04 trailblazer, brakes dragging after new pads, calipers, master cylinder

Rhizzlebop

Registered Member
Original poster
May 3, 2019
22
South Carolina
So, I took my TB to a guy who does my auto work to get the brakes improved. I had like they were a little weak and I tow my camper with it, so wanted it right for spring.

he pulled all pads off, and odd thing, he told me both front calipers froze and even with clamps he couldn’t push them out. (Made no sense to me cause he said they were not froze when he test drove)
So he did 4 sets of new pads, 2 front rotors, and a master cylinder. Not sure if it was new or rebuilt but I think it was aro7 d $160 for the MC
He also told me he had a hard time bleeding them, and he replaced all the fluid. But he finally got it bled

well, I get it back and the front brakes are dragging. Feels like I’m towing 1000 lb extra weight. The pedal is harder and quick to clamp down. If I let off gas it feeels like it’s slowing down quicker

I drove 20 miles figuring out what was going on, stopped for gas and when I left it was good. Not dragging but the brakes feel not so strong like before I took it to him

today I drove again. Good at first, but 10 miles out it starts dragging again. I get there and wheels are super hot and smells like I came down a mountain.

I turn th3 motor off on off on. P7 p brakes hard with it running and off. Finally it releases and drives home normal but a bit soft the whole 20 miles.

I’m reading maybe a bad master cylinder, possible air he didn’t bleed or maybe the booster?
It all seems related to the fact he couldn’t push the original calipers out and said they froze. I think something was holding them. I’m planning to take it back to him to fix but I’d like input on what you guys think it could be. He’s an hour away so I’d rather get it right this time.
 
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Mooseman

Master Blaster
Moderator
Dec 4, 2011
22,559
Ottawa, ON
What do you mean that you got the brakes "improved"?

Do you mean that he couldn't push the the calipers pistons in? What about after opening the bleeders? Could the pistons be pushed in then with the fluid coming out? If not, I'd be suspecting stuck calipers. I've had one caliper seize and then the other the next year but it's very unusual for both to go at the same time the same way. Could be the fluid was way overdue with moisture in the system destroying the calipers.
 

budwich

Guru
Jun 16, 2013
1,739
kanata
You should check and / or replace the flex hose running from the solid line to the caliper. On other vehicles, I have seen issue with something causing the flex line to be "less than transmissive" resulting in new caliper "binding" and even not being able to compress when connected back to the line. Not sure if it was foreign material stuck in the line or deterioration of the rubber itself. Since you seem to have bleed problems, that also points to some form of issue with the flow domain.
 

Rhizzlebop

Registered Member
Original poster
May 3, 2019
22
South Carolina
I don't know specifically what he opened when he did it. I wasnt there. He does car repair every day, has a 2 bay garag with lifts on his property, and does tons of auto work, day in day out.
I just found it odd for both to sieze at the same time. Nonetheless, He DID replace both calipers, turned all 4 rotors, all new pads, and replaced MC, and now its doing this weirdness where I drive once and the front calipers are dragging, and then again they aren't, and once half way of the drive it was good, and after using the brakes a couple times to stop, they did it again.

Trying to get a target on what might need replaced now, or if the MC he put on is just not working right. Or possibly the booster?
 

gmcman

Guru
Dec 12, 2011
4,545
Did he maybe pinch off the brake lines when he did the master cylinder? That can cause dragging.
May still have some marks on the rubber hose from the locking pliers.

Could have been old hoses and the tight clamping may have broken something loose inside
 
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Mooseman

Master Blaster
Moderator
Dec 4, 2011
22,559
Ottawa, ON
Have also seen the rubber lines just swell shut inside but you say the brakes worked fine before the work?

What about the ABS valve? Maybe it's gummed up or stuck. If he has a capable scanner, try cycling the ABS for bleeding.
 

Mektek

Hobbyist
May 2, 2017
613
FL
Were the calipers new or newly rebuilt?
If they cut corners on the rebuild and reused the original pistons - that could be the source of the problem. The phenolic resin pistons can swell with age at the outer end. When the pistons are pushed back in for new pads they can stick. My cheap brake job turned into much more $$$ when I found I needed new pistons. I speculate that the metal pistons from the rear calipers can be used in the front and then they will last forever.......
 

