2007 Dodge Charger SRT8: DIY Front Brake Job Walkaround
by Dan Edmunds, Director of Vehicle Testing on December 11, 2015
Pt 1 | Pt 2
In our last episode, I had to cancel the brake job on our 2007 Dodge Charger SRT8 because it turned out the old rotors were too thin and I had to get my hands on some new ones. The reality of my schedule led to a two week delay, but the situation was not yet dire. The pad wear indicators were not yet making noise.
Or were they?
Coming back from dinner with the family, I dabbed on the brakes as I wheeled the Dodge into our driveway. My wife and daughter grabbed for their ears and said, "Can you hear that?"
The alleged noise hadn't made itself known any of the multiple dozen other times I'd used the brakes that evening, so the pad wear indicators must have just barely started making contact with the rotors. Not yet a full-fledged squeal, they were warming up by emitting the dreaded high-frequency "teenager noise" that can make a dad feel like an old man.
So I wheeled the Charger down the driveway and parked it behind the house where it needed to be for the next morning's brake job.
This is a job done that must be done one side at a time, a case of sock-shoe, sock-shoe, not sock-sock, shoe-shoe. So you might as well make it easy on yourself and crank the wheel all the way to the side you're working on.
But a steering wheel never likes to stay put way out there at full lock. They always sneak back a half-turn or more when you let go. There is such a thing as spring-loaded clamp that goes between the seat and wheel, found mostly at alignment shops and used when they need to hold the wheel centered while they adjust the toe-in. But I'm not an alignment shop. Enter one long fruit-picking pole.
Don't laugh, it works. And it's not tearing up the wheel or the door seal. I checked. Barely any resistance is needed to keep it from unwinding, anyway.
These are four-piston fixed calipers, in which two pistons push on each pad. And these pads are indeed thin. You know it's bad when the remaining pad friction material is slimmer than the pad's own backing plate.
But these are not the pad retaining pins I expected. The big pins sometimes have tiny retaining pins of their own, but not here.
Careful inspection reveals the pin holes on the inner face of the caliper are larger than the outer ones. A few exploratory taps with a nail-set punch gets them moving.
It turns out that expanding barrel clamps were holding them in place.
These parts are to be saved and reused when we put it all back together.
Steady but firm pressure applied to the pad backing plate with the butt-end of a hammer will compress the pistons on that side enough to open up a gap so I can pull the pad out.
But I have to keep going. The pistons need to be pushed far enough to make room for the full thickness of the new brake pads.
I don't own a piston retracting tool made for the purpose because I don't do this regularly enough to justify the cost. Instead I'm leaving the second pad in place while I use the first pad as a lever against the first pair of pistons, taking great care not to nick and damage any piston seals. There isn't much leverage, so it takes 10 or 15 seconds of steady pressure to ease them in. It's crucial to push on both pistons together, otherwise one would simply pop out while I pushed on its partner. That would be what we in the industry call Bad News.
Any time you retract pistons you must keep an eye on the brake fluid reservoir and be prepared to extract some fluid. The level will rise as the pistons are pushed in to make room for the thicker new pads, and you don't want it to overflow. Brake fluid is quite corrosive and damaging to paint, and the brake booster and master cylinder areas are hard to get at if you need to clean it up.
This is why I never top-up the brake fluid reservoir in between pad changes. It's normal for the level to go down as the pads wear. In fact, this trait is a useful indicator of how much the pads have worn. And it's why reservoirs have widely separated Max and Min lines. Your goal is to merely prevent it from ever dropping below Min, not keep it at Max.
In all likelihood you'll never have to add a drop unless you're actively doing something like bleeding the brakes. Actual fluid leaks are extremely rare, so the fluid level will almost certainly come back up to Max line once full thickness pads (and rotors) are installed.
But in this case it's clear someone has topped-up the fluid in this car. I'm going to have to suck some out at some point during this pad change. This question is "when?" Which is why I've got to keep an eye on it.
Here's the real pad wear indicator, you can see how it's just barely starting to make contact and emit the dreaded teenager noise. We caught it at the right time.
Once you've got one pair of pistons retracted, you need something to hold those pistons back and prevent them from popping out while you lever in the opposite pair. Enter one scrap of wood. Don't laugh, it works. I could have slid in one of the new pads temporarily, too.
With the pads out all four pistons retracted, it's time to take the caliper off. But we're not going to open or remove any brake lines. And it's important to support the caliper and make sure the hose doesn't get kinked or pulled tight.
A daisy-chain of zip ties makes it easy to hang the caliper nearby so there is no stress on the brake hoses. I've looped them around the upper control arm
What you can't see here is how stuck the rotor is. I tried a dead-blow hammer, but I just made a bunch of noise. It's rusted in place, which isn't all that rare.
There's no need for swearing or an hour-long wait for oil penetrant to *maybe* loosen things. Why not trot our three dollars-worth of nuts and bolts instead? The threads don't screw into anything on the car, they'll just pass through the caliper mounting holes. All that matters is that the diameter is fairly big. All-thread bolts are a good idea, too.
Use the ratchet to keep the bolt from turning. This way, the bolt will grow in the direction of the rotor as you tighten the inside nut with your wrench. The second nut at the end is optional; it's there to spread the load on the rotor, which is more of an issue if it this contraption happens to contact the machined surface of the rotor, something that's not going on here.
Alternating between the upper and lower bolts a quarter-turn at a time, it doesn't take long before a "pop" signals the rust bond has been broken. I continue for a couple of extra cranks to make sure the bond is broken all the way around.
Yuck. Look at that rust. But I've seen worse. A Texas toothbrush is good for knocking the worst of the loose stuff away, but you don't need to be obsessive about it.
It is a good idea to spread a thin coating of anti-seize compound on the hub-to-rotor interface to prevent this from happening again. Those who live in seaside areas or where winter road salt is used may want to consider this a necessary step.
New versus old. Incidentally, these new rotors don't have the minimum thickness stamped on them like the originals did. Write it down or save a photograph in your files in case this ever comes up again.
I like to use a couple of lug nuts and washers to seat the rotor and hold it tightly in place before I install the caliper and pads.
Now I can cut the zip ties and tighten and torque the calipers.
The arrows indicate which way the rotors should rotate under the pads. That makes this the right-front corner.
Anti-squeal compound came in a tube with the pads, so I smeared it wherever the pad backing plate would make contact with the pistons or the caliper sliding surfaces.
The anti-rattle preload spring goes back in under the pins. It's best to first get the top threaded through and feed the upper pin into place before you put any tension on it.
Now you can push down on the bottom and preload the spring before feeding the lower pin through.
Don't forget to re-seat the pin barrel clamps with your hammer and punch.
It's good to dab a little anti-squeal grease where the spring might contact the caliper.
That was all just the first side. Now it's time to reset everything to do the other side. This is a good time to check the brake fluid level.
In this case I didn't have to remove any when I switched from left to right, but it had come up past the Max mark. Our Charger's reservoir had enough excess capacity that I didn't have to extract any until I'd completed both sides.
Done. The pedal will be very soft for the first brake application because I pushed the pistons in farther than necessary to get the new pads in. But even after that the brakes will lack initial effectiveness and bite until it all beds in. Green Fade, they call it. In this case it lasted a couple of miles before they started to feel strong.
How long did this take? About 90 minutes, not including the time it took to rush over to the hardware store for the bolts. Call it an hour if I back out the time I spent taking pictures. It could easily be less the next time. This is a pretty straightforward brake job.
Dan Edmunds, Director of Vehicle Testing @ 75,148 miles