Brake System - soft pedal, 25% brake force

mac11

Veteran Member
Joined
Jan 18, 2013
Location
Injeana
TDI
04 Passat
This is for my 2002 Nissan Xterra with the 3.3L supercharged engine.

Brake system was working perfectly fine. I changed the front pads and all of a sudden the pedal is soft, goes all the way to the floor and has to be pumped a few times to get enough pressure to stop the truck. The hydraulics were not opened up. Simple pad replacement.

Since then I have done the following:

bled the system to try to remove air using the 2 person method
bled the system with a vacuum pump
replaced the master cylinder
bled the entire system with a vacuum pump
replaced both front calipers.
bled the system with 2 person method
bled the system with vacuum pump.



The front passanger side is scraping the pads against the rotor enough to keep it clean. The front driver side is so inoperable the rotor remains rusty as if it has been sitting for months even after driving a good distance and using the brakes to stop the truck several times.

There are zero visible leaks in the system and over a period of ~3 months the fluid level has not dropped.

I am at a loss at this point.

what am i missing?
 

DPM

Top Post Dawg
Joined
Mar 16, 2001
Location
Newtownards, N. Ireland
TDI
2019 Rav4 AWD Hybrid, Citroen C4 BlueHDI
is the driver's side disc rusty on both faces or just one? A seized sliding caliper is a possibility. Was the whole assy replaced or just the hydraulic bit?
 

mac11

Veteran Member
Joined
Jan 18, 2013
Location
Injeana
TDI
04 Passat
is the driver's side disc rusty on both faces or just one? A seized sliding caliper is a possibility. Was the whole assy replaced or just the hydraulic bit?
to answer your question, I'm not sure if the rear face of the drivers side rotor is rusted. Give me a few minutes to run out and check.

Of note:
(1)both the front calipers have been replaced.
(2) neither the old, nor the new calipers are frozen. all 4 would push the pistons out when it was taken off the rotor.
(3)these oem calipers are dual piston sliding calipers.
(4)last night I was noticing a creaking noise from the front left (drivers side) corner when I would apply the pedal.
 

mac11

Veteran Member
Joined
Jan 18, 2013
Location
Injeana
TDI
04 Passat
Sorry been on the phone all night. Literallu
Just hung up at 230a.

The dust shield in this thing is enormous and will have to pry it back or pull the caliper off to determine the condition of the back of the rotor. Didn't get a chance once I got home from work. Will do it before I leave in the morning.
 

Ol'Rattler

Top Post Dawg
Joined
Jul 3, 2007
Location
PNA
TDI
2006 BRM Jetta
We need you to focus on what we are trying to tell you.
Prying the shields back to look at the backside of the rotor isn't very bright.:rolleyes:

You will damage (kink) the shields. Rust on the inner side of the disk probably isn't causing you problem, anyway. If the brakes are operating correctly, there will be no rust.

Remove the calliper, remove the carrier and then the rotor will come off easily for inspection by removing 1 screw.
After that, you can answer DPM's question by putting the calliper back on with the disk out of the way and see if the calliper slides inboard and outboard freely on the mounting pins.

Something that is important when doing Dub brakes is to always replace the disks when you replace the pads. You did replace the disks, right?

Some people have gotten by and not replaced the disks, but down the road, braking performance will be compromised if you don't. Dub rotors don't really have enough material to last through 2 sets of pads.
 
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mac11

Veteran Member
Joined
Jan 18, 2013
Location
Injeana
TDI
04 Passat
Read the 1st line of the OP

The calipers don't come off like that. They are captive behind the 4wd hubs.
 

DPM

Top Post Dawg
Joined
Mar 16, 2001
Location
Newtownards, N. Ireland
TDI
2019 Rav4 AWD Hybrid, Citroen C4 BlueHDI
the caliper bolts onto the carrier. But the little bolts that retain it screw into the slide pins.
Pull the caliper as for a pad change and see if the two mounting points slide in and out, or simply remove the wheel and use a large g-clamp through one of the big holes opposite the pistons to push them back a touch in-situ. The caliper then should move freely in & out a bit...
 

mac11

Veteran Member
Joined
Jan 18, 2013
Location
Injeana
TDI
04 Passat
the caliper bolts onto the carrier. But the little bolts that retain it screw into the slide pins.
Pull the caliper as for a pad change and see if the two mounting points slide in and out, or simply remove the wheel and use a large g-clamp through one of the big holes opposite the pistons to push them back a touch in-situ. The caliper then should move freely in & out a bit...

This.

Thanks for the heads up to check the slides. I overlooked them as this all started at a pad change.
 

Ol'Rattler

Top Post Dawg
Joined
Jul 3, 2007
Location
PNA
TDI
2006 BRM Jetta
Read the 1st line of the OP

The calipers don't come off like that. They are captive behind the 4wd hubs.
Opps, didn't catch that. But still, The OP has floating calipers, just like any other modern car with disk brakes.

Even though the mounting is different than on a Dub, the calipers still needs to move freely on the sliders or there will be braking and uneven wear issues.
 
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