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Car Forum / Chevrolet / Chevrolet Trucks / December 2004brake pad installation
Hi All: Dumb question (maybe). It's been years since I did this to an old Datsun so I cannot remember. When you install brake pads for the front disc brakes, I believe you need to losen up the caliper so that the pads can be removed. Then you put the new ones in and tighten up the caliper. I remember watching someone a few years ago that actually had to do one extra step to the caliper after putting in the new pads. I can't remember if he had to squeeze the calipers together and then tighten them. I don't think it's enough to simply put the pads in and tighten the caliper. What are the proper steps to installing front brake pads in my Chevy truck (or even a Chevy Barretta)? thanks again!!! 1: Take off the wheel. I suggest jacking up the truck first. 2: Fight with caliper slide bolts made out of soft metal that have torx heads on them. Round them out, and try to pound in the next size up. Expand it past that, and then buy bolt-outs to finally get them out. 3: Decide that you should replace the slightly cracked flex hose, destroying the hard line causing the need to put in a new hard line from proportioning valve to the frame, then put in yer new flex hose. 4: Try to lightly tap out the banjo bolt on the caliper and have it snap off, and need to borrow the wifeie's car covered in grease because calipers weren't in the plan (like $11 each at the zone). (in a pinch you can bleed at the flex hose, I've done it and when I finally did it right I noticed absolutely no difference.) 5: Install new calipers, auto zones "performance friction" lining. Instillation is the reverse of removal, make sure to put brake grease on everything that moves in relation to something else, besides the actual pads.... caliper slides, caliper cylinder, etc etc..... Yea... that's about how it goes on every f/s truck I've worked on. Hope this helps. GMC Gremlin > Hi All: > [quoted text clipped - 11 lines] > > thanks again!!! Pads are fairly easy in both vehicles. I believe the step you are recalling it to reseat the piston back into the caliper after you remove them.. You will not be able to fit the new pads over the rotor without doing so. You can use an old pad on the piston and a "C" clamp and SLOWLY seat the piston. OR you can buy a special tool that fits inside the caliper and will do the same thing. DO NOT REFILL the break fluid reservoir until each side has been done. DO NOT remove both calipers from the rotors and then press them. If you do, ,you will force the opposite piston out on the ground and make a big mess, and then have to rebuild the caliper and then bleed the brakes and all that jazz..... Basically, do one side at a time, from the time the wheel comes off until the time the wheel goes back on. I also use disc brake quiet on the BACK of the pads, and grease the caliper slides. when all is done, check the fluid level. THEN before you even think about putting the key in the ignition, pump the brake pedal, and bring back the feel. It will go to the floor the first time you hit it, and I'll tell you it is a heart in the throat moment if you forget to pump them before you try to take off. As for the Beretta, I would replace the rotors. They are cheap, ,and quick to do (two extra bolts) and you will not have to wait on a machine shop to cut them. Basically a little more cash, BUT hours saved. Truck, take the time and get them turned, and repack the bearings while you are at it. You will feel a world of difference if you take care of the rotors too. Make sure you press the pistons in at least ONE of the calipers before headin to the machine shop. When you get back, start with that side and carry on. Oh yeah, , Gremlin is right.....be carful of the bolts that hold the caliper in place. Depending on the year, they could be either torx OR hex... (allen key) Have fun Eightupman > Hi All: > [quoted text clipped - 11 lines] > > thanks again!!! Also I have heard it is recommended that you let the fluid out through the bleed valve instead of pushing it back (through the anti-lock system) into the reservoir. > Pads are fairly easy in both vehicles. > [quoted text clipped - 54 lines] > > > > thanks again!!! > Also I have heard it is recommended that you let the fluid out through the > bleed valve instead of pushing it back (through the anti-lock system) into > the reservoir. Absolutely true ABC, the garbage that collects in the calipers could mess up the seals in the anti-lock valves and pumps. On a rear wheel anti-lock set up, not awfully an expensive lesson, one a four wheel anti-lock, it can be a very expensive lesson, with the all in one set ups where the anit-lock valves, pumps, accumulator, brake booster and master cylinder are one