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Discussion Starter · #1 ·
Hi

So this morning, I changed the front rotors and pads; This was largely uneventful, aside from one piston on each caliper being very hard to retract.

3 out of 4 pads had plenty left; The 4th pad was bare metal and the reason this project happened today - this pad was the inboard passengers side (picture attached comparing the inboard and the outboard pad - the other two pads are the same).

Before doing the job, my MPG was between 18.6 & 19.4 MPG; Today, I am down to 14.8 MPG !!!!

My daily commute is easy and consistent; 10 miles on regular roads, followed by 30 miles of highway. As soon as I hit the highway, I get to 65 MPH and hit cruise control. I never hit traffic, the drive is the same. Every single day. One way is slightly uphill, and obviously the other is slightly downhill, but when I get home at night, I'm always around 19 MPG.

What could I have possibly done to cause such a dramatic reduction in MPG? I've coasted the car, and it's not trying to stop; It doesn't seem like the brakes are 'working' when they shouldn't be.....
 

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The pads should be wearing symmetrically - when they're not it's because something's binding. A piston that's not retracting could cause that kind of thing.

If your MPG problem IS related to the brake pad dragging, you will have one VERY hot brake disc when you roll to a stop after driving at speed for a while. This is where one of the cheap infrared thermometers from Harbor Freight https://www.harborfreight.com/non-contact-infrared-thermometer-with-laser-targeting-69465.html comes in handy... just shoot the rotors and see if one or more is a lot hotter than the others. Keep in mind that they're supposed to be hot when you drag a 4,400 pound vehicle to a stop from speed, so coast as much as you can when you're going to be measuring.

Or, get a squirt gun and see if water boils off one rotor - if you have enough drag to basically sap 20% of your power, you're gonna have one really hot rotor!
 

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You can use your hand as a rough thermometer. Bring it close - BUT DON'T TOUCH - the wheel area. Compare side to side.

Did you remove, clean, and lube the caliper slide pins? (items #12 and #13 here: https://www.acurapartsnow.com/auto-...tomatic-engine/chassis-cat/front-brake-2-scat)

Another test is to jack up the vehicle and rotate the wheels by hand. You should feel the same amount of resistance on both sides.
 

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Discussion Starter · #4 ·
Thanks Habby, had a feeling you'd be in the response mix :)

Great idea - I have a harbor freight 2 doors down from where I work, so I'll likely grab one tomorrow. The only change in the car from yesterday to today was, yesterday brakes were grinding, and today brakes & rotors were replaced; Nothing else has changed. It's either a massive coincidence, or something to do with the brakes. And may well explain why 1 out of 4 pads was completely worn down.

Now - assuming that to be the case, I assume I'm looking at a new caliper, which leads me to ask, should I replace both at the same time, and what equipment do I need to buy to do the work - it's been over 20 years since I replaced a caliper, and I seem to recall that bleeding the lines can be a PITA without the proper tool(s).
 

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I wouldn't sweat replacing both calipers. That does make sense on a lot of things when one of two breaks (like a shock, bushing, O2 sensor, etc.). But it's not exactly like the MDX calipers have been problem-prone. If it was mine, I'd just replace the one (assuming that's what you find is wrong, of course). I'm really thinking that you're going to find that's the case, since one pad was ground to dust while the rest were fine.

It's always possible that it's just a stack-up of events that conspired to affect your gas mileage, including (but not limited to) a less than wonderful tank of gas, a big headwind, not catching the lights like you normally do, heavier stop-and-go traffic, etc.
 

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Discussion Starter · #6 ·
You can use your hand as a rough thermometer. Bring it close - BUT DON'T TOUCH - the wheel area. Compare side to side.

Did you remove, clean, and lube the caliper slide pins? (items #12 and #13 here: https://www.acurapartsnow.com/auto-...tomatic-engine/chassis-cat/front-brake-2-scat)

Another test is to jack up the vehicle and rotate the wheels by hand. You should feel the same amount of resistance on both sides.
I did not remove, clean and lube the parts you suggest. Can you tell me what lube to get?
 

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Discussion Starter · #7 ·
Ok so after my drive in, I took a bottle of water and squirted some onto the drivers side. Nothing.

