Rear Brake Calipers - 2009 M35X

[bluedevil30]

I've just replaced the rear brake calipers on my 2009 M35X with 167K miles for the 2nd time. The first was at 110,000 (replaced with aftermarket) and the 2nd time was last week. Front calipers are fine. Is there some design issue that causes the rear calipers to seize up prematurely?

[steve_c]

Yes,
Old brake fluid builds up water, forming acidic contaminants that corrode calipers & seize the piston to the bore.
Brake fluid moisture migrates down to the calipers, where it then does its dirty work.
Calipers will last the lifetime of the car if you flush the system every 2 years as recommended. (I do mine every season).

A major problem I still see today with my own eyes, and on videos like U Tube are people (I cannot call them mechanics)
who push back the piston into the caliper (so new pads will fit), without flushing the old fluid out the caliper bleeder screw first.
When you do this, you are pushing corrosive contaminated fluid back into the lines.
I always reset pistons into the calipers only after a thorough fluid flush at each of the calipers.
Even then, I crack the bleeder while pushing the piston in so the fluid bleeds out the caliper bleeder screw, and does not migrate up the lines.

My opinion is is that a lot of people do not want to fool with bleeder screws because caution is needed with frozen bleeder screws, and opening the system can introduce air into the lines requiring bleeding/purging the air out.

[ZMQguy]

Could also be rear brake hose failure. I've seen this many times on many nissans. The hose will collapse internally but appear to be just fine. It let's fluid pass through under pressure to press the piston out but won't let the fluid back through to let the piston retract, keeping constant pressure on the pads.

[ZMQguy]

I would highly doubt the issue is old brake fluid when you have already replaced the calipers twice. The old fluid would have been flushed out during the install of the calipers, most likely. I'd bet 90% if not all of your fluid is new going to the rear calipers.

[bluedevil30]

Original front calipers are still fine at 167K, so it isn't a fluid replacement issue. The rear calipers looked very rusty like they are taking a big dose of road salt. Is it possible that the aftermarket calipers just rusted out faster than the OEM ones?

[ZMQguy]

As dumb as this may sound, that rust is caused by the excessive heat of the calipers dragging. I have the exact same issue on my drivers rear. I purchased a new hose, I'll be installing it this weekend. I cleaned all of the oxidation and rust off of my calipers to paint them. 3 days later only one had rusted, the drivers rear. I purchased all new pads, and hawk zinc coated rotors, which are rust proof. Guess what happened. Drivers rear rusted. I removed the rust again, painted all of my calipers and rotor hats. Guess what's happening.... the paint is burning and peeling, on the drivers rear. The only one I've ever had a rust issue with is the one that's dragging. Like I said I've seen this many times on many nissans, only in the rear. I can almost guarantee once I change the hose back there all of my issues will be fixed. Hope my experience helps you out.

[bluedevil30]

It was my driver's rear caliper that seized.

What do you mean by dragging? Are you replacing the brake line hose? Why will that help?

Thanks!

[ZMQguy]

Yes, I replaced my drivers rear brake hose this evening and it fixed the problem. Dragging just means grabbing, or as you call it seizing. I also did two rear brake hoses today on a customers 2011 altima. It's a pretty common issue amongst most 2004-present nissans. I'm very surprised there isn't a sticky on it on this forum. The altima today had 78k on it and all brake pads were gone. Rears should never wear as fast as the fronts.

So, here's a simplified explanation of how power brakes work and fail. Your brakes are powered by a vacuum Booster, which is powered by vacuum from the engine. When you press the brakes a piston in your master cylinder pushes fluid to all of your calipers, boosted to many PSI's by the Booster. That fluid pushes out the piston in your caliper, which presses on the pads which press on the rotor and your car slows down. When a brake hose collapses internally the boosted fluid can get through the collapsed hose to press the calipers piston. It cannot get back out though, due to the collapsed hose. This is further compounded by the extra heat now being generated at that caliper from the extra friction/drag. The extra heat is now making matters worse because it's causing the trapped fluid to expand, pressing the piston against pads and causing more heat and more drag. Now the brake is basically applying itself.