Intermittent brake fade
Thread Starter
|
Junior Member
Joined: Oct 2018
Posts: 259
From: NORCAL
5 cents worth - brake fade means your pedal still goes to the floor sometimes? No leaks you said.
Does it have rear drum brakes?
I've been following up to here but now something came to my mind. You said it did it most of the times when you had backed up.
How about parking brake application?
This relates to rear drum brakes. When incorrectly assembled or with the incorrect brake pads it is possible for the pads to move around laterally. Means left and right seen in driving direction. Then they may slip off the brake actuators which then can fully extend without pressure.
Still the front should brake the vehicle. Not sure if your Blazer is diagonal or front and rear brake circuits.
Could it be that it is a mechanical failure where one or both of the rear brake pads slip off the rear actuator(s)?
I would look into the same at the front, making absolutely sure that all is to spec's.
Does it have rear drum brakes?
I've been following up to here but now something came to my mind. You said it did it most of the times when you had backed up.
How about parking brake application?
This relates to rear drum brakes. When incorrectly assembled or with the incorrect brake pads it is possible for the pads to move around laterally. Means left and right seen in driving direction. Then they may slip off the brake actuators which then can fully extend without pressure.
Still the front should brake the vehicle. Not sure if your Blazer is diagonal or front and rear brake circuits.
Could it be that it is a mechanical failure where one or both of the rear brake pads slip off the rear actuator(s)?
I would look into the same at the front, making absolutely sure that all is to spec's.
I started noticing it upon backing up when I was wheeling and almost went over the side. Currently it does it in forward also. However it has rear discs. Still trying to figure out what Christine was referring to about the parking brake. I DID do some adjusting on it at the wheel as it was totally inoperable but cannot say if the brake fade was present prior to that. Going to try and start isolating wheels to attempt to pin it down. Will keep you all posted...
Thread Starter
|
Junior Member
Joined: Oct 2018
Posts: 259
From: NORCAL
Christine's quote...
"Following (because this is something I'd like to know how to fix if it every happened to me).
The only thing I could add is that I've done some thinking about the parking brakes and the circuit that overrides the daytime running lights (DRLs). Have you done any servicing on the parking brake pads? My understanding of the switch is that it is a simile contact switch so that its indicator light coming on or not could indicate something with the parking brake cable adjustment. BTW, the parking brake cable adjustment is separate from the parking brake shoe adjustment. That has to be done at the rear axle. I am familiar with the 4-wheel disk brakes system with the parking brake shoes on the inside of the rear rotors.
__________________
1999 Blazer LT 4dr, 4WD, AT
ZW7 Prem. Smooth Ride Susp.
NVG 236-NP8 4-Button transfer case
Rear Axle: GT4 3.73:1, G80 locking diff. 1.25" wheel spacers
2" Susp. Lift with RC upper cntrl arms w/30 x 9.5 R15
Dynomax cat-back exhaust"
"Following (because this is something I'd like to know how to fix if it every happened to me).
The only thing I could add is that I've done some thinking about the parking brakes and the circuit that overrides the daytime running lights (DRLs). Have you done any servicing on the parking brake pads? My understanding of the switch is that it is a simile contact switch so that its indicator light coming on or not could indicate something with the parking brake cable adjustment. BTW, the parking brake cable adjustment is separate from the parking brake shoe adjustment. That has to be done at the rear axle. I am familiar with the 4-wheel disk brakes system with the parking brake shoes on the inside of the rear rotors.
__________________
1999 Blazer LT 4dr, 4WD, AT
ZW7 Prem. Smooth Ride Susp.
NVG 236-NP8 4-Button transfer case
Rear Axle: GT4 3.73:1, G80 locking diff. 1.25" wheel spacers
2" Susp. Lift with RC upper cntrl arms w/30 x 9.5 R15
Dynomax cat-back exhaust"
Thread Starter
|
Junior Member
Joined: Oct 2018
Posts: 259
From: NORCAL
EUREKA!!!! I have found it!
EUREKA!!!! I have found it! The problem that is....
I will post some photos if requested but it turned out to be a simple matter.
The front disc brake calipers are being pushed against the after-market upper A-arms when making a tight turn. A Superlift 2 1/2" lift was installed and the rear tube of the upper A-arm hits the upper bolt of the floating side of the brake caliper when the steering is fully turned either left or right. It hits the caliper before the lower steering bump-stops make contact. In doing so, it pushes the floating part of the caliper into the rotor pushing the pistons in on one side and forcing fluid back up into the MC. So after making a sharp turn, the floating part of the caliper returns to its normal position leaving a gap between the rotor and the pads. So it takes a large amount of pedal travel for the pistons to get the pads seated back on the rotor. They get so far away that they barely made contact with one brake application leading to the pedal going to the floor and just barely making a stop.
They no longer make this particular lift kit for Blazers and I can see why. There is no recommended "fix". I thought about adding metal to the bump stop but that would dramatically increase my turning radius. After conferring with others I am going to grind an angle on the bolt head that holds the floating part of the caliper as well as grind some off the tip of the A-arm tube on an angle where it does not seem like it would compromise the structural integrity. This should provide enough clearance between the arm and the caliper bolt to prevent any more contact.
After multiple ABS bleeds. Removing the ABS completely. New front hydraulic hoses. New calipers. New master cylinder.... It was right under my nose (so to speak) all the while and a simple, non brake system failure, problem. A little grinding and I should be good to go.
I plan on doing this in the next few days so will update after the road test. I also plan on re-installing the ABS system again once this is remedied.
From here on in I hope everything else will be up-grades instead of retro-grade....
I will post some photos if requested but it turned out to be a simple matter.
