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Stop here! Let's talk about brakes

2456740

Comments

  • Thanks for the informative post and confirmation that the need to do rotors at 28K is unlikely.

    I'll pull the wheel tonight and check the pad width.

    As far as brake feel goes - both Sienna's we have (Yes, two) started breaking firm and then went softer - now I'm beginning to think it's either a wear attribute of the OEM pad OR perhaps brake dust as Sienna's seem to accumulate a lot of dust.

    Yes, I do like firmer even though I'm not a leadfoot and will consider the Raybestos product as they're made locally.

    Have you heard at all of the Hawk brand brake pads sold on Tirerack.com?
  • brorjacebrorjace Posts: 588
    TheWolverine, I've never heard of brake dust affecting pedal feel. Can you explain it as you understand it?

    I've heard of Hawk pads, but only vaguely. There are so many different pads out there and my Honda Civic goes through a set of pads approximately every 100,000 miles just like my Integra before it. So, I don't have first-hand experience with a lot of high-performance brands. Axxis Metalmasters, which used to be Repco Metalmasters was a line of brakes the company I worked for used to sell and I can easily vouch for their quality and performance.

    Oh, and jlflemmons, you're right about dropping fluid often being a sign of wear. My fathers 2000 Mercury GrandMarquis is losing fluid and the front pads dust terribly. I pulled one of the front wheels at 20,000 miles and his brakes are more than 1/2 gone. 30,000 miles per set are typical of these cars ... at least that is the case with the way Dad drives. >;^)

    --- Bror Jace
  • rs_pettyrs_petty Posts: 423
    Thanks for reply. I'll be flushing the system soon. Correct me if I'm wrong, but I don't think systems "lose" fluid. The fluid is compensating for wear of the pads and appears to be low. Am I missing something.
  • brorjacebrorjace Posts: 588
    rs_petty, you're correct that brake systems don't 'lose' fluid overtime like a typical engine might 'use' motor oil while everything's fine. If your fluid level is dropping, you're leaking it or the friction material on your pads is wearing down significantly. Either case bears inspection.

    I just wanted that to be clear.

    --- Bror Jace
  • jlflemmonsjlflemmons Posts: 2,242
    If you are seeing lots of brake dust on the wheels between washes, chances are good that you have a "soft" pad. While these are very good about not squealing, they do wear quickly. This has been a big problem on '88-'98 GM half ton trucks. Going to a high metal content pad will help, but may squeal. There are some new pads on the market which use other materials to get better mileage without the noise.

    Rotor/Drum turning: If you do not have any pulsation in the pedal or steering wheel when stopping, and there is no scarring on the braking surface, there is no real need to turn. When turning due to pulsation, only a very small amount of material should be removed. It takes very little warp to create a major amount of pulse.

    Jim
  • brorjacebrorjace Posts: 588
    jlflemmons, Yes, that brake dust used to be material that was on the pads. And if it's no longer on the pads ...

    We just switched the tires around on Dad's big Merc. Marquis and the rear disc brakes looked really good. They'll easily go 30,000+ miles and the fronts were even newer looking. (He's at around 20,000 miles right now). His 1994 car of the same make and model used to go through brake pads (especially the rears) at 20-25,000 miles, depending.

    I agree on the light-as-possible resurfacing ... or going without if the rotor looks really clean. The only probably you might get on a smooth rotor is bits of the corrosion on the edge of the rotor (which come off when the rotor is turned) might work their way into places and cause mildly annoying noise. gently remove as much of this by hand if you decide your rotors don't need resurfacing.

    --- Bror Jace
  • As a lubricant - purely hypothesis there - should have made that clearer in my post - and at this point I'm in over my head (LOL)!

    Thanks for the tip on the Axxis product.
  • jlflemmonsjlflemmons Posts: 2,242
    it was not unusual to have a set go 80K on a full sized Cutlass. I understand similar results can be had with the new ceramic based pads, but I have had no experience with them.