Hawaiianbasshead

Registered Member
May 2, 2021
46
Kailua Kona HI
Did my front calipers, soft lines and brake booster because mine was sticking. Took it driving today and sure enough, still sticking fmln🤦‍♂️ I suppose I'll throw an abs valve at it next... only fronts were hot
 

Mooseman

Master Blaster
Moderator
Dec 4, 2011
22,559
Ottawa, ON
Did my front calipers, soft lines and brake booster because mine was sticking. Took it driving today and sure enough, still sticking fmln🤦‍♂️ I suppose I'll throw an abs valve at it next... only fronts were hot

What about the master cylinder?
 
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Hawaiianbasshead

Registered Member
May 2, 2021
46
Kailua Kona HI
Yeah, asked my landlord for help when I got home. He cracked hard lines at master and had me press the brakes. He said it's dual stage and was sticking on the front side and pressure released when he cracked that line. Worst part is it looked like a new master... clean fluid and reservoir when I got it even. It loosens up when it sits than soon as I drove it a bit, every time lockage and stiff pedal, just didn't drive it enough recently to get there. He said the pedal is from that pressure in the master that he bled off. Rear brakes are cold because the fronts are the ones locking and the rears don't have to do anything. Might have the water pump and thermostat since it got to boiling again, so it wasn't just the fan clutch... 🤦‍♂️ front brakes were smoking from my 10 minute drive home. 😶 was late to drop swb for motor also so left it down in front of his shop and stuck the key under the door. Thanks for the help we were out messing with it before I saw ur reply when I got home
 

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mrrsm

Lifetime VIP Donor
Oct 22, 2015
5,988
Tampa Bay Area
You'd be surprised at the number of Auto Parts Stores that have Boxes on their Shelves with "Return To Stock" items received back from customers who could not get the Damned Things properly installed and/or damaged them to boot and returned some of the Old Parts mixed in with 'The New'.

The next unsuspecting customer standing at the Counter might be buying someone else's Headache as a result of an In-Store Re-Stock of Damaged Goods. @Hawaiianbasshead ...Your Landlord is a Very Clever Dude and he did you a very good turn.

This Video describes ANOTHER Problem that even with the R&R of and Brand New Master Cylinder, if the Front Brakes Lock Up right after full re-assembly... If the Master Cylinder-to-Brake Booster Push Rod is TOO LONG ...this problem can occur. But, the Diagnosis is Simple and Sweet to investigate the matter (whether MOPAR or GM):

 
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Rhizzlebop

Registered Member
Original poster
May 3, 2019
22
South Carolina
Just to follow up on this. After I took it back to him, he changed the brake booster and that fixed the issue. No problems since. Just so I know, are you guys saying the 04 trailblazer has a separate abs valve module? For some reason I thought that was built into the booster but I don’t know. Anyhow he did the booster snd that fixed it. Thanks. Again everyone.
 

mrrsm

Lifetime VIP Donor
Oct 22, 2015
5,988
Tampa Bay Area
Great News... and Yes... this image shows where GM hid this Damned, Complicated Thing:
 

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Mooseman

Master Blaster
Moderator
Dec 4, 2011
22,559
Ottawa, ON
If the Master Cylinder-to-Brake Booster Push Rod is TOO LONG ...this problem can occur.
I remember one guy who came here who had that issue with that push rod in the booster to the MC or the rod from the pedal to the booster that would ever so slightly push on the MC when installed. I can't remember what the fix was and can't find that thread.

Take the MC mounting bolts off and see if the rod is pushing on the MC's piston.
 

mrrsm

Lifetime VIP Donor
Oct 22, 2015
5,988
Tampa Bay Area
As long as all of the surface areas of the inner Master Cylinder Four Bolt Flange are in contact offering full support... it would be possible to make an "MLS" - like set of Thin Metal Gaskets out of Aluminum or Thin Brass Sheets and extend the space in between the MC Inner Plunger cavity and the tip of the Push Rod ...just enough to allow the Hydraulic Pressure to bleed off.
 

