Topic: Brake Caliper "Sliders"

[No H2O]

Other than those that have opposed piston calipers on our cars or motorcycles, the vast majority of brake calipers uses sliding pins.

I just serviced a friend's car. One of the front brakes was getting far warmer than the other brake hat on the disc, a sign of a caliper piston or sliders not being as free as they should be (almost always the sliders).

Sure enough, the top pin, the one with the shaved down lengths every 120° was fine, but could use a cleaning and lube. The lower one was in rock tight and needed Vise Grips on the hex to pull it out (it wasn't seized), but that rubber at the tip must have swelled likely due to some clown in the past using a petroleum grease causing the rubber to swell instead of a silicone grease.

The QUESTION IS, what is the purpose of that rubber sleeve? I have my own ideas based on 50+ years of wrenching, just want to know if your thoughts line up with mine. Or better yet, a factual article on the net somewhere.

Needless to say, the front brakes are completely frictionless now till you apply the brakes. Same for the rear brakes that I did over a month ago. Being a FWD, the rears spin freely (5+ turns) with a flick of the wrist as they should.

[ktm525]

Best I could determine was noise but no definitive answer. I went through stuck pins on the LR4. No fun.

[Dante]

I had exactly the same experience with the front calipers on my friend's Forester two weekends ago. The lower pins were stuck to the point where we had to wrestle them out with all sort of tools and methods. No sliding whatsoever as you can imagine.

The rubber boot was melted/torn inside to pieces. The mechanic who did the previous brake job used copper anti-seize. We got some generic pins from CT as an emergency measure, but I wasn't too keen on their fit/movement either. I recommended him to buy the OEM (inexpensive) and replace them next time when the wheels are off (winter tire swap the latest).

[ktm525]

With pin bushings always silicone. No exceptions.

[Dante]

With pin bushings always silicone. No exceptions.

I know but tell that to some mechanics LOL...they will think you are an a$$hole customer who "knows it all".

[rrocket]

It is, essentially, a vibration dampner.

[No H2O]

With pin bushings always silicone. No exceptions.

I know but tell that to some mechanics LOL...they will think you are an a$$hole customer who "knows it all".

KTM & Dante, I have heard that so often and it is exactly why I do it all myself to a far higher level than they do. Strange that I do not have a certificate hanging on my wall telling me I know what I am doing.  The only trade I need is a gas fitter to sign the card for insurance reasons when I am installing a gas HWT or furnace.

[No H2O]

It is, essentially, a vibration dampner.

Exactly what I was thinking. In the few cases I have come across where vehicles had that type of pin, little wonder the calipers were not free-floating. Luckily I caught it in time and both pads on each side were equal in thickness. Got to use them again and the dics were fine. Replacement in a couple of years...maybe.

Thanks everybody!

[Dante]

With pin bushings always silicone. No exceptions.

I know but tell that to some mechanics LOL...they will think you are an a$$hole customer who "knows it all".

KTM & Dante, I have heard that so often and it is exactly why I do it all myself to a far higher level than they do. Strange that I do not have a certificate hanging on my wall telling me I know what I am doing.  The only trade I need is a gas fitter to sign the card for insurance reasons when I am installing a gas HWT or furnace.

That's what I do too for brakes (and everything I can do on the driveway) and it's not to save money but to do it right. Another thing I think some mechanics don't do is thoroughly clean the bracket. The pads on my buddy's car were rather stuck too. They didn't come out without some effort which is also not normal. We cleaned the bracket until the pads slid in easily and it took some elbow grease and time to do so with a grinder and a wire brush attachment.
This is an 11-12 years old car on original calipers so rust build up is expected.
Oh, some bolts were over tight... We torqued them to spec...

[ktm525]

How many mechanics check for runout after they have installed the new rotor on the hub? Probably close to zero.

[No H2O]

That's what I do too for brakes (and everything I can do on the driveway) and it's not to save money but to do it right.

Exactly. Saving money is just a bonus.

Another thing I think some mechanics don't do is thoroughly clean the bracket. The pads on my buddy's car were rather stuck too. They didn't come out without some effort which is also not normal. We cleaned the bracket until the pads slid in easily and it took some elbow grease and time to do so with a grinder and a wire brush attachment.
This is an 11-12 years old car on original calipers so rust build up is expected.
Oh, some bolts were over tight... We torqued them to spec...

