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Discussion Starter · #1 ·
Hi,
I have just replaced the front disc brake pads, rotors and the rubber caliper slide pin boots on my 2008 Trailblazer, as the right front outer brake pad had worn completely away, and so it chewed up the rotor's outer surface. The inner pad still had about 1/4 of its friction pad's thickness left. The brake caliper slide pin rubber boot kit, came with orange, ribbed plastic bushings/sleeves.

This is what I bought: https://www.oreillyauto.com/detail/...sc+brake+caliper+slide+pin+rubber+boots&pos=0

When I removed the lower caliper slide pins they had a black plastic bushing/sleeve in a groove near their ends. I have been told that the bushing/sleeve is to prevent damage to the sealing surface of the rubber boot when reinstalling the lower caliper slide pins.

I removed the existing black bushing sleeves and then cleaned up those lower slide pins. Then I installed those new orange bushings/sleeves on the lower caliper slide pins. and greased them and their 'bores' with synthetic disc brake grease and I installed the slide pins back into the caliper mounting bracket.

I noticed that it took a lot more effort to move those lower caliper slide pins in and out with the new orange bushings/sleeves. So, I removed the lower caliper slide pins once again, and after removing the new orange plastic bushings/sleeves, I reinstalled the original black bushing and sleeves and re-assembled the front disc brakes. With the original black bushings/sleeves installed it takes less effort to move the slide pin in and out than it did with the new orange ones. That being said, it still takes more effort to slide the lower slide pins in and out that it does the upper slide pins, which do not use the bushing sleeves.

My question is: Should I have just left out those bushing/sleeves altogether or not? Some say that I should have.

I have not driven the vehicle anywhere since, other than to turn it around in the asphalt parking area in front of my home. Today I will be replacing the rear brake pads... I Thank You for your time.
 

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Being plastic --- the new orange ones will shortly "flow" to better dimensions and if you can press the pins in by hand, imagine how much more so: a hydraulic system with a booster and your foot on the other end can do!

I do not follow this logic either:
I have been told that the bushing/sleeve is to prevent damage to the sealing surface of the rubber boot when reinstalling the lower caliper slide pins.
 

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Discussion Starter · #4 ·
Look at the diagram and you will understand that there are no rubber bands below. They need to be removed.
View attachment 58394
TB Vega, I appreciate your reply, but they (you refer to them as "rubber bands") do show up in the diagram... as parts #6 & #7. Part #6 is the caliper slide pin with the groove near its left end, and part #7 is the soft plastic bushing/sleeve (in the diagram).
 

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@Scratchin My Head,

You stated that you had 1/4 of the pad left on one pad .... I imagine the other edge was metal-to-metal - right? <just asking>


There seems to be some functional mystification here ----- The boot (#10) is to protect the bushing (#7) and slide pin (#6) from becoming contaminated from dust from the pads (#12).


Those pins (#6) float the caliper (#1) by having the thru bolts (#4) screw through the caliper (#1) locking them into a geometrically-parallel sliding joint.

The caliper bushing (#7) must act as a live joint to be able to compensate for pad wear, knockback and minor misalignment, although most of that compensation is in the caliper piston(s) (#9) themselves as they continually move outward as the pads (#12) are consumed.

√ Notice also that you only have 1 bushing (#7) per caliper --- because there is only need for one (1) per-caliper to keep the slide pins (#5) from "freezing" in the slide holes in the caliper mounting bracket (#13).​

How can they "freeze"?
√ Because a rigid parallel set of pins with no allowance for variations in parallelism, would not survive in such a highly contaminated and dirty environment.​

Without that plastic bushing to give a little tolerance for the slide pins in the "floating part" - the caliper itself - the slides would "jam" and get caught at the slightest contamination and create very bad pad wear characteristics.

IOW ---> if the slide doesn't freely move in and out, then you'd only be using 1/2 of the friction material on the piston side of the calipers because the slide would not be able to follow the outside pad as it typically wore.

That bushing should start life anew as somewhat tight - a lot tighter than an old bushing at least. Be sure to use the lubrication in both those slides that came with the mounting hardware kit .

I hope that's clear for you.
 

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Discussion Starter · #6 ·
Ravalli Surfer, Thank You for your interest, and the clarification and very clear explanation regarding that 'plastic bushing'. It is much appreciated! Yes, the right front brake pads were worn down, with the outer pad having gone 'metal to metal' due to there not having been any 'wear sensor clip' (?) on that pad to warn that the pad needed replacing. Only the inner brake pad had a wear sensor. So, I wound up having to buy new rotors too. The front and rear brakes are done, but based on what you replied, I will be removing the front calipers to replace the original 'black' plastic bushings with the new 'orange' ones. The rear brake caliper slide pins had no plastic bushing on them nor were any of them turned down with a groove in them down to allow for any plastic bushing.
 

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Trailblazer 2008 LTZ (4.2L) (Destroed) :((. Now Trailblazer SS (2006)
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TB Vega, I appreciate your reply, but they (you refer to them as "rubber bands") do show up in the diagram... as parts #6 & #7. Part #6 is the caliper slide pin with the groove near its left end, and part #7 is the soft plastic bushing/sleeve (in the diagram).
I understand what you are talking about, my phrase was a little wrong, this is due to inaccurate translation. Genuine parts (numbers 6, 7 and 10) are sold under GM P/N 88965686 and have black plastic on them. Aftermarket parts have orange plastic, you probably bought one of these kits
GM P/N 88965686
Packaging and labeling Packing materials Font Wood Box


Tool Household hardware Cylinder Auto part Metal




Aftermarket parts have orange plastic ACDelco 18K1749X (2006-2009)
Hood Automotive exterior Bumper Auto part Plastic bag
 

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Ravalli Surfer, Thank You for your interest, and the clarification and very clear explanation regarding that 'plastic bushing'. It is much appreciated! Yes, the right front brake pads were worn down, with the outer pad having gone 'metal to metal' due to there not having been any 'wear sensor clip' (?) on that pad to warn that the pad needed replacing. Only the inner brake pad had a wear sensor. So, I wound up having to buy new rotors too. The front and rear brakes are done, but based on what you replied, I will be removing the front calipers to replace the original 'black' plastic bushings with the new 'orange' ones. The rear brake caliper slide pins had no plastic bushing on them nor were any of them turned down with a groove in them down to allow for any plastic bushing.
Not sure I've ever seen both the inner and the outer pads with what we used to call: "Tattletale" noise makers.

Really - when pads get that thin, they should have been changed miles ago anyway.
 
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