    Rear discs on a car should last well beyond the fronts as their primary purpose is to keep the car in a straight line when stopping. The braking loads of a vehicle shift heavy to the front, hence the front calipers, rotors, and pads are larger. On the new GM trucks, a dynamic proportioning valve varies the percentage of braking force between the fronts and rears depending on the load in the truck and multiple other feedback from sensors. I have owned several GM trucks over the years and this 2000 model 3/4 ton has far and away the best brakes I have ever seen on a truck.
  • alcanalcan Posts: 2,550
    GM and Ford (not sure about Chrysler) have used height sensing proportioning valves for years to compensate for variations in amount and placement of payload. Also reduces rear anti-lock activity on vehicles so equipped.
  • I have a 2000 Toyota Sienna with only 10,000 miles. The rear drum brakes squeak when light pressure is applied on the brake pedal. It squeaks regardless if the car(brake) has warmed up or not, and also if the weather is dry or wet.
    My dealer has re-surfaced the drums and then replaced the drums but the squeak keep coming back. On my last visit, my dealer told me they have inspected the brakes and there is nothing wrong and I just have to get used to it.
    Does anybody have any ideas?? It is very annoying.
    Could brake dust be a factor? I noticed that every time the dealer did something, the squeak would go away for a couple weeks. My guess is that every time the drums are removed, some of the dust would fall off.
  • jlflemmonsjlflemmons Posts: 2,242
    ...meaning they adjust the brakes in real-time to the changing conditions of your drive. While the previous generation of proportioning valves was an improvement over none at all, technology has stepped up to the plate on these new systems. If you haven't had a chance to drive one of these new systems you should. It is almost unnerving to see how quickly you can stop a big truck, even with a load in it. A HUGE improvement over the previous GM truck brakes.
  • spokanespokane Posts: 514
    The dealer is probably correct that the brakes are functioning safely. But you are right, they are not supposed to squeak and, if the warranty is in effect, Toyota must correct the problem. Your comments on the brake dust are also correct. The drum surface condition was not a likely cause of the problem; the dealer's action indicates you may want to go to another dealer with an experienced brake technician. The inside edge of each brake shoe rests on the backing plate at three or four points - your contact points may not be properly lubricated. A burr at one of these contacts points, on either the edge of the shoe or on the backing plate, could also be the source of the noise. Similarly, if the ends of the shoes don't fit properly, noise can result. The shoe friction surface can also be the culprit.
  • burdawgburdawg Posts: 1,524
    Drum brakes, while they have been around for decades, are poorly understood by most people, even many mechanics. I can't tell you how many times I've seen shoes installed backwards, not ground to the correct radius for the drum when installed, etc. Actually, the best explanation I've ever seen of how drum brakes work and how to service them is in the original shop manual for my 55 Buick. If you've ever tried to stop a big heavy car like that with non-power assisted drum brakes on all four wheels it will become clear why it was important.
  • joe3891joe3891 Posts: 759
    Had a 1967 Chevy station wagon without power brakes,at times it would scare you.
  • andre1969andre1969 Posts: 23,571
    ...manual drum brakes all around. It actually wasn't TOO scary, until they failed! I don't know what size they were, maybe 11"? My '68 Dart has 10" drums, so I'd hope that a car that outweighs it by about 1000 lb would have beefier brakes!
  • I took my old Dodge Aires in a few days ago because the brakes wouldn't work. The initially throught that it was the brake pressure regulator valve. Would've been a $400.00 repair.

    Does anybody know what this thing is, and why it's so expensive?