Too many insert new stainless steel shims without cleaning the pad carrier bracket they press into. I remove all the rust with a fine file and on all three sides and then coat the pad carrier with zinc anti-seize to slow down rust where the shims sit. Then I press my "new" stainless steel shims into place. Pads slide right in without a struggle and are free to move.

I also pump out my caliper piston about 75% of the way, lift the rubber boot and then clean the inside with Q-Tips (about 30+) and isopropyl alcohol till the Q-Tips come out clean. Then I apply silicone grease under the boot. My friend who has my 1999 CR-V now still has the same calipers on it at 25 years.

Of course this isn't a one-hour brake job but it is done right and I only need to do it ever 5 years.

[No H2O]

How many mechanics check for runout after they have installed the new rotor on the hub? Probably close to zero.

Too many forget to take a Scotch-Brite pad on a drill and clean the rust between the inside of the brake disc hat and the hub surface. Obviously with a new disc, that is not an issue, but the hub surface is.

BTW, after doing a brake job I always run on the highway and with nobody behind me, I coast to a stop just using the hand brake the last few feet. All brake hats should be at ambient temperature plus a couple of degrees higher...basically cool.

[Firm]

How many mechanics check for runout after they have installed the new rotor on the hub? Probably close to zero.

Too many forget to take a Scotch-Brite pad on a drill and clean the rust between the inside of the brake disc hat and the hub surface. Obviously with a new disc, that is not an issue, but the hub surface is.

BTW, after doing a brake job I always run on the highway and with nobody behind me, I coast to a stop just using the hand brake the last few feet. All brake hats should be at ambient temperature plus a couple of degrees higher...basically cool.

Hub surface is a big one, a good % of 'warped' rotors out there are because some either didn't properly clean the hub surface, or they slathered on a bunch of anti-seize (or similar) in big globs and it causes the rotor to sit very so slightly unevenly on the hub, as the rotor wears, more and more runout develops.

I've been in the industry my whole career - never seen anyone measure runout after installing on a vehicle, though technically every ASE instruction tells you to.

The other thing to be mindful of with pins like the ones pictured in the original post - you want to make sure you have just a very little amount of lube on the tip past the rubber. People get sloppy and will install the pin with a big glob of lube on the tip, it can create hydraulic pressure when you push the pin into the bore, which creates drag.

[Seafoam]

 What brand of lube do you guys use for the pins ? That stuff can be quite pricy for just a little can.

[Dante]

I currently use Permatex (orange), but they have new formulas now.

[ktm525]

Syl glyde. Don't use anything synthetic/ceramic. 100% silicone.

[Firm]

Heard good things about Syl Glide. I have a few bottles of the Permatex stuff I've been using for years, one bottle seems to last forever as I probably only do 3-4 brake jobs a year. I prefer the purple to the orange, easier to spread.

[ktm525]

I'm sure you can get away with Permatex etc as long as rubber bushing caliper pins are not involved. The silicone does not dry out thought 2-4 years it's still a gliding.

[Firm]

Yeah, I've never had a problem with it. My driving style tends to be 'easy' on brake wear, so I tend to get a long while out of my brake jobs. The front on the Escalade haven't been touched since I did them in 2016; Wagner rotors and pads (which were good quality back then...not now), I regularly inspect them and they're still easily 60%+ and have about 100K kms on them. Been through 2 sets of rears in that time, but that's more so a function of the way that trucks braking system is setup with some rear bias. 

[No H2O]

What brand of lube do you guys use for the pins ? That stuff can be quite pricy for just a little can.

I use VersaChem "Synthetic Caliper Grease & Brake Quiet", an 8oz/227g bottle that I bought well over 20 years ago. I use it on the pins and under the caliper piston boot.

I also have a bottle of Permatex "Ceramic Extreme Brake Parts Lubricant", a 100% Synthetic Formula - -50F to 3000F so they claim.

The price of a bottle is a mere fraction of what a brake job costs and if you know what you are doing and are particular, your brake job will be better than the job done in a shop.