New brake system initial fill discussion

[P10crew]

I’d like to start a discussion on the filling of an all new brake system on a build of mine.
The system consists of (4) Wilwood twin piston calipers, CPP master cylinder with combo valve and stock C10 pedal assembly.
I have confirmed that if I leave the brake light switch off of its mount that the pedal will stroke the mc piston far enough to bottom it out in the bore so bench bleeding should not be necessary.
My idea is to completely retract all 4 calipers and gravity fill all four corners till I get a good stream of fluid then attach an Oringed lexan mc lid with vacuum tap and pull a vacuum on the complete system from the lid with the hopes that any trapped air will migrate to the vacuum source.
My concern with this plan is that I’m not sure if the vacuum will shift the combo valve and block a port.
My goal in all this is to avoid at all cost having to remove bench bleed plugs and connect lines over top of an expensive paint job because for me it’s nearly impossible to not have fluid dripping before the lines are tight.
Do you think this is a solid plan?

I would really like to see how the mfg’s fill a brake system because I really doubt they are assembling with a wet bench bled master cylinder.
Ideas?

 

[wings&wheels]

I like to gravity fill then use a pressure bleeder to finish. I just did calipers, PDWA and wheel cylinders on my TR6 and '72 Rover a few years ago using this plan. I pump up to 5 psi or so and slightly open up a bleeder on one side (or circuit if you have a diagonal split), then do the other side until I get a flow, the open both up a bit and increase pressure, bleed until no bubbles, etc.

I try to avoid bench bleeding, it is messy no matter how careful you are...

 

[meep]

I’ve successfully done it in the car, just took me more time to work it out. The extra extension of the pedal rod should help. Does the MC tilt upward towards the front?

 

[P10crew]

I’ve successfully done it in the car, just took me more time to work it out. The extra extension of the pedal rod should help. Does the MC tilt upward towards the front?

No sir the master is level. Did you use vacuum?

 

[meep]

No sir the master is level. Did you use vacuum?

no - but if I recall the MC was pretty level. I probably got lucky. I’ve done it on the bench too with the hose kit, but found basically I was just pumping the fluid in a circle until all the bubbles were worked out, and I agree, it’s going to drip no matter how careful. many old beach towels might be a good second choice.