Disc brake pin

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Nov 9, 2008
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Toyota seems to call this an "Pin, W/Hole(For Front Disc Brake Anti-Rattle)", I call it a pain in the rump... If i ignore it for more than a year it requires hammering and an hour's worth of effort (per side) to drive them out.

In the past I would just replace after a couple of years, they are soft steel and so they bend the tip; but after working on them yesterday, I am struck by the fact that they are now reduced diameter and looser in the caliper now. Thus they might not seize too quickly this time around? I still feel like I should get some spares to have on hand, but that leaves me wondering: just what is the downside of these pins having a loose fit? No braking force is transmitted through these pins, rather, they just hold the pads in place (instead of removing the caliper to change pads, you can just drive these pins out and it's supposed to be a quick brake pad change--yeah right!--I always have to hammer out the pads as they seize to the caliper too).

I've been applying Honda M77 moly paste to these pins (and the sliding surfaces of the pad ears), to try to slow down the seize; honestly, it was my fault that stuff got stuck this time around, as I neglected to bust everything apart last spring (it was 2 years and 12k since I last did this job).

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Wow, that's rusty! Not sure how long it would last, but I'd think about painting them or otherwise getting some sort of coating on those.

It's not unlike the Bendix design on my 82 Mercedes, but those use cotter pins to keep them in place. Those are always marginally hard to drive in and out, so I use a small punch.

I put anti seize in the holes to keep something there. So far so good but the car doesn't see a ton of water.

Given the level of rust and the number of times removed, are you sure it isn't the hole diameter that has enlarged?

Being loose, to me, would indicate that they are reliant on the pads being in place and either imparting some hanging downward force, or some extra friction, to keep the pins from backing out. It looks to me like they could only back out to the outboard, and I'd suspect if they went too far, they would get clipped by the wheel. Is there supppsedmto be. A otter pin or other retaining pin on those? The image from the parts diagram shows a little thing sticking out at 90degrees...

The pins on the top and bottom of your pic look different lengths. Is that correct?
 
Pins are the same length. Or they were until I hammered on them. I did use a drift on at least one of them (I used pliers until I remembered I had drifts, yeah not very bright of me). They have (or had) a taper on the backside.

The hole diam is probably getting larger by now. AFAIK they are original calipers. They certainly are an interference fit, until the pins are driven out, then they are nice loose fit. There is a clip that retains them, I can't find a good photo though.

I'm not sure how many times the pins have been replaced, probably 3 times if I had to guess, maybe more--I bought it at 73k with new pads, and I have to believe the prior owner must have done brakes at least once. They sure don't last long on this truck!

Would copper anti-seize work better than M77 here? I wonder if that is my mistake.
 
The clearance between the pin(s) and the hole(s) should be relatively "loose". I mean, not sloppy loose, but not tight or interference fit. The issue is almost certainly rust developing on both surfaces which eliminates the clearance. I've seen videos of people doing brake jobs on piston designs like these but in areas w/o rust and they tap them out with ZERO effort.
 
I live south of you and I haven't seen the pins rust like yours on any of my Toyotas. I assume you are getting Toyota OEM pins based on the picture
you have given us. I am a lube nut but I don't lube those particular pins. I sand them a little to get them shiny and slide them back in. I don't know what
to tell you. Maybe coat them with some type of thin rust preventative? I don't think I would use any type of heavy grease.
 
PasteLube, will have to look into that.

And no, I would not call it a good design for the rust belt. I think if someone was doing pads on a yearly basis (or lived in the south) it'd be fine, or better, but for me it's not a very good design. I've found the single piston setups have less problems on my vehicles--not issue free, but not nearly as bad.
 
Many years ago when I first picked up my 4Runner I had to deal with those pins and it's alot harder than it looks! I had no air tools and no matter how much pounding, I could not get them out! I gave up and just bought new calipers. I now lube these every season when I swap my tires.
 
The best solution is to pull the pins out at least once a year, clean, lube and reinstall. I got the point where I neglected mine for a couple of years and had to cut them and use an air chisel to get them out.

New pins are cheap too. I have gotten to the point where once they become at all suspect, I buy new pins. I have used aftermarket and Toyota, both seem to work the same despite being not identical. A buddy of mine with a Taco does the same and he's had his for almost 15 years in the rust belt with no issues.
 
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