Hey guys, been having some really weird intermittent braking issues, hoping you could help me out.

Sometimes when i brake, its 100% straight and everything is fine.
Sometimes, if i slightly touch the brake pedal, my steering wheel turns about 1/8 of a turn very quickly (Vehicle stays straight).
And sometimes when i brake my vehicle veers so sharp to the right that i feel like I'm going to crash and i could probably do a sharp U turn if i had enough momentum.

- Both front calipers are brand new
- Rotors/Pads, and the rear drums were new in January

I realized that both calipers were seizing, so i replaced them a couple weeks back. And as a result some of my brake pads are kind of uneven, however not enough to the point to steer me into the ditch.
Shop said there were a couple very small kinks in the Hardlines, but nowhere near enough to cause the issues i was having.
Rear diff was leaking gear oil through both rear drums about 3 months back, however it was all cleaned up so i don't think that's it.

Buddy mentioned that he thinks it could be the soft lines rotting out any causing a 1way check valve, just an idea.


Kind of on a budget right now, so i can't really afford just to replace everything. I'm hoping that someone has had a similar problem and could point me in the right direction.

You take $100 and give it to someone with the skills and tools to properly diagnose you brake system.

A few things off the top of my head they are going to check is run-out on the disc, line pressure and volume displaced at the cylinders.

Then you go toss a finger to the guy that told you a slightly crushed hard-line wasn't a significant issue.

Hydraulics really isn't a place for "oh it looks fine". This sort of reaction of the steering is wholely down to an imbalance in one of two places the hydraulic system or the road traction and its a safe bet your not hitting ice on your left wheel consistently.


There is a sort of redneck test you can try, pump up your brake pressure now crack the bleeder valve and measure the volume released over time, now do the same thing on the other side. Odds are you'll find its different.

You are leaving out some important information, when you replaced your calipers did you replace the brake pads? Did you replace or resurface the rotors?
When you "cleaned up" the rear brakes after the gear oil leak did you replace the shoes? Resurface or replace the drums? Properly adjust the rear shoe to drum clearance?

If you didn't do any of the above your problems could be:
The front pads aren't worn into the old grooves (even if not visible to the eye) on the rotors
The rear shoes soaked up gear lube and even after cleaning when they are heated more will leach out and coat the drums
As stated, the brake hoses and hard lines can be your culprit, though the hard lines being crimped would likely be causing issues all the time.

It sounds to me like there is one other variable that could be causing the intermittent and changing issues, heat. Once the brakes get hot does it pull the same every time you hit the brakes?
You could also try applying the parking brake (carefully!) without allowing it to lock as you are moving and see if you experience the pull. This will tell you that there is definitely an issue with the rear brakes but does not rule out that there may also be an issue with the front.
Also, loose front end parts could allow the steering/suspension to shift under braking which could cause a pull.
I hope this helps, get back to us with more info.

Thanks both of you for the help.

Co_94_PU
So if im leaning towards the right, its my left side not working correctly?
And ill try that redneck test out later today


akwheeler

When i replaced the from calipers i did not replace the pads or rotors. And i didn't replace the rear brake shoes as the shop said i would burn off any gear oil residue. Front brake pads are next on my list.

And as for the idea of heat causing this, sometimes when i pull out of my driveway in the morning i loose braking in one side immediately, so i don't think its heat.

I'm just confused for how intermittent it is. The only hard lines that get moved around consistently are the ones attached to the calipers, so i was planning to pickup a used set of those and toss em in to see if it changes anything, along with the soft lines.



I know in reality i should get a professional to come out and help. however like i said i am on a bit of a budget, so I'm hoping to narrow it down before hand, spend 20 bucks on a couple used parts off of a parts rig and see if it helps.

No not exactly. If the right side has more pressure on the brake face than the left, you'll get a pull to the right. This could be the left side slipping due to low pressure or oil, or the right side having higher pressure. So all you really know is the right side has more friction than the left which could be pressure, volume, warped rotors, or dirty pads or rotors.

Whoa that's a big flag there. Please elaborate!

Hard lines don't move, that's kind of what makes them headlines, they are steel tubes and aren't moving except a slight bit on the outside of the clamps that attach them to the frame.

I'm going to assume you misspoke here and you mean the soft lines between the caliper and frame braces headlines. You're going to spend $10 on a used part at upullandpay where you can get new hydraulic hoses from Rock auto for $9?! Why..

Trying to save money on important safety equipment isn't a good idea, and in this particular case you'll actually spend more at the pull your own parts junk yard than you would for brand new parts. Granted these aren't new OEM parts.

My time is worth more than a diagnostics fee at this point. Were talking drive to the salvage yard, find a donor, pull your part, drive home, oh need lunch cause that took three hours, get home, swap the hose, oh it's dark now I'll have to test it tomorrow, crap I've got a leak because I was rushed trying to beat sun down, now I can't drive to work without risking a fire, soo I'm out a day and half and a days pay..

