Advice on Changing Pads in a Parking lot

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hemi71x said:
Use a 6 point 3/8 socket, on the bleeder screw to reduce the chance of rounding off the head on the bleeder.

I replied earlier hoping that you wouldn't break off the bolts holding down the pad clips, but i guess you removed them ok without snapping the head of them off.
Those things are the ones that usually break, if your working on a car that went through lots of winters.
But bleeder screws rust up, seize up also.

I don't think you followed instructions in retracting pistons back into their bores.
You leave one side of the old pad in the caliper, to keep them from coming out, while you compress the other two, on the rotor side that your working on.
Then put in that new pad on that side, then do the other.

Sounds like you went metal to metal on the rotor(s) so your only doing a half assed job anyway by just replacing pads, without machining the rotors, or replacing them, if they are undersize.
But anyway, replacement pads will at least get you back on the road again, and at least stop, other than being metal to metal.
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I actually did replace the calipers about a year and a half back. I think that the "rebuilt" calipers from rock auto didn't get a quality bleeder screw on there, and it got eaten really quickly. even the plastic ratcheting end of my wrench ate it. I know this isn't the "right" thing to do, but as I said, I'm away from home and just trying to make this thing work, I'm not going for longevity, just functionality. I guess I could take 67dart273 up on his offer of turning the rotors, but that's a more involved job than I'm comfortable doing with the tools I have. I did leave the one pad inside the piston, and then tried to compress the pistons, but in my attempt to not buy tools I have at home, I was doing so with a screwdriver, I'm sure if i had a clamp, it would happen more easily.
 
Tooljunkie said:
Pads wont last long on fubar rotors.
That being said,remove one pad, replace it then pump up brakes. Replace next one and so on. This way you minimize the amount of fluid displaced back to resevoir.
Theoretically you shouldnt have a problem with fluid, unless it was topped off as pads wore down.

All new pads and new rotors reservoir filled then it should never need topping up. Low fluid indicates worn pads or a leak.

a goood mathemagician could calculate the volumes of calipers and resevoir and have an indicator when pads need replacing, that is if they all wear evenly.
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I think for that formula, the volumes of individual pistons would be needed, and the reservoir's volume. Then you just relate the drop from the reservoir into the distance that the pads have worn by.
 
You are WAY overthinking this. There is a big difference between booksmart and streetsmart.

68Valiant225 said:
I think for that formula, the volumes of individual pistons would be needed, and the reservoir's volume. Then you just relate the drop from the reservoir into the distance that the pads have worn by.
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4spdragtop said:
You are WAY overthinking this. There is a big difference between booksmart and streetsmart.
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Probably true. I know that just because I know how something works, that doesn't mean I'll be able to put it back together once I blow it apart. Learned that the hard way a few times.
 
Update: I've got the pads in all around, but had to take the thin metal shield off of the backs of the driver's side pads, just couldn't get them to go in with them in. Is that okay for 1000 miles? At this point, I'm just hoping I can get these brakes to last me until december when I can really dig in to in my garage at home. Once I get some lunch and the weather cools down a bit, I'm gonna double check the passenger side and take her for a test drive.
Also, the passenger side pads were down to metal (i know, gotta fix the rotors, but it actually sounds like the machine shop at school might be able to help with that) but the driver's side pads were looking like they were barely used, maybe 2-3mm down from the brand new pads. So somewhere, the proportioning must be off REALLY badly. I knew the car pulled to the right under braking, but I didn't realize it was only being pulled by that caliper. No idea how the proportioning happens, so input there would be helpful.
Fortunately working on a muscle car in a parking lot attracts other car guys, so I met a dude with a GTI that said he's got a bunch of tools and is willing to help, so that's a plus.
 
So my dad may have solved WHY the passenger side brake is working harder than the driver side. The front of the frame is bent pretty badly, I'm waiting for my body guy to fix it (he's a big time mopar guy, does more E bodies than anything, but knows his stuff). So the frame is probably responsible for the super uneven braking, but is there a way to adjust the factory installed metering to push more pressure to the driver caliper?
 
Another update, I think the passenger rotor is actually ok. I remembered that I have the 68 service manual (why i didn't look at that earlier for pad changing procedure is embarrassing). This says that the "tell tale tabs" are intended to contact the rotor and make terrible sounds so that you replace the pads. Manual says that the tabs "are not detrimental to the function of the braking disk". So I shouldn't have to worry about the rotor
 
Pistons hanging up. Only thing that would cause uneven wear. Either one side isnt applying or other side isnt releasing. Im leaning towards one side not releasing. Seen many that heat up and pads start to disenegrate.
Couple thing cause it. Hose failure,they turn into a check valve and hold pressure in caliper.
Other is the pistons are phenolic,a fiber material that wear and **** in the bore.
 
Proportioning is not left to right, it's the ratio front to rear. If it's pulling there's a problem in the brakes or as you say, a bent frame. If the frame / alignment is OK, pulling can be rotor finish/ damage, stuck pistons, problems with tubing and fittings or even fluid or grease on the pads

So far as turning rotors "or not" it is impossible, really, to tell by looking. Rotors must have parallel finished sides, AKA not tapered, and both have a reasonably even "same as" the other finish. The other little "gotcha" is the ridge outer/ inner. This wears as the pads/ rotors wear, and new pads wont "sit" on the pads quite right in that case

The short answer is, sometimes you can get away with it, and sometimes not
 
Cutting a rotor on anything but a brake lathe will ruin the rotor. As mentioned above the surfaces have to be dead nuts parallel.
Replace it or get a brake shop to measure it and cut it.
 
