BRAKE PEDAL FEELS SOFT - 04 TB LT I6 4.2 4X4

webdawg

Original poster
Member
Jun 26, 2014
247
Ever since I have gotten my trailblazer the way the brake pedal operates on it seems soft. First I had the brakes professionally bled at Firestone. I did the ABS engagement thing on dirt roads over and over. It did make a bit of a difference.

Now I just changed all my calipers because the front two were bad. They were making a creaking noise that probably could have been fixed with a small rebuild but the AC DELCO rebuilds were only about $40 a piece. I also replaced the rubber brake lines because, well, why not (the vehicle is old), those were cheap too.

So down to the issue. I have read some posts on other sites (http://forums.trailvoy.com/showthread.php?t=49391&page=9) and other places and they conclude that the feel of the brake pedal on the trailblazer is just naturally long/soft.

Listen, I do not think I can get this thing to the floor, but it seems to get close. The car stops, if I were to try and get the pedal to the floor while the car is moving, I would most likely be thrown through the window.

If I am stopped, I am not even pushing that hard and I can get pretty far, if not almost to the floor (I honestly think I just stop before I hit the floor, I do not want to brake anything.) Now it is not like I am not pushing to get it to the floor, I am. It is just it is nothing like the new braking system I have in my 2010 equinox. When you push on a pedal in a newer car, it just stops. It would take a lot more leg to make that thing go down.

Is this just how it is?

I do not think my brake booster is leaking.

The ABS works great, it pushes back.

I just bled my brakes and the entire system has new fluid. (I was not able to engage the abs bleed, I do not have the correct scan tool)
 

Mooseman

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Dec 4, 2011
25,257
Ottawa, ON
I went through the same thing when I first got my TB. Bled brakes, replaced the master cylinder and bled some more, had them bled by the dealer for the ABS, same. I think it's because of the aluminum calipers up front. My '06 9-7x has cast iron calipers and it's much more solid.
 

mrrsm

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gmcman

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Dec 12, 2011
4,656
I think it's because of the aluminum calipers up front. My '06 9-7x has cast iron calipers and it's much more solid.
The TBSS has the iron calipers up front as well, and that was apparently GM's reason to using them for the reduced flex.

For the OP, did you purchase the vehicle used? If so there's no telling what pads are used and if they have been glazed. If you have the SWB you could get the LWB brackets and the larger rotors if you have at least 17" wheels, won't fit with the 16" and reuse your calipers. Or..you could get the TBSS brackets and the iron calipers but they're a little pricey.
 

littleblazer

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Jul 6, 2014
9,265
I always thought it was the calipers as well, but the envoy (2002) is rock hard. I'm pretty sure both use the same one, but the envoy feels much better. I really wonder if it is actually the brake booster, depending on how it is configured depends on how it feels. More boost is a softer pedal from my understanding.
 

webdawg

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Jun 26, 2014
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mrrsm

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gmcman

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Dec 12, 2011
4,656
I would try to bleed yourself to be sure. Get a 2nd person to have them pump the pedal, start with the RR, LR, RF, then LF. With the engine off, pump the pedal 5 times and hold it down, crack the bleeder with a clear hose attached and observe the fluid. If bubble (s) then repeat until no bubbles and then bleed for 3 or 4 pump up cycles. Don't let too much fluid flow from the bleeder, just enough to see movement and make sure the person inside doesn't lift their foot until you give them the OK that you have tightened the bleeder.

Doing this will ensure (in your mind) that you have at least tried to get the air out then you can see if the ABS cycling will help.
 

gmcman

Member
Dec 12, 2011
4,656
I was playing around yesterday and I found a way to cycle the ABS but it requires lifting all 4 wheels....I'll post this shortly in the brakes and suspension section. Basically raise all 4 wheels, engage 4WD, lightly clamp a front line with vice grips and when you apply the brakes at about 20 mph, the clamped tire will not slow down or will do so with a delay and this cycles the ABS pump.
 

Mounce

Member
Mar 29, 2014
13,667
Tuscaloosa, AL
Square body Chevy's I would consider to have a soft pedal. TB feels great compared to my brothers truck which is sketchy to drive to me because of how nonexistent the brake pedal feels. Gotta go through half of the travel before brakes start to engage. Always felt like that.

So, what I'm saying is, TB brakes feel good to me, never noticed an issue with the feel and actually prefer it. I guess different people have different expectations.
 
