Best way to bleed completely new brake system

[WondrousBread]

I am finally ready to install my new brake Master Cylinder on my Rx7, but wanted to know the best way to go about bleeding the system.

Normally, I'd just bench bleed the MC, install, and then bleed all four calipers. But I have brand new calipers on all four corners, brand new lines, and a brand new MC. There's no fluid left anywhere in the system. Op

My thinking is that there are two courses of action:

1. Bleed the current MC and lines as installed, then bench bleed the new cylinder and swap them.

2. Bench bleed the new cylinder, install, and then bleed the lines.

Clearly option two is preferable, but my concern is that after installing the MC and going to bleed the lines, the freshly bled cylinder may drain into the empty lines leaving me with an un-bled MC.

If a Master Cylinder is bench bled and then installed on an empty system, will it drain and require being removed and re-bled on the bench? Or will I be able to fill as normal by keeping the reservoir filled while pumping the pedal until the fluid leaves the line on each corner without bubbles?

Thanks, Chris

 

[sloinker]

Bench bleed the MC, vacuum bleed the corners while maintaining the level(s) of the MC. An assistant may be useful. You can try gravity bleeding also but I prefer the vacuum method. If ther is an antilock brake controller you might go to a Mazda specific board and query there.

 

[Traction]

Air-powered vacuum bleeding has always worked perfect for me, many times, with a completely dry system all by myself in 30 minutes with a quart or 2 of brake fluid. It is so simple. I use an OTC vacuum bleeder. No need to bench bleed either.

 

[bdcardinal]

Bench bleed, and then bleed the corners but use an auto-filler. OTC brake filler

 

[wings&wheels]

I have never had to bench bleed an MC. The last car I did a complete brake OH on (MC and wheel cyls), I opened the bleed screws, filled the MC, waited until I got some flow then closed the bleeds, attached the pressure bleeder and then bled each corner.

 

[atikovi]

My repair manuals for cars of the 70's all show bench bleeding and the one for a 2012 Cruze does too. I would do it. There isn't a bleed screw on a MC and I can imagine an air bubble easily being trapped in the bore.

 

[buck91]

I would just use my Motiv PowerBleeder.

 

[eljefino]

Some cars need bench bleeding. All depends on if the MC goes "uphill" away from the firewall and where the pressure taps are. If I had instructions to do it, I wouldn't not.

 

[splinter]

I'd manually prime and bleed the master cylinder before fitting.
Originally Posted by buck91
I would just use my Motiv PowerBleeder.

+1

 

[nthach]

Bench bleed the MC, and either pressure bleed or gravity bleed the wheel ends. If you have ABS, there might be a certain procedure to bleed the modulator as well. And with certain weird cars, you need the OEM diagnostics tool or a aftermarket scan tool with bidirectional control to disable the brake-by-wire and allow for the wheel ends(calipers or wheel cylinders) and electrohydraulic system to be bled and purged.