Once I get back out there, I'll check to see if the brakes are hanging up on either side.
Also, according to the factory manual, the rotors aren't any more fubar than they were before the grinding noise. Not that the rotors don't need to be turned, but if they do, it shouldn't be because of these pads.
I'm assuming that the unevenness is being caused by the frame. That damage has slowed me down so much. Have a sway bar to put on it, but can't. Need to redo front suspension, but can't. Now its probably destroying brake pads. I don't even care about the body work that needs to get done at this point. I just want the frame where it should be
 
Final (hopefully) update. Everything is in, it all works well. Bedding in the pads fairly soon, which is something I didn't do last time I put in pads, so hopefully it'll help. These pads did have probably close to 10k miles on them, so I guess that's the life of the brakes?
 
68Valiant225 said:
Final (hopefully) update. Everything is in, it all works well. Bedding in the pads fairly soon, which is something I didn't do last time I put in pads, so hopefully it'll help. These pads did have probably close to 10k miles on them, so I guess that's the life of the brakes?
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No!
I have a M/T and I think it's possible to get 8 or 10 times that amount of miles out of a set of pads in street duty.
And I cannot for the life of me, imagine how a bent frame can cause premature brake pad wear. A pull while driving, yes. Premature pad wear, no!
Go back to posts 35 and 36, something is wrong, with the brakes!
 
IIRC, the only thing that pulls the pads off the rotors in the KH system (as well as most calipers) is the rubber piston seals. The residual pressure valve is for drums? Usually the front calipers only go through a distribution block (manifold) off the M/C. Nothing in there to change L/R pressure.
 
AJ/FormS said:
No!
I have a M/T and I think it's possible to get 8 or 10 times that amount of miles out of a set of pads in street duty.
And I cannot for the life of me, imagine how a bent frame can cause premature brake pad wear. A pull while driving, yes. Premature pad wear, no!
Go back to posts 35 and 36, something is wrong, with the brakes!
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Alright. I'll hop underneath next chance I get and see if the piston isn't retracting when I let off the pedal. What is the best strategy for getting the pistons to retract?
I was hoping I would get someone who knew what the life should be, I was thinking that the pads wore a bit too quickly, and looking at the driver's side pads, I can see how they would last 10 times longer than the passenger side did.
 
If the passenger side wore out that soon, I bet the pull was to the right.
As already mentioned; there are three possibilities;
1) the right side was dragging continuously causing the pull and frying itself.,Or
2) the left side wasn't working at all, and so the right side had to do all the work, Or
3) some combination of the two.
As to #1) On KH 4-piston calipers there are only two things that cause this situation; either the pistons are seized or you have a problem in the line,be it a plugged hardline or a collapsed hose; some already mentioned.
As to #2) This can only point to seized pistons, or a bad brake line, either hard or flex.

So I would look at the left side first to see if it's working. This should be an easy test. Just spin the wheel and hit the pedal hard and fast, then immediately release. You will need a helper on the pedal. The wheel should slam to a halt, and then you should be able to freewheel it as soon as the brake is released, as in, instantly. If it does not instantly freewheel, something is wrong! If it does not apply, something is wrong! It could be hydraulic, or it could be mechanical. We will have to find out which.
The next thing I would do is crack the bleeder and have the helper gently apply a little pedal and see if the fluid comes out in a nice steady stream. If it doesn't, the line is plugged. Go up to the Combination Valve, and crack the line there,looking for fluid. If you get it there, go down to the flex line and check the m/c side. If you get fluid there, replace the flex line.
But, if fluid came out the bleeder, then the caliper is bad, or 1 or more pistons is stuck. To find out what's going on, you will have to pull 1 pad out. Then watch the pistons as the helper gently depresses the pedal. Do not full stroke the pedal, there is no need for that. As soon as you see 1 piston begin to move, signal the helper to stop and release. The piston should immediately retract a few thousands of an inch. Repeat as often as necessary until you see it retract. As soon as that piston is proved, install a spacer in there to prevent that piston from moving. (Perhaps you can flip the pad back in there standing on its end.) Then prove the second piston is similarly retracting. When that side is proven, lever the pistons back into their bores and re-install the pad, then pump the pedal a couple of times to normalize everything. Now remove the other pad and check those pistons similarly.
The seal-retraction is usually pretty small, but the KHers have pretty fat square section O-rings that when new,pull back more than most. I'm gonna guess at least .005 to .010. The O-rings last forever, but the grooves rust up and then the retraction becomes less. But, the thing about KHers is that the pistons fit really tightly in the bores, and it doesn't take much rust to cause them to seize up. So go find the seized piston(s).
But I don't think you will have this problem. More likely is a problem in the flex-hose.
And if this side is working 100%,then,we're off to the otherside,lol
 
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I would simplify the diagnosis, front end up on stands,hard push on brake pedal,then go spin the wheels. That will give you a clue if anything is hanging up.
Another thing, but not likely with your calipers is the pads themselves sticking in the calipers. If the worn out pads came out with little difficulty then thats one you can rule out.

Something else to consider,the quality of friction materials. White box brake pads (no name brand) dont stand up very well, also doesent explain premature failure.
 
I certainly hope it's in the line, the calipers were replaced after the debacle with the pad falling out, since that caused a piston to overextend, and it got gacked at some point, so it wasn't going to move freely. I'll follow the inspection steps next.
 
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