Need help Bad, please

[ubtripn]

This is the order of events:

1. Front brakes and wheel cylinders removed
2. All hardware replaced (Retainer issue fixed)

I had good brake pressure before. (These are power brake drums) but I cannot build pressure back. I have bled them the normal way then gravity bled them with almost half a gallon of fluids, no visible leaks, just cannot get pressure.

Shouldn't I be able to bleed the front end on it's own since it is in a separate loop than the rear?

What else can I do??

Thanks.

[72chevynoob]

1- visually inspect all brake lines for leaks because if fluid can get out, air can get in
2 if disks ensure right side up and on correct side of vehicle (calipers can be switched side to side, which will leave the bleeder screw pointing down and your brakes wont bleed out.

Yes, the front and rear should bleed separately.

What is your bleeding procedure?
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[Secret Squirrel]

I'd bleed all the lines, don't forget to check the cap for leaks. I had to use two rubber gaskets on my master cylinder to get it to seal (i.e. build pressure).

I seen bubbles while my buddy pumped the pedal, if the lid don't seal you will not get pressure. I eventually decided to gravity bleed the lines in the correct order (farthest to close). Took about an hour and gave me time to unwind.

[Tx Firefighter]

Originally Posted by Secret Squirrel

I'd bleed all the lines, don't forget to check the cap for leaks. I had to use two rubber gaskets on my master cylinder to get it to seal (i.e. build pressure).

I seen bubbles while my buddy pumped the pedal, if the lid don't seal you will not get pressure. I eventually decided to gravity bleed the lines in the correct order (farthest to close). Took about an hour and gave me time to unwind.

That's incorrect. The seal of the master cylinder lid has no bearing on the pressure being made in the master cylinder. That is a function of the piston inside the bore. All the reservoir of fluid in the master cylinder is there for is to assure the piston has a steady supply of fluid as needed. Gravity does the rest. The rubber gasket is simply there to keep fluid from spilling out of the reservoir when the truck goes through day to day various turns and bumps. The fluid in the master cylinder reservoir is never under any pressure (other than atmospheric).

[jjzepplin]

Originally Posted by Tx Firefighter

That's incorrect. The seal of the master cylinder lid has no bearing on the pressure being made in the master cylinder. That is a function of the piston inside the bore. All the reservoir of fluid in the master cylinder is there for is to assure the piston has a steady supply of fluid as needed. Gravity does the rest. The rubber gasket is simply there to keep fluid from spilling out of the reservoir when the truck goes through day to day various turns and bumps. The fluid in the master cylinder reservoir is never under any pressure (other than atmospheric).

x2

[Secret Squirrel]

Originally Posted by Tx Firefighter

That's incorrect. The seal of the master cylinder lid has no bearing on the pressure being made in the master cylinder. That is a function of the piston inside the bore. All the reservoir of fluid in the master cylinder is there for is to assure the piston has a steady supply of fluid as needed. Gravity does the rest. The rubber gasket is simply there to keep fluid from spilling out of the reservoir when the truck goes through day to day various turns and bumps. The fluid in the master cylinder reservoir is never under any pressure (other than atmospheric).

That is great news, now I can put the new chrome cap on ... thought I had bought a dud! Thanks

[Secret Squirrel]

Originally Posted by Tx Firefighter

That's incorrect. The seal of the master cylinder lid has no bearing on the pressure being made in the master cylinder. That is a function of the piston inside the bore. All the reservoir of fluid in the master cylinder is there for is to assure the piston has a steady supply of fluid as needed. Gravity does the rest. The rubber gasket is simply there to keep fluid from spilling out of the reservoir when the truck goes through day to day various turns and bumps. The fluid in the master cylinder reservoir is never under any pressure (other than atmospheric).

That is great news, now I can put the new chrome cap on ... thought I had bought a dud! Thanks

[BluTrukker]

One thing that nobody mentioned is to ensure you adjust the shoes out to the drum before you bleed (if you sre pumping the pedal to bleed) other wise you will have a pedal that goes to the floor and you may overstroke the cylinders.

[ubtripn]

Ok. Thank you. Can air in the rear lines mess up the front when they are on different circuits?

