Brakes Pulling Left

Indycars

Indycars

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The brakes on my 93 GMC Suburban are pulling left upon initial application, then it brakes straight. It is heat
related, in the morning you can NOT feel it, but about 1/2 way home after work and it's bad again.

I have bleed all four wheels, but this had no effect. My thoughts were the front calipers, but the parts guy suggested the
flexible front brake lines. I never thought of this, but with the age of the vehicle they should be replaced anyway. So I bought
two caliper and two brake hoses.

Any other possibilities ??? My daughter is taking the vehicle to move some items to anther state and is picking the
vehicle up this Thursday or Friday. Needless to say I would like to have it braking straight !!!
 
Thanks for the helpful comments ! In my mind I should concentrate on the front, the rear would have less
of an effect on the pulling left problem.
 
I had a similar issue. Car was pulling right - I checked rotors and pads I even pulled apart and carefully cleaned the calipers making sure the piston was not sticking. I was baffled when the problem (getting worse) did not go away.

Turns out it was indeed the brake hose.

As you released the brake pedal the master cylinder would suck brake fluid away from the caliper releasing the pads. My problem was that, on one side, the hose collapsed under the vacuum causing the pads to continue gripping while the other released. This led to the car pulling right.
 
Brake hose is the first thing I look for as well, had it happen several times especially on older cars, which is mostly what I drive. ;)
 
DorianL said:
I had a similar issue. Car was pulling right - I checked rotors and pads I even pulled apart and carefully cleaned the calipers making sure the piston was not sticking. I was baffled when the problem (getting worse) did not go away.

Turns out it was indeed the brake hose.

As you released the brake pedal the master cylinder would suck brake fluid away from the caliper releasing the pads. My problem was that, on one side, the hose collapsed under the vacuum causing the pads to continue gripping while the other released. This led to the car pulling right.
Click to expand...

I'm not sure we have exactly the same problem? Did yours.....
- Drives Straight (No Brakes Applied)
- Upon initial application of brakes it pulls to one side
- After both pads made contact, braking was straight again.

Does this sound like the problem you had or did your vehicle pull to one side all the time ???
 
Randy_W said:
Brake hose is the first thing I look for as well, had it happen several times especially on older cars, which is mostly what I drive. ;)
Click to expand...
Brakes hoses are more of a problem than I thought, thanks for the comments Randy !
 
You describe it perfectly, as soon as some flow gets to the brake on the other side it straightens up. The side it pulls to would be the good hose in this scenario and the other would be clogged, collapsed, etc... Sometimes it's so bad that it doesn't get any fluid pressure on the bad side and you can end up i9n the ditch, or worse. No guarantee this is your problem but I'd look there as well.
 
Randy_W said:
You describe it perfectly, as soon as some flow gets to the brake on the other side it straightens up. The side it pulls to would be the good hose in this scenario and the other would be clogged, collapsed, etc... Sometimes it's so bad that it doesn't get any fluid pressure on the bad side and you can end up i9n the ditch, or worse. No guarantee this is your problem but I'd look there as well.
Click to expand...
Last night I replaced both caliper and the left front brake hose. The right hose would NOT come loose
at the steel line. I didn't want to force the issue and damage the steel line.

But wouldn't you know it, the truck pulls left, therefore I need to replace the side that won't come loose.
 
try heating the fitting with a propane torch just a bit and spray it cool with a good penetrating oil several times, that usually results in the fitting freeing up, that 50%/50% mix of marvel mystery oil and acetone works as does the new loctite freeze release

use the correct tube fitting wrench
flarenut.jpg

freeze.jpg

LoctiteFreeze&Release.JPG

READ THIS

viewtopic.php?f=59&t=807&p=8498&hilit=rusted+spray#p8498
 

I did try several cycles of heating with a propane torch and then applying PB Blaster and attempting to loosen with
line wrenches. I wasn't aware of the Loctite Freeze & Release, sounds like it's worth a try if I can find it locally.
 