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Chickenhawk

Member
Dec 6, 2011
779
Before I expose an UGLY TRUTH about the auto repair business, let me just say that the pad actually contributes a lot to the feel of the brakes.

GM made the brakes to 'feel' softer than previous models so they feel very 'easy' to the soccer mom on a test drive, and to address complaints that previous GM SUVs had an excessively hard brake pedal feel.

Change the pads, bleed the brakes again and take it out on a gravel road to do three or four hard stops, enough to get the ABS kicking in.

Just changing the pad will change the feel. OEM pads tend to have an increasing bite toward the bottom which, for brake pedal feel sensitive folks like myself, gives a disquieting feeling that nothing much happens for the first inch of travel. Akebono aftermarket pads solved that problem and lasted for years. (Im am not hard on brakes; I just have high standards on feel.)

When my slotted rotors (dumb idea) wrecked the pads prematurely and delaminated layers of rusted metal off one side of the rotor, I switched to the best pad one can get for our platform - the NAPA Adaptive One. It is the same or nearly the same pad as the Raybestos police pursuit pad, and felt like new Akebono pads; just the right balance of soft and firm.

If you don't know what the previous owner put on for pads, expect the worst. Ceramics are OEM and one should NEVER use anything else. If they replaced them with semi-mettalic because some counter clerk oversold them junk as "just as good" as OEM, there is part of your problem right there.

Now for the ugly truth. The WORST pads one can get are the so-called "lifetime brakes" from the quick lube/muffler/brake shops.

This is how these shops rake in HUGE profits:
- They give you the absolute cheapest pad they can find, simply because they know that 75% of their customers will never come back to claim on worn pads. Plus, when they charge $80 for a $10 pad, they can afford to replace someone's pads six times and still make money;
- They actually WANT you to wear out your pads quickly and return many times for the "lifetime brakes." They already charged you $600 for a set of four $10 pads, $5 in installation parts and half an hour of labour. They give you another set of $10 pads for "free" and then charge you $80 for the installation parts because of course they are not covered. (Read the fine print.)

The GMT360 has a softer pedal feel overall than other makes. It does not make it worse; just different. But of you want a better feel, get a better pad and cycle the ABS on gravel if you bleed the lines.

When bleeding, I prefer a pressure bleeder rather than a vacuum bleeder because it pushes air and rust OUT the bleeder screw threads, rather than IN the threads. (I use the PowerMotive bleeder dry, because I hate cleaning up the fluid afterwards.)
 

AWD V8

Member
Jan 12, 2015
463
My recent experience with my Envoy brakes.

A couple of weeks ago I had a car run a stop sign and I tried to stop but glanced off the driver's side of the other car. Did $4,400 damage to my truck, hardly a mark on the new Acura MDX

During the braking it was like slow motion, I could see the car pull out, I hit the brakes but the truck did not haul down. My dash cam video looks like I just wasn't trying to stop. I had the brake pedal pinned!

I've worked on thousands of different make vehicles, and to be honest, the brakes on these suck! In fact my last 3 S10/15 were not much better, my G van was not good!

My wife's Outland will throw you through the windshield if you jab the brakes. I had to do a quick haul down on the freeway at night and no fade, solid feel and it stopped FAST!

My Envoy does have heavy 20" wheels, but I can only bring the ABS into action on a wet surface. If the brakes are unable to active the ABS you are not getting the maximum braking that the tire traction can provide. When I had the 17" OEM wheels and stock size Michelins The tires would lock fairly easily if I hit the brakes hard.

I have machined rotors on the front and recent Raybestos Ceramic pads. I use these pads in most of the jobs I do with little negative feedback. I have used the Napa Adaptive pads with great results. I've planning on replacing the front pads with Hawks and a premium coated rotor like Stop Tech. Also seriously considering stainless lines and SS calipers to firm up the pedal and get some better modulation.
 

littleblazer

Member
Jul 6, 2014
9,265
Oh no. If I floor the pedal it damn near launches you through the windshield on the voy or tb. Actually I've locked the wheels and almost put the car sideways on dry pavement during a panic stop. (Semi pulled in front and made a u turn on a 55 mph road roughly 100 feet away, down hill too) Don't get me wrong, it's not rock hard like the escalade or sierra but those both use the power steering pump as a booster vs vaccum like ours, that changes everything. The envoy feels like I would think it should, 1/4 of the travel and it's plenty for a normal stop. Mine is more like half and it does the same. Only time it didn't stop was when the abs kicked in at like 20 mph, slow speed abs on these just rolls forever it seems.
 

gmcman

Member
Dec 12, 2011
4,656
My Envoy does have heavy 20" wheels, but I can only bring the ABS into action on a wet surface.

There is quite a bit of rotational force with those large wheels, but I want to speculate that you still should have been able to stop at a respectable rate.

I'm with Littleblazer, mine seems like it could lift the rear off the ground if there was enough traction.

I'm running the stock setup as well, but one thing comes to mind...how worn are your tires? The braking distance is greatly increased with worn tread, 3-4/32 compared to 9-11/32 is drastic difference in stopping distance.

My favorite combo is NAPA ultra premium rotors with Akebono ceramic, but I do want to try the adaptive one pads if they are similiar to the police pursuit...I didn't know this.

Edited for content.
 
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mrrsm

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It is absolutely true that the more the Mass of any Rotating Object is moved further away from its Center of Rotation...The Greater its Angular Momentum becomes ...and the more stable its Gyroscopic Rotational Speed becomes...and last but not least.. but most important.. The Harder it Gets to Slow Down the Spinning Object from its Inertial Rotation!
 
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gmcman

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Dec 12, 2011
4,656
WOW...! What interesting, Spot-On, "Laws of Physics" Observation!

It is absolutely true that the more the mass of any rotating object is moved further away from its Center of Rotation...The Greater its Angular Momentum becomes ...and the more stable its Gyroscopic Rotational Speed becomes...and last but not least.. but most important.. The Harder it Gets to Slow Down the Spinning Object from its Inertial Rotation!

:blinkhuh:


You stated:

"My Envoy does have heavy 20" wheels, but I can only bring the ABS into action on a wet surface. If the brakes are unable to active the ABS you are not getting the maximum braking that the tire traction can provide. When I had the 17" OEM wheels and stock size Michelins The tires would lock fairly easily if I hit the brakes hard."


So it seems that you were pointing out a traction issue.
My comment merely suggested that EVEN with the larger wheels, you should have still been able to stop. So I don't quite understand your response.

But you didn't answer my question as to how worn your tires are.
So basically........ were just trying to help you......:tiphat:
 

Kurb

Member
May 3, 2014
89
The brakes on my TB have felt good since I switched to OEM pads. When I used aftermarket pads from the local parts stores, they were not that good.

If the pedal is traveling excessively, there is probably air in the system somewhere. It could also be a bad master cylinder, but I have yet to experience that, even on high mileage vehicles.

I have had trouble getting a good bleed. I had an old car that I sold to friend with bad breaks that I had tried to bleed multiple times. After a brake line failed on him, I helped him replaced it. After we bled the brakes, it was the best the brakes had felt.

I remember seeing some posts on here where people said their brakes got much better after taking their TB out on a dirt road and slamming on the brakes to engage the ABS several times.
 

littleblazer

Member
Jul 6, 2014
9,265
I may try an automated bleed with a tech 2 just for fun and see what happens.
 

AWD V8

Member
Jan 12, 2015
463
:blinkhuh:
You stated:

"My Envoy does have heavy 20" wheels, but I can only bring the ABS into action on a wet surface. If the brakes are unable to active the ABS you are not getting the maximum braking that the tire traction can provide. When I had the 17" OEM wheels and stock size Michelins The tires would lock fairly easily if I hit the brakes hard."


So it seems that you were pointing out a traction issue.
My comment merely suggested that EVEN with the larger wheels, you should have still been able to stop. So I don't quite understand your response.

But you didn't answer my question as to how worn your tires are.
So basically........ were just trying to help you......:tiphat:

Your comment to me? or the OP?

I just jumped in with my experience. I understand that a larger diameter tire, that is heavier, will reduce the braking ability, but that I had expected that the factory brakes would still have had sufficient reserve to perform a decent quick stop. In this particular situation I was on a fairly steep downhill grade and it is a heavy truck.

Traction wise, these tires are pretty good. Considering power, I cannot spin these tires on dry pavement, OEM tires, sure, lots of tire spin. Tire traction is only an issue when they are slipping. While trying to stop in this situation, their was no tire slippage. The tires are worn about 50% for the record.
 

AWD V8

Member
Jan 12, 2015
463
My comment was to MRRSM, but my question about the tires was to you, sorry I combined them without clarification.

