An actual car post...
in [Toyota]
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From: Hachiroku ハチロク on 9 Oct 2009 18:46 1989 Suby GL Coupe, AWD. Spongy brakes. I did the obvious and flushed/bled, but it didn't help a lot. I got a set of pads and waiting for the weather to clear. This car has disc fronts and drum rears. When I did the flush/fill I was unable to loosen the bleeder on the left rear backing, and didn't want to snap it off, so that one is not flushed, but what came out didn't look too bad, anyway. One thing; the car has been siting since April, and the rotors were rusty. After just a few miles the driver's side rotor came clean, but the passenger's side just has a 1" stripe in the middle of the rotor. I'm going to have a look at that caliper and see if it's stuck open, scuff the rotor with a wire brush and install the pads and see what happens. Too bad the rest of the car didn't stay as nice as the motor and tranny...they're great. And parts are becoming scarcer than parts for my Supra!
From: hls on 9 Oct 2009 19:53 "Hachiroku ハチロク" <Trueno(a)e86.GTS> wrote in message news:pan.2009.10.09.22.46.24.990948(a)e86.GTS... > 1989 Suby GL Coupe, AWD. > > Spongy brakes. I did the obvious and flushed/bled, but it didn't help a > lot. > > I got a set of pads and waiting for the weather to clear. This car has > disc fronts and drum rears. When I did the flush/fill I was unable to > loosen the bleeder on the left rear backing, and didn't want to snap it > off, so that one is not flushed, but what came out didn't look too bad, > anyway. > > One thing; the car has been siting since April, and the rotors were rusty. > After just a few miles the driver's side rotor came clean, but the > passenger's side just has a 1" stripe in the middle of the rotor. I'm > going to have a look at that caliper and see if it's stuck open, scuff the > rotor with a wire brush and install the pads and see what happens. > > Too bad the rest of the car didn't stay as nice as the motor and > tranny...they're great. > > And parts are becoming scarcer than parts for my Supra! At some time or the other, you are going to have worry that bleeder valve free (or snap it off in the caliper assembly). Usually, but not always, you can make them yield. I have snapped one off only one time in my life. Since you havent replaced the pads yet. maybe you should free up everything when you put your new pads on. If the old pads are sort of welded in by rust, then wire brush everything when you put it back together to be sure it is taught, but moving. I have seen new clean pads that had to be adjusted to the caliper mount. Most calipers are not that hard to rebuild. If I were going to do it, I would do both sides. I would emery cloth the pistons and cylinders, wash them out with methanol, and reassembly with new elastomers and seals. Then flush like crazy. Whether your old discs (rotors) are worn unevenly or warped will have to be evaluated.
From: Tegger on 9 Oct 2009 20:03 =?iso-2022-jp?q?Hachiroku_=1B$B%O%A%m%=2F=1B=28B?= <Trueno(a)e86.GTS> wrote in news:pan.2009.10.09.22.46.24.990948(a)e86.GTS: > 1989 Suby GL Coupe, AWD. > > Spongy brakes. I did the obvious and flushed/bled, but it didn't help > a lot. Spongy brakes can mean a lot of possible problems. In no particular order... 1) Air still in the lines. It can be difficult to budge stubborn bubbles in the calipers without removing them from their mounts and using the "turn and tap" method. 2) Aftermarket pads that are too hard. Requires excessive pedal pressure to make them function. 3) Seized pistons somewhere. Makes the ones that do slide well work extra hard. 4) Flex hoses that expand when pressure is applied. This happens when fluid is not changed in a timely manner. 5) Other parts not moving properly, such as pads, pins, etc. 6) Rust buildup anywhere in the caliper assembly components. A Dremel, Sil-Glyde, aluminum anti-seize, and 50-grit emery cloth are your friends. > > I got a set of pads and waiting for the weather to clear. This car has > disc fronts and drum rears. When I did the flush/fill I was unable to > loosen the bleeder on the left rear backing, and didn't want to snap > it off, so that one is not flushed, but what came out didn't look too > bad, anyway. > > One thing; the car has been siting since April, and the rotors were > rusty. After just a few miles the driver's side rotor came clean, but > the passenger's side just has a 1" stripe in the middle of the rotor. Then you have a sticky piston. Here's a trick: Eject the piston far enough that you can get a Vise Grip or set of Channel Locks on the piston lip. You do NOT want to span the piston, but grip it at one spot between the outer and inner surfaces. Now clamp down hard and turn the piston. It will probably be mightily difficult to turn