RTH Help me diagnose by bad brakes

Joined
Dec 17, 2006
Messages
888
Location
Central Coast, CA
Website
www.coastal-aquariums.com
going to drop all of the details here, so apologize in advance if it's long winded, but easier to lay it all out in advance then to answer a bunch of questions.

I replaced by front pads last week, after putting everyting back together and setting in the pads, my brakes SUCK. They weren't awesome before the new pads, but they are really bad now.

As I was doing the brakes, I noticed the lines closest to the calipers were pretty cracked, so I ordered all new stainless lines from Slee, including some extended lines while I was at it since I never changed them after I lifted the rig. I installed those and bled everything very well. Order of bleed: LSPV, RR, LR, LSPV, RF, LF. I also went and activated the ABS a few times driving in some dirt.

Brakes still suck

Bled again today and brakes still suck. The pedal doesn't go all the way down, it gets firm like it should, but after braking a couple of times, you have to push really hard to stop, definitely not safe to drive, emergency stops are non-existant.

before bleeding, I changed out the rear bleeders to speed bleeders because me OEM bleeders were plugged up with muck and wouldn't bleed.

Bleeding technique: I tried a few things, I bought a MightyVac, but it won't really pull any significant amount of fluid when pumped up to 15 lbs. I also tried my brothers pressurized bleeder. I made an adaptor for the cap and got the PSI up to 15 and again, it would barely push any fluid into the collection cup. So I did the two man brake bleed with my wife working the pedal and bled quite a bit of fluid out, until it was nice and clean. In all, I've used at least two large bottles of fluid.

I checked the vacuum out of the manifold and into the brake booster and it's pulling about 20lbs. I put a vacuum on the booster check valve nipple and when I got it up to 15 lbs, it very slowly leaked down (about 1.5 lbs in 5 minutes). I called my dad about it today (used to work for Willwood Brakes) and he suggested I grab a gauge and see what the pressure is at the calipers.

When I said the brakes weren't incredible before changing the pads, I'm guessing they were close to average for a rig on 35's with full armor. ABS was almost impossible to activate on dry asphalt. (please let me know if your rig on 35's can brake hard enough to activate ABS on dry asphalt).

So, any thoughts? What would you do next? I really need to get this thing driveable ASAP but I don't want to go broke paying a shop to work on it. I don't have a huge knowledge of brake systems, but I can tackle replacing most items with little reading/YouTube.

Edit with info I forgot to add initially: the brakes are extra terrible in reverse, just in idle or on a very mild hill, it wants to roll and not stop, brakes do almost nothing and get hard. quick butt pucker moment for sure.

Thanks in advance
 
Last edited:
Joined
Jan 12, 2016
Messages
157
Location
Australia
Sounds like a booster issue when you say 'pedal doesn't go all the way down, it gets firm like it should, but after braking a couple of times, you have to push really hard to stop, definitely not safe to drive, emergency stops are non-existant'
With your bleeding order, why do you start at the LSPV? Normally you start furthest from the reservoir and work your way towards it - for LHD models > RR, LR, LSPV, RF, LF
 
Joined
Dec 17, 2006
Messages
888
Location
Central Coast, CA
Website
www.coastal-aquariums.com
Sounds like a booster issue when you say 'pedal doesn't go all the way down, it gets firm like it should, but after braking a couple of times, you have to push really hard to stop, definitely not safe to drive, emergency stops are non-existant'
With your bleeding order, why do you start at the LSPV? Normally you start furthest from the reservoir and work your way towards it - for LHD models > RR, LR, LSPV, RFI

I read in the past to start with LSPV, but I also read to do it after the rears, so I just did both, I figured it couldn't hurt. And I'm in the USA, so LHD.

Booster has been mentioned, but I don't want to just start replacing parts without having a decent confidence via some sort of diagnosis that this is indeed the problem. I've wasted enough money that way on other issues.
 
Joined
Dec 8, 2006
Messages
10,852
Location
New Jersey
Website
www.sdsysdesign.com
The fact that the brakes got worse after a pad replacement indicates that the rotors may be severely grooved. If that's the case, then it will take some time for the pads to bed into the existing rotors.
It also sounds like the brake system has been neglected.
 
Joined
Dec 17, 2006
Messages
888
Location
Central Coast, CA
Website
www.coastal-aquariums.com
The fact that the brakes got worse after a pad replacement indicates that the rotors may be severely grooved. If that's the case, then it will take some time for the pads to bed into the existing rotors.
It also sounds like the brake system has been neglected.
Nope, the rotors are not severely grooved. What about my story says that the system had been severely neglected? I feel like you're reaching for things with your response. What was the link supposed to help me with? Not very associated with my issues except towards the bottom where someone says they can lock up their brakes.
 
Last edited:
Joined
Dec 8, 2006
Messages
10,852
Location
New Jersey
Website
www.sdsysdesign.com
What about my story says that the system had been severely neglected?
Your words, "I changed out the rear bleeders to speed bleeders because me OEM bleeders were plugged up with muck and wouldn't bleed."
"I noticed the lines closest to the calipers were pretty cracked"

These are clear signs of neglect.
 
Joined
Jan 19, 2005
Messages
3,366
Location
South west utah
Slap some new rotors in it and I bet your good to go.
 
Joined
Dec 17, 2006
Messages
888
Location
Central Coast, CA
Website
www.coastal-aquariums.com
Your words, "I changed out the rear bleeders to speed bleeders because me OEM bleeders were plugged up with muck and wouldn't bleed."
"I noticed the lines closest to the calipers were pretty cracked"

These are clear signs of neglect.


