Brake bleeding sequence

[martyn]

While at the Get To Know Your 7 day yesterday, we were given some instruction on bleeding the brakes.

When bleeding the fronts, we were told to do the inboard side of the calliper first followed by outboard side.  The explanation was that bubbles would rise and get trapped in the inboard side if done in the wrong order.

At the time, this made sense to me but I didn't really think about it too much.  Looking back now it seems that it should be the opposite.. outboard first then inboard.

What’s the correct sequence?  Does it really matter that much?

[John Vine]

I think the basic principle is to start with the bleed nipple nearer the master cylinder, and then work outwards from there.  Thus, you would bleed the inboard side before the outboard.  This also ensures that, when replacing the fluid entirely, new always pushes out old.

JV

[elie boone]

It depends on the layout of the T pice for the front brakes, i stop bleeding a side when most of the big bubbles are gone, go to the other side and do the same, then you go back to the first caliper and bleed properly, after that you do the other side.

[John Vine]

But wasn't the OP asking about which side of each 4-pot should be bled first -- inboard or outboard?

JV

[martyn]

Yes, not worried about front, back left or right etc.  Just the order for the front callipers that have two bleed nipples.

They suggested inboard first as it prevents bubbles getting trapped there when doing the outboard side.  That seems wrong to me so I am wondering if the technician I was speaking with got it mixed up.

 

[John Vine]

The GTKY7 technician's guidance matches the CC Assembly Guide:

 

"The uprated front brakes have two bleed screws on each calliper. Remove the dust cover from the inboard bleed screw on the front LH calliper. Connect the flexible tube to the bleed screw and operate the brake pedal several times. Whilst mounting pressure on the brake pedal open the bleed screw and allow compressed air and brake fluid to flow into the container. Tighten the bleed screw before the pedal is released. Repeat the procedure until no air bubbles are visible in the released brake fluid. Remove the flexible tube and replace the dust cap. Carry out the procedure for the outboard bleed screw. As a final check on system integrity, apply pressure to the brake pedal and check all connections and bleed screws for any sign of leakage."

 

I can see the reasoning.  If the inboard side has been bled thoroughly, there are no air bubbles between that side and the master cylinder, therefore there is no way bubbles can subsequently appear on that side.

JV