In this article we look at ways to free seized brakes on your car, van, or 4×4. “seized brakes” can often be the term or phrase given to describe a “binding brake” or a “stuck brake”, sometimes an MOT failure may list it as a “brake bind”. Generally there will be two common reasons for this:
- the brake caliper piston has become stiff or stuck in its travel within the brake caliper bore, or
- the brake caliper sliders have become stiff or stuck in their travel within the caliper carrier
Rather than making this into one big long article covering both possible causes, I am just going to focus on the brake piston in this one, and I will cover the slide pins in the next article.
Although there are many different designs of brake caliper out there, they all work on the same basic principal so the methods and techniques shown here will apply in nearly all situations, you just may need to alter or adapt them slightly to suit your own equipment. One last little thing before we get into it, be aware that in some cases a deteriorating brake hose can sometimes cause a brake to bind, so be sure to rule this out before deciding the issue you are having is with the brake caliper. Lets take a quick look at why a brake caliper piston can seize just now, so you can stop it from happening again, then we will get right on to how to fix it.
Reasons a brake piston can seize
Essentially what happens when a brake piston binds or sticks is that the piston has rusted within the caliper bore, often due to a failure of the dust boot letting dirt and moisture in. Have a look at this video for a good exapmple of a damaged dust boot:
If you listen to what he says, he mentions that he might have damaged it when pushing the piston back, maybe he should have followed this guy’s advice:
How To Free Off A Seized Brake Caliper
Right then, so after hopefully establishing why your brake piston has become stuck in the caliper, you’re going to need to sort it out. Now obviously just replacing the whole brake caliper unit would be one option, but I’m guessing the reason you are reading this is because for what ever reason you can’t do that. So lets look at how to get in to the guts of the caliper and fix the problem.
Here’s a good video which is very real world for most of us doing vehicle repairs on the driveway. There are some very good pieces of advice in this one, so have a good listen to what he says too.
If you have some workshop equipment you can use, such as an air compressor, you can use this method to force the stuck pistons out:
If you have access to slightly more specialised equipment, you can use this method. It is worth noting that if the pistons are really stuck and the above method using the air compressor (or even a higher pressure air cimpressor) doesn’t work, then you’d really want to try this way using hydraulic pressure (air is pneumatic pressure at not as forceful as the air will compress easier than hyfraulic oil):
It is a bit long at nearly 10 minutes, but I find the guy quite entertaining!
Right then, one last thing, if your brake caliper pistons are really really stuck often just getting them to move a little bit, breaking the seal if you like, will be enough to then use some force to pop them out either on or off the car. You can do this by gripping the end of the piston with some decent pliers and twisting it back and forth. You’ll need to secure the caliper so it doesn’t move while you’re doing this, and be careful not to kink the brake hose!
Well that’s about all I’ve got for this one, I hope it has helped you. If you know of any methods I have missed let me know in the comments below.