The service manual says (1993) bleed brakes starting at right rear and left rear next and right front and then to front left drivers side. Why not start at front left drivers side and proceed?

 

It's probably the radical left Democrats that are causing your brake issues. Keep voting for the Dems...and you're going to just keep having issues with your brakes. I'm sure of it.

 

On planet earth, it doesn't matter which order you bleed them in...or if you bleed them all or just one, or what ever. It depends on the repair and your goal, what really needs to be bled, and how. For example, when I'm changing brake fluid, to expedite things, I bleed them ALL 4, at the same time.

 

I do not vote Demorat! I donate my money to the party that up holds the law!

 

Exactly. See post #2.

Good luck with your brakes.

 

The brake bleed protocol is based on the length of the brake lines from the master cylinder. If you look closely at the brake line schematic you will see that the right rear has the longest line and so on down the line. This routing is predicated by the location of the anti-lock pump/mechanism. The idea is to clear the farthest point of air first and then the next farthest, etc.

In the old pre anti-lock days the recommended protocol was different as the lines were shorter and direct to the master cylinder.

 

Actually, the front right is the longest line. ABS is in the rear, so the front lines go to the rear, then all the way back to the front. So...it's not based on line length.

 

With abs the main thing is to prevent air getting trapped in valve block. So you don't want the master cylinder drain out while you have it apart.

 

Rule of thumb is to go in order of the farthest from the master cylinder. Not sure exactly why.

 

The longest run can hold the most volume of air for a given circuit. If the longest run is full of air, you may run out of master cylinder stroke before building any pressure in the other line on the same circuit, so you may have to go back again to the corner where you started if a logical sequence is not followed to bleed the air from the biggest offender first, which is not very efficient.

Keep in mind that the master cylinder stroke may not be equal for both circuits, especially in the case of a black/white or front/rear circuit split and caliper volume also varies greatly front to rear as a function of piston diameter and number of pistons per caliper. The ratio of line volume and caliper volume to master cylinder stroke on a given circuit is what is important, assuming a common bore diameter.

If only one corner is affected due to caliper service for example, then non of this matters. Simply bleed the affected caliper.

 

No good reason.



Where is the pressure coming from? Why are we "building pressure" during bleeding?



YES. KISS.

 

Furthest came before split systems. So up intil 1968 without disc brakes. The single system any leak results in no braking other than parking/emergency brake. They are a pain, without a aid whether pressure or vacuum bleeder. I'm going with the engineers had a reason to do it that way.

Action by the master cylinder applies hydraulic force on the on the braking components. Since air compresses and fluid doesn't, the air absorbs the force instead transmitting it.to the braking components. Results the pistons will travel maximum distance within master cylinder with little to no braking. As air is purged during bleeding process the volume of air loses its ability to absorb the hydraulic force and pressurized.,however force to braking components is still reduced. Once the air is purged,hydraulic force is applied to the braking components. The hydraulic force is applied to caliper piston moves to clamp pads on rotor. Because more force is applied piston than required to overcome the distance to clamp rotor pressure builds up throughout hydraulic circuit including brake pedal applying the initial input.

It is not recommended to service single brake components calipers hoses, rotors, drums, or wheel cylinders. DIYs aka non professionals can do pretty much what ever the want as long.as its their vehicle. If doesn't work out they can try plead ignorance or poverty. Many times what is going on the right may occur on the left shortly after right side is repaired. In some cases there will be unequal breaking. Professionals caught shortcuting when things go wrong far more serious consequences. Brake fluid service doesn't exist in GM manuals. Fully bleeding both front or rear ensures existing degraded aka dark fuild has been removed for half the brake fluid has been replaced.

 

Unfortunately, I didn't. I'm still unclear about why pressure is or needs to be built during bleeding.

 

Copy. I do it differently, so not really any pressure.

 

As opposed to internet opinions, I go by the service manual: RR, LF, LR and, finally, RF. (just for those that wish to know what the engineers that built the car have to say about it)

 

That's fair. You know WHY they say it? :

I've bled so many brakes on so many cars, for so many years....I know what works. I also know how and why it works, which is why I also know the "sequence" doesn't matter one whit.