Another brake question

[supton]

Replaced a rear caliper on my 2010 Tundra last fall, and it's never been the same since. Low pedal for a while. I recently bled the brake some more (both rears, just cracked the bleeders as my Mityvac refuses to properly pull brake fluid) and that helped. But it feels like the brakes are just not there--really have to push to get decent braking. Almost like a booster issue, or bad bite on the brake pads. And no, pedal is not going to the floor, it just seems harder than it should be--not as hard as having zero power brakes, but nothing like my other two vehicles. I let it sit for four hours (engine off of course) and it still had vacuum in the booster. So I'm thinking not a booster. I did have new OEM pads and rotors put on 1.5 years ago. I then drove it very little, like 4,000 miles over the next year, maybe 1,000 miles this winter. It sits--a lot. And outside. Could the pads be wonky? Should I do some high speed braking events and check to make sure all four heat up properly? I'm thinking that is first thing to check, maybe one end or the other isn't doing its job. I did not do the pad install but I'm not entirely sure how they could be screwed up--and I'm not dragging a brake either (no hot rotors when I park). I'm 99% sure I got the better OEM pads, but I'd have to look. Both rotors appear to be doing something, as they are mostly clear of rust. [Sometimes you can spot a dead caliper as the rotor is crusty as all get out. Not the case here.]

 

[Donald]

Re-bleed the rear brakes with a helper.

 

[HangFire]

Originally Posted by Donald

Re-bleed the rear brakes with a helper.

Yes, after replacing the crush washers around the banjo bolt, and removing/replacing the bleed valve.

 

[supton]

Originally Posted by HangFire

Originally Posted by Donald

Re-bleed the rear brakes with a helper.

Yes, after replacing the crush washers around the banjo bolt, and removing/replacing the bleed valve.

Why would I need to do that? It's not losing brake fluid, and the pedal is not doing the slow drop to the floor. It's sealed up. Do you think it's got an obstruction and thus the banjo bolt isn't flowing fluid?

 

[HangFire]

I was keying on the pedal low part, then re-bleeding helped. Indeed the hose might be coming apart inside, and creating an obstruction. Also once pads are used on a stuck caliper/pins, they never seem to be the same. They often work, but have less stopping power, or make grindy noises.

 

[mclasser]

Gravity bleeding doesn't appear to be cutting it. Take it to a trusted shop that can machine flush all 4 corners & cycle the ABS valves in-case air's stuck in there. I replaced a rear caliper and gravity bled it for an hour. The pedal didn't feel as firm as before so I took it to my indy who pressure bled all 4 wheels. Some small bubbles came out that caliper, along with some more up front. Pedal was rock hard afterward.

 

[slacktide_bitog]

Speed bleeders are awesome

 

[lbhsbz]

Make sure you've got the correct caliper for that side of the truck...bleeder should be on top. You mentioned that it sits outside a lot. That's going to let the rotors rust up and get pitted. Degraded rotor surfaces don't perform well. A good rotor surface should be almost mirror smooth. If you can feel anything pits/defects running your fingernail over it, that's your problem.

 

[Dave9]

We seem to be splitting off on two different tangents. Either: A) You pedal is softer, which means you need to bleed it or you have a master cylinder wear problem. or B) Your pedal is not softer, is firm but your stopping distance seems to have increased - this seems less likely unless you're driving like a maniac and or have a tape measure to test this. If this is the case, yes you could have an issue with glazed pads, contaminated rotors (aka warped is often the term used even if not truly warped) or rust on your pad rails or caliper sliders. When you replaced the caliper, was it leaking on the pads and maybe that is not cleaned off well? Brake hoses, they could need replaced by now and cause some softer pedal but they don't tend to suddenly be worse right after doing a rear caliper. That is most likely air still in the system (possibly made difficult to remove if it's the wrong side caliper as lbhsbz mentioned). However, if the brake hard lines are not rusted on to the point where you risk breaking them trying to swap the soft lines, then you might go ahead and replace the soft lines as they are quite inexpensive if you settle for a quality aftermarket brand instead of genuine Toyota. Toyota does not make special superior brake hoses. They just cost more. Ultimately it is time to pull the wheels and check them. Listing all the things is nowhere near as useful as hands on inspection and trying to bleed again. Pits on the rotor will not matter at all. If this were true, nobody would ever want drilled or slotted rotors. That tiny bit of surface not in direct contact at the moment, makes no difference enough to notice. However, the first mile or so you drive after a vehicle has sat a long time to build up a rust coating, will potentially make noise and cause some extra drag, similar to if you had left your parking brake on.

 

[supton]

Originally Posted by lbhsbz

Make sure you've got the correct caliper for that side of the truck...bleeder should be on top. You mentioned that it sits outside a lot. That's going to let the rotors rust up and get pitted. Degraded rotor surfaces don't perform well. A good rotor surface should be almost mirror smooth. If you can feel anything pits/defects running your fingernail over it, that's your problem.

