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Discussion Starter · #1 ·
I have a shudder issue with my 2014 Mazda 6 (105k miles). The symptoms are felt especially in the steering wheel, and are most pronounced when feathering the brake pedal at 65+mph. From what I read, this points to a runout issue in the front rotors, the potential causes of which could be several. The front calipers are original, but rotors were replaced 2 years ago (<16k miles) along with pads. I am used to the feel of slide pins in other make cars - an aspect of this car's pins has me perplexed. The lower pins have always glided much less freely than the top ones. The design of the lower pins is different - specifically, it has a diameter that is stepped (at its inserted end) to accept a rubber collar/band. This collar seemed to be at the root of the glide issue. The pin can be very difficult to remove completely from the caliper - the collar seems to get hung up somewhere, and it can even break when the pin is ultimately forced out.
Replacement collars are available in kits (Advance Auto), and they look appropriately sized, but no amount of lube seems to convince these lower pins to slide freely once back into position. It almost feels as if my install efforts push the collars out of their stepped diameter on the pin - ng, I bet. Mechanics on youtube have advised just leaving these collars off. My questions: 1)what is the function of these collars, 2) could their tightness possibly be at the root of my rotor/shudder issue, 3) is there any particular method for reinstalling these lower pins that would ensure the collar's integrity and position, 4) has anyone else suffered this problem and found success by simply leaving the collars off.

Thank you for any response!
 

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If you could send a link to the item you purchased so we could see what it is that you're talking about, that might help.
 

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Discussion Starter · #3 ·
First link shows the glide pins for the front brake system. The one with the constant diameter goes on top, the one with the step goes on the bottom. Second link shows a glide pin boot kit, which includes the rubber collar I mentioned in the original note. The OEM glides are milled in the same way as these, and the collars slide on and feel the same as these after markets. My glide pins are the originals - the collars have been replaced, in part because its almost impossible to remove the glides without destroying the collars. Repeating the earlier note, the collar significantly impedes re-installing the pin - I suspect the collar might even be forced out of its step or becomes damages when the pin is installed. The resulting feel of the glide is unnerving - much much stiffer than the top pin, almost feels frozen. This is the result for the lower pins on both driver and passenger side. All pins look in great shape - no rust anywhere in sight.


 

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To be honest, all of those bits and pieces look correct, as per rockauto.com as well. Everything in that kit needs to be in place. If there is a problem, you may not be installing them correctly. Remember to clean out all the old grease before installing the new pins and rubbers.
 

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Discussion Starter · #6 ·
Actually, I've attempted to replace these collars several times, and I end up with the same result. With the replacement collar in place, I've been unable to convince the pin to slide back into place. For some reason, the lower pin doesn't have the flats machined into them, and I think this introduces a hydraulic effect that resists all my efforts to force the pin back in place. I'd really appreciate detailed suggestions as to how to perform what I originally figured would be a very simple task!
 

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If you re-use those collars or have ANY sort of debris or residual grease in the bore or on the pin they have a very high probability of being displaced out of the groove slightly when you put the pin back in and they will jam in exactly the way you're describing. You do not need much pin grease when servicing brakes (the seal is what keeps it from being contaminated) but you DO have to get all the old grease and gunk out of the hole in the caliper and off the pin.

You will note that those collars have several very small relief notches in them. That pin should have a bit of "springiness" to it when installed.
 

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Discussion Starter · #8 ·
I might need to devise a tool to clean the bore to the level you advise. FYI, the "jamming" of the pin that I feel occurs at the outset. As soon as I proceed to push the pin beyond the dust boot, there is significant resistance. I do see the notches cut in the collars - I suppose these could relieve the pressure buildup when installing the pin. But I would have to put almost no lubricant on that collar (plugged notches would prevent the pressure relief). Will try your suggestion to diligently remove all grease in the bore.
 

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I might need to devise a tool to clean the bore to the level you advise.
No need to devise a tool. Use a good brake cleaner. Be sure to remove the rubber boots because brake cleaner can damage them. Spray the crap out of the bore and make sure it is completely dry before proceeding to the next step. Ensure that you are using brake grease and NOT axle grease or something of the sort. You don't have to drown the caliper pin in grease, just give it an even coat and then slide it back in the bore.
 

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Ding ding ding ding.

Brake cleaner works just fine, but make VERY SURE to get it all out of there (e.g. compressed air or similar.)