the piston, and the Vise Grips will probably slip and gouge the metal, so clamp HARD. And have a file handy to clean off the burr that will surely be created. Then you need some silicone grease. AGS's Sil-Glyde will do. Then you need a plastic syringe from a woodworking store, with a really big nozzle. You clean off the rubber boot with brake cleaner spray, eject the piston an inch or so, then inject Sil-Glyde under the boot with the syringe. Now work it round and round, in and out, repeatedly. Chances are good the piston will free up really nice. Unless it's choked with rust and gum, of course. Eject the piston, pinch the boot, and look inside to see how clean the piston is. > I'm going to have a look at that caliper and see if it's stuck open, > scuff the rotor with a wire brush and install the pads and see what > happens. Don't scuff the rotor. Free the piston, then let the brake pads do the scuffing for you. > > Too bad the rest of the car didn't stay as nice as the motor and > tranny...they're great. > > And parts are becoming scarcer than parts for my Supra! > That's one big problem with owning older cars that aren't considered "collector" cars. I'm even running into parts unavailability for certain trim components with our '99 Tercel. -- Tegger
From: Tegger on 9 Oct 2009 20:16 "hls" <hls(a)nospam.nix> wrote in news:c7Odnd-c84txUVLXnZ2dnUVZ_qydnZ2d(a)giganews.com: > > "Hachiroku ハチロク" <Trueno(a)e86.GTS> wrote in message > news:pan.2009.10.09.22.46.24.990948(a)e86.GTS... >> 1989 Suby GL Coupe, AWD. >> >> Spongy brakes. I did the obvious and flushed/bled, but it didn't help >> a lot. >> >> I got a set of pads and waiting for the weather to clear. This car >> has disc fronts and drum rears. When I did the flush/fill I was >> unable to loosen the bleeder on the left rear backing, and didn't >> want to snap it off, so that one is not flushed, but what came out >> didn't look too bad, anyway. >> >> One thing; the car has been siting since April, and the rotors were >> rusty. After just a few miles the driver's side rotor came clean, but >> the passenger's side just has a 1" stripe in the middle of the rotor. >> I'm going to have a look at that caliper and see if it's stuck open, >> scuff the rotor with a wire brush and install the pads and see what >> happens. >> >> Too bad the rest of the car didn't stay as nice as the motor and >> tranny...they're great. >> >> And parts are becoming scarcer than parts for my Supra! > > At some time or the other, you are going to have worry that bleeder > valve free (or snap it off in the caliper assembly). Hachi's seized bleeder is in a rear drum cylinder. > Usually, but not always, you can make them yield. I have snapped > one off only one time in my life. Then you don't live in a place that has significant snow each winter. Leave them for a few years in that case and permanent seizure is a definite possibility. > > Since you havent replaced the pads yet. maybe you should free up > everything when you put your new pads on. If the old pads are sort of > welded in by rust, then wire brush everything when you put it back > together to be sure it is taught, but moving. I have seen new clean > pads that had to be adjusted to > the caliper mount. > > Most calipers are not that hard to rebuild. That's true for the fronts. Rear calipers that incorporate parking brake meachanisms are wildy complicated and a lot more difficult to restore. > If I were going to do it, I would do both sides. Agreed. To make sure both sides end up with equal characteristics. I'd NEVER rebuild or replace just one on an axle set. > I would emery cloth the pistons and cylinders, I would not. Run your fingernail down a brand-new piston. Does it hang up or catch anywhere? No. Now run your fingernail down a surface that's been emeried even with fine cloth. /Big/ difference. Any roughness will result in a sticky piston, plus it will wear the hydraulic seal very quickly. Emerying the cylinder bore is somewhat less objectionable, provided it's cleaned thoroughly afterwards. Clean off any gum on the pistons with solvent. If rust remains or if the cleaned surface catches your fingernail anywhere, replace the piston. -- Tegger
From: Vic Smith on 9 Oct 2009 21:24
On Fri, 9 Oct 2009 18:53:11 -0500, "hls" <hls(a)nospam.nix> wrote: > >At some time or the other, you are going to have worry that bleeder valve >free (or snap it off in the caliper assembly). Usually, but not always, >you >can make them yield. I have snapped one off only one time in my life. > Since it's rear shoes it's a wheel cylinder. Cheap to replace. But I've sometimes just bled at the line connection instead, and had no sponginess. And people define sponginess differently. Sometimes it's normal pedal travel. But it's his car, so he knows how it should feel. --Vic |