I wheel/hunt super dusty areas, with an occasional creek crossing, getting muck in the bleeders is far from neglect. The little rubber covers are gone, but up until this bleed, I haven't had issues with the bleeders. I probably could have just cleaned them out but decided new ones would be a decent idea. The hoses are cracked because they are old. Everything wears out at some point and with a few exceptions, I don't go around replacing things that are still in working order, these wore out and were replaced. That's kind of the opposite of neglect. Unless you are suggesting that I remove them annually, and clean lubricate them, proloning their life. Pretty sure nobody does that.

I appreciate you trying to help, but pointing out perceived neglect is not helpful and does nothing to help diagnose my suddenly dangerous brakes.
 
Joined
Apr 14, 2016
Messages
1,872
Location
Oregon
OEM bleeders were plugged up with muck and wouldn't bleed.

You haven't rebuilt or replaced any of the calipers, right? If so, you almost certainly have nasty rust in the rear calipers, along with pitted caliper pistons. You might also have water remaining in some crevice in there, which could explain why your brakes rapidly worsen.
 
Joined
Dec 17, 2006
Messages
888
Location
Central Coast, CA
Website
www.coastal-aquariums.com
Slap some new rotors in it and I bet your good to go.

4 new rotors? How is that going to help drastically? Why would the sudden poor brake situation, which immediately followed new front pads indicate new rotors as a fix? The current rotors don't have many miles on them. Probably Less than 20k.
 
Joined
Dec 17, 2006
Messages
888
Location
Central Coast, CA
Website
www.coastal-aquariums.com
You haven't rebuilt or replaced any of the calipers, right? If so, you almost certainly have nasty rust in the rear calipers, along with pitted caliper pistons. You might also have water remaining in some crevice in there, which could explain why your brakes rapidly worsen.

Pretty sure all 4 calipers are original. Just curious, why do you say nasty rust in the rear calipers specifically? This has been a west coast vehicle it's whole life, very little rust on the vehicle, unless you are suggesting internal rust from the fluid. You could well be right about the condition of the pistons, but again, why would it be a huge change immediately after changing the front pads? I've never had the brakes go to s*** after changing pads in the past, with the same procedure.

Any way to check those pistons short if just buying new calipers? I'm trying to avoid the shotgun approach of just replacing things one by one until it's better. I would prefer to figure out where exactly the problem is and then replace the necessary parts.
 
Joined
Apr 14, 2016
Messages
1,872
Location
Oregon
why do you say nasty rust in the rear calipers specifically?
Because that's been my experience. My personal theory is that the rear brakes don't get nearly as hot as the front brakes, so any moisture that makes its way past the seals (and it certainly does) condenses, settles, and starts rust.

Any way to check those pistons short if just buying new calipers?
Yeah, you disassemble them.
 
Joined
Apr 14, 2016
Messages
1,872
Location
Oregon
Incidentally, the FSM shows the braking system pressure reaching nearly 1,500 PSI up front and 800 PSI in the rear. If your bleed nipples weren't flowing, then you definitely had debris packed from the back side (inside the caliper), because no dust accumulating on the nipple hole outside the caliper is going to resist several hundred PSI.
 
Joined
Dec 17, 2006
Messages
888
Location
Central Coast, CA
Website
www.coastal-aquariums.com
Incidentally, the FSM shows the braking system pressure reaching nearly 1,500 PSI up front and 800 PSI in the rear. If your bleed nipples weren't flowing, then you definitely had debris packed from the back side (inside the caliper), because no dust accumulating on the nipple hole outside the caliper is going to resist several hundred PSI.
those pressures would only be achieved when the rig is on and the booster is doing its job, we bled the brakes with the engine off, no booster activated at that point. Do you bleed your brakes with the engine running?
 
Joined
Dec 17, 2006
Messages
888
Location
Central Coast, CA
Website
www.coastal-aquariums.com
Super weird that you didn't mention that in your first post. Are they Toyota or aftermarket?
I missed that detail, probably because it wasn't associated with the current situation of bad brakes after changing pads.
 

nukegoat

Should have bought a Jeep
SILVER Star
Joined
Apr 10, 2013
Messages
6,536
Location
San Jose, CA
Pretty sure all 4 calipers are original. Just curious, why do you say nasty rust in the rear calipers specifically? This has been a west coast vehicle it's whole life, very little rust on the vehicle, unless you are suggesting internal rust from the fluid. You could well be right about the condition of the pistons, but again, why would it be a huge change immediately after changing the front pads? I've never had the brakes go to s*** after changing pads in the past, with the same procedure.

Any way to check those pistons short if just buying new calipers? I'm trying to avoid the shotgun approach of just replacing things one by one until it's better. I would prefer to figure out where exactly the problem is and then replace the necessary parts.
New pads mean the seals are riding on a different part of the piston. If the rotor is misaligned to the caliper for some reason (bent, loose wheel bearings, etc) then it's conceivable even that the piston is cocking over in the bore etc. Lots of possible things going on.

Honestly though your entitled-to-our-diagnosis attitude makes me not want to help you at all
 
Joined
Apr 14, 2016
Messages
1,872
Location
Oregon
those pressures would only be achieved when the rig is on and the booster is doing its job

Baloney, chicken legs.

probably because it wasn't associated with the current situation

LOL

Anyway, you seem more interested in arguing with people who are giving their free time to help you than you are in actually solving your problem, so I'm out.

Maybe the brakes actually work fine and the whole problem is that you're too... Sensitive?
 
Joined
Nov 9, 2012
Messages
12,874
Location
Olathe, KS, USA
When you squeezed the caliper pistons back in order to install the new pads, did you open the bleeders (remove the bleeders) prior to this or did you just compress the pistons, shove in the pads, then bleed them?

Yes, there is a difference.
 

Users who are viewing this thread

Top Bottom