Brake Caliper Question

The back story:
Six years ago, when I aquired my 95 Volvo 850 turbo I had to have the brakes, rotors etc replaced. Two years ago, my Passenger side front Caliper siezed up and wrecked my rotors. It was Christmas and I was lucky to get in to a shop to have the rotors, calipers etc replaced. My memory is fuzy, but for $1500 I’m pretty sure they did both calipers?
Recently I drove my car 5 hours up to visit with my girlfriends’ parents for the weekend. While I was there I noticed that my drivers side front caliper was sticking.
(steering wheel was shaking though the road was smooth, when I got out, only that caliper was hot and the wheel was covered in black dust)
It was saturday night, Sunday all the shops were closed (rural area) and sunday nightI had to be home to fly for a business trip. Being on a farm, we had some heavy tools including an impact wrench. so we jacked the car up, removed the wheel, removed the brake caliper from the roter. We used a C clamp and a metal bar to compress the piston in the caliper. Then put a block of wood in, the caliper and pressed the brakes causing the piston to expand. Compress, Expand, Compress, Expand, Compress, then Reassemble. The piston was visibly rusty where I could see it, but it moved well enough under the c clamp and brake pedal.
I drove the whole way back, everything was smooth, I was getting 24+ mpg average, I stopped to check the brake temp periodically, and its fine. Now I’m on my business trip, and when I get back home in a week I’m supposed to drive 5 hours up to my family’s place right after I return. I will have 1 afternoon where I can rush the car out to a shop, which I will definitely do, I will at a minimum change/flush the brake fluid and replace the two bolts that I loosened and reused that are supposed to be single use only.

The questions:
Could something be wrong with my master brake cylnder that’s causing the brakes to sieze up and wreck my rotors?
Do I necessarily need to replace my rotors ? (I think I caught this one right away and the rotors might be undamaged)
Do I necessarily need to replace both calipers ( I don’t drive much, remember, they should be less than 2 years old with at most 10,000miles on them,l more likely only 5,000)

Obviousl I will rely somewhat on the story I get from the shop I go to after they inspect, brakes are critical safety equipment and so I’ve shyed away from working on them myslef in the past, unlike engines, but I would like some learn-ed opinions on what’s absolutely required and what might be ‘fleecing’ here.


A caliper can seize up in several ways. Offhand, it sounds like the piston was not seized in the caliper bore.
Maybe it’s possible the caliper was binding on the sliders? Those should be serviced during caliper replacement or during any brake job even if the calipers are not replaced.

If the piston was pushed back into the bore without too much effort then I might suspect the caliper is ok and the sliders are the cause.

As a DIYer you can probably get by without rotor servicing. A shop doing the job for hire has certain protocols that should be followed.

Why can’t you re-use the caliper bolts?

If it was the outboard side of the rotor that was damaged, it wasn’t the piston that caused the problem, it was the pins (aka bushings) that the calipers float on. They are known to stick on occasion and should be lubed each time the pads are replaced. This is often overlooked.

I had a similar problem caused by crud in the brake fluid blocking one of the return ports in the master cylinder but that would cause 2 diagonal brakes to stick. If you have an internaly collapsed brake hose to that caliper it can make it stick.

Thanks oldtimer and ok4450!
The sliders were actually free moving enough that the caliper slid apart on me unexpectedly as I was removing it from the disk, I’ll take a closer look at the diagonally opposed brake roter to see if there are any signs of issues there. after seing your post abou the collapsed brake hose. I did a bit of searching online and some people have also mentioned that sometimes rust can plug up a brake hose and act as a ‘check valve’ allowing the brake to tighten and not loosen up. As of now I think a partial blockage or collapse in the brake hose sounds like the most likely culprit.

It’s a 20 year old car…How many miles on it? Has the brake fluid ever been changed? Do you have the work-order from the repair a year ago?

the caliper bolts can stretch, causing a caliper to drag

Brake lines can collapse internally, because they are rubber and deteriorate over the years. I would change them and lube the caliper pins.

Changing ALL the rubber flex-lines is a good idea at this point…The calipers must be free to move back and forth on their mounts, not rusted solidly in place…Think about the term “Floating Caliper”…The caliper pistons must be free to move (retract) with only modest pressure from a C-clamp… They should move smoothly as you turn in the clamp with very little force…

A complete brake restoration on this car, new everything, would cost more than the car is worth…

I’ve been in your position with a 1976 Fiat. I got so I could pull the front caliper, run the piston in and out 10X and be roadworthy in 15 minutes. It would last 6 months and I’d have to do it again. After 2 years got sick of it and threw a new caliper on it. Never had a problem with the other (front) caliper.

I would inspect and/or replace the piston seals. They are what returns the piston in the cylinder (and thus releases pressure on the pad) when brake pressure is released. As the piston moves outwards from its static position (1) the fluid seal is deflected (2). When the hydraulic pressure is released the fluid seal regains its static position, moving the piston back and providing clearance at the friction pads

@Mechaniker‌, I’d just go ahead and replace the seals. I can’t see going that far into the brake caliper to simply inspect the piston seal and re-use the old one… Ditto for the dust seals.