It's easy to confuse me :blinkhuh:

Tires are pretty good, I've used them on my previous trucks. Tread is about 50%

So traction is not the cause of a long stopping distance.
 

littleblazer

Member
Jul 6, 2014
9,265
It panic stops okay while towing too to be honest. Just like replace the pads after because it conplains... alot. The only thing that seemed to help some was a bleed with new fluid. But it still isn't great. Oh well.
 

Camdo

Member
May 16, 2015
71
The brakes on my 2005 Envoy SLT 4.2L are disappointing to me. The pedal has a soft feel. I cannot lock the brakes or engage the ABS on a hard brake on dry road surface. In a panic hard brake from 60 mph, the pedal will gradually sink to the floor (or almost) as it comes to a stop, at maximum vehicle deceleration ( in other words although the pedal seems to have reached the floor, brake pressure remains at maximum, just at the edge of locking). I have wondered if this is normal performance or if something is wrong. I purchased the vehicle used and the pedal has always felt this way. Three years ago I replaced the pads (AC Delco GM OE) rotors (AC Delco GM OE front, AC Delco Professional rear), and calipers (NAPA re-manufactured Eclipse) and the pedal felt the same way. Last week I fixed failed rear rotors by replacing the rear pads (NAPA Premium) and rear rotors (NAPA Premium uncoated) and left rear caliper (Napa reman Eclipse on warranty which I now think was actually okay), power bleed the system and used Tech 2 ABS bleed. Pedal feels the same, still soft but acceptably usable. The description of OP in post #1 is exactly my same experience. Should I accept this soft pedal or investigate further. That is the question.
 

mrrsm

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Oct 22, 2015
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No. Your "Right Foot Brake Pedal Sensor" inside your Head is THE Most Reliable Tactile Input Signal you have right now... and the concern it creates in your feelings about Safety... are Spot On. If you have not done these additional things... Please consider:

(1) Obtaining a "Pressure Bleed" Apparatus and Follow the Directions documented in this Thread:


(2) Examine your Brake Lines for any Bulging Under Pressure when having a second party depress the Brake Pedal HARD and observe the Lines at EACH Wheel. Replace them if necessary with OEM Quality Brake Lines.

(3) Remove the Master Cylinder to a Bench Vise and perform the task of a "Bench Bleed" as per these Videos:



(4) Replace the Master Cylinder if you determine that it is Failing after performing a proper "Bench Bleed" and you STILL suffer with a Spongy Pedal. Please... Use NAPA and GM OEM New or Re-Manned Master Cylinders as these are a MUST in this situation. Make sure to Re-Visit the Link above for THE Best Method for performing a Power Brake Bleed. After all of this Time, Effort and Expense, the Brake Pedal WILL feel return to feeling Rock Hard on Contact if these procedures are followed to a "T".
 
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Camdo

Member
May 16, 2015
71
My conclusion of the soft pedal problem is that it lies within the ABS module. With a Tech-2, solenoids within the ABS unit can be manually activated and disabled. By a certain combination (which I have forgotten) a hard brake pedal can be obtained. Unfortunately, manual activation will reset automatically so you cannot bypass the ABS action permanently.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
I also tried that on the 02, same soft pedal, done by the dealer and myself. The Tech 2 has a brake bleed operation for the ABS.
 

Camdo

Member
May 16, 2015
71
I did the Tech-2 brake bleed too, but it did not cure the soft pedal. An interesting note is the GM manual states that the Tech-2 operation is only the first step and that the conventional manual bleed (pedal pushing) is the final bleed. I also tried pressure bleeding. I isolated the master cylinder with plugs and got a firm pedal so eliminated that component as a culprit. In total I bleed about 2 gallons of brake fluid thru the system looking for a soft pedal cure. I am quite convinced the problem is in the ABS module given the Tech-2 exercises.
 

Camdo

Member
May 16, 2015
71
The manual states: Pressure bleed first to establish base system, then manual bleed (pedal pump), then do the Tech-2 bleed of ABS, then follow up with another manual bleed. Repeat procedure until desired pedal firmness is obtained.
 

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Camdo

Member
May 16, 2015
71
Here is a schematic of the entire brake hydraulic system including the internals of the ABS module. By exercising certain solenoids (items 11, 12, 16, 17 front brakes, and 6, 8 rear brakes) a firm pedal can be obtained.
 

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