unit, possibly more than the car is worth. Also anti-lock or otherwise, if more than two years the brake fluid should be flushed, and the entire system re-bleed. Course I am sure there are some here that will say that's being anal. Whitelightning OK, curiosity has got me. How can a sealed system become contaminated with the "garbage that collects in the calipers".? I can understand fluid needing to be changed regularly due to age, overheating, deteriorating hoses or lines. Unless there is a particular valve or component in the ABS system that is not partial to negative(reverse) pressure (which I am not saying there is NOT one, I just don't recall one), I see no reason to possibly break off a bleeder screw and cause a bit more work or inadvertently introduce air into the system. Eightupman > > Also I have heard it is recommended that you let the fluid out through the > > bleed valve instead of pushing it back (through the anti-lock system) into [quoted text clipped - 10 lines] > anal. > Whitelightning IMHO it is very similar to the action of the engine pistons. As the piston moves in and out any crap that sticks to the piston can potentially work its way back into the fluid. The piston is the interface from fluid power to mechanical power. The system is not perfectly sealed or there would be no room for the motion of the fluid. Mike > OK, curiosity has got me. How can a sealed system become > contaminated with the "garbage that collects in the calipers".? I [quoted text clipped - 45 lines] >> entire system re-bleed. Course I am sure there are some here that >> will say that's being anal. Whitelightning Not buying it. Engine pistons are MADE to reciprocate. An engine piston is created to take the pressure on its face. The oil rings (yes I meant rings... plural) prevent the oil from entering the cylinders and in fact scrape the excess oil away on the downstroke. The other two rings seal the cylinder to maintain pressure and to prevent blow by. As the rings wear, oil consumption can increase, and will loose compression. Furthermore, the fluid pressure (brake system) is placed on the back of the piston in a single holding stroke where the seal is made to prevent fluid from expelling forward. The master cylinder is where the return of the fluid takes place. It is not filled to capacity, and the rubber diaphragm in the lid is there so fluid movement can occur. Eightupman > IMHO it is very similar to the action of the engine pistons. As the > piston moves in and out any crap that sticks to the piston can [quoted text clipped - 12 lines] > > a bleeder screw and cause a bit more work or inadvertently introduce > > air into the system. <snip> All pistons reciprocate. Some faster than others. Motor oil lubes the cylinder walls in the engine. Brake fluid lubes the cylinder walls in a caliper or brake cylinder. It doesn't matter which rings you are talking about they all need some kind of lube to slide in the cylinder. You should always bleed off the crap in the low points of the system when you service the brakes. It does really matter how it gets there. But, the crap is there and should be purged. > Not buying it. Engine pistons are MADE to reciprocate. An engine > piston is created to take the pressure on its face. The oil rings [quoted text clipped - 32 lines] > > <snip> > OK, curiosity has got me. How can a sealed system become contaminated with > the "garbage that collects in the calipers".? I can understand fluid [quoted text clipped - 6 lines] > > Eightupman Well lets see the master cylinder is vented to atmosphere(I know the cap has a rubber gasket but trust me on this, its not an air tight seal). Brake fluid is not a petroleum product, but rather a mix of glycerol's, and is hydroscopic, that is to say it absorbs moisture like a sponge. The moisture laden fluid is heavier than clean fluid, it settles to the low points in the systems, calipers and wheel cylinders. This moisture laden fluid causes rust. As the caliper piston slides back and forth across its seal it wears bits off the seal, which mixes with all the other garbage in the caliper bore. And in all the systems I have worked on I do not remember a valve sensitive to reverse flow ether, would kind of defeat the purpose of anti-lock brakes if there was one as fluid is moving back and forth every time the pedal is pressed and released, and hundreds more times per minute when the system becomes activated. The tolerances on the valve bodies is were the problem lies, the garbage can jam a valve. The brake fluids hydrosopic properties are why the stuff should be replaced when the brakes are done. The manufacturers say every 2 years or 24,000 miles. 