    Checked again with the master mechanic and decided it was the master cylander. I got a new one this time since it was the 3rd one in 4 years. Want this one to last a little longer. Half the price and seems to work OK.
  • swschradswschrad Posts: 2,171
    could be the ABS regulator valve, these don't look like much and cost like pure mithril, delivered by unicorns, and installed by elves on triple-time.

    the entire brake regulator system hanging on or near the master cylinder is basically also a series of regulating and proportioning valves that do different things with the fluid stream depending on pedal pressure and response from the downstream brake system, so that is rather complicated and somewhat pricey as well, but I would have trouble believing over $400 worth
  • wtd44wtd44 Posts: 1,211
    I am surprised that the first suspect component wasn't the master cylinder. What were your initial symptoms? Did the brake pedal "drift" to the floor when you stepped on it?
  • Help! My brakes are "automatically' being applied on the front only and only after the car warms up. As I drive, the front brakes apply harder and harder until I have to stop. Letting the car sit for an hour or so and then I can drive off. One mechanic suggested calipers but my experience has been that calipers either stick or not and are not usually temp. dependent. Also, weird that this is happening to both front and not rear. It has been suggested that the brake lines have given out and are collapsed and acting as a one-way valve. Any thought or suggestions?
  • wtd44wtd44 Posts: 1,211
    Let's say that you have a pair of "bad" calipers that do not want to "relax" adequately (and rapidly) when you take your foot off the brake. The disk pads will drag and heat up. If that persists long enough, the heat will boil the fluid and the lock up takes hold. Or, if not a boiling problem, it could be mechanical. Perhaps the pad pistons are just plainly sticking in the bores and cannot move back out of the way when the pressure of the pedal is released. I can't imagine a proportioning valve having anything to do with it. The calipers are the prime suspects.
  • chavachava Posts: 2
    i feel miserable that i drove my new car for 5-6 miles on the high way (at about 70 miles/hour) before I noticed that my parking brakes were on. I do not remember if they were pushed in fully, but i was able to drive at 70 miles/hour and felt a slight vibration. I looked at the panel and the "brakes" indication light was screaming at me. I disengaged the parking brakes immediately. I am really annoyed at myself. Would I have damaged anything ? I was driving a Toyoyta Camry.
  • wtd44wtd44 Posts: 1,211
    The best assurance one way or the other is to take a direct look at the rear brakes. The dealership where you bought this new car ought to be willing to look for you for free.
  • Attempting to replace rear brake pads on a 93 Accord. Cannont get caliper piston to retreat to accomodate thickness of new pad. I have done brake jobs on my other cars and was able to compress caliper piston with the aid of a c-clamp. Cannot get Honda caliper to budge. Bent a 5" c-clamp like a wet noodle. Is there a trick to depressing this piston or do I have a problem with the calipers? Any advice greatly appreciated.
  • alcanalcan Posts: 2,550
    The rear caliper pistons are mounted on jack screws which are rotated by the parking brake lever, forcing the pistons out and applying the parking brake. The caliper pistons must be rotated clockwise when retracting them. This winds them back down the jack screws. . Universal retractor kits are available for loan from many auto supply houses. This applies to virtually all rear calipers with built in parking brake.
    Do not allow dust boots to twist when retracting pistons. Align cutout in pistons with notches in pads. Also, if equipped with ABS, open bleeder screws before forcing calipers back to avoid pushing contaminated fluid back up the system and into the ABS pressure modulator.
  • Thanks for the info alcan. Ended up having to put old pads back on to get to work today. Should be easy this time since already had them off once! Will try again as soon as I can locate retractor.
  • sivi1sivi1 Posts: 82
    had a 65 corvette one of the first with 4 wheel discs. i was 21 when i bought it. drove like a madman back then and never put pads on till they ground into rotors. (65000 mi). had rotors turned and new pads, worked perfect. 30 years later my maxima and 4runner both had warped rotors under 30000 mi. and i sure drive more conservative. moral: thin rotors made with junk steel. new electric furnaces use scrap steel instead of the old method of intergrated steel mills.
  • Brakes just aren't what they used to be. They were long lasting and dependable, so long as you got on them soon enough. Recent brakes seem to be very effective, quick stopping, and worn out in no time. That favors the brake repair people, but is it a good trade off for vehicle consumers? I spend way too much time "worrying" about the brake pads and shoes on my several current vehicles.
  • cyranno99cyranno99 Posts: 419
    I am not sure that I would agree with you. Brakes now are probably better, but they take a beating because of more stop-n-go traffics. Also, the performance of modern brakes are, in general, superior to the days of old.
  • isellhondasisellhondas Issaquah WashingtonPosts: 20,225
    Back in the "old days" we were lucky to go 20,000 miles on a set of lining.

