rustyShake

Vehicle: 2001 Tacoma 2wd, 2.4L

My last set of brake pads only got about 15k miles on them before the wear indicator started screeching. Evidently my brakes had been dragging, not sure for how long, although there was some life left on the pads, maybe 30% remaining. I replaced my front drivers side caliper when I replaced the pads 15k miles ago, and I thought now the passenger side caliper was sticking, so I just replaced it, put in new pads, bled the system, and it still drags. It is just the front wheels that are dragging. It takes two hands to turn the hub. When I take off the caliper it spins freely.
So yesterday I replaced the master cylinder, bled the lines in the proper order and the proportioning valve (rear passenger, rear drivers, front passenger, front drivers, proportioning valve). Still dragging!
Today I did some more troubleshooting. I'm getting flow to the calipers. If I open the bleed valve I get a slow gravity flow. When I flip up the caliper and watch the piston while my helper presses the brake it appears to be working properly. It extends when the brake is pressed and retracts slightly when they let off the brake.
When I open the bleed valve I get a slow and steady stream, not a shot of fluid. However, even with the bleed valve open it is hard to turn the hub with no noticeable improvement.
I also tried loosening the master cylinder from the brake booster to see if perhaps the push rod was an issue. I loosened the MC as far as I could without taking the two bolts all the way off, I'd say about 8 mm. Still no bueno. WTF?
Today I played with the adjusting rod on the BACK OF THE PEDAL, not the MC side. I went all the way in both directions and neither did a thing.

Can anyone help me out? My thoughts are bad brake hoses (I ordered two which should be in Wednesday next week just in case). Brake booster? Proportioning valve? I'm tired of throwing parts at this thing. Any help? I'm losing sleep over this thing beating me.

Thanks!

skypilot

iTrader: (1)

Well there is no front proportioning valve. Second why do you feel 15k is bad? I get 40k on my '88 but I do all highway and have normal size tires. What kind of pads? I use semi- metallics, not the organic kind that wear faster. Simple heat, mine get really hot in traffic, and then nothing. Also brake rotors today are all made in China; they do not wear at all like the Jap made rotors. Also Before I put on fresh "new" rotors I have a truing cut / pass to verify they really are "in spec" most times you take off .005 to .008, one was .010 to true up. That can eat pads.

I am going to assume you have power brakes. how many miles on this rig? It possible your booster is not returning to zero and that's your problem.

wyoming9

iTrader: (1)

What kind of driving??

Better yet just what brake pads

If I recall correct with the wheel off it does take some effort to turn the rotor.

With these pads how was the braking ??

If I got excellent braking I would not mind changing pads and Rotors every 6 months

rustyShake

Not sure what you mean by a "front proportioning valve". The LSPV, if i recall correctly, distributes braking pressure between the back axle and the front axle. So, yes, the LSPV could be sending more pressure to the front axle causing the brakes to drag.
The pads were nothing fancy, I don't recall exactly. Probably were organic but still, this seems like very fast wear. Plus there is the drag that is ongoing.
165000 miles on the truck.
Booster is a possibility. Today I undid the booster line going to the intake manifold and drove around the block a few times but the brakes continued dragging.
I don't care so much about the life of the pad, more concerned about the drag on the rotors.

rustyShake

The pads were cheap. I don't care about changing pads. Braking was average. Changing rotors every 6 months seems excessive.
I am concerned that something is wrong and I prefer to find the problem and fix it rather than replace parts on a regular basis. Dragging brakes leads to hot rotors and hubs which can lead to failed bearings and calipers. It's only a matter of time before this causes many other problems. Not to mention poor performance and MPG.

akwheeler

Have your rotors been warping? when you put it in neutral and coast does it come to a stop quicker than it should? if not I'd say you are chasing a ghost, but the brake hoses are a possibility, but if the wear is even from side to side your issue would have to be hydraulic pressure still being applied to the calipers. If you crack a bleeder you would get a squirt rather than a gravity drain if there is an issue. as to the 15K miles that would probably be a reasonable expectation if you live in San Francisco or somewhere with a lot of hills and stop and go traffic.

rustyShake

Rotors have not been warping. I do not really notice a difference in coasting when I let off the brake but this is not normal drag. The hubs get HOT after driving a couple of miles with very light braking. I can't even get one full free spin rotation out of the front wheels WITH THE WHEELS ON. It takes two hands to turn the hub with the wheels off. That is not normal.
I do not live in a hilly place and I am a very conservative driver, not a jackrabbiter.

skypilot

iTrader: (1)

That just sounds normal. Maybe the pressure is a little up on the upside of tolerance. But all I can think of is the residual pressure check valve is clogged or falied somehow or the vacuum booster is bleeding over and has excessive apply force. There is I think 10lbs of residual pressure to keep the pads warm for stopping, metallics and semi-metallics need to be warm so they work, otherwise through the red light you go; just like the first Hertz Mustang's.

15k sounds right for an organic pad, that saves the rotor at the expense of the pad.

Also the LSVP in the back is a load variable proportioning valve, it does re-route excessive pressure to the right front caliper/ and across. So I see your point, but its so very usless that its just disregarded.

wyoming9

iTrader: (1)

Your front hubs are getting to hot to touch in light braking at 0 Degrees Fahrenheit you might have a problem

At 80 Degrees or more not so much .

During the Summer one brake application my calipers are hot enough to burn my hand even after pulling off the wheel

One way to know for sure install brake pressure gauges in the 2 front lines .

Go from there

rustyShake

That seems like an awful lot of drag for normal. I had buddy's Frontier up on the jack this weekend and his front wheels spun freely, at least two or three rotations easily. That seems like normal, not a half spin at best.

wyoming9

iTrader: (1)

I can only go by what is in front of me

I have no idea what a frontier is but for the good old days when I was young

fierohink

Just to eliminate causes, if you pull the calipers can you spin the hubs freely?

Personally I run OE toy pads. On my '94 I got 50+k to a set. Now that was with a 5sp that carried some of the load of deceleration, but it was also in the hills of western Pennsylvania.

What do the caliper pins look like? If the pads can't slide on the pins they'll stay engaged.

Have you flushed you calipers? Take the pads out and pump the peddle to get the Pistons to extend. Open the bleeder and push the pucks all the way back in to push out all the fluid in the caliper. You may have contamination inside the calipers preventing them from retracting fully.

You need to take a systematic approach to each component.

jmeineck

From everything you've said in the first post, it sound like your disc brakes are working correctly.

Your helper pushed on the brakes the piston activated and then retracted some. Which is exactly what they should do. That showed that you proportioning valve are working like they should.

It sounds like in your comparison of spinning your hub with caliper on and spinning your buddies Frontier wheel is not a fair comparison. One test has the full weight of the tire and rim and the other only has the weight of the hub. Of course the wheel is going to spin free and the hub is not. Also the hub will not free wheel with the caliper on and the brake pads adjusted properly. Try jacking up your rig and spin the front tire and see if it stops at a 1/2 turn.

If you think the 15k is not what you should be getting then check the quality of the rotors and pads. This could also be caused by a lot of winding down hill driving. lots of dirty driving ie, sand, dirt, mud driving.

If your brake lines are very old then it is possible that the inner casing has deteriorated and could be clogging up the line possibly making them act like the proportioning valves are malfunctioning, but I think that would cause more troubles than what you seem to be experiencing.

Well if nothing else everything is new now!!!

jmeineck

Ok, if it takes 2 hands to get this to spin with the tire on that does sound like to much drag.

Are the caliper mounts true? Or is either one skewed even a little?

wyoming9

iTrader: (1)

My Brain is not the best above freezing

With this front Brakes Drag issue I don`t think you ever mentioned the Sweet smell of burning brakes .

Are they getting that hot ?/

If so then you have a problem I thought you might have already checked the normal things Like Cocked pads

Corroded pins

Stuck Caliper although most of mine seize fully engaged