hi all, if this has been covered before I am sorry but I couldn't find anything searching. heres my problem. I changed the brake pads and rotors all around at 160k miles I now have 184k miles. within the last couple months it started to have a slight pull to the left when I would brake. the day before thanksgiving it got really bad and shot me in to the next lane when I was on the freeway. so I changed both front calipers thanksgiving day. I left out of town thanksgiving night for a 1500 mile trip, was loaded down with four guys, coolers, hunting gear and pulling a 16ft boat and never really had to get on the brakes so didn't get to check it. well when I get home and unloaded two days ago I go check it and it still will intermittently pull left when I brake hard. so not having time to mess with it I took it to a shop they suggested replacing the brake hoses going directly to the calipers and they checked all my suspension and front end and found that I had a bad hub and bearing with some slop in it on the drivers side (I was hearing a growling from there last week) and suggested that could be the reason. I had both front hub and bearings replaced and both front brake hoses replaced and it still will have an intermittent pull to the left when I brake hard. any ideas? I was thinking maybe a master cylinder but have been told by a few people and the shop that that wouldn't be it. thanks for the help

 

A master cylinder cannot cause a brake pull.

But stuck rear calipers can, and I didn't see you mention that you replaced them. They are known for binding up the pins in the slides and causing a pull to one side or the other.

 

Yep, rear calipers can cause a hard pull either direction depending on which side the problem is on. Been there, done that.

Sounds like you have taken care of the usual suspects in the front for pulling: calipers and unit bearings. You may try bleeding the system again...really good. I developed a slight pull a few weeks ago. Pulled left when braking. I bled the fronts, and sure enough I got some air bubbles out of the passenger front. Once done, the pull was gone and has stayed gone.

 

Plus one on the bleed, bleed, bleed. March of this year I replaced front calipers with OE from ford, front rotors and pads from Performance Friction Corp, new OE Ford rotors, pads, and E brake shoes on the rear. Did the rear left and right axle steel brake lines from Ford, and replaced the rear axle feed flex line, along with the left and right flex lines to the front wheels on account of the newly fixed lift, which UN-intentionally increased it's height. I had no pull before, and a wavering to strong pull afterward, I ended up bleeding more than 32oz of fluid through the system till everything was good. I made a homemade self bleeder from a large Vlasic pickle jar, drilled 2 holes in the top lid, inserted 2 rubber hoses in each, one longer than the other, positioned the jar higher than the bleeder with the long hose connected to the bleeder screw, and the short hose resting higher up. This allowed me to do a power bleed with the vehicle running and allowing the hydro-boost and master cylinder to push that fluid through. Since the jar was higher than the bleeder, it would allow the hose to keep fluid in it while allowing the air to rise to the top, so when you release your foot on the pedal any potential fluid sucked back in would contain no air. The large jar would give you several pumps before it's full. When all was said and done, no matter how hard I brake it now stops strait.

 

An infrared temp gun is a fantastic tool for diagnosing stuck calipers.

$16 on amazon. No excuse not to have one.

 

Ok I was wondering if the rear calipers would or could make it pull. So to make sure I understand this right the master cylinder only separates front and back and applies pressure evenly to the front and back it doesn't separate it by tire?

 

That's correct.

 

Ok thanks guess I will replace the rear calipers and hoses and hopefully that does the trick.

 

ok so Thursday night i got back from a 3k mile trip to Wisconsin for Christmas and my brakes still would pull to the left. i never replaced the rear calipers or brake lines. i went to the car wash thursday night and used the high pressure hose to wash all the salt off of it and sprayed all underneath really good and i went back Friday since i didn't have anymore cash on me and hit it all again. i hit the brakes, axles, frame and everything i could hit without laying down on the ground. since its lifted 6 inches I'm confident i got it all and ever since then it is back to braking normal and hasn't pulled to either side. what do you guys think it could have been. i puzzled because it pulled to the left, i changed components it still pulled to left and then i wash it with a high pressure hose and it stops. unless there was mud or something messing with a rear caliper that i never changed.

 

Just a matter of time before it starts sticking again. One of my rear calipers is hung up again and I just did brakes on it earlier this year. Sometimes I can feel it "un-stick" and it straightens right out again.

 

I forgot to post the solution, sorry.

After being very frustrated while several places looked at it and came up w/ several ideas, I took it to my local Midas and said "replace the damn master brake cylinder" They took another look and ended up finding a service bulletin. They followed the steps in there and ended up switching the Left and Right front rotors. I don't remember if they also switched the pads, I don't think they did.
Sure enough, that worked. I guess this was such an issue that they came out w/ a service bulletin.

 

That worked?

I suspect that there's an underlying issue and the pull will return, but if the brakes have behaved for the last 2 and a half years, fantastic!

Sure would like to know what the SB had to say regarding the cause.

 

It did work and I'm very happy now. I think I saved the SB (they printed it out for me) and if I can find it, I'll post it.