And what @tango said -- make sure you are using pin grease. I like this stuff:
 

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Discussion Starter · #11 ·
Well team, here's my progress. I've removed the pins, dust boot and also removed the caliper bracket to ensure a thorough cleaning and drying out. Unfortunately, the reinstallation of that lower pin is a PITA. The OD of the pin with that rubber collar is so tight against the bore of the sleeve in the bracket. Have made several attempts at lubing, including application of the smallest amount in the bore. The rubber collar protests. If I try to urge it with more force, the collar typically pops out of its "seat" and rides up to the dust boot end of the pin. Have gotten to the point where the collars I have (from parts kits) are now stretched or swollen - mis-shaped enough to require another purchase. Taking the ride to the store will be a good way to cool off. Just so you don't think I'm alone in my frustrations, check out this youtube clip. As an engineer, I'll be the first to admit that no design is perfect, and that there are always missteps. But I think the person in the video is likely off base. Mazda didn't just put collars on the lower pins for the heck of it. I don't know exactly the effect to expect by removing the collars for good. Unfortunately, my closest Mazda service center is tight-lipped about their garage techniques. But really, there has to be a trick to getting these collars back on without damaging them- right?

 

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Discussion Starter · #13 ·
Thank you for the interest from all of you. While both the caliper and glide pins are OEM, the boot kit (which contains the bushing/collar of interest) is from Autozone. Btw, there are dozens of comments online about these collars - they are used in many different cars, and apparently lots of people have struggled with them. The update in my situation. I have for some time used the same Permatex 24110 lube that Tickerguy suggested. Despite what it says on the can, the collar appears to be stretched/swollen enough so that it binds and is no longer useable. I saw several suggestions to try Sil Glyde, so I cleaned everything up, put a new collar on, coated the parts only moderately with Sil Glyde, and voila - the parts go back together, glide smoothly, and without any suggestion that the collar jumped out of its slot. I'll be interested to see for how long the glide keeps this nice feel. It clearly is operating more like the way it was designed (no binding, stuck feel). I have the feeling it would be a good idea to have a kit of fresh new collars available every time that lower pin is pulled!
 

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I have never had a problem with new sleeves on mine, and I've done a couple of sets of brakes.

I DID try to reuse them once -- and they bound up exactly as you described.

This is the A/C Delco part number that I've used on my "6" with success:

Keep a set around; it's $10 and when you have cause to pull the pins (which, unless the seals are damaged, you should need to other than when doing a brake job) replace them.
 

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I cleaned everything up, put a new collar on, coated the parts only moderately with Sil Glyde, and voila - the parts go back together, glide smoothly, and without any suggestion that the collar jumped out of its slot.
Very important step that I was alluding to in my suggestion. Too much lubricant was causing the entire thing to hydrolock. Remember that the pin doesn't move through as long a stroke as say a strut. It is really only moving fractions of mm at a time so the wads of lubrication is not necessary. A little, as they say, goes a long way....or in this case...all the way! Congratulations!
 

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I have never had a problem with new sleeves on mine, and I've done a couple of sets of brakes.

I DID try to reuse them once -- and they bound up exactly as you described.

This is the A/C Delco part number that I've used on my "6" with success:

Keep a set around; it's $10 and when you have cause to pull the pins (which, unless the seals are damaged, you should need to other than when doing a brake job) replace them.
When I did my brakes recently, I had zero problems with my pins and collars. Didn't even think that the collars were even removable! The right rear, lower pin was really jammed in there though, and was obviously binding. It took some time to get it out, but once I cleaned it up and lubed it, no problem fitting it back. I guess we are among the few, the proud, and the brave!
 

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Discussion Starter · #17 ·
Good advice re the amount of lube to use, Tango. I'll be very interested to see how this Sil Glyde holds up as we get into the cold and slush. Re your rear brake pins - on my 2014 Mazda 6 (Grand Touring), neither glide pin on the rear brakes has a rubber collar. Only the lower pin on the fronts have that collar. I get the impression that this is a common setup for many vehicles.
 

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There should not be any contamination in the slider bore; the entire point of those rubber boots with their bellows is to seal that area entirely against environmental contamination as that part of the car is, obviously, exposed to a LOT of dirt, water, salt and whatever else is on the road. If the boots are deteriorated to any degree they should be replaced on inspection and, if you detect compromise, dismount the caliper, clean the bores and pins, replace the bushing and re-lubricate it.

Provided the boots are in good condition I've done brake jobs on cars that haven't had the bolts out for five+ years and the pins and lubricant are still serviceable.
 

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Good advice re the amount of lube to use, Tango. I'll be very interested to see how this Sil Glyde holds up as we get into the cold and slush. Re your rear brake pins - on my 2014 Mazda 6 (Grand Touring), neither glide pin on the rear brakes has a rubber collar. Only the lower pin on the fronts have that collar. I get the impression that this is a common setup for many vehicles.
My car is a 2G (2013 USDM) so I have one collar on each rear caliper and two on each up front.
 

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Discussion Starter · #20 ·
An update. Today I changed out the front rotors and pads. There were < 16k miles of wear on them, but I suspected that my issue with the tight glide collars likely caused the rotors to warp. Sure enough - after the change out, my brake shudder problem went away. I feel more confidant now that the new collars and the Sil Glyde (and a more sparing application of it) have the glides working as they should. I'll be checking these glides on a regular (bi-monthly?) basis, check to verify that the gliding continues. Thank you for your interest and suggestions!
 
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