How To Repair A Brake Caliper
It's a beautiful spring day, and a perfect time to break the winter seal on the garage and drive around in your classic Corvette, vintage motorcycle or whatever pride and joy you lot happen to take stashed inside. Off with the cover, and the engine turns over willingly, thank goodness. A quick warmup and y'all're off for a loop around town.
All of which is fine, until the engine seems a little ... reluctant to maintain speed. As you plow a corner, y'all catch that unmistakable whiff of burning sweat socks--y'all've got a dragging brake caliper. Sure enough, ane of the front end wheels is too hot to touch. Y'all limp the few blocks home at depression speed. At present your Saturday morning drive has just mutated from a fun-filled jaunt into an afternoon's worth of work chasing down a replacement caliper. A quick trip to the automobile parts store, followed by a round of telephone calls to dealerships and stores within an increasingly large radius turns up nothing. Yous'll have to rebuild the caliper yourself.
Near restriction calipers that fail get replaced with either a new office or a rebuilt one. Indeed, we picked up a rebuilt caliper for this story at the local NAPA store. Industry-wide, it's common practise to return used calipers to a cardinal rebuilding station where the caliper assembly is rebuilt. It will be stripped to the basic casting, cleaned of all vestiges of route grime past automated equipment, and glass-bead-blasted or shot-peened to remove any and all corrosion and rust. After a quick inspection, it'southward reassembled with a new piston, seal and bleeder bolt. Inside the box with the like-new caliper assembly, yous'll find fresh sliding pins and any other hardware that should be replaced--and sometimes, new pads also. All you demand to do is install the caliper, drain it, and y'all're back on the route in a few minutes. Oftentimes, the modest price of this rebuilt assembly is less than the over-the-counter price of the aggregate parts you'd accept to buy separately to rebuild the unit yourself. No wonder pro mechanics rarely carp to rebuild calipers anymore.
Simply you've gotten the bad news from at least a one-half-dozen countermen in the concluding hr--no rebuilt, or even new, calipers until the centre of side by side week. And that scotches your plan for traveling to tomorrow afternoon'due south car testify. I savvy counterman, an old-schoolhouse guy, has a suggestion: He knows that the cylinder bore on your caliper is common to several other cars. And he does have generic brake piston seals in your size. Y'all rush over to his store and selection upwards a prepare of seals and a couple of pints of fresh brake fluid. Price: less than your lunch at the fast-food drive-through window.
One caveat: If your frozen caliper is a rear caliper, with attendant parking-brake cables and internal antipushback hardware, you'll need to consult the service manual for rebuild advice. Also, have annotation that we're talking well-nigh calipers here. If your rotors are out of true, worn besides thin or scored past the dragging pads, you'll need to remove and machine or replace them as well. Your brake organisation is not a skillful place to cut corners. Okay, I'm off my safety soapbox.
Brake Information technology Down
Offset loosen the lug nuts, cake the rear wheels and become the motorcar upwardly on jackstands. Here's your chance to interruption all of the caliper bolts loose while that caliper is nevertheless mounted to something solid. Judicious tapping and some penetrating oil should help interruption the bleeder bolt loose. Use a flare-nut wrench on the bleeder--it's less likely to round off the small-scale, hollow bolt.
Odds are, if the prophylactic flex line screws direct into the caliper casting, you may need to remove the rubber brake line at the far end get-go. Ditto when using a flare-nut wrench on the restriction line. Consider replacing the steel or prophylactic brake lines if they are older than your canis familiaris.
On the Bench
Strip the caliper of the pads, shims, springs and sliders or pins. Remove the outer dust seal, also. At present y'all need to remove the piston--simply you lot'll rapidly realize at that place'southward no style to take hold of it. Become a piece of wood slightly thicker than both brake pads stacked together. Put that wood in the caliper aft of the piston, and add together low-pressure level compressed air to the inlet port. Pop! Your piston is out. And so is your little finger if you're not paying attention. The same goes for your corneas if you don't cover the whole deal with a store towel to contain the flying brake fluid. If the piston is stuck--which is how we got into this mess--the process may take a little more than time and force per unit area. If your caliper has more than than one piston, use more woods, clamps or whatever to release one at a time.
Left: Apply some nonscratching tool, similar a popsicle stick or this nylon cable tie, to pry the seal loose from its groove. Correct: Nosotros sawed this GM caliper in half so you could see inside--this shows evidence of serious corrosion pitting in the base of operations of the bore. We cleaned information technology with 600-dust paper.
Inspect the piston. Rebuild kits usually include a new piston, merely if you're gleaning from generic parts, you may be stuck, literally. Minor surface blemishes can be polished out with moisture 2000-grit sandpaper, but whatsoever pits in the metal means replacement will be necessary. I've had replacement pistons machined out of stainless-steel bar stock for oddball cars.
To get the O-band free, use something that won't impairment the caliper diameter. Odds are, corrosion built up betwixt the piston and bore is what made things stick. Different surface damage to the piston, minor pitting of the diameter is no big deal--the foursquare-cut O-ring seals between its recessed groove and the piston, not to the outer bore. Clean up the diameter surface with wet 600-grit wet-or-dry paper, then thoroughly make clean the entire caliper of all dirt, rust, abrasives and old brake fluid with hot, soapy h2o. Some two-piston calipers may have internal prophylactic seals--so no hydrocarbon solvents, delight.
All clean and dry? Lubricate the piston with clean restriction fluid and slide information technology into the diameter. In one case the piston is squared up, information technology should slide in all the mode with moderate finger pressure. If non, find out why. Remove the piston again, install the new seal, lubricate again with fresh fluid and push it on dwelling. Add the outer dust boot, and reinstall the freshly rebuilt caliper. Repeat on the other side. Don't exist lazy and rebuild or replace but i side. Brakes should e'er be maintained as an axle set, non ane corner at a fourth dimension. Top off the reservoir with fresh fluid, and bleed the arrangement (see "Haemorrhage Your Brakes," April '07).
Once everything is clean, put it all back together. Exist sure to tidy up or supervene upon any sliding pins or raceways so the caliper tin can move dorsum and forth as the pads wear.
Brake Pad Tech
Non all brake pads are created equal.There's a pick today of various friction materials used in pads to exercise the piece of work of really stopping your car. Asbestos used to be a major component of restriction pads, but OSHA regulations now brand this carcinogen deficient. Organic materials such as Kevlar, frequently plant in OEM brake applications, stand for a compromise of pad life, braking aggressiveness, dusty wheels and racket. If you're interested in a longer-lasting pad material, wait into a premium metallic or ceramic lining. These materials can sometimes bleat or hiss, wearable out the discs faster and cover the front wheels with ugly dust. Performance cars, like that Corvette of yours, might cease improve with metallic pads. The downside is that those polished rims--aside from the price--will exist covered in grayness dust afterwards a solar day's bulldoze.
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Source: https://www.popularmechanics.com/cars/how-to/a3915/4305927/
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