Hawaiianbasshead

Registered Member
May 2, 2021
46
Kailua Kona HI
Funny, I just read a review on amazon while looking at master cylinders about a rod being too long and using washers 🤦‍♂️ glad I'm reading this now too. Knew something was off when it was both front calipers initially, than again after calipers but booster was letting air out on pedal release making like a whooshing noise or such... I forget. Hopefully it's stopping good soon. Thanks for all the support guys 🍻
 
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Hawaiianbasshead

Registered Member
May 2, 2021
46
Kailua Kona HI
In reality it could still be my pushrod length.. Mine didn't look adjustable besides adding washers but I suppose I should test it and see.. maybe it's long enough to not release front side fully and the master cylinder is still good 🤷‍♂️ did say in his video mopar and gm were the same.guess meaning orientation as I think it was the firewall side he cracked that let off the fronts. I'll make sometime to check before ordering a master cyl. There was a washer falling into original booster when I pulled master originally. Stuff just fell apart when I 1st pulled master
 

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mrrsm

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Oct 22, 2015
5,988
Tampa Bay Area
The thing to look out for is not allowing any Gap to emerge around the Perimeter of the Master Cylinder Flange that can allow for Water-Weather-Insect intrusions since having single round washers might invite such problems... versus having a complete, symmetrical Metal Gasket in between.

Bear in mind that there are an enormous number of times that the MC is subjected to Vacuum Assisted Pressure that you will not necessarily feel when you step on the brakes... but which might not be very good for an ill-seated and ill-supported MC Flange. Read Post #14 too... The OP discovered that the problem was with the Brake Vacuum Booster Unit ...NOT the Master Cylinder.
 
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BradyinKy

Registered Member
Nov 29, 2021
10
40390
I ended up here after a search based on the exact same symptoms.
I can cold start it and everything is fine. After 5-10 miles, the system feels "pumped up". My pedal is grabbing at the very top and my brakes are dragging. I know it's only my front brakes because I can put it on the lift when it's symptomatic and the rear wheels spin fine while the front are very difficult to turn.
So far, I've changed both front calipers, the power booster, performed a complete flush of the lines, re-bench bled the master cylinder, yet the symptoms persist. The pedal DID get overall better after replacing the power booster, but I'm still getting intermittent dragging brakes after getting things warmed up.
I was searching for info about adjusting the brake pedal rod, but I'm unable to find confirmation thar the tbs have that capability. The only thing that could be causing mine to "appear" shorter is that the firewall to booster gasket is shot, but that could hardly be considered a spacer, as it's a a very thin rubber gasket.
I'd love to see a more definite answer of what might be going on... Is it really possible I got another bad booster out of the box?
 

Rhizzlebop

Registered Member
Original poster
May 3, 2019
22
South Carolina
I ended up here after a search based on the exact same symptoms.
I can cold start it and everything is fine. After 5-10 miles, the system feels "pumped up". My pedal is grabbing at the very top and my brakes are dragging. I know it's only my front brakes because I can put it on the lift when it's symptomatic and the rear wheels spin fine while the front are very difficult to turn.
So far, I've changed both front calipers, the power booster, performed a complete flush of the lines, re-bench bled the master cylinder, yet the symptoms persist. The pedal DID get overall better after replacing the power booster, but I'm still getting intermittent dragging brakes after getting things warmed up.
I was searching for info about adjusting the brake pedal rod, but I'm unable to find confirmation thar the tbs have that capability. The only thing that could be causing mine to "appear" shorter is that the firewall to booster gasket is shot, but that could hardly be considered a spacer, as it's a a very thin rubber gasket.
I'd love to see a more definite answer of what might be going on... Is it really possible I got another bad booster out of the box?
I wish I could help. A new brake booster fixed mine. He had replaced the master cylinder initially and that didn’t help. The booster solved and had no issues since. I’ve since sold the car to a family
Member and still no issues with the brakes.

My understanding is the electronic valves that operate the brakes are part of the booster which I think was key to the repair. That could be entirely incorrect.
 

BradyinKy

Registered Member
Nov 29, 2021
10
40390
I wish I could help. A new brake booster fixed mine. He had replaced the master cylinder initially and that didn’t help. The booster solved and had no issues since. I’ve since sold the car to a family
Member and still no issues with the brakes.

My understanding is the electronic valves that operate the brakes are part of the booster which I think was key to the repair. That could be entirely incorrect.
Interesting, and thanks for the confirmation!
I do have a replacement MC on its way and I'll go ahead and swap it since I've got it, but if that doesn't work, then I'll warranty the new booster and give that one more try.
Again, thanks for the follow up!! It's bizarre how our symptoms are exactly the same for such a random issue.
 