1% moisture content will lower brake fluids boiling point almost 50 degrees. At 6% dot 3 brake fluids boiling point drops from 475 degrees to 255 degrees. dot 4 drops from 480 degrees to 275 degrees. I don't think I would want to come down a long grade loaded heavy with that in my brake system. Silicon brake fluid wont adsorb moisture, instead you end up with pockets of water in the system. The other problem with silicon is that it foams, and as such is not recommended for 90% of the current anti-lock systems. I've often had a good chuckle watching people change parts on a brake system. They put nice new hoses and calipers on and then bleed the brake system, pushing all the nasty stuff from the master cylinder through their nice new parts, rather then empty the master and then clean it out with a clean rag, re fill and then flush.. when done get you a nice piece of 3/4" dowel, or an old broom handle or even your snow brush for you northerners and prop it between the seat and the brake pedal so the pedal is depressed about an inch. This will move the master cylinder pistons just past the compensating ports and keep the system from going dry while your working on replacing wheel cylinders, or hoses or calipers. http://www.shotimes.com/SHO3brakefluid.html is a good page on brake fluid. Be happy you have Chevys. Little known fact, Honda uses a natural rubber diaphragm in their power booster, if the master cylinder starts leaking fluid, the booster has to be replaced as well. Whitelightning OK, you have not said anything that I didn't already know. Yes, brake fluid is hydroscopic....anybody with schooling knows that. Moisture brings down the boiling point....obviously. Replacing the brake fluid when replacing hard (hydraulic related parts) I'll buy that for a buck. It's not that hard to run new fluid through the system MOST times. So this guy wants to change pads...and perhaps service the rotors. No where does he mention replacing calipers. Still no reason not to press the pistons back into the bore without cracking bleeders. For SNG's I pulled out the manual for a 1996 Beretta/Corsica (with ABS) and checked out the brake pad/caliper R&R procedures. And lo, ..."remove half the fluid from the master cylinder" I will assume that this will prevent spillage. 3... "lift and safely support vehicle" step 4, "Position a large "C" clamp over the caliper with the screw end over the outboard brake pad. Tighten clamp until the caliper piston is pushed in enough to bottom the piston." Nothing about opening bleeder screws, or warnings about "garbage in the calipers" For the record, I never said your way is WRONG....I just don't see it your way. Many ways to get to the bottom line. Eightupman > > OK, curiosity has got me. How can a sealed system become contaminated > with [quoted text clipped - 49 lines] > fluid, the booster has to be replaced as well. > Whitelightning "Eightupman" <eightupman@newemail.com> wrote in message news:gNOvd.6392 $fQ1.519202@twister.southeast.rr.com... > So this guy wants to change pads...and perhaps service the rotors. No where > does he mention replacing calipers. Still no reason not to press the > pistons back into the bore without cracking bleeders. Several references around the net (just because it is on the net doesn't make it true but it is a reason): From: http://brickboard.com/FAQ/700-900/Brakes.htm "Editor's Note: Clamp off brake rubber line and open bleed screw on ABS-equipped cars so you don't force contaminated fluid back to the ABS unit." From: http://www.diynet.com/diy/ab_brakes/article/0,2021,DIY_13682_2277655,00.html "Important: On older brake systems, the old brake fluid from the piston was sometimes simply forced back into the braking system, rather than bleeding it off. It's critical that this never be done with ABS systems. Any debris forced back into the system could cause serious problems, necessitating in a very costly repair" ======== ======== "Eightupman" <eightupman@newemail.com> wrote in message : . OK, curiosity has got me. How can a sealed system become contaminated with the "garbage that collects in the calipers".? ========== ========== white.lightning2@verizon.net (Whitelightning) replied: the master cylinder is vented to atmosphere(I know the cap has a rubber gasket but trust me on this, its not an air tight seal). Brake fluid is not a petroleum product, but rather a mix of glycerol's, and is hydroscopic, that is to say it absorbs moisture like a sponge. The moisture laden fluid is heavier than clean fluid, it settles to the low points in the systems, calipers and wheel cylinders. This moisture laden fluid causes rust. As the caliper piston slides back and forth across its seal it wears bits off the seal, which mixes with all the other garbage in the caliper bore. <snip> http://www.shotimes.com/SHO3brakefluid.html is a good page on brake fluid. Whitelightning ====== ====== A+ :) ~:~ MarshMonster ~:~ |
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