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Discussion Starter · #1 ·
I have a friendly heads-up to all on here regarding our rear brakes. Back when Emma was still fairly new I had to jack up the rear end and noticed one of the wheels wasn't turning freely so I set it up with the dealer and of course, it turned just like it was intended but I couldn't help but wonder if that was the cause of my disappointing fuel economy figures. In fact I posted about it here but I can't find that thread now.

Cut to three or four days ago when I was going down a fairly steep hill that I can normally coast down and have to brake to keep from hitting 50-55 MPH. Well I got to the crest and took my foot off the accelerator and Emma slowed down dramatically. I actually had to keep my foot on the gas the whole way down the hill and last night when I got in the car, both rear brakes made a loud metallic 'pop' when my weight was taken. I called a friend to pick me up and did a night drop at the dealer, fully expecting it to not do it when they checked it out this morning. Well sure enough they called me and said both rear brake calipers need to be replaced.

I find this a bit odd as we don't use road salt here and none of my past Hyundais have ever had issues with the rear calipers. At any rate, the dealer is over-nighting the parts and they hope to have it back to me tomorrow. I've got to go up to Tacoma on Friday so I'm very interested to see if this will impact my mileage positively. Fingers crossed, I'm hoping so!
 

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Discussion Starter · #4 ·
I spoke with my advisor and he said the technician loosened the bleeder screw and once he did that, the wheels turned freely so clearly it's not a caliper slide issue but an internal defect within the calipers and the flow of brake fluid. He also told me they were "almost fully stuck on" which makes me seriously wonder how long this has been an issue. From day one, maybe? I'm hoping to get the car back today.
 

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I hope that they will be replacing the pads and rotors if severely warn under warranty
+1 John. I think that is a reasonable request, considering what's been discovered. Afterall, while they're already in the area...
 

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Brake servicing is very important. At least once a year. Twice a year if living in cold climates where road salt is used.
That's insane.

I can't imagine removing brakes (calipers, slides, pins, and whatnot) to grease them twice a year. That is a design flaw.

However, I can add from HD Elantra part and KIA Rondo - both have tendency to size up rear brakes. While front is OK, rear is not. Never had a problem as OP described, but indeed one of my rear calipers was slightly dragging on Elantra.
Simple cleaning and greasing solved the problem.

clearly it's not a caliper slide issue but an internal defect within the calipers and the flow of brake fluid.
Could you elaborate that? Do you have more info on what could cause the brake fluid not flowing back?

You see, within the caliper not many parts can be causing an issue... Either the orifice is open or not. The piston moves or not. Besides, how likely it is for two rear brakes to get stuck at the same time??
The question is - which part of brake system is responsible for both rear brakes at the same time? Master brake cylinder, eventually ABS unit, but this has one section per wheel...

Therefore, I would check all the parts to make sure it is OK. Maybe there is something in the master brake cylinder (some debris from brake fluid/worn seal/oring) that is stuck and pushes the brakes?
Just a thought...
 

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That's insane.

I can't imagine removing brakes (calipers, slides, pins, and whatnot) to grease them twice a year. That is a design flaw.
It takes a whole 10 minutes per wheel. Plus I rotate my tires twice a year anyways so i am already there. Keep in mind of the climate and road salt that is used up here in Quebec.
 

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That's insane.

I can't imagine removing brakes (calipers, slides, pins, and whatnot) to grease them twice a year. That is a design flaw.
Hoo boy, it's like the Santa Fe forum all over again. :)

Realistically once a year - or possibly even once every second year - should be enough to avoid seizure. But John is absolutely right; it's a very simple DIY procedure that salt-belt drivers would be well-advised to follow.

The design flaw is more of a trade-off: Tighter-fitting brake pads which are slightly more likely to seize, but dramatically less likely to generate nuisance complaints about noise & vibration (the bane of many service departments, especially in this age of rear-wheel disk brakes and open wheel designs which expose them to the elements). This tradeoff does place an extra maintenance burden on salt-belt owners, but the way I see it it's no different from rustproofing. Skip if you don't feel it should be necessary, but understand that there might be consequences down the road.