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Thanks Grump, I never knew about the MMO and acetone mix, I keep the Marvel on the shelf all the time. :cool:
 
Turns out it was the RIGHT front brake hose. Of course it was the one that was a pain to get off, but waiting another
day helped. Even after getting the threaded connection broke loose, the steel line was still stuck inside the nut. I could
only turn the nut about 1/8 turn before the line would bend/kink.
But with some patience and CRC Freeze Off (couldn't find Loctite Freese & Release locally) it also yielded to my will. http://www.crcindustries.com/files/Free ... 0Sheet.pdf
http://www.youtube.com/watch?v=b0BaowQvL6c
 

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those freeze sprays seem to work best when you previously cycle or rapidly repeat an expansion contraction cycle several times, pre-heat the problem threads several times with a propane torch to about 250 degrees F and cool them off with a 50%/50% mix of marvel mystery oil and acetone then let the freeze spray free it up on about the third or forth heat-lube-cool freeze in rapid succession, that maximizes the expansion & contraction and tends to allow the penetrating lube to suck into the threads
one more place a IR temp gun comes in handy
viewtopic.php?f=59&t=807&p=1177#p1177
http://www.professionalequipment.com/xq/ASP/ProductID.3461/id.22/subID.177/qx/default.htm
T504-4254_product.jpg

when selecting an IR gun for automotive use, you really want to be able to read from 0 F deg-about 1400F deg. to cover most conditions you'll test for
AA300torch.jpg


keep some penertating oil/acetone, mix a torch, and freeze spray plus the IR temp gun, in the shop
7349.jpg
 
grumpyvette said:
those freeze sprays seem to work best when you previously cycle or rapidly repeat an expansion contraction cycle several times, pre-heat the problem threads several times with a propane torch to about 250 degrees F and cool them off with a 50%/50% mix of marvel mystery oil and acetone then let the freeze spray free it up on about the third or forth heat-lube-cool freeze in rapid succession, that maximizes the expansion & contraction and tends to allow the penetrating lube to suck into the threads
Click to expand...
If you are replacing the rubber brake hose, do you need to limit temperature to 250 F ???
 
Indycars said:
grumpyvette said:
those freeze sprays seem to work best when you previously cycle or rapidly repeat an expansion contraction cycle several times, pre-heat the problem threads several times with a propane torch to about 250 degrees F and cool them off with a 50%/50% mix of marvel mystery oil and acetone then let the freeze spray free it up on about the third or forth heat-lube-cool freeze in rapid succession, that maximizes the expansion & contraction and tends to allow the penetrating lube to suck into the threads
Click to expand...
If you are replacing the rubber brake hose, do you need to limit temperature to 250 F ???
Click to expand...

I doubt its critical as the brake calipers get a lot hotter than that 250F on a hard stop from high speed , but Ive always been a bit concerned with damaging parts and a rapid and repeated 300 temp change cycling, ( 250F plus up and -40F down) in temps and oil soak with penetrating oil should be sufficient to allow the parts to loosen up...at least its usually worked for me!
 
I took the brake lines and cut them up as you can see below, but I couldn't see anything that pointed to
my problem. At every cut I saw the same thing, just like the pic of the single piece of brake line. Oh
well, I don't have the same research budget as a major corporation.
 

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you can usually see , problems with a visual inspection of those lines when you get a buddy to stand on the brake pedal while the cars got the tires off and the calipers can be inspected while the cars up on jack stands, when the lines are defective, as they tend to bulge, leak or the calipers don,t cycle in and out easily.
Id suspect you had or have the same issue I had, a sticking PISTON in the caliper
 
The only component I changed during the last effort was the Right Brake Hose, thats when the pulling
went away. I did bleed both front brake lines again of course.

I did have new front pads, but decided not to change them so I could tell if the hose was the problem.
 
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