Brake caliper slide pins

[steved]

How free should the caliper slide pins be? I gave one that is really free, and the others were tight... they were pretty hard to slide by hand.



I lubed them up, they at least slide. The brakes have been apart one other time... they have 180k on them, and were worn fairly evenly for those kinds of miles...



I had my 99's slide bushings swell because - used a spray lubricant... I have only used silicone grease on these.

 

[rkressg]

They should move freely. There is probably corrosion in the bushings. New bushings and bolts are about $20/side from NAPA. Just replace them. You will need to file out the junk (rust pack-out) where the bushings sit (rubber boots) to make it all fit again.

 

[steved]

The bushings look like new. The rubber must be swelled?

 

[steved]

Its hell working in an office and not with your hands... I have forgotten so much detail, it really sucks.



I had this caliper pin issue in two of my own trucks... the 94 and the 99. Its been nagging at me because I knew I had fought with this before and figured out the issue then.



Dawned on me today the answer to my problem... as soon as I bought the new rubber isolators.



The rubber isolator that the metal caliper bushing rides in gets moisture between it and the caliper. That in turn causes corrosion between the rubber isolator and the caliper, which then causes the isolator to "swell" tighter onto the caliper bushing, and ultimately causes the caliper bushing to become tight and not allow the caliper to move on its slide pins/bushings.



I remembered removing those rubber pieces, and needing to take a round file to the rust that had built up under them. Once the rust was removed, I then used never-seize to prevent corrosion again and installed new bushings with silicone grease.



So now I know what I need to do to the truck this weekend to finish it...

 

[steved]

They should move freely. There is probably corrosion in the bushings. New bushings and bolts are about $20/side from NAPA. Just replace them. You will need to file out the junk (rust pack-out) where the bushings sit (rubber boots) to make it all fit again.

When you said bushings and corrosion, I was thinking the metal slide bushing, not the rubber... you are correct in your thinking.

The Dorman kits cost me $8. 50 per end (one front and one rear) for the new rubber pieces with the brake shoe shims...

 

[MLee]

If you bathed the rubber guide in that slid glide grease (outside) before install, would the silicone repel the rusting? It shouldn't wash away. Thats a good find/suggestion Steved. To bad that when the gray matter isn't used much it becomes like tree bark

 

[steved]

I remember finding that the replacement caliper rubber isolators aren't affected by <bearing> grease and anti-seize like the OEMs are.



Silicone grease would probably do the trick, and not affect the rubber (for sure)... unprotected it lasted 180k.

 

[steved]

I just got done replacing the rubber isolators. Rust between them and the caliper was the issue.



They were actually "froze" into the caliper, and took a little work to remove. The rust was removed using a round/rat-tail file... and there was quite a bit in there.



The slide pins are very free now, the way they should be.



I also sucked all the brake fluid out of the master cylinder, and then flushed the fluid to the rear calipers using a vacuum pump. That was the first time using a vacuum pump, and I don't know why I didn't try it sooner.



Front brakes (and rotors) tomorrow...

 

[brods]

Good post Steve. Everyone should consider checking (and cleaning the bores if necessary) as a mandatory step when doing brake service. Mine were bad enough to completely wear out the rear pads and chew up a rotor in 80K. I foolishly only kept tabs on the front pads expecting them to wear out long before the rears. A recent intermittent humming from the rear during low speed (5-10 mph) made me check them out and caught it just before it went metal to metal.



Anyhow, what specific lubricant did you use for the boots/pins. The high temp brake caliper lube I have is much tackier and thicker than the white almost powdery lube that was in the boot. I could not find any lube spec in the service manual.

 

[steved]

Permatex makes a silicone slide-pin grease... that's what I used for the pins. I used never-seize inside the bore (between the caliper and bushing).

 

[TBartlett1]

I live in the NE and stuck or very stiff caliper pins are quite common.

Several manufactures use this pin & rubber bushing design.

I've stopped using Neversieze on brakes long ago. I've found that Neversieze tends to wash out where the Permatex synthetic brake grease stays put much longer.

I also clean the rust from between the caliper slider boot & slider pins and use the brake grease there also as previously stated.

I use the brake grease at all slide points on both disk & drum. I used the rat tail file method until I found some abrasive cones that mount in an air grinder.

Dremel also sells kits with small drum sanders that will work nicely. This greatly simplifies the cleaning process & does a better job.

If there is a lot of corrosion and you remove all of the rust you could create an excessively loose fit. Remove only enough rust to allow the pin to slide easily within the rubber bushing with a little grease applied. Then grease the caliper bore and inside the rubber bushing liberally. Stuck pins due to rust will no longer be an issue.