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Discussion Starter · #1 ·
Had some time to play with the calipers I pulled from a Trooper and a Passport. Couple of questions for you real mechanics.

1. Lower piston is before cleanup, upper piston is after. Hard chroming looks to be okay. What do you guys think? Re-useable?





2. The pins are quite obviously different. Does it matter which pin is upper or lower? One has a sort of spring retainer on the end, and the other pin has three flats machined on the pin.



3. Looking at this photo, there doesn't seem to be any logic to the pin placement in regards to upper or lower. The Trooper calipers are on the left, and the Passport calipers are on the right. The pin placement is as I pulled them from the trucks.



Thanks for any feedback.
 

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The pin placement is important. One is a guide pin and the other is a lock pin. The previous owner of a 95 rodeo that I used to have had reversed the pins and jammed up the caliper. I found this out the first time I replaced the brakes, had to replace the caliper.

Scott
 

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The Guide Pin goes into to upper hole by the bleeder which is on the top when the caliper is mounted. The Lock Pin has the rubber tip and goes into the lower hole. I would junk the piston because the plating is damaged and will just rust up again.
 

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Discussion Starter · #4 ·
Okay, so the guide pin is the one with the machined flats and goes into the upper hole, and the lock pin with rubber tip goes into the lower hole. Great info. Thank you. Looks like someone in the past got those pins installed incorrectly.

The gunk on the pistons was not rust. It looked like a build up of oily dirt, like the rubber boot had a tear or something. It came off quite easily with a blast of WD and a wipe of the rag. The chroming is hazy though. I'll take your advice on replacing them.

Next question is are replacement caliper pistons available? Guess I'll do a google search.

Thanks again for the help.

Buster28 said:
The Guide Pin goes into to upper hole by the bleeder which is on the top when the caliper is mounted. The Lock Pin has the rubber tip and goes into the lower hole. I would junk the piston because the plating is damaged and will just rust up again.
 

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Take some emory cloth and clean those pistons up and they'll be fine! Before you put those back on, pump a couple of reservoirs of brake fluid through those lines and get some clean fluid in there.
 
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