It might help to know that this is not unique to Hyundai cars. It happened to my 2004 Nissan Quest, and a quick search of "seized rear brakes" turns up 181,000 hits affecting every brand from Acura to Volvo. It might also help to remember that today's cars require dramatically less maintenance than ever before... if anything we've been spoiled into thinking that they should be 100% maintenance-free.
 

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Don and John,

I do understand that it must be done and I mentioned that all my cars suffered from it. But twice a year that is a little too much.
And 10 minutes? Maybe one could squeeze it into 10 minutes if it is an additional job during wheels swap/rotation.
But then again - remove pads, push the piston in, remove the sliders.
Clean everything, inspect for rust/damage/wear. Put back together with fresh grease.
Torque the caliper (pins).

I do it every two years.


As per design flaw.
Dirt is one thing, but rust is the other.
What I discovered in my cars was the shims were rusty. Whether the material was poor, or it was improperly assembled to begin with.
Actually, I do not remember seeing grease on pads on my new Rondo back in 2008... it was all dry.


But that is off topic.


I still want to know what caused the calipers to not let the piston to go back.
 

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Discussion Starter · #11 ·
Well the parts haven't shown up and I work from 1 to 7 so I won't be getting my car back today. :dry: When I pick it up I'll make sure to ask them to elaborate on what caused this, if they know for sure.
 

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Well the parts haven't shown up and I work from 1 to 7 so I won't be getting my car back today. :dry: When I pick it up I'll make sure to ask them to elaborate on what caused this, if they know for sure.
I had a new Honda motorcycle that did the same thing, I was riding along and could feel the rear caliper not releasing. I looked at it on the side of the road and determined the internal return passage to release the pressure was not doing so. To get it to the dealer, I released the bleeder screw and it squirted out brake fluid and released the pressure. I just didn't use the rear brakes again riding over to the dealer. The fix was to clean the cylinder out and that was handled under warranty and was never a problem again. Just debris blocking the tiny internal passages. Sounds like the same scenario.
 

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Debris. A "sealed" brake system. I'm not smart enought to figure out what debris it could be. Probably any number of things. An assessment by a professional should get this resolved, hopefully. Not disputing the statement, just questioning what might be the root cause. Puzzled and interested because I certainly don't want my brakes doing this.

Looking forward to the eval by the tech and the owner's (Andrew's)
response.
 

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Discussion Starter · #14 ·
Fingers crossed it gets done today. I have to go to Tacoma tomorrow and would much rather fill the Elantra's tiny tank than put V-Power in one of my parents' Acuras. It isn't that they're bad cars but rather that both require premium fuel, one has a 19 gallon tank and the other a 22 gallon. And the MDX only gets 23 MPG on the highway.
 

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I would suspect that the debris would be crap left in after machining or perhaps it was filled with some debris laden brake fluid.

Why would either Acura require premium gas? Honda can't design a knock sensor that retards the spark?
 

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Discussion Starter · #16 ·
Well I've gone from having brakes on all the time to having almost no brakes at all. :dry: Upon picking the car up I noticed that I had to push the pedal well past the 50% point to get any sort of response at all. Now we all know how the Elantra pedal should feel; push it past 50% normally and you'll wind up as a part of the windshield. I took it back and the tech test drove it, saying it felt 'normal' so I took the car home hoping it would improve but it hasn't. It was when I went to take a friend home that I felt a sick sensation in my stomach and realized I didn't trust the brakes at all anymore so I took my mom's car. Roadside assistance is picking Emma up shortly....I'm not driving her another foot until the brakes feel like they should and this means tomorrow's trip is also cancelled. :dry:
 

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How can a mechanic work on a car's brakes and then not road test it???

Andrew, if not for bad luck you'd have no luck at all...
 

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Wow, that really sucks. Looks like they left air in the system
They might, but this could be determined by a few quick pumps. The pedal would go up if it was air.
I doubt that is the issue here, though. But I am not saying that is not possible.

I feel more like it is long/far travel of the pistons/pads.

IF they put new pads/rotors on rear they may not be adjusted/fitted correctly what will cause the extra travel.
Also, improper assembly (backplate, springs...) pushing the piston back will cause long travel...



Andrew, did they explain why the pistons were stuck?
 

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There is not much adjustment that can be done on the calipers or pads, It is not like drum brakes. As far as fitment is concerned, i would be very concerned if a dealer mechanic was unable to install a set of pads and rotors properly.
 
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