Help: Bleeding brakes

[juddski88]

OK, so I feel a little dumb posting this but:

I have had weird brakes ever since I put the truck together last year. the first 80% of the pedal travel does nothing, then the last 20% is good brake action...not great, but good. I swapped in a newer 08 hydroboost and new 01 master cylinder and just "bench bled" the cylinder tonight in the truck with the supplied plugs. I then went around to every corner twice starting from the furthest corner and working to the nearest and bled the calipers until I couldnt hear or see air.

Brakes are just the same as they were before all this!
Could the ABS module have gone bad from sitting open for a few weeks? I dont remember how long it sat without the brakes hooked up but it was a while. I have run out of idea

 

[blackdirtymax]

I have the same brake issue Tim


Built motor , duel fuelers , 60's overs , gtx4202r

 

[RENODMAX]

Think of how much air a fuel system can have from a build. I would bleed the living bejeesus out of the brakes. Also make sure your lines dont have any points where they could be sucking air. I know this all sounds stupid but its like checking fuses. Have you upgraded your lines to the calipers or are they stock? You could also try some trailer brake alcohol if there has been any condensation buildup.

 

[x MadMAX DIESEL]

sub

 

[jmaz268]

a mityvac bleeder is what I use.....

They are amazing for bleeding brakes.

Mine never seem to have be dead.

 

[battlegraduate09]

same issue here, done the same things as the OP several months ago, no difference. changed pads and calipers as well

 

[madmatt]

use a pressure bleeder and run a shit load of fresh fluid through them. i had this issue on a truck and used like a gallon of fluid to get them to start acting right.

 

[JoshH]

If you have access to a good scan tool you can do an automated brake bleed on the ABS pump.

 

[juddski88]

we did try an autobleed once before with a Tech2..maybe we need to spend more time at it?

 

[Harbin_22]

Doesn't the power steering fluid have a big effect on it? Did you use whatever ps fluid that is recommended

 

[JRODS*LB7]

:laughing4::screwy:

 

[MACKIN]

Although you changed it still sounds like a Hydro-Boost problem. I also use a Mighty-Vac I don't like to do the Old school peddle pump method.

When I did the brakes on my dually and went with a synthetic flush my brakes have NEVER been better.

If it's not the Hydro Booster maybe Josh is onto something with the ABS bleed since it probably went dry sitting. Whats weird is if I'm reading your post correctly that you had this issue prior to swapping all the parts?

 

[juddski88]

Correct, same issue prior to swapping in new hydroboost and MC.

Power steering fluid is All new sythetic too. I have done many brake jobs and fluid flushes on these trucks and I am very thorough because there isnt anyone else around me that cares enough to do a full service properly. I have a pneumatic bleeder that I use to get most of the fluid to the bleeder, then finish them using the pump and hold method. Then I usually take it out and lock up the brakes so the abs cycles.

 

[xcablb7]

Are you 100% positive the lines are in the correct place on the abs pump? I find it odd how the brakes hold as good as they do but the pedal is so low, and does not pump up

 

[Chevy1925]

When you swapped in the new hydroboost, did you make sure the rod was the same lenght as the 01 you had and everything else measured out right?

If thats ok, have some one hold the brakes down and crack the master cyl lines open like you would bleeed the brakes at the calipers. Sometimes you get a bubble in there bench bleeding wont catch

 

[juddski88]

Rod length is the same. Im going to recheck the line routing on the module today James, and crack the master cylinder fittings to see. On a good note, 6gal of fuel got me back some fuel pressure! Lol. Im waiting at the alignment shop now....no more almost kissing the wall

 

[xcablb7]

great! you set ride height first ? moving the bars is going to change the alignment quite a bit, but anything will be closer than it was !

 

[juddski88]

Ride height is set. We changed some stuff while it was on the rack out of curiosity too...moving up or down 1" barely affected anything

 

[xcablb7]

really ? different from what i've found, but I only checked ride height and then with bolts out. now go fill it with fuel and send me a data log! lol

 

[Chevy1925]

Ride height is set. We changed some stuff while it was on the rack out of curiosity too...moving up or down 1" barely affected anything

really ? different from what i've found, but I only checked ride height and then with bolts out. now go fill it with fuel and send me a data log! lol

It depends on where your adding or subtracting that 1". If your ride height is set almost leveled on a stock truck, changing 1" of ride height has a greater affect on alignment compared to a truck that is at or a bit below stock ride height