'63 brake bleed question

[whateverpratt]

I just replaced my master cylinder since it was the culprit of a long time leak that became a lot more prominent over the last week. I bled it before install, and now I need to bleed my wheel cylinders so I don't have to pump the brakes to make them feel like they will stop the truck.

I am wondering about the bleed sequence I should use. The truck has manual brakes and drums all the way around. I have the shop manual, and it says left rear, right rear, left front, right front. My brother said he bleeds his malibu left front, right front, right rear, left rear per his shop manual (also manual brakes drums all the way around).

My question is, is there a correct way, and if there is, why is it correct? Does it matter what order I do this in?

It seems like a silly question to me, but I've had different people tell me different sequences and ways to bleed the brakes. I was just wondering if anyone had some valuable insight.

[davbowen]

always start bleeding the longest brake line first. should be lr, rr, rf, lf.

[cg285]

Originally Posted by davbowen

always start bleeding the longest brake line first. should be lr, rr, rf, lf.

what i am going to say most will tell you i am wrong. but, as a professional, doing this for 45 +years....
i bleed master cyl first and closest whl next, etc. you are pushing (purging) air thru the system so why would you do the rear and work to the frt?

assuming you don't have a pressurized brake bleeder, and are using the pedal method, do not pump the pedal.
instead your helper should crack the bleeder, you push the pedal down once and hold, your helper closes the bleeder, you release the pedal (and count to 5 slowly so the mstr cyl has time to draw in new fluid). repeat until clear, go to the next one. try it, it's faster and easier

btw a buick engineer turned me on to this method a very long time ago

[davbowen]

The order in which the wheels are bled is usually specified in the vehicle's shop manual.

There are many techniques for bleeding brakes and lots of gadgets to make the job easier. But for removing air bubbles from the system, one approach works the best. That's the "old fashioned method", which requires a 2nd person to push on the brake pedal while the you open and close the bleed screw. This 2-person method generates a sufficient jolt to the brake fluid to knock loose pesky bubbles and allows them to be flushed away.

I was taught to start with the wheel furthest from the master cylinder and work your way closer. This will also allow the system to be bled in such a way as to minimize the amount of cross contamination between the new and old fluid.

I do know that with the advent of the newer vacuum pumps you need to bleed the system with your sequence, closest to M/C first ending with the farthest.

I'm always open to new ideas and I'm getting ready to replace all the lines on my 63. I have a vacuum pump system and plan to bleed them using your sequence.

[whateverpratt]

I did lr, rr, rf, lf today, twice. The brake fluid coming out of the bleeder valves started out pretty cruddy at first, but now wverything is nice and clean as far as the fluid goes. Only the left rear had any noticeable air bubbles.

My brakes aren't any better than before I bled them. The first time you push on them the pedal goes nearly to the floor before you feel any braking, and the second push gets very firm and brakes after 2 inches of travel. My left front is braking exceptionally hard. If I try to lock up the wheels, only the left one will lock.

Maybe I should bleed them again. Or perhaps it's an adjustment issue.

The way that I bench bled the master cylinder was new to me. The instructions said to mount it in the truck and plug the port (the MC came with a plastic plug). You then pump the brakes slowly and with only about an inch of travel until you don't see air bubbles coming up into the reservoir.

I followed those instructions, and I think it worked. The air bubbles stopped, and the pedal got very firm.

Any thoughts? Bleed the mc again? Bleed the wheel cylinders again? Adjust the brakes? All the above?

[tincan1966]

With a manual, drum brake system, the actual brake shoe adjustment is very critical. I would remove the drums and make sure you do not have any wheel cylinders leaking, as well. Also inspect the self adjusters to make sure they are working, then adjust the shoes(with the drums installed) so there is a slight drag felt while spinning the drum. Adjust all 4 to the same amount of drag, then try re bleeding the brakes and see if the pedal improves.

[Red4x4]

Thread with some good info, subscribed so I can find later. Thanks

[Sharps40]

Originally Posted by whateverpratt

I did lr, rr, rf, lf today, twice. The brake fluid coming out of the bleeder valves started out pretty cruddy at first, but now wverything is nice and clean as far as the fluid goes. Only the left rear had any noticeable air bubbles.

My brakes aren't any better than before I bled them. The first time you push on them the pedal goes nearly to the floor before you feel any braking, and the second push gets very firm and brakes after 2 inches of travel. My left front is braking exceptionally hard. If I try to lock up the wheels, only the left one will lock.

Maybe I should bleed them again. Or perhaps it's an adjustment issue.

The way that I bench bled the master cylinder was new to me. The instructions said to mount it in the truck and plug the port (the MC came with a plastic plug). You then pump the brakes slowly and with only about an inch of travel until you don't see air bubbles coming up into the reservoir.

When one wheel locks first you have a bad adjustment of that wheel and/or its opposite. Occasionally this can also be a sticky cylinder. For now....

Keep bleeding till the system is firm above the floor on one stroke. Then go play with adjustments.

I followed those instructions, and I think it worked. The air bubbles stopped, and the pedal got very firm.

Any thoughts? Bleed the mc again? Bleed the wheel cylinders again? Adjust the brakes? All the above?

Paragraph 2 is the answer to your problem......at this point you still have air in the lines since the pedal pumps up with multiple strokes. Keep bleeding and bleeding. You may have to run as much as a pint or more thru all 4 to push the air out...remember you are pushing it down and it wants to rise up.

In paragraph 4 you bench blead the master and this is required but is only step one of the job. Now you have to get the air out of the lines. Those air bubbles started out close to the master when you took off the old one and now have to be slowely pushed thru many feet of tubing to the wheel cylinder bleed screws.

After you get a firm pedal on the first stroke....then go back and check/draw the shoes closer to the drum. Drawing the shoes closer to the drum will cause the pedal to feel firm much higher in the stroke (i.e. when the pedal firms up with one pump close to the floor the shoe to drum gap is too large on at least one wheel).

pump and pump and pump and pump and then pump some more after a smoke break. they will come up eventually. I've seen it take hundreds and hundreds of pumps to clear a line or three.

[Sharps40]

Remember 1 hard and fast rule.

1. If it will pump up from being on the floor its because you have air in the lines or master cylinder...period.

[KJSR]

Make sure your brakes are adjusted correctly. Everything you have described could be a result of that as well.