    Today, I usually go at least 75,000 before need a set of pads.
  • mrdetailermrdetailer Posts: 1,118
    On my Dodge the brakes give the sound of air escaping when pressed. A couple of weeks ago, when it started to touch the floor, I took it into my generally very dependable repairman. They spent a long time diagnosing it -- twice. The originally thought it was a brake pressure regulator valve $400 to repair. Ended up replacing the master cylendar (new) for $200.00. It brakes better most of the time, but in my opinion I still have a problem slamming on the brakes. They are very slow. I also still hear the puff of air when pressing on the pedal. Any ideas?
  • I honestly feel that my experience is directly the opposite of yours! I have found that in the past, brakes seemed to go a long time, and now, with the underengineering and ABS and traction control, most cars go through brakes quickly.
    Check the vacuum unit on that brake system, and especially check the hose attachments for leaks. New hose can often times improve matters.
  • alcanalcan Posts: 2,550
    Check the felt or sponge filter/silencer where the brake pedal push rod enters the power booster. Might have come loose and be hanging off the push rod.
  • mrdetailermrdetailer Posts: 1,118
    I'll check both of those things out.

    I've replaced a number of vacuum hoses that go to the engines last summer so one on the brakes wouldn't be a surprize.
  • alcanalcan Posts: 2,550
    If vacuum supply to the booster is low due to a split, disconnected or collapsed vacuum hose the net result will be a lack of assist (hard pedal). Brake boosters are vacuum suspended. They have vacuum on both sides of the diaphragm when the engine's running and pedal released. When the pedal's depressed it admits modulated atmospheric pressure into the rear chamber. That's probably the noise you're hearing. The pressure differential across the diaphragm pushes it and the master cylinder pushrod forward, providing assist. Or something like that.....
  • In 1998 I "cured" a 1972 Scout II, by changing the vacuum hose and the fitting (grommet) that holds it into the booster cannister on the firewall. the difference was dramatic. NAPA had the parts.
  • 91 chevy S10 2wd

    On my way home today when I push the brake pedal and it travels a little further than normal. I pumped the brake a few more times and the brake light turned on on the dash. I knew I lost fluid so when I got home I checked the master cylinder and sure enough one half was empty. I filled and pumped brakes again so I could find the leak - brake fluid dripping out of right rear drum. I replaced the wheel cylinder that was bad and now heres where it gets tricky.

    After I installed the new wheel cylinder and put the brakes back together, I tried to pressure bleed the rear wheels. The new wheel cylinder wasn't a problem. About four trips of the brake pedal and all the air was gone. I loosed the bleed screw on the old wheel cylinder and barely any fluid came out. I tried pressure bleeding this side a few times and nothing. Finally I took the bleed screw out and then I finally got a little fluid to come out but not much.

    I tried the pedal and it is stiffer than it was but still not right. The brake light is still on on the dash. I know my front brakes are okay so I'm not too worried but I still have some air trapped in the rear lines. Any ideas on things to try to get it out? I suspect something may be clogged on my left rear wheel cylinder so I may replace that tomorrow but I'd like to avoid it if possible.
  • alcanalcan Posts: 2,550
    The portion of the master cylinder bores in the area past the pistons' normal travel are probably in the same condition (corroded and pitted) as the failed wheel cylinder. When a hydraulic failure occurs it allows the master cylinder pistons to travel further down their bores, into the pitted area. This will often damage the primary seals on the master cylinder pistons.
  • revkerrevker Posts: 33
    Hello all. I've got 2 '98 Blazers, 4x4 LS and LT. I pull a 4500lb boat w/trailer. both trucks have just about 70K miles. I am just changing the brake pads for the first time since owning it. problem i'm having is that i can't take off the rear brake rotor. the brake rotor has a score and i'd like to have it resurfaced at autozone. i've got 4 wheel disc brakes. the rear brake rotor is the drum type. i just can't pull it off like the ones in the front. i'm thinking maybe the parking brake is holding it. i tried tapping it with a mallet lightly but it's the same thing. is there something i'missed? calipers are already off the hub. anyone have done this before? any input on this matter is greatly appreciated. thanks.
  • gdo123gdo123 Posts: 6
    Is there anything special you have to do to change the
    break pads (disc), if you have ABS. I have heard you should let
    the brake fluid bleed out, rather than force it back.
    Is this really an issue?
  • alcanalcan Posts: 2,550
    Yes. The system should also be flushed. Here's why:

