Brake caliper bolts seized
 

Hi guys,

I've been hearing this faint clunking sound while going over bumps recently so I stopped at a shop nearby. I was told my brake caliper bolts had seized (see attached diagram). I am not very technical, but I'd like to have the forum's second opinion.

The tech tells me the two bolts on the calipers would normally slide during braking as the brake pad grips the brake disc. In my situation, both of these bolts had seized and one of them isn't sliding. The sound is coming from the gap created because one of the bolts not sliding. He also tells me this is not an immediate safety concern but my brakes aren't working at 100%.

To fix this problem, he says it is more cost effective to replace the entire caliper. What do you guys think?

Thanks.

I had this happen, not fun.
The cause can usually be traced to the little rubber boot that goes around the slider pin, if that guy gets the slightest of tears (it can dry out and crack) and moisture gets in there, it kills the lubricant and the pin seizes.

Best bet is to remove the caliper, get a bench clamp, vice grips LOTS of ____ spray (the stuff you use to break rusted bolts off, I forget the name, auto stores will carry it) and then let that stuff soak for a while.
once that's happened, slowly try to work the pin out. Make sure you are pulling that pin STRAIGHT because if you snap it, your'e fucked.

I managed to get mine loose with LOTS of carefully applied brute force, I replaced the rubber boot and the slider bolt and the brakes have been great ever since.

If the caliper is seized, I would definitely get that resolved soon as it'll lead to uneven braking and in a hard stop situation the car could pull in one direction (as only one brake is fully engaging) and that could be a safety concern.

good luck, let us know how it goes.

A used caliper can be had for under $60.

I had two seized slider pins on one of my front calipers on my Infiniti. I took some PB blaster and about 15 minutes of wiggling with a channel lock, and I freed it. I cleaned the slider pin with some silicon oil and a Scotch Brite pad, then cleaned the inside of the hole with silicon and a pipe cleaner. A bit of scrubbing got all the corrosion off. I made sure it was lubed with brake grease and assembled it together. It has been working fine for a month with no clunking or uneven wear.

Try that. If it doesnt work, take a torch to it. If not, then swap the caliper out.

I believe there is a rebuild kit available. I don't have the part number atm.

Hey guys, I appreciate the prompt response. Gathering from your answers, from the shop's standpoint, it seems to make the most sense to simply replace the calipers rather than spending the labour hours on trying to get a few bolts released.

Since that shop didn't charge me for looking into it, I just dropped off my car at a Mazda dealership during my lunch break for them to diagnose and get a second opinion on this clunking sound.

EDIT:

I just heard back from the dealership. They found cause of the clunking sound to be the loose/worn Racing Beat sway bar links. I asked them how my brakes are, they said they didn't check and it'd be another separate diagnostic fee if they were to check. I am thinking I should see it for myself, how can I proceed about seeing if my caliper bolts are seized?

So I removed my wheels and tried to see if seized slider bolts is a problem that can be observed visually. I spun the brake discs and they turn fine, and I grabbed onto the brake discs to shake them, nothing happened. Not a very fruitful attempt... so if anyone knows how to determine if slider bolts are seized, please let me know. Thanks.

Take the caliper off and try to push/pull the bolts; they should move.

Mine siezed in 2007, took them apart, removed the corrosion and regreased with a silicone base grease. Still good today.

^what Stealth said. I'd do it soon as you can as a stuck bolt can cause uneven wear on the pads as only one side of the pad is moving back and forth. So take the caliper off, and check the bolts (pull them **all the way out of the caliper** to see what their situation is, then check the pads as to even wear on all four edges. When this happened to me, the pads were toast because of this uneven wear - if you put them back after freeing up the bolts, they'll just assume their previous slanted position.

Got exactly this problem... was changing the pads today, upgrading from (previous owner) Sumitomo to HP+. I had a hard time to get the caliper out to begin with and then when I saw the pads I knew something was wrong; normal wear on outter pad, inner pad had 1mm left on it!!!

With the lower slider pin seized there was no possible way to get the caliper back on with the new pads. Since it's a 17mm head I was able to make it turn with the rachet, but never to get it out there. Now I'll try to find a used caliper or go see a mechanic if he can pull it out :(

Did you experience any noises due to the caliper bolt seizure?

Yes I sometime had a clunking noise, not sure if it's the same as yours or if it's even related, but under braking a would get a "clunk" before complete stop and then another "clunk" while accelerating.

To verify if your slidder pins are seized, take out the 2 caliper bolts (14mm), the ones you circled in green, take the caliper out and there they are, circled in red. Verify if they move freely, if they're stuck try rotating them with a ratchet (17mm) and you'll have an idea of how bad they are. Mine was completly stuck, had a hard time to make it rotate.

My clunking appeared under different circumstances. My clunking would appear when going over certain bumps. Not all the bumps. Anyway, my problem is fixed now. I didn't need to get my calipers replaced.

Caliper siezed on me.
 

My driver side caliper also sized when I changed the brake pads last Saturday. Took it to the dealer and slap me with a $750 to replace it!!! Bullshit! Looked online and bought a used on for $60. Now can anybody show me a thread on how to remove and replace the caliper, pics, handbook? Its it just a few bolts to remove or something. If anybody can help out that would be great.:rock: