Bleeding brakes

[W-motorhead]

Dear 348/409ers,
I plan to replace both, front wheel cylinders on my '63 Biscayne. When I bleed the brake system afterwards, can I limit the bleeding to the front wheels or do I need to bleed the rear wheels also. What I don't know is how far air, introduced from the front, can travel throughout the entire hydraulic system.
Dan Fults

 

[64ss409]

You could try bleeding just the fronts. If pedal is low or spongy, bleed all.

 

[blkblk63ss]

When you replace the front cylinder's and disconnect hose ,cap hose so fluid will not run and drain out line's to master cylinder. I disconnect hose where it attache's to hard line and cap hard line. That way you can screw hose into cylinder and then connect hose to hard line without draining too much fluid. Then after cylinder's are on, simply open bleeder's one at a time remove mc cap and keep level up and you can gravity bleed just the front's ,no air will be in the rear cylinder's or line's.With this method you are only refilling your new wheel cylinder's, and a little lenght of hose . Do not pump your brake when gravity bleed you will suck air back in when bleeder is open. Just let it drip till no bubble's are seen and clean fluid is present.When i did my car ,all empty, i filled master cylinder and bench bleed it and put on car and then i bleeded all wheel cylinder's using a in and out vacuum cup that come's with a myty vac vacuum hand pump and i used a ac vacuum suck down vacuum pump to keep a constant vacuum to the cup, save's a lot of hand pumping and a constant vacuum, just keep mc full of fluid. Worked very quick and remove's all air.You don't need this method as gravity will work just fine for just the front cylinder's.

 

[63impalass409]

I always bleed all anyways just to change the fluid, I am lazy but not that lazy that I would risk my life or someones else's by cheating.

 

[blkblk63ss]

I always bleed all anyways just to change the fluid, I am lazy but not that lazy that I would risk my life or someones else's by cheating.

I n his case ,don't know his fluid condition how old ,if it is would be good idea , good point!!!!

 

[W-motorhead]

Many thanks. You are right. There's no excuse for laziness when it comes to brakes. I'll bleed the system completely.
Dan Fults

 

[blkblk63ss]

Well, really if you want to do the job right why not replace all wheel cylinder's , pressure will start to leak at weakest point,older wheel cylinder's. Check all your hose's front and rear for cracking, check all hard line's for any thing rubbing on them. Replace hose's if hard and brittle. If master cylinder is old or has a lot of crud laying in the compartment,replace it .Then you can flush system and for sure you will have trust worthy brake's, for a long time. Don't be lazy!!!!!!!!!! Been doing brake's and anti lock's since 1971,have not endangered any one's live's ever on brake failure.Brake failure's can happen quickly without warning . If Brake petal goes to floor with a single system compartment master cylinder failure, you will lose all brake's,so just some trusted advice.

 

[303Radar]

Use one of the hand vacuum pumps to bleed the brake. Less mess and no chance of introducing air back into the system since you won't be pumping the brake pedal.

 

[blkblk63ss]

I have no mess doing with the method i described. If you have a hand pump and vacuum cup,use it if not just put a vacuum hose over the open bleeder and let it drain into a container .you will not get any air into system either way . Just be sure to keep mc full with lid off and don't pump brake petal as you are bleeding cylinder's. Be sure to rinse your backing plate if it is painted or fluid will eat the paint off eventually.