[bk2life]

Originally Posted by ubtripn

Can air in the rear lines mess up the front

yes.

if any air is in the sytem you will have a soft pedal.

[ubtripn]

ok. I also cannot get any fluid out of the drive rear bleeder. Is replacing that line hard? Do I have to special order it?

[70CHEVYBB]

You need a master cylinder.

[Tx Firefighter]

You'll probably think this is not very helpful, but over the years, I've gotten to where on every truck I build, I just replace the master cylinder, all wheel cylinders and all three rubber hoses every time. Take all the old stuff off, blow the steel lines out with solvent and air hose, then replace the above mentioned parts. Do the front wheel bearing service and new shoes and hardware as needed at the same time. You might spend 200 bucks doing it this way, but when you pour fluid into the new master cylinder, they will bleed out nice and clean and you'll have fresh brakes to enjoy for a long time. You'd be surprised how nasty the inside of old brake hydraulics get over the years. And hoses swell shut on the inside when they get old. You'll get fluid through them under pressure, but not gravity. And, they'll hold you brakes applied when you release the pedal, ruining your drums and shoes in short order.

[ubtripn]

I will do so. I just figured I didn't need a master cylinder since it was working before but they are cheap.

My Driver's side rear drums have metal hoses attached directly to them. This is normal right?

[68gmsee]

Originally Posted by ubtripn

........My Driver's side rear drums have metal hoses attached directly to them. This is normal right?

Yes. The rubber hoses are located where flexing occurs -on the front wheels and top of rear axle shaft.

[Tx Firefighter]

Yes. You have one rubber hose from the rear frame rail down to the axle, then it splits off with metal hard lines from there over to each wheel cylinder. The rear hose can be a pain to change, but they're dirt cheap and yours is surely pretty beat after all these years.

[ubtripn]

Ok, so if I replace hte two metal hosesin the rear, the MC and the rubber hose in the rear (The front ones are new) then I can just fill and bleed the system the normal way right?

[Stocker]

If you're gonna do all that, might as well replace the rear wheel cylinders too. They are more likely to be bad than the hard lines anyway. And if they are bad, they can definitely cause a soft brake pedal. Besides, you still haven't fixed the problem of not being able to bleed the rears. Did you ever try to clear out the bleeder valve? If that one rear won't bleed, you'll never have good brakes.

[ubtripn]

I havent tried yet to clear the valve but i will tonight. Wouldn't fluid come out where the valve is though if it was a plugged valve.

Thanks all for the help byt the way.

I just love how a simple brake shoe job mushrooms into a thousand more parts, oh well, it's always that was =)

[Stocker]

Originally Posted by ubtripn

I havent tried yet to clear the valve but i will tonight. Wouldn't fluid come out where the valve is though if it was a plugged valve.

You mean if you completely remove the valve? Yes, you should get fluid out of the wheel cylinder if the valve is removed. BTW, with the valve in your hand, you should be able to blow air through it -- if you can, it's not plugged.

If that's the case, you still might have a bad wheel cylinder. Before going into the rear brakes, try cracking open the hard line to the wheel cylinder and see if you can get fluid out of the hard line. If so, the wheel cylinder is definitely bad (plugged). If you can't get fluid out of the hard line, it -- or the hose (or the hard line coming from the MC) -- is plugged or crimped.

[ubtripn]

Just so I know, the standard front drum brakes have two retainer springs one is longer than the other. Does the longer one go on the shorter shoe that faces front? I can't imagine it would matter much but I want it perfect.

[Stocker]

Originally Posted by ubtripn

Just so I know, the standard front drum brakes have two retainer springs one is longer than the other. Does the longer one go on the shorter shoe that faces front?

This pic shows a longer spring going to the short (front) shoe, so you're probably right. Other than that, I don't know. I always do one side at a time, so I can reference to the other side. I also lay the parts out in the order I remove them, just in case....

[ubtripn]

I will do that, pull open the hard line, remove and replace while also checking the bleeder valve. Thanks so much for the advice.

[ubtripn]

Yeah, Layed them out only to have them kicked over by the dog but I just didn't pay the right attention. there was a lot going on. That pic is the rear but I bet it applies to the front spring wise. Thanks for the help!

[ubtripn]

Got it, thx!