Mooseman

Master Blaster
Moderator
Dec 4, 2011
22,559
Ottawa, ON
Check my post #16 above and check that push rod is not pushing against the MC piston.
 
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Mektek

Hobbyist
May 2, 2017
613
FL
When you say that only the front brakes stick, that is suspicious. I had a problem with the front calipers sticking after installing new pads. The plastic pistons were defective - I replaced all 4 and the problem was fixed. The rear aluminum pistons do not have this problem.
Did you have new or rebuilt calipers? If they were rebuilt they may have kept the old pistons that looked just fine - but weren't.
 
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BradyinKy

Registered Member
Nov 29, 2021
10
40390
Check my post #16 above and check that push rod is not pushing against the MC piston.
I'll definitely be checking the when I replace the MC tomorrow. Does that confirm that the pushrod or pedal linkage is adjustable or would it mean I have a 'wrong part' in place?

When you say that only the front brakes stick, that is suspicious. I had a problem with the front calipers sticking after installing new pads. The plastic pistons were defective - I replaced all 4 and the problem was fixed. The rear aluminum pistons do not have this problem.
Did you have new or rebuilt calipers? If they were rebuilt they may have kept the old pistons that looked just fine - but weren't.
They were rebuilt calipers from the local autozone. It would be a hell of a coincidence for both fronts to be wonky out of the box though, no? Occam's razor suggests to check something that would be affecting them both first (IMHO)

Again, thank you all for the advice and suggestions. Even if I'm not trying any of them first doesn't mean I'm ruling them out.
 

Mooseman

Master Blaster
Moderator
Dec 4, 2011
22,559
Ottawa, ON
Does that confirm that the pushrod or pedal linkage is adjustable or would it mean I have a 'wrong part' in place?
I remember another similar thread where it was the pushrod in the booster that was too long. Pedal linkage is not adjustable. You could verify it against the old one. If it sticks out too much because of the pedal linkage, some have resorted to putting washers or shims on the MC mounting studs.
 

BradyinKy

Registered Member
Nov 29, 2021
10
40390
I remember another similar thread where it was the pushrod in the booster that was too long. Pedal linkage is not adjustable. You could verify it against the old one. If it sticks out too much because of the pedal linkage, some have resorted to putting washers or shims on the MC mounting studs.
I can do that, but I hate rigging something like that. It should work at factory spec. If something's gone out of spec and causing the pushrod to be 'too far into the MC', then I'm compelled to find out why. Whether it be that someone before me has put a wrong part on or that there's grit inside the MC cup causing it to ride high on the push rod.. just gotta figure out what's going on.
 

BradyinKy

Registered Member
Nov 29, 2021
10
40390
An update.
I'm still fighting this issue.
To date, I've replaced the master cylinder, power booster, both front calipers and pads, and front brake hoses. I still get a pumped up pedal and brake drag after about 10 miles. Something's acting like a check valve in the system after things warm up.
I've flushed the fluid a couple times, but I've NOT tried chattering the ABS. Am I leaving something on the table by not doing that?
 

mrrsm

Lifetime VIP Donor
Oct 22, 2015
5,988
Tampa Bay Area
If this action has not been undertaken yet... It might be time to Raise The Vehicle on 4 Tall (Non-HF) Pin-Locked Jack Stands, then use a Bright Flashlight and crawl all around the vehicle's underbelly AND on top of Engine Area from ALL of the Brake Line Feeds on down ...looking for any kind of Crushed Fittings, Kinked or Twisted Brake Lines or any Lines along the Frame that may have been acci-DENT-ally... Dented Nearly Flat.
 

BradyinKy

Registered Member
Nov 29, 2021
10
40390
it appears it's a clearance issue somewhere. I did the "washer trick" and spaced the master cylinder out by one washer and it hasn't pressurized since then... so it was just dragging the tiniest bit, boiling the fluid (or swelling the pads) and pressurizing the system. Now, what has changed from the factory specs to cause the decrease in clearance??
 
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TequilaWarrior

Active Member
Dec 5, 2011
458
Central Pennsylvania
it appears it's a clearance issue somewhere. I did the "washer trick" and spaced the master cylinder out by one washer and it hasn't pressurized since then... so it was just dragging the tiniest bit, boiling the fluid (or swelling the pads) and pressurizing the system. Now, what has changed from the factory specs to cause the decrease in clearance??
Did you remove your dust shields?
 

