[bbourassa]

2016 MAZDA CX3 AWD Sport

Gentleman....and, of course, ladies too. I just polled a dumb move while changing my brakes and rotors (front & back). Although I may have made a mental note of where each caliper guide pin should go, my trouble with figuring out how to get the brake piston back sent my brain into forget-mode. Using a pair of needle-nose pliers I turned the piston back easily. At any rate, after changing rear and then front pads & rotors, I had questions as to why the guide pins were different and whether or not I had them replaced correctly.

After consulting 2 mechanics, with no definitive explanation as to why they are different and where each one should be placed, I got a copy of the brake caliper assemblies from the dealer.

While I was not very sure which pin went where on the rear calipers, I was 98% certain of the placement of the front guide pins. Only issue is, they do not match my cars final assembly.

Both rotors are located in front of the axles, so if you take the caliper in the drawing and mentally place it on the rotor, the guide pin locations are as follows:

guide pin with three flat section along length of pin ends up on top, or higher from the ground.
guide pin with the dark rubber bushing ends up lower...closer to the ground.

Surprisingly, after checking my work, I found that the pins were inserted as in the drawing.

NOW, with the front brakes, since I was certain I had the pin setup correct I checked the drawing and was surprised to see what I saw! If you mentally place the caliper assembly for the front wheels on the rotor in aprox the 1-2 O'Clock position. The guide pin position is reversed from the rear and reverse from how I replaced them.

My question that follow are:

1) Is the mechanical drawing incorrect?
2) What is the reasoning for the different guide pin designs

Thought I bought the car with 22k miles on it, I assume that the brakes have not been altered.

Thanks for any help on this!

NOTE: After review of the mechanical drawing. I noticed the text at the bottom stating that the drawings are for the ''left-Side" only, which I assume is the drivers side. Still not sure if the guide pins are in the correct position, and why they differ, front to back.

 

[anchorman]

The calipers would actually work with two plain pins but many of the Japanese caliper manufacturers use this differential pin arrangement. The plain pin is called the Guide Pin. The one with the rubber bush is called the Lock Pin and and is usually positioned at the trailing (second pin for a point of the disc to pass) end of the carrier. However, as you have seen, this is not always the case and as you have seen is sometimes the other way around because the vehicle testing found it to be more effective that way. Its purpose is to limit the amount of movement in the caliper body and stop it resonating or chattering as the disc rotates. It also limits movement of the caliper and prevents it “drifting” back away from the disc. One or both of the pins can be fluted which allows lubricant to remain in contact with the sides of the pin and avoid it sticking. There are misconceptions about guide pins. The first very common one is that they should be removed and re-greased periodically. They are in fact designed to maintenance free and should only ever be greased at caliper overhaul or if the boots have been changed. The second is that they resist the forces of braking which they are nowhere near capable of doing. They simply allow the caliper to slide in reaction to the piston pushing the inner pad into contact with the disc. The caliper bridge then applies the outboard pad into contact with the outer face of the disc with an opposite but equal force. All the forces of braking are transferred to the suspension leg via the brake pad abutments on the carrier.

The guide pins should only be greased with silicone or ceramic based grease which have a moderate/high melting point of about 280C (535F). If anybody has a pot of copper based grease it should be used for about the only good reason I can think of and that is to stop your wheelie bin being blown away in the wind. None of the brake manufacturers recognise it or aluminium based greases as suitable for modern brake assembly. These greases are clay based and congeal as soon as you turn your back on them.

The piston in these “floating” calipers is inverted and keeps the fluid well back from the disc. No fluid crosses the caliper bridge so overheated fluid is a thing of the past. This allows the use of lower boiling point brake fluid and the Japanese prefer to use DOT3 which has a very high lubricity quality compared to DOT4. It is much better at lubricating rubber parts and the super fine tolerance parts inside the modern ABS/VSC valves.

I've attached some better diagrams of the brakes on the CX-3.