Bleeder is on top. I call bogus on needing mirror smooth though. I usually run rotors past 100k (5 years) and as a rule they are always badly grooved. Work fine, but I usually do pads and rotors as a result. This vehicle does sit a lot, it will go a week between uses, sometimes two, but the rotors seem no worse than my other vehicles.

Originally Posted by Dave9

We seem to be splitting off on two different tangents. Either: A) You pedal is softer, which means you need to bleed it or you have a master cylinder wear problem. or B) Your pedal is not softer, is firm but your stopping distance seems to have increased - this seems less likely unless you're driving like a maniac and or have a tape measure to test this. If this is the case, yes you could have an issue with glazed pads, contaminated rotors (aka warped is often the term used even if not truly warped) or rust on your pad rails or caliper sliders. When you replaced the caliper, was it leaking on the pads and maybe that is not cleaned off well?

Pedal moves further than expected, because the brakes are just not doing anything, relatively speaking. Then it seems like one has to push hard. Not "no booster hard" but it's not Toyota easy either. My other two vehicles, as soon as you touch the brakes, you can feel something; and as you press harder, braking force increases exponentially. This vehicle, it's like a linear response, but with very little in the first half inch of pedal movement. Does not help that it's an automatic and that the torque convertor "fights" against you (although my other automatic isn't nearly as bad as this one). I haven't tried doing a brake stand with it, perhaps I'll try that tonight and verify ABS action. Sounds like I just have to bite the bullet and give it to a shop to look at. Once I figure out the other car's problems I can get this one in.

 

[Trav]

Originally Posted by supton

just cracked the bleeders as my Mityvac refuses to properly pull brake fluid) and that helped.

Start by replacing the bleed screws.

 

[burla]

I used to think you can't make gains in braking with the same anti lock brake setup, I was way wrong. I tried Wagner OEX pads and they stop way sooner then toyota OEM. Lots of bite, I never really thought I had a problem, I just changed the pads because they were due at 40k miles, and the SUV stops way sooner, grabs very well. I see you are fussing with rear brakes, but usually it is Front brakes that supply most of the braking. For 42 bucks a set, I'd just toss two up front and see what happens. When you did the caliper, you also did all the brake pads 4 corners with oem?

 

[kr_bitog]

Originally Posted by supton

Originally Posted by lbhsbz

Make sure you've got the correct caliper for that side of the truck...bleeder should be on top. You mentioned that it sits outside a lot. That's going to let the rotors rust up and get pitted. Degraded rotor surfaces don't perform well. A good rotor surface should be almost mirror smooth. If you can feel anything pits/defects running your fingernail over it, that's your problem.

Bleeder is on top. I call bogus on needing mirror smooth though. I usually run rotors past 100k (5 years) and as a rule they are always badly grooved. Work fine, but I usually do pads and rotors as a result. This vehicle does sit a lot, it will go a week between uses, sometimes two, but the rotors seem no worse than my other vehicles.

Originally Posted by Dave9

We seem to be splitting off on two different tangents. Either: A) You pedal is softer, which means you need to bleed it or you have a master cylinder wear problem. or B) Your pedal is not softer, is firm but your stopping distance seems to have increased - this seems less likely unless you're driving like a maniac and or have a tape measure to test this. If this is the case, yes you could have an issue with glazed pads, contaminated rotors (aka warped is often the term used even if not truly warped) or rust on your pad rails or caliper sliders. When you replaced the caliper, was it leaking on the pads and maybe that is not cleaned off well?

Pedal moves further than expected, because the brakes are just not doing anything, relatively speaking. Then it seems like one has to push hard. Not "no booster hard" but it's not Toyota easy either. My other two vehicles, as soon as you touch the brakes, you can feel something; and as you press harder, braking force increases exponentially. This vehicle, it's like a linear response, but with very little in the first half inch of pedal movement. Does not help that it's an automatic and that the torque convertor "fights" against you (although my other automatic isn't nearly as bad as this one). I haven't tried doing a brake stand with it, perhaps I'll try that tonight and verify ABS action. Sounds like I just have to bite the bullet and give it to a shop to look at. Once I figure out the other car's problems I can get this one in.

If you have no action on initial half inch but it is normal when you push further, then it is just brake pad worn issue. So you may have changed the rear, pad but the culprit is worn front pad. So question is it really normal when you push further or really harder before it slow down which indicates glazed pad problem.

 

[supton]

I think the pads have 10,000 miles now, it wasn't driven much after all pads & rotors (F&R) were replaced (caliper was replaced even later). Hmm, more miles than I recall. If it's not raining and I get some time I'll pull it apart this weekend, sand the pads I guess, slap back together. See if I can find anyone to pump the brakes for me to bleed again. I wouldn't be surprised if this is rear brake biased. Everything changed with ABS. OEM's could bias brakes to the rear and then use ABS to cut any wheel lockup issues; by doing so they could cut down on brake induced front end dive. That or perhaps the ABS controller can actually dial pressures on the fly--pull in the rears first, then somehow use fronts in an increasing manner. Don't forget, it's a truck, under load the rears are doing more than expected. Really wish it was a month later, it's too early to swap on all seasons, that's a great time to R&R brakes.