The front disc brake calipers are being pushed against the after-market upper A-arms when making a tight turn. A Superlift 2 1/2" lift was installed and the rear tube of the upper A-arm hits the upper bolt of the floating side of the brake caliper when the steering is fully turned either left or right. It hits the caliper before the lower steering bump-stops make contact. In doing so, it pushes the floating part of the caliper into the rotor pushing the pistons in on one side and forcing fluid back up into the MC. So after making a sharp turn, the floating part of the caliper returns to its normal position leaving a gap between the rotor and the pads. So it takes a large amount of pedal travel for the pistons to get the pads seated back on the rotor. They get so far away that they barely made contact with one brake application leading to the pedal going to the floor and just barely making a stop.
They no longer make this particular lift kit for Blazers and I can see why. There is no recommended "fix". I thought about adding metal to the bump stop but that would dramatically increase my turning radius. After conferring with others I am going to grind an angle on the bolt head that holds the floating part of the caliper as well as grind some off the tip of the A-arm tube on an angle where it does not seem like it would compromise the structural integrity. This should provide enough clearance between the arm and the caliper bolt to prevent any more contact.
After multiple ABS bleeds. Removing the ABS completely. New front hydraulic hoses. New calipers. New master cylinder.... It was right under my nose (so to speak) all the while and a simple, non brake system failure, problem. A little grinding and I should be good to go.
I plan on doing this in the next few days so will update after the road test. I also plan on re-installing the ABS system again once this is remedied.
From here on in I hope everything else will be up-grades instead of retro-grade....
BF Guru
Joined: Dec 2016
Posts: 5,610
From: Moscow, ID
EUREKA!!!! I have found it! The problem that is....
I will post some photos if requested but it turned out to be a simple matter.
The front disc brake calipers are being pushed against the after-market upper A-arms when making a tight turn. A Superlift 2 1/2" lift was installed and the rear tube of the upper A-arm hits the upper bolt of the floating side of the brake caliper when the steering is fully turned either left or right. It hits the caliper before the lower steering bump-stops make contact. In doing so, it pushes the floating part of the caliper into the rotor pushing the pistons in on one side and forcing fluid back up into the MC. So after making a sharp turn, the floating part of the caliper returns to its normal position leaving a gap between the rotor and the pads. So it takes a large amount of pedal travel for the pistons to get the pads seated back on the rotor. They get so far away that they barely made contact with one brake application leading to the pedal going to the floor and just barely making a stop.
They no longer make this particular lift kit for Blazers and I can see why. There is no recommended "fix". I thought about adding metal to the bump stop but that would dramatically increase my turning radius. After conferring with others I am going to grind an angle on the bolt head that holds the floating part of the caliper as well as grind some off the tip of the A-arm tube on an angle where it does not seem like it would compromise the structural integrity. This should provide enough clearance between the arm and the caliper bolt to prevent any more contact.
After multiple ABS bleeds. Removing the ABS completely. New front hydraulic hoses. New calipers. New master cylinder.... It was right under my nose (so to speak) all the while and a simple, non brake system failure, problem. A little grinding and I should be good to go.
I plan on doing this in the next few days so will update after the road test. I also plan on re-installing the ABS system again once this is remedied.
From here on in I hope everything else will be up-grades instead of retro-grade....
I will post some photos if requested but it turned out to be a simple matter.
The front disc brake calipers are being pushed against the after-market upper A-arms when making a tight turn. A Superlift 2 1/2" lift was installed and the rear tube of the upper A-arm hits the upper bolt of the floating side of the brake caliper when the steering is fully turned either left or right. It hits the caliper before the lower steering bump-stops make contact. In doing so, it pushes the floating part of the caliper into the rotor pushing the pistons in on one side and forcing fluid back up into the MC. So after making a sharp turn, the floating part of the caliper returns to its normal position leaving a gap between the rotor and the pads. So it takes a large amount of pedal travel for the pistons to get the pads seated back on the rotor. They get so far away that they barely made contact with one brake application leading to the pedal going to the floor and just barely making a stop.
They no longer make this particular lift kit for Blazers and I can see why. There is no recommended "fix". I thought about adding metal to the bump stop but that would dramatically increase my turning radius. After conferring with others I am going to grind an angle on the bolt head that holds the floating part of the caliper as well as grind some off the tip of the A-arm tube on an angle where it does not seem like it would compromise the structural integrity. This should provide enough clearance between the arm and the caliper bolt to prevent any more contact.
After multiple ABS bleeds. Removing the ABS completely. New front hydraulic hoses. New calipers. New master cylinder.... It was right under my nose (so to speak) all the while and a simple, non brake system failure, problem. A little grinding and I should be good to go.
I plan on doing this in the next few days so will update after the road test. I also plan on re-installing the ABS system again once this is remedied.
From here on in I hope everything else will be up-grades instead of retro-grade....
When I did my lift, I used the Rough Country upper control arms but not the whole kit. I got them to sell me just the upper control arms. You might consider using the RC upper control arms but let's hope your fix works first!
Moderator
Joined: Nov 2007
Posts: 2,185
From: Zurich
Reminds me to ask about suspension modifications if such a problem pops up the next time.
And suggest what I always do. Car on the lift, flashlight, check every thing related to brakes and suspension and do full turning of the wheels.
Hard to diagnose from a distance.
Glad you got that one straightened out.
And suggest what I always do. Car on the lift, flashlight, check every thing related to brakes and suspension and do full turning of the wheels.
Hard to diagnose from a distance.
Glad you got that one straightened out.
Thread
Thread Starter
Forum
Replies
Last Post
Adam Turner
2nd Generation S-series (1995-2005) Tech
2
Jun 21, 2012 08:37 PM
05box
2nd Generation S-series (1995-2005) Tech
4
Apr 23, 2008 07:25 PM
