# Word to the wise about caliper replacement.



## quadraria10 (Jul 6, 2010)

I replaced the passenger side rear caliper, last fall with a reman AC Delco pro line replacement. Been getting some brake rubbing noise when pushing lightly on the brakes, so I thought I would dig into it. Lo and behold, the bottom caliper slide pin was seized, and when I finally got it out powdered rust was coming out of the hole and the pin was really rusting and pitting. For some reason when I installed the caliper, I did not bother regreasing the slide pins, as I assumed that with a new caliper, that the new pins would have been properly lubricated. It appears that there was zero grease on that bottom pin, or it was very minimal. So in the future, I will always lubricate the pins even with a new or newly rebuilt caliper.
I cleaned the pin as best I could with rust remover, 200 grit sandpaper and then metal polish, and will buy a new one shortly and change it out in the next week or two.
Now here is the strange question. The stuck pin has caused the outside pad to wear prematurely and it's almost at min thickness. So I need to replace pads as well. When I ordered the caliper I bought a loaded one that came with ceramic brake pads. So I have two AC Delco ceramic pads lying around. Would it be nuts to use them to replace just the outer pads on both sides in back so that all of the pads on both sides are even, with new ones on the outside and 1/2 worn on the insides? ( insides have wear indicator). So in effect I would have Bosch ceramic pads on the inside and AC Delco ceramic on the outside, and leaving the current two year old rotors in place. This is obviously the super cheap way to go, but I wonder if it would have any effects on braking? Otherwise, I will order new pads, and hardware and change both sides for about $50.
Yesterday though I saw options on Amazon for a kit with 2 rotors and new pads for under 70$ that included free delivery which is an amazing deal, but it seems so cheap its hard to believe. Basically they would be providing the parts for approx the delivery cost RockAuto would charge. I will look into them more.
:nerd:


----------



## quadraria10 (Jul 6, 2010)

Decided to just order another set of Bosch Quietcast pads and a new set of caliper pins. Found them to be great pads that are silent and leave the rotor surface super smooth. So this way I will keep the rotors that are still good, and simply be replacing the pads with identical ones to what is on the car now.
I could not find any info about using two different pads on the inner and the outer surface, other than a discussion where a mechanic advised against it due to the potential for different abrasion levels or brake bite which would wear the rotor surface differently. As material from the pad has to transfer to the rotor, I figure it might cause a problem that I would potentially avoid by using the same brand and type of pads that I am currently using. 
The Bosch are copper free, whereas the AC Delco have lots of copper visible in the pad surface.


----------



## rogoman (Dec 16, 2004)

When installing new pads it's always a good idea to use new rotors or to re-cut the old rotors to remove any waviness and lateral deflection. Just make sure the old rotors have enough meat for a re-cut.

Using half worn pads on new or different rotors is not a good idea as the pads will have different wear patterns meaning that there may be air gaps between the rotor and the pad which will sacrifice braking efficiency. To try to correct that condition, you would have to heavily burnish the pads during test runs with hard braking; then you will probably end up with glazed or warped rotors.


----------



## smj999smj (Jan 1, 2006)

^^agree^^ I would not advice mixing different brake pads. FYI, most AC Delco brake parts are made (or remanufactured by Raybestos). Copper is commonly found in ceramic pads. Generally speaking, better quality ceramic brake pads will often show a lot of copper in the lining material.


----------



## X-hale (Apr 17, 2017)

Good tip on checking the grease on new calipers. I have installed a few assuming they were lubed. It's so easy to just bolt them on without messing around with grease etc. From now on I'll be checking them first.


----------



## quadraria10 (Jul 6, 2010)

So high copper content is good in ceramic brake pads, but it is being removed now for environmental reasons? Maybe I could have used the AC Delco pads. What I was proposing was just replacing both rear outer brake pads and leaving the inner pads which are only roughly 1/3 worn in place. The rotors are less than 2 years old, and the braking surface on both is smooth with no grooves and minimal lip and they should be fine. I will replace the old Bosch ones with new Bosch ones, and hope for the best.


----------



## quadraria10 (Jul 6, 2010)

I may have been a little rough on AC Delco. While replacing the pads, I found the lower pin on the driver's side was seized as well. A job getting it out and then cleaning the hole for it, so that a new pin would slide smoothly. The new caliper probably had a light coat of lubricant after all. 
I am just coming to the conclusion that the caliper pins should be removed and lubricated twice a year. I also suspect that the small boots simply do not seal properly to prevent moisture from getting onto the pins. I replaced mine but they don't seem to seal fully any better than the old ones.
What really amazes me is that the brakes still seemed to work ok. I gather there are a lot of cars driving around with seized caliper pins.


----------



## otomodo (May 23, 2008)

Just don't over fill it with grease. Last fall i add some grease to the pins and the upper pin couldn't get to the bottom. After one week of brake heating smell, i decided to empty all of the grease and add just enough so the pin could touch the bottom.