 

[mainemanx]

As always, expert advice from the Anchorman ... extensive experience with brake manufacture.

 

[bbourassa]

anchorman,

I appreciate greatly the "extensive" reply regarding my concerns. What I find ironical from all the drawings I've seen is that the placement of the fluted-pin and lock-pin are never the same. In this case, the front caliper shows two fluted-pins and no lock-pin!

I see your advice on pin lubricant. What I uede was Permatex® Ultra Disc Brake Caliper Lube and just noted that they also sell:


Permatex® Ultra Disc Brake Caliper Lube(The one I used - does not list a temperature rating)
Category: Specialty Lubricants - Brakes
An environmentally-friendly, green, non-melting, synthetic lubricant. It is formulated to lubricate under the most adverse brake conditions, assuring that critical caliper pins, and sleeves remain lubricated throughout pad life. For metal-to-metal contact only.


Permatex® Ceramic Extreme Brake Parts Lubricant
Category: Specialty Lubricants - Brakes
A 100% synthetic formula, coupled with real ceramic solids make this premium brake lubricant our longest lasting, most temperature resistant way to silence brake noise. Effective from -50°F to 3000°F (-46°C to 1649°C), this product maintains its lubricating integrity under the most extreme conditions. Resistant to corrosion and contaminants, it will not wash out. For metal-to-metal contact only.


Permatex® Silicone Ceramic Extreme Brake Parts Lubricant
Category: Specialty Lubricants - Brakes
Permatex Silicone Ceramic Extreme Brake Parts Lubricant protect and lubricates every part of a brake assembly and prevents comebacks caused by irritating brake noise.
-Formulated to reduce brake noise, vibrations and harshness
-Dampens natural vibrating frequencies
-Treated with the latest, rust, oxidation and anti-wear additives
-Fortified with high concentration, high temperature, ceramic solids
-Stays in place, protects at extreme temperatures (-54F – over 3000F)
-Chemical and corrosion resistant
-Will not wash away
-Compatible with most plastics and rubbers used in Disc Brake Caliper systems
-Meets JIS K 2228 with EPDM and Nitrile rubbers

Will I be OK with the lube I used or should I replace?? Suggestions?

Also: The diagrams you posted. I've been trying to get my hands on such drawings for the this car. Is this a purchase one has to make or are they listed on a website, or not accessible at all to me?

Thanks for all you help!

Brian

 

[anchorman]

Hmm, well all the work has been done for me and I just use Ceratec which is marketed by the Pagid, Mintex and Textar friction material companies. It sounds rather like your third option given the temp range and the compatibility with rubber parts. This article tell you more and why not to use copper grease;

https://textar-professional.com/textar-training-center/the-use-of-copper-grease-on-modern-brakes/

The diagram does show two fluted pins but it also shows the location of the rubber bush. The diagrams are part of Mazda’s online manual. You have to be registered and affiliated with the motor trade. Browsing the manual is done by subscription. I have some pdf’s and you can find some by trawling the internet. If there’s anything you particularly want to see just shout up and I’ll see if I’ve got anything. Here’s a few of interest.

 

[bbourassa]

@anchorman,

Well, I almost certain that it is not copper based, but since they do not mention a temperature range with the product I used, is a bit to think about. It is fully synthetic which is at least part of the need for use with rubber parts. Oil-based lube would be horrendous I have heard. And given I live in the NE US. the temps are not exceptionally high or dry. I don't drive much, about 5K/yr.....almost not worth having a car. Would get on without one if I could, but can't.

Thanks for your time and input.

 

[flannel]

My experience :
I had problems with my rotors blued on outside. I Used copper grease when I changed my pad.

"These greases are clay based and congeal as soon as you turn your back on them"
Yes i found that too after few hours..
Since few months, I changed the rotors and this grease for another one specific for pins and take off this rubber (some mechanics says that they take off this rubbers because they can cause problems) because I had doubts with this anti ratting rubbers and I have never heard any noticeable noise from the brakes to this day.