TequilaWarrior

Active Member
Dec 5, 2011
458
Central Pennsylvania
damn good question. Personally, I didn't, but now I can't remember if there's any on there or not.. I don't think there are.

Could that seriously be it??

My apologies.... I just reread your post.... you said "master cylinder"... my mind read "caliper" somehow... dust shields should not make a difference, period.... especially if spacing the MC improved your issue.
 

BradyinKy

Registered Member
Nov 29, 2021
10
40390
My apologies.... I just reread your post.... you said "master cylinder"... my mind read "caliper" somehow... dust shields should not make a difference, period.... especially if spacing the MC improved your issue.
MC was replaced and it improved pedal feel but it didn't improve the issue with the pedal pumping up to the point that the pads dragged. How do the dust shields come into play with the described symptoms? If mine are missing, that would certainly be something I'd look at.
 

TequilaWarrior

Active Member
Dec 5, 2011
458
Central Pennsylvania
MC was replaced and it improved pedal feel but it didn't improve the issue with the pedal pumping up to the point that the pads dragged. How do the dust shields come into play with the described symptoms? If mine are missing, that would certainly be something I'd look at.
My incorrect reading of your statement might have had merit if it was the calipers you replaced and the dragging continued. Removal of the dust shields moves the rotor inwards by the thickness of the dust shields (not much, thousandths of an inch). If the inboard pad is dragging it could be that the clearance negated by removing the dust shields could be enough to alleviate the dragging in the first place. It's a moot point if nothing has changed at the wheel. It sounds like there was an issue at the MC and shimming it cleared that up. My dragging issues required me replacing all 4 calipers. I was turning rotors blue and boiling my brake fluid. I did a full fluid change/flush and it reduced the boiling some, but rotors were still blueing. After caliper replacement, no more blueing and a very tiny bump in mileage.
 

Mooseman

Master Blaster
Moderator
Dec 4, 2011
22,559
Ottawa, ON
It's possible that aftermarket parts might not have the exact same specs or measurements to work properly. Maybe the depth of the piston in the MC is not quite the same as the original or the pedal shaft is not quite the same on the booster or the piston pusher "pill" is just a little longer. Check and compare with the old parts. I would have no problem running it with the spacers like that.
 
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mrrsm

Lifetime VIP Donor
Oct 22, 2015
5,988
Tampa Bay Area
...and with "Technical Specs" in mind...this On Topic Tech Article on "How to Diagnose and Fix Brake Drag" is very insightful:

 

BradyinKy

Registered Member
Nov 29, 2021
10
40390
My incorrect reading of your statement might have had merit if it was the calipers you replaced and the dragging continued. Removal of the dust shields moves the rotor inwards by the thickness of the dust shields (not much, thousandths of an inch). If the inboard pad is dragging it could be that the clearance negated by removing the dust shields could be enough to alleviate the dragging in the first place. It's a moot point if nothing has changed at the wheel. It sounds like there was an issue at the MC and shimming it cleared that up. My dragging issues required me replacing all 4 calipers. I was turning rotors blue and boiling my brake fluid. I did a full fluid change/flush and it reduced the boiling some, but rotors were still blueing. After caliper replacement, no more blueing and a very tiny bump in mileage.
I also replaced the calipers and the condition persisted. (to date, I've replaced the booster, master cylinder, brake hoses, calipers, and pads). It's possible a previous owner removed the dust shields and that's when the issue began and I inherited it and replaced a bunch of parts trying to resolve it.


It's possible that aftermarket parts might not have the exact same specs or measurements to work properly. Maybe the depth of the piston in the MC is not quite the same as the original or the pedal shaft is not quite the same on the booster or the piston pusher "pill" is just a little longer. Check and compare with the old parts. I would have no problem running it with the spacers like that.

Oh, but if I had the old parts... :sadcry:

So far, the spacers seem to have done the trick. That said, I'm going to take a look to confirm whether the dust shields are there or not (and I really don't remember seeing them when I was working on the front brakes).
 

NJTB

Platinum Donor
Aug 27, 2012
579
Flemington, NJ
Google adjustable brake booster rod, they may still be available.
It's a brake booster rod with a screw and nut, and can be adjusted longer or shorter.
 
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