Another "T" braking problem

[WMG]

Been doing a complete make over of the bucket. Included is work on the brakes. Last summer the brakes worked great would lock up the wheels if applied hard enough. Some info about the system; my m,aster cylinder is mounted on the fire wall with a hanging pedal, originally the brake lines ran along the bottom of the body to the top of the diff from there the lines went to the rear wheels. Teh line form the MC to the TEE was 1/4" then changed to 3/16". I changed all the lines to 3/16". Changed the routing to follow the frame up the kick up then TEE'd to the wheels. Except for the line size and routing nothing has changed, pedal and MC are the same geometry is the same. I cannot seem to get the rear brakes to bleed properly constantly get bubbles out the bleeder and no action on the wheel cylinders. There are no leaks in the system have gone back and checked all the fittings they are tight. Front brakes bled like they should getting action on the disc pads. Not getting any good pedal, goes to the floor. What am I over looking? Not doing right? No leaks any where including wheel cylinders. Can't afford the fluid the bleeding process is taking. HELP!

Wayne

 

[grazza]

Is the rear T higher than the MC? I asume the T is the highest point in the brake system? If so try jacking the front of the car up until it is at least level and try bleeding the rears again.

As for the fluid. Don't loose it. Clean a jar out with Metholated Spirit until it is spotless. Put a small amount of brake fluid in the bottom of the jar. Get a length of clear plastic tube, long enough to connect to the bleeder and reach into the jar and bleed the brakes normally. Return the fluid in the jar to the MC as required until the system is fully bled. Never return the fluid to the original container tho' as that could cause contamination of the unused fluid. Hope it works out for you soon.

 

[WMG]

The MC is the highest point of the braking system. Was always told that bled brake fluid should not be used again as it has air in it that cannot be removed. Do nt know if it an old wives tale but -----. Still trying to figure out why I cannot get all the air out and why I have the pedal going all the way to the floor all the time.

 

[WMG]

Did some more thinking about the situation. There is one small geometric change that was made. I made the panel on the front of the fire wall thicker, went from 16ga material to 1/8" thick. This would change the effective length of the push rod from the pedal to the MC piston. Will try to change this tonight and see what happens.

 

[Hotrod46]

It is possible that you formed an air trap at the kickup in the frame. Try to find someone that has a pressure bleeding setup. They will move the fluid in a constant stream and not give bubbles time to rise back to a high point. That can happen with the traditional foot pumping method.

I have that problem on my 46 and pressure bleeding was the only way to get a good firm pedal. Took a while to figure it out.

Mike

 

[Lee_in_KC]

I am a big fan of speed bleeders. Made bleeding my system dirt simple and a one-man job.

 

[Track T-4]

What's a good source for a speed bleeder?

 

[Lee_in_KC]

I got mine from Summit. Be sure to get the ones with thread dope on them. Without the dope, air will bleed past the threads when you release the brake pedal. Here's what they look like. They have a spring-loaded ball valve inside that lets fluid out when you press the pedal, but won't let air (or fluid) back in.

You also need a bleeder bag like this...

Here's the linkage to the Summit listing... clicky thingy

You'll need one for each caliper because you leave them in after bleeding, just like regular bleeders.

 

[putz]

This is how i have found the best way to get air out. Have full master open bleeder have somebody push peddle to the floor and hold it down while you tighten bleeder.Repeat until all air is out at the shop I worked at we called this redneck pressure bleeding. Then when have full fluid then pump them up they are usually good this way.

 

[WMG]

Got it. Lengthened the push rod from the pedal to the MC. Got enough piston travel that enough fluid was moved to get the air out of the system. Have good pedal again, firm but not solid 3-4" from the floor. Starting the engine tonite for the first time since rebuild last Nov. and on the weekend take it out for the first shake down rum of the complete rebuild.

Lee those speed bleeders might be just the thing will have to get a set. Bleeders that are in cyl. now have very poor heads on them interesting that all 4 were a different size 3/8", 5/16", 10mm and 9mm made for some interesting expressions when I tried to use the right wrench sort of went **(&%$%%^&^##(^(&%&^$*%( or words to that effect

 

[Wild Mango]

The fluid de-aerates after about 10 minutes. Putting fresh bled fluid immediately back into the system may introduce small amounts of air. The only thing that breaks fluid down in service is heat, but water pollutes it. When you change your fluid every 12 months as you should, dispose of the waste fluid as per used oil, all three dots are toxic.