If you’re going to overhaul the calipers on the bench, may as well replace the brake hoses

Thanks all for the advice! Cycling the piston with a C clamp was ‘easy’ and the floating slides move easy too, brake hoses seem relatively straight forward. I do have all the records for the work I’ve had performed, but they’re at home and I’m travelling now so I can’t check the detailed line items, but I will definitely look to confirm the age on the calipers when I get home. The independant shop I took the car to two years ago are super perfectionists so, I’m pretty cerain they replaced the brake fluid when they replaced the rotors that were destroyed when the passenger side calipers siezed up on an 8 hour drive and I didn’t notice (and I suspect did everything in symetrical pairs) they did a transmission fluid flush at that time too and then gave me an itemized list of ‘you should plan to fix x, y, z but you can wait a little while’. I’ve been working my way through the list slowly myself because its hard going to a shop to justify so much expense when the blue book value is so low. Even when I’m lusting after a shiny new car, I can’t really justify it, I’d need to shell out a whole lot more money to buy a car with even half the features in similar condition to this. So, in the past two years I’ve done the PCV, odometer gear, stuck shifter button, power seat, heated seat, rear turbo seal and the power antenea cabin fan myself.

I somehow didn’d see @Mechaniker’s response in my earlier reply. I love the diagrams, they really help clarify the point. I could imagine that some crud has gotten into the brake lines, or those seals and is causing just a little excess friction or braking the vacum seal there just enough that the seals didn’t return the pistons that very small amount. Once that happened, the brake heated up, causing the brake fluid to expand a bit an seize up even more makeing the matter worse. When I cycled them with the C clamp, I probobly knocked the crud (hose or seal) loose (for now) and temporarily fixed the issue for my return drive. This will last until the crud (or some new crud) blocks something up or brakes the seal again. Likely somehting similar was what happened to @Insightful’s 1976 Fiat. Replacing the fluid, as @Caddyman suggests could alleviate the issue, but replacing the rubber parts like @BustedKnuckles and @db4690 suggest would be a good move first since the brake fluid would need replacing after that work anyways. Maybe rather than rushing out to a shop first thing when I get back from my trip, I can leave this for a couple weeks?

If so, I will order the hoses, seals, dust covers and wait for a nice fall weekend where I can put the car up and bench the calipers for a proper overhaul and do the hoses when I go to reinstall.


I’ll be a spoiler here . . .

Actually, I think you should get this handled ASAP

Here’s my reasoning . . . if the caliper is sticking or the brake hose is collapsed, the brakes will be worn down to nothing in no time flat. Because the pads will not retract, no matter what

There’s a vehicle in the shop right now with a collapsed hose. A few months ago, it came in for a brake job, and one corner was wasted. The pads on that corner were down to metal, and the rotor was worn down so bad, that it was way past saving. It was probably 1/8" below minimum thickness, almost down to the fins of the vented rotor

Whoever worked on it then did not catch the hose. They replaced the pads, rotors and calipers. They lubed all the sliders, and the caliper is not hanging up in any way.

A few short months later, it’s back with exactly the same problem. The brakes are so gone, the vehicle is actually dangerous to drive. This vehicle went from brand new pads down to the backing plate in maybe 3000 miles, due to a bad hose

Just to be clear, there is deep disagreement on this forum on whether the caliper’s piston seals are responsible for retracting the piston.

I agree they are inexpensive and worth changing because while you’re in there, you can clean any “pitting” in the piston or caliper walls.

Also, as noted, definitely replace the rubber hoses - without question.

Even though I think I ‘solved the problem for now’ and am not wearing my brakes excessively at the moment, based on @db4690’s comments and my own paranoia about brakes, I took my car into the shop this morning as I’m about to have another long drive ahead of me tonight and I’m just not quite equipped to do this work by myself right now today (simply too jet lagged from my trip and too many other errands to run today). After some investigation they’re pointing at faulty hoses in the front. They disconnected them and said that they’re not dripping as steadily as should be expected so I told them to go ahead and replace those, the fluid and the rear ones while they’re at it (based on @knfenimore and @db4690 's comments). I checked my records and the December 2012 work that was done did replace both front calipers and roters with rebuilt ones so those and the seals/dust caps should actually be in good shape @Caddyman. The same writeup mentions 1% water content in the brake fluid, so I could imagine that contributing to some crud in the rubber brake lines if there were any ferrous metal there to corrode, even thought the brake fluid was replaced then. $400 seems slightly high replace the hoses and fluid, but I’m guessing $100-$150 for parts and about 1 hour of labor from one tech with another to help out for a couple minutes to bleed the system? On a brighter note, I should be rolling over the 99,999 mile marker in less than 5 miles.


thanks for the update