Soft brake pedal

[doslucero]

Looking for some advise.  I've bled the brakes in the correct order many many time and continue to get bubbles while bleeding.  I've replaced the two front calipers. and put thread tape on every bleeder valve to make sure its air tight.  I see no leaks anywhere.  The brake pedal continues to be soft after every bleed attempt. The next thing I am going to try is using a power bleeder that hooks up to the fluid reservoir. Is there any other thing I should try before replacing the brake master cylinder? 

 

Thanks

[Son of Marty]

Did this start when you replaced the calipers? if so make sure the bleeders are facing up. Are you loosing any fluid?

Edited June 18, 2020 by Son of Marty

[NYNick]

Check the reservoir cap gasket. Is it 40 years old?

[doslucero]

This started before the calipers were installed.  Calipers have bleed valves pointing up. This started after I took the rear subframe out and refreshed all the bushings and put it back in. 

[doslucero]

I recently installed a new reservoir cap. 

 

[2002FjordBaur]

Following with interest... same with my brakes, even using a power bleeder.

RHD or left? I have the RHD dual servo added complication and no leaks but definitely air in the system.

New everything, servos, MC, calipers, rear cylinders, flex pipes, etc.

I pump the pedal and its firms up.

Is PTFE tape on bleeder threads worth it?

Edited June 18, 2020 by 2002FjordBaur

[Son of Marty]

Did you replace the hoses in the rear? They if original may not have taken the removal well old hoses are brittle.

[Mike A]

You don't need any power bleeder. I don't know how others bleed their brakes, many use the two man method, but I have been going solo for years without the help of any pricy power bleeder either vacuum or pressure type. You need a Tilton brake bleed bottle or you can be really cheap and make one as in this video . But the technique is bullet proof and you get to replace the brake fluid as a twofer. You have to monitor the fluid level in the resevoir as you pump the pedal. but on an 02 you can see the level from the driver's seat .   If you continue to get a spongy pedal the problem is in your hard parts somewhere.

 

Edited June 19, 2020 by Mike A

[AustrianVespaGuy]

Brake workflow:

1.) Check for leaks

2.) Adjust rear brakes

3.) Bleed brakes

4.) Replace flexible brake hoses (& re-bleed)

5.) Replace rear wheel cylinders (& re-bleed)

6.) Rebuild front calipers with new seals/boots (& re-bleed)

7.) Replace master cylinder (& re-bleed)

[02Les]

3 hours ago, 2002FjordBaur said:

Following with interest... same with my brakes, even using a power bleeder.

RHD or left? I have the RHD dual servo added complication and no leaks but definitely air in the system.

New everything, servos, MC, calipers, rear cylinders, flex pipes, etc.

I pump the pedal and its firms up.

Is PTFE tape on bleeder threads worth it?

 

Just in case it makes a difference.........on RHD you should bleed the Servo cylinders first, then rear cyls, then front.

[doslucero]

4 hours ago, Son of Marty said:

Did you replace the hoses in the rear? They if original may not have taken the removal well old hoses are brittle.

I replaced the hoses on all four wheels within the last 2 years.  They are in good shape. 

[TobyB]

Sooooo...  if the problem started when you opened up the rears, i'm gonna guess that

there's still air in there.  It can be hard to get out.

 

I DO advocate a bit of pressure on the reservoir- a bike pump is plenty, just a few psi-

and then bleed and bleed the rears again.  Adjust the shoes so they're just touching,

but do it with the wheel on (it's really hard to do this) or the drum secured 

(2 box- end wrenches as spacers under the nuts is my method)

and get them almost too tight  (you might want to back them off later, but for this exercise, carry on)

DO make sure the adjusters (each one) can lock up the drum.  If one's way out,

it adds soooooo much pedal travel.

In my world, that's the real reason to go to rear discs...

 

That's always worked for me on everything but the clutch.

(parenthetically yours)
 

fwiw,

t

['76mintgrün'02]

You may not need a pressure bleeder, but they work really well.  I just use mine as an air pump and stop to fill the reservoir as needed. 

 

I've made three catch containers, similar to what Mike A showed, but used Poulsbo Pickled Herring jars.  I have three little 9/32" wrenches that are close enough to 7mm that they work fine on the bleeders.  

 

It is kind of a bulky thing to store, but makes me happy every time I use it.

 

 

I'll bet the power bleeder will solve your problem.  Just to confirm the caliper bleeding sequence, it's Upper Inner Outer (You I Owe).

 

Tom

[Stevenc22]

I recently switched from a motive pressure bleeder to a vacuum bleeder. I LOVE MY VACUUM BLEEDER! (Get a good one, not an ebay special, those dont work well)

 

https://www.amazon.com/Capri-Tools-Vacuum-Brake-Bleeder/dp/B00OM751EC/ref=sr_1_6?dchild=1&keywords=vacuum+bleeder&qid=1592573118&sr=8-6

 

Make sure your rear drums are correctly adjusted because a badly adjusted rear drum will cause soft brakes!

[AustrianVespaGuy]

Word to the wise if pressure bleeding, keep the pressure VERY LOW so that you don't blow the clutch feed line out of the clutch master cylinder. . . words of experience here (and it wasn't THAT much pressure, just old rubber!!!)