----------



## quadraria10 (Jul 6, 2010)

Thanks for the tip Otomodo. It's particularly true of the pin with the rubber bit at the end. Too much lube and as you say the pin won't seat. In my case, it was more a question of cleaning out the holes due to corrosion and then rolling up 250 grit sandpaper which I wetted to sand the bore hole. I made sure the pins slid smoothly before reassembling.
As an aside, the mystery of those small rubber tips continues. I thought that the pin with the rubber went on the bottom, and that is the case on mine for the driver's side. However, on the passenger side with the newer rebuilt caliper, the pins are the reverse of the other side, and so the rubber tipped one is in the top position.
Have they just gotten reversed, or is there a difference in the hole internals? If so I can see how the caliper bracket that houses them would be the same part, but simply flipped for use on the other side. Or, should they both be in the same position, meaning the holes are identical. For some reason, I thought they might not be the same because the solid pin would not go into the bottom hole but this was before I fully cleaned it. Anyhow, it seems that they work fine either way.

I just looked at part diagrams and it shows the pin with the rubber at the end going in the bottom position. This is what I have on the driver's side. However, the Right side one rebuilt by AC Delco has the pins in the reverse position. I am now officially confused. Would AC Delco have inverted them or do they go in different positions depending upon the side? And ultimately does it make any difference??


----------



## rogoman (Dec 16, 2004)

You're going to need some high-temperature grease to lubricate those pins. This is a synthetic lubricant designed for machinery that can withstand temperatures of several hundreds of degrees Fahrenheit; easy enough to get an auto parts store. Brakes generate a tremendous amount of heat because they're essentially a piece of metal used to slow down another piece of metal moving at highway speeds. The last thing you'll want is for the lubrication on your brake caliper pins to be unable to take the heat.

As to the orientation of the pins, the FSMs do not mention the difference of the pins. Here's some info about someone's Honda calipers/pins taken from a web site:

"Bill R said:
Many of the Honda vehicles have the same type of brake caliper
guide pins. For most, the top and bottom guide pins are different. For our Honda
CRV ( 2005) the bottom guide pin is round and the top is basically a round pin
with three lengthways flats on it. In the Honda manual it states that if these are
reversed, excess tire wire, vibration and uneven pad wear can result. I was talking to
a service rep at the local Honda dealer and he said all the pins were reversed and
all the pads wore uneven and had to be replaced. I see people on u -tube doing
brake replacements on Hondas but not mentioning this important detail."

Here is a picture to demonstrate what Bill R is referring to:


----------



## quadraria10 (Jul 6, 2010)

Well, its taken research. but I think I understand how the caliper pins are supposed to work.
Basically, there is a leading side pin and a trailing side pin. The lead pin will absorb more heat and needs to dissipate it. The trailing side pin has the rubber bushing on it to absorb vibration and chatter and won't get as hot.

Now here is where it gets fun. The lead pin will be the one that the rotor rotates into rather than the end pad from which the rotor rotates away from. If you picture a dot on the left rear rotor and imagine it going counterclockwise, where that dot first touches the brake pad is the lead edge, and the other end of the pad it emerges from is the trailing side.

What this means is, depending upon where the caliper assembly is placed on the rotor, the lead and trailing edges will change.

On the X trail, the rear left caliper is positioned to contact the left side of the rotor, or you could say it's on the right when facing it.
This means when the car is driving forward the left rear wheel is turning counterclockwise. Consequently, the leading edge of the pad would be the bottom, and the trailing end the top.

Conversely, the front left caliper is positioned on the left when facing it. So for it when the wheel is turning counter clockwise the lead edge will be the top end of the pad and the trailing edge will be the bottom.

You can do the same exercise for the right-hand side. You just need to remember on that side the wheel would be turning in a clockwise direction. 

What this means in practice is that for the rear of the X trail the lead pin should be on the bottom and the trailing pin with the rubber in the upper position. For the front, it would be the opposite and the lead pin would go on top and the trailing pin with the rubber bushing on the bottom.

So I concluded AC Delco had it right, and I figured I must have flipped them at some point on the left side. However, what is weird is that the Nissan parts diagram has the rubber tipped one as going on the bottom. Furthermore, a quick scan of rear brake videos one for the X trail and 3 for the Rogue which uses the same rear caliper, showed all 4 having the rubber tipped caliper pin going in the bottom position which should be the lead side. 

That had me curious so I looked at an Altima video where the rear caliper was on the left or inside, and it had the pin with the rubber boot on the bottom which would be the trailing side and correct as per my theory above. And when I look at the pins for the front calipers on the X trail which are also to the left, the lead pin is the solid one and goes on top and the trailing pin with the rubber goes on the bottom. 

So, sorry for the long post, but I cannot figure out why the parts diagram shows the pin with the rubber tip going on the bottom for the X trail, when due to the orientation of the caliper that is the lead end. Could Nissan engineers have gotten this wrong, or does it really make no difference in practice which pin is up or down?

I will put out there that it seems a lot of X trails and Rogues for that matter have had rear brake issues. Could the rubber tipped caliper pins in the lead pins which supposedly experience more heat be causing part of the issues?