I'll spent a day pulling out my seats and carpet to scrub the carpet and vacuum under it because well that's $400 ($100/hr) for the mobile detailer. Bit when I need a $200 tool for 30 minutes and can pay someone $100 and never need this tested again, I'm going to go to a professional. It's like doing an alignment at home, yes I can rig something up for $20-50 and spend several hours, OR I can slap down $80 and go get an ice cream cone and come back in an hour.

When i mentioned that my hardlines move around more, i was meaning that when work has been done on the front end, which quite a lot has been done, those hard lines get taken off and put back on frequently so i would think there is a higher chance for them to accidentally bend. And as for the cost of them, I was on a parts site that wasn't rock auto and they were charging 40 per line, i typically use rock auto for everything but i was under the assumption that they were just expensive everywhere, so ill order new ones ASAP. I also have pads on the way.

And what i meant for when my brakes fail immediately, i mean that the 3 symptoms i get (Either they work as intended, my steering wheel moves as if there is play but i it brakes straight, or i veer to the right), isn't dependent on whether or not they are warm or not. I've paid attention to the set and setting on when everything is happening and as far as i am concerned it sometimes happens when i pull out of the driveway in the morning, and it sometimes not.

I daily drive the hilux but i also have a little toyota matrix on the side for when inevitably things fail on my toyota, (Just swapped insurance over the other day actually), so I'm not too concerned. Wheeling/Camping/Roadtrips and other related things are my primary hobby, and while Im willing to pay to get it fixed asap, i like checking if its just a simple fix first before i drop a few hundred on getting a shop to do it, which is the reason why i posted here. If i replace the pads/lines and it isn't fixed, ill bring it to a shop.

Given that feedback I recommend just flushing the brake fluid and reevaluate after.

So a flush basiclly entails filling your brake fluid resivior to the top, attach hoses to the bleed valve, plumbing the hose into a container (clean dry old water bottle with an inch of new fluid in it), and opening the bleed valves. You need to keep the resi full, and can close the bleed valves when you get nice clean/clear fluid in the hose. You can do this one at a time, side at a time.
This is going to get rid of burnt, contaminated, and dirty fluids. These can effect your brake pressure, clog lines, and destroy seals. You're looking at maybe $5 for hoses, and $10 for a big bottle of fluid. You might still wind up replacing some hoses, fabbing hardlines, or spending $100 on diagnostics, buy you can you'll know you have clean fluid (sans water, rust particles, and not degraded from heat), this will make your diagnostics guys job easier (he's not going to cut you a break on that one hour minimum, but it makes it way less likely he will need to charge you additional hour for flushing the system).

The big variable here is how well the brake system was maintained ("regular " flushes, not abused).

Disconnecting the flare fittings isn't an issue, dropping the caliper such that the hose jerked and hard-line might of bend which can lead to that kinked line you/your-mechanic mentioned is an issue. These kind of fittings aren't like your household water line compression fittings where your olive and nut aren't reusable a JIT flare fittings is reusable unless you do something like cross thread it which means you have to redo the flare because you had to cut it off to change the threaded nut.

Thanks for the info thus far. Really appreciate it buddy. I think i have a good game plan going forward and when i figure out the problem i will post it here for future people.

Have you tried applying the parking (emergency) brake while driving like I suggested?
Since it applies ONLY the rear brakes it will tell you if you have a pull or pulsation in the rear.

Vehicle is uninsured and off the road for a bit due to unrelated engine issues im dealing with. Ill check that out for sure though next time i go out for a rip.

Did some work on the issue. New calipers, pads, and soft hoses, Still having some slight issues.

1/3 of the time when i brake, my steering wheel slightly jerks to the right, but keep going straight
1/3, i veer to the right
1/3, acts as intended and brakes normally.

Seems to act up more when im braking down hill.

When i replaced my pads, it seemed like the right hand side pistons were more stiff than the left. It required significantly more force to depress the pistons in the calipers. And also, the right hand side rotor looked like it was covered in a bit of rust compared to the other side. I sprayed some brake clean on it and went on my way, looks normal now.

My next step is replacing the hard lines between the soft hose and the calipers, hopefully that does something.

Felt good to hear this until I read "hard-line between hose and calipers" had a good laugh regardless.

Anyways what your maybe dealing with is clogged, rusted hardline. Which is what I suspected at the start. You also mentioned a crushed hard-line. Both rusted internally and crushed lines are going to restrict flow and cause imbalance.

Only reason i haven't replaced them yet is because i couldn't find the parts locally. Im gonna order them on my next parts order and cross my fingers it fixes it.