Did the same to the passengers side and it boiled on impact. In a dramatic way, too!!!!

I'm guessing there's a chance that rotor is going to warp????

Definitely have some resistance in there and tomorrow morning I'll be removing the calipers and cleaning & lubrication as suggested above.
 

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I did not remove, clean and lube the parts you suggest. Can you tell me what lube to get?
This is what you want:




Should be available at auto parts stores.


In an emergency you can use lithium white grease or anti seize grease, but you want to use the Silicone grease as soon as possible because the others may eventually rot the black rubber seals that cover the pins.
 

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Ok so after my drive in, I took a bottle of water and squirted some onto the drivers side. Nothing.

Did the same to the passengers side and it boiled on impact. In a dramatic way, too!!!!

I'm guessing there's a chance that rotor is going to warp????

Definitely have some resistance in there and tomorrow morning I'll be removing the calipers and cleaning & lubrication as suggested above.
If either pin is really sticky, a good way to clean both the pin and the bore that it goes into is this:

Screw the bolt into the center of the pin.

Spray some rust buster or WD 40 into the bore.

Use an electric drill with an adapter for a socket, and put the proper sized socket (usually 12 mm) on the adapter.

Use this to spin the pins.

Remove the pin and flush the dirty fluid out with new.

Do this until the fluid comes out clear and not rusty.

The pins should then move freely.



When you install the pads in the caliper frames, they should go in and fully seat against the rotors without using any force. If they require force, inspect the the area on the frames where the pad tabs sit, They may be rusty. File off any rust until the pads can easily be installed and removed by hand. It is best to use a light coat of high temperature or anti seize grease on the pad tabs to inhibit further rusting.
 

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Discussion Starter · #10 ·
Bluepill,

Thank you for that information - gonna attempt this first thing tomorrow before work. I'm losing around 120 miles per tank right now!!!!

That said, MPG is getting better, which means it's wearing that new pad down real fast!!!!
 

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If the rust was heavy I would rebuild the calipers or change for new ones altogether... Sticking caliper pots means there is rust inside the caliper behind the piston skirt.
 

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Discussion Starter · #12 ·
If the rust was heavy I would rebuild the calipers or change for new ones altogether... Sticking caliper pots means there is rust inside the caliper behind the piston skirt.
If that's what I end up doing, so be it, but I am on a tight budget, and they appear to be around $80 each. I will try to fix before I replace.

Just trying to find videos to go along with the above instructions.
 

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The remanufactured calipers pay for themselves as the OEM rebuild kits from honda (01463-S3V-A10) hover around 50 bucks per side...

Still cheaper than the remano calipers I know but you are also getting only seals for 50 bucks. For 80 bucks you get all new caliper and bracket, Honda wants 400 bucks for the same thing.
 

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Discussion Starter · #14 ·
So, took the caliper and bracket off; one of the slider pins was seized beyond belief; nothing I did at first released it.

I ended up spraying copious amounts of WD40 onto it, waiting 10 minutes and then tried to get it to move, to no avail.

Ended up putting the bolt into it, and eventually got to move it slightly, then used a ratchet/socket to get it moving more and more, building up heat in the bracket. After 15 minutes, it was moving with reasonable ease, and then took a screwdriver and gently tapped it out - this took about 20 minutes. Then cleaned out the bore using a paint gun cleaning brush. The bushing was in bad condition and stuck in the bore; took another 10 minutes to get that out.

Bought new slider pins, and a boot/bushing kit, along with caliper lubricant. Put it all back together, and so far so good.

Thanks for the info - I'm about to drive to work, so I'll see what the results are!!!
 

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Yee haw... another result! Congrats on the fix.

And don't worry about heat warping the rotor - heat alone almost never actually warps a rotor. What makes most rotors FEEL "warped" is keeping the brakes applied after a really hard panic stop. The rotors and pads go to crazy-hot temperatures, and the pad material essentially "cooks into" the rotor surface, leaving that part a little more sticky than the rest, so it pulls every time it goes through the pad under braking.

If you DO feel some wiggle in your steering wheel under braking, just try running some sandpaper over the rotor to see if you can remove any contamination.
 
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