Should I just leave mine alone, or change them as per Nissan spec or change them as I think they should go?


----------



## quadraria10 (Jul 6, 2010)

Rogoman thank you. I had not realized that the green Permatex brake lube I have been using only goes up to 400 degrees Fahrenheit. I need to get something like this stuff
https://www.canadiantire.ca/en/pdp/...8pk1BNfjwaAocLEALw_wcB&gclsrc=aw.ds#store=176

which is good up to 3000 degrees farenheit.

I have been using the wrong stuff for the caliper slide pins! 

I would be curious as to your thoughts about what I wrote about the pins above.

I am hoping for some help from the best and brightest here because I now have to remove the calipers pins and regrease them with proper high temp grease. The green stuff you can buy in packs or small tubes I now know does not do the trick and pretty much guarantees an eventually seized pin.


----------



## quadraria10 (Jul 6, 2010)

Well to end this, I am going to go with what Nissan specs and put the bolt pin with the rubber on the bottom and the full metal one on top. Same as was in the videos, and when I checked a Nissan Murano which uses the same rear pads, but which differs in that the rear caliper is on the left, for that they spec the rubber tipped one on top and the full pin on the bottom.
So for some reason that I cannot find the pin placement for the rear of Nissan SUVs appears to be the reverse of what you would expect based upon what I described earlier. Who knew caliper pins could be so complicated?

(Also means AC Delco got it wrong in the way they installed the pins.) Come to think of it, it was the AC side causing the problem I noticed, and not the seized pin which was burnished black, and missing its bushing. Either way, the prob was the bottom one on both sides. I am hoping the higher quality brake lube for the pins will be the thing that makes the most difference.


----------



## otomodo (May 23, 2008)

Isn't the rubber pin tip suppose to be the pivot point to change the pads?

Personally i never used that method, i always take the whole caliper out so the rotor can be cleaned(grind rust lip)


On the service manual they explain how to do it.


----------



## rogoman (Dec 16, 2004)

quadraria10 said:


> Rogoman thank you. I had not realized that the green Permatex brake lube I have been using only goes up to 400 degrees Fahrenheit. I need to get something like this stuff
> https://www.canadiantire.ca/en/pdp/...8pk1BNfjwaAocLEALw_wcB&gclsrc=aw.ds#store=176
> 
> which is good up to 3000 degrees farenheit.
> ...


What you wrote about the pins above makes good sense. The rotor first enters where there's a solid pin, then travels down to the rubber tipped pin. The purpose of the rubber tip on the trailing pin is to reduce/eliminate rattling. When re-assembling the calipers, we'll just make note which side the caliper is mounted and the forward direction of the rotor in order to place the solid pin where the rotor first enters the caliper.

The brake lub that I've been using is:
Permatex product 24125 Ceramic Extreme https://shop.advanceautoparts.com/p...VA18NCh3WYQWREAQYASABEgL8avD_BwE&gclsrc=aw.ds


----------



## quadraria10 (Jul 6, 2010)

Thanks for confirming what I thought. I think I could flip the pins with no drawbacks, but the fact that the Murano, and Rogue also reverse the pins from what I think would be leading vs trailing edge in the rear has me thinking maybe there is something I am missing in my understanding.
I watched an engineering explained video on brake temperatures, and according to it 300 degrees Fahrenheit is about the top temperature brakes will hit in regular driving, and strangely enough on the Honda rear brakes they were filming, the actual temperature they were measuring at the trailing end of the pad was slightly higher than at the lead end. However, we are only talking a few degrees difference.
The good news about that is that the green Permatex rated up to 400 F that I have used is not the end of the world, and nothing will seize until I change it next weekend or the one after. I bought the orange stuff $23 + tx as the specs seemed almost identical, and was 7 bucks cheaper than the purple stuff for a jar that I will have for the rest of my life based upon the amount I use.

That is interesting Otomodo-- basically, Nissan says to remove the solid pin both front and back to move the caliper cylinder. For the rear of the X, I have always removed the bottom pin as the brake line is partly in the way when removing the top one in back. My guess is that is purely to limit wear on the little bushing at the tip of the other pin that is not removed.


----------



## quadraria10 (Jul 6, 2010)

Just found out you can buy a small tube of good permatex at Can Tire. No need to buy a big jar. 
https://www.canadiantire.ca/en/pdp/permatex-silicone-ceramic-brake-lubricant-28-ml-0381412p.html#spc

Supposedly this is the same as the Red permatex sold in the US which is a step up from the purple and is more rubber safe.


----------



## quadraria10 (Jul 6, 2010)

To further add to the mystery of the pin placement I checked for the Subaru Forester, and the Mazda CX-5 which both have the same right sided caliper set up in the left rear as the X trail. Like Nissan, Subaru puts the rubber tipped pin in the lead position, while Mazda puts it on top in the trailing position. 
I wonder how mechanics deal with the placement. Neither the service manual or part diagrams distinguish the pins in their pictograms. To actually see which is which, I have had to look at pictures of the actual part.


----------

