About Compressing a Caliper

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How to Compress a Caliper....5

Learn why its important to compress the caliper and how its done when changing the brake pads on a car with expert automotive tips in this free online auto repair and car maintenance video clip.

Part of the Video Series: How to Replace Rear Brake Pads
Promoted By Zergnet


Video Transcript

MARK BLOCKER: Okay. In this segment, we're going to cover compressing the rear caliper. The rear caliper on this system, because the parking brake is integrated with the caliper is different than your standard brake caliper where you use like a pair of pliers or maybe a C-clamp to compress the caliper in where it's just hydraulic fluid behind it and you're just squeezing-- compressing the caliper back in, so you have enough turns to put your pads back in. Because this system uses a parking brake integrated with it, the center piston actually, for the parking brake application when you apply park and the brake lift up on the handle, it pulls on a cable and that cable pulls a ratchet which turns the piston. It actually forces it out into the--make contact with the brake pad under the rotor to give you the rear brakes for the parking brake application. And they use a mechanical device rather than trying to use a hydraulic device. Whereas you put your foot on the brake, it gives you hydraulic pressure to stop the car. You have to continue the hydraulic pressure there in order to lock the break or hold pressure against the brake. That can't be done when you're out of the vehicle in those methods. So, they came up with the ratchety mechanical mechanism to hold the piston against the brake pads to give you pressure there for you for use of the parking brake. So, you simply just can't squeeze that back in like you would a standard caliper. That one has to be twisted and turned as it's pushed in. It's kind of a simultaneous thing where you're twisting and pushing inward at the same time. They have a specialty tool designed specifically for that. It can be gotten at most any auto repair place where you pick up parts or tools and equipment for automobile repair. It's a small cube that has various points of contact on there for depending on your point of application, because this system is used on a lot of the newer cars with rear disc brakes. This tool provides you with the different fasteners or different teeth requirement, a lot of them are spanner type socket wrench. But it gives you an assortment of six different combinations depending on the application of the vehicle that you're using. In this particular one, there's two different sides that have round pivot points on it, and this is the narrower of the two sides that I'm going to use for this caliper here. The tool would cost between $5 and $15. It's highly recommended. The money you're going to save by doing your rear brakes by yourself the first time will pay for the tool. If you can't find it, don't have accessibility to it, can't get it or for whatever case you don't have it with you, and at that time, there's a couple of other methods that you can use to press that caliper. One of which, if you just took a large channel lock if you look at the caliper itself, the piston has got notches in it. There are four of them. And that's the selection you want to choose, whichever application, drive or fits in those correctly, and fits snugly, and you'll turn it with an extension and a ratchet. If you don't have that available, you can grip it on the outer edge only, just out here on the very edge. You don't want to go pass where the rubber boot is or drip at all where the rubber boot is; that's going to damage a portion of the piston that uses a seal for the boot to prevent dust and contaminants from getting inside caliper assembly. And you just grip it on the outside by the very edge, and as you're twisting you want to turn it in counterclockwise position, you also want to be providing the downward force. This is kind of tricky and cumbersome, and it's going to slip off on you if you're not careful and you could pinch your finger or thumb. So if you use this method, go very slowly and be very careful because you don't want to mar up those surfaces and you don't want these pliers to slip off and grip or injure your fingers. That's one alternative method. Another alternative method you could use is a small wrench that's just large enough to span the distance between the two points and big enough to have to make contact into the two grooves, then you push in with this, using a pair of pliers or a presser and slide it on the end of the wrench, that's where [INDISCERNIBLE] in the grooves and that gives you the leverage that you need. And then you could twist and turn in with the piston in that format. Okay, now I'm going to show you a procedure for compressing the caliper and I've given you a couple of different options. If you don't have the specialty tools that are readily available, we'll go ahead. That will conclude how to compress the piston in the rear brake caliper with the parking brake mechanism. Watch our next segment, we're going to do the actual compressing the caliper with the specialty tool, rear brake system with parking brake.


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