver to push the piston in. It is spring loaded and will come back out by it's self. Put the end of the bleeder tubes in the fluid and bleed until no bubbles ore coming out.
Easiest if held solid in a vice.

 

What he said!

 

OK. I'll give it a go. Thanks guys.

Gustave

 

Make sure that you mount it by the mounting ears in the vise and not by the body of the master cylinder. If you mount it by it's body you will warp the center bore that the piston travels in, also keep it level while you are bench bleeding it.

 

Will do. Thanks. Gustave

 

Hi Folks,

So the time has finally come for me to bench bleed the new CCP master cylinder. I've got it clamped in a vice, with the little plastic tubes leading back up the reservoir. Nice clean brake fluid. But I've been pumping the piston with a screw driver for some time now and absolutely nothing is happening. No fluid movement at all, just some small air bubbles coming out of one of the pin-holes in the bottom of one of the reservoirs.

Is there a trick to how you stroke the MC to get the fluid going?

All I can think of right now is to let it sit for a while and see if gravity helps me out.




If anyone has any tips they would be appreciated.

Thanks,

Gustave

 

Gravity did the trick. I just needed to wait a little while.

Regards,

Gustave

 

You really need to have it somewhat full and the ends of the tubes in the fluid so you aren't sucking air back into the M/C. If it was mine I would push the tube ends in the fluid and start over.

 

Pushing the tubes farther did help. I was in fact sucking air back into the tubes, but not until some fluid actually started flowing!

Thanks,

Gustave