    http://www.batauto.com/articles/brkfld.html
  • If you have, or can get, a repair manual on your particular car, I suggest following the procedures as described there. Haynes and Chilton are very entertaining reading. (:oÞ
  • I also read a comment somewhere that if your car has
    ABS, you should also disconnect the battery, since there
    is pressure in the ABS accumulator.

    Also, if someone is pumping the brakes for bleeding, do
    you have to have the master cylinder cover on, I'm assuming
    you need it on, to preserve pressure in the system.
  • alcanalcan Posts: 2,550
    The info re releasing pressure applies only to integral ABS systems which use an accumulator to provide power assist. If the vehicle has what looks like a conventional master cylinder and booster, it's not an integral unit (most aren't).
    The master cylinder cap covers the reservoir only. It has nothing to do with developing pressure in the master cylinder bore. A good idea to keep in on while bleeding the system however, as brake fluid is one of the best paint removers around.
  • ". A good idea to keep in on while bleeding the system however, as brake fluid is one of the best paint removers around. "
    I don't mean to be nit picky, but!
    You need the top off the reservoir for replenishing the level as you diminish it as a result of the bleeding. I guess you could take it off, put it on, take it off, put it on, ... until the job is completed.
  • Believe me, you want to keep the cap on the master cylinder reservoir. One good push on the brake pedal without the cap will send brake fluid all over the engine compartment.
  • alcanalcan Posts: 2,550
    "You need the top off the reservoir for replenishing the level as you diminish it as a result of the bleeding. I guess you could take it off, put it on, take it off, put it on, ... until the job is completed."
    You just described the procedure used by anyone who produces quality work. If there's air in the system, it's compressed when the pedal's depressed. Upon release of the pedal the air expands and can force a geyser of fluid out of the reservoir and all over the booster, firewall, and painted surfaces. At the very least there's a mess to clean up in the engine compartment.
  • So when you are changing brake pads, do you open the bleeder, with tube running from
    bleeder valve into jar, force the piston back in, watch break fluid bleed out,
    replace pads and then bleed that side?
    I have changed pads in the past, never bled the system, and never had ABS before.
    Thanks for all the info.
  • If you are just replacing pads and not doing anything with the brake hoses or calipers, here is the sequence I would recommend:

    1. Jack up vehicle, take off tire and such.
    2. Pop the hood and take the cap off the master cylinder reservoir.
    3. Remove the caliper being careful not to let it hang my the brake hose.
    4. Get a large C-clamp and push the piston back into the caliper. Keep the old brake pad on the caliper so the load from the clamp is distributed.
    5. After the pistons are pushed back into the caliper for each wheel, put the cover back on the master cylinder reservoir.
    6. Finish installing the new pads and reattach.

    You should not have to do any bleeding at all if you are just replacing pads.
  • alcanalcan Posts: 2,550
    No argument that many people change pads without problems as outlined in the above post. However, considering that by the time pads are due for replacement there's about 5%-6% water absorbed into the brake fluid, it'd be an appropriate time to flush the system to prevent future hydraulic system component failures.
  • Don't forget, that as you push the caliper pistons back into their bores, you are raising the level of brake fluid in the master cylinder reservoir. Under certain circumstances you might push fluid over the top edge of the reservoir, thus spilling it. I have found it to be a good idea to remove some fluid from the chamber as a preventative, and then replace it later with fresh, as needed.
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