Doing my front brakes today, one slide pin on one front brake was frozen solid. This is a 2009 Hyundai Elantra.
Thankfully, the caliper pin is terminated with a 17 mm nut head. So I grabbed my 17 mm wrench and after maybe 40 minutes of twisting, and turning, and twisting, and hitting, and turning, and twisting, I got the pin free.
So, I cleaned it up with WD-40 and re-lubed it with high-temperature wheel bearing grease and reinstalled it.
The thing is though, the other pin on the driver’s side was fine, and the two pins on the passenger side were fine?
Talk about one extreme to the next. Why is this possible on four similarly designed parts installed in two similar locations?
The stuck pin wasn’t just stuck, it was thermonuclearly bonded to the caliper bracket. What’s up with that? And yes, the rubber boot was intact.
Salt, dirt, dust, just about anything can eventually freeze a caliper. In my limited experience it’s always been after a car has been sitting for awhile.
Manufacturer quality problem. Not all pins are created equal or of the same metal compound mix. Factories source parts from various suppliers. Some are better than others and occassionally quality suffers. Swap it out for a new one.
I had that happen with my nephew’s 1994 Geo Metro once. A caliper slide pin/bolt had not only seized but broke off when I tried to remove it. Slide pin bolts for that car are kind of small. After removing the caliper I had to heat the crap out of the steering knuckle to remove the rest of it.
On most cars the pins are actually threaded into the steering knuckle (like a bolt) so they have a hex or other head on them. My friend’s Ford Explorer has drive in retaining pins instead of the threaded pins most cars use so they are certainly not standard.
It’s necessary to have a pair of flats or a hex on this style guide pin so that the bolt that attaches the caliper to the pin can be properly tightened and loosened. The pin (when not rusted into place) can freely slide and rotate within its bore. This diagram shows, from left to right, the caliper fixing bolts which screw into the pins, the caliper, the caliper guide pins, and the caliper mounting bracket into which the pins fit. Here’s a view of the mounting bracket with the pins in place and the fixing bolts started into them, and here’s a view of the of the same components with the pins withdrawn from their bores.
There are other designs with different types of pins, but this is what the OP’s car has.
I’m glad they did. Otherwise I would have had to remove the caliper mounting bracket and perform a pin-ectomy in the basement on a vice, using vice grips.
As it was, I just used a 17mm wrench and after many, many, many blows with a mallet I was able to start twisting the pin back and forth, back and forth, back and forth… at first only by 10 or 20 degrees in each direction until I worked up to the point where it would pretty much turn 360 degrees, and even then it was a bitch to get out.
If I can’t turn the pin on the car, I remove the caliper mounting bracket and clamp the pin’s hex or flats into a vise. Then, using a good amount of penetrating oil, I get a prybar onto the caliper body and carefully coax it into moving. Carefully so as to avoid having the pin break, which means getting a new bracket and a new pin. Usually once it starts to move, it’s just a matter of time working it as you did.
Once the pin is out, I clean out the bore in the caliper body with a drill bit. Sometimes I can save the pin, getting it good and clean with an abrasive disc, otherwise a new pin isn’t very costly.
It’s possible for it to be so badly siezed that the pin won’t come out without breaking. Heating with a torch is not advisable as it can alter the temper of the bracket, which can weaken it.
