I'm doing my first brake job (pads and rotors) on the Suburban. I'm on my first wheel, and was remounting the caliper bracket and cleaning the guide pins. I put fresh silicone on each pin and tested the movement. One moves in-and-out freely, the other moves, but doesn't seem to travel as far in and out. So then I kept testing it, and the more I pushed it in, it seemed like it was creating a vacuum. So when I first started, it would push out naturally. But as I kept pushing it in, it wouldn't seem to "push out" as much..till finally, it seems like it isn't responding at all. So, then I removed the pin, broke the vacuum, reinserted it, and the same thing happens...eventually, it barely moves in and out. The other pin isn't acting like this.

Is the rubber boot supposed to "push out" the guide pin? There are no tears in the boots, and they "look" fine. But since they are 8 years old, I was wondering if new boots would make a difference.

I looked at pictures on rock auto--it looks like there is a metal cylinder at the bottom of each boot that is inserted into the caliper bracket, is that right?

Is it possible to remove 8 year old boots without tearing them? I thought about removing it and spraying the cavity with brake clean to remove the old lubricant, which is black and probably not helping me. I've heard the brake clean can eat the rubber, that's why I'm asking the question.

Thanks!

 

Grease will create a suction, normal. Some caliper pins may have a rubber sleeve on one of them and they ''seal'' better.
Pins only move very slightly in normal operation. Main thing is that they move freely and are not frozen up.
I only replace the boots if they are torn letting water / salt inside them.

 

A picture is probably worth a 1,000 words. So, that left boot is the one giving me troubles. It looks like only one of those billows is flexible...the other one looks crushed. So the left pin doesn't have the same amount of in-and-out travel as that right pin. I'm guessing it's time to replace these, but let me know if I'm missing something. Thanks again.

 

Thanks repairman54. I think I might be over-analyzing this, but let me check. If I pull out both guide pins and break the vacuum, and then reinsert, both pins are about level.

Then, as I start pushing them both, one boot begins to collapse a little and won't push the pin back as far as the other.

I noticed that my interior pad had a lot less material (basically none) than the exterior pad. That's one reason I'm probably over-thinking this. However, these bushings look like a real pain to install, so I'm not trying to create a tougher job for myself if replacing these is unnecessary.

Here's a better shot of each to show the difference. I'm not having any problems from this one:





The other one starts out looking like this:




And then after about 10 pushes...it flattens out a little to look like this. Af this point, their is 7mm difference from where this pin sits vs the other side.

 

As long as you can move them by hand and they are not rusted up they are fine. It's just that one is sealing air better around the boot than the other.

 

Thanks repairman54! That's exactly the reassurance I was looking for. I'm heading back to the "shop" (aka my driveway) now. Much appreciated : )