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How to change brake rotors and pads?

LouG

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I also suggest that on the front brakes you crack the bleeder and force the pads back with a screwdriver levering against the rotor and caliper.

This prevents any crap in the pucks from being forced back up the line, and I also suggest gravity bleeding them by just opening the bleeder a little when done and letting a little fluid drain out. then add fluid AS YOU GO from corner to corner
Good idea. I remove the pads and spray a dose of brakecleen around the pistons etc before retracting them.
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DarkHorsePremium

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I never thought about using bungee cords before for a brake change! Great suggestion.

Can you post a picture of your pad spreading tool?

I am guilty of being in the screwdriver club. :facepalm:
Sorry for the late reply. Yes. The Lisle 29100. That's the one I have too.
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LouG

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Greetings,
One thing I didn't see mentioned here. I recommend you remove some of your brake fluid from the reservoir before compressing the pistons. When you push the pistons in, the brake fluid level increases in the reservoir. If the top is off it will dump in your engine bay. This will make your life a lot easier. I use a pad spreader. I never use a screwdriver even if I'm going to replace the rotor and pads. Poor man's method.... Some people use C-Clamps, rags and wood door frame shims. If you're not really careful though you'll scratch your calipers. Another item you absolutely need are bungee cords. These are used to hold the caliper up and out of the way. You can wrap it around the spring and then take the tension off of the brake line. Do not let your calipers hang on the brake lines 🙂.

If you're going to do a brake fluid replacement / flush, I use a Motiv bleeder. Another thing that's often overlooked and mentioned above.... A good OBD II reader that can cycle your ABS module. Old fluid will remain in the module if you can't electronically cycle it. I saw something about service mode (above) and don't know if that's just for the parking brake or if it can be used to cycle the ABS module as well. I've only had my Mustang for 2 months but I've been running big brakes for over a decade. Make sure you have a good supply of brake grease on hand, and brake kleen.

When you take the rotors off the hubs, make sure the hub surface is absolutely clean. Wire brush off any surface rust. Put a thin coating of brake grease on the hub or on the back of the disc hat. Don't get any on the lugs. Use brake kleen to clean all of the springs, pins, retention clips and surfaces. Clean brake components function better and remain quiet. You can put a thin film of brake grease on the back of of your pads. It won't hurt the piston boots and further ensures quiet brakes. If you don't put a film on the back plates, vibration will cause noise.

I'll probably think of some other stuff 😂 but these are some key things to look at. Don't scrimp, assemble all the tools you'll need. To get the pins out on the calipers you need a proper punch set. You can do a lot of things with the wrong tools, but you will mar your calipers. Just take your time. Hope this helps.
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BimmerDriver

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Sorry for the late reply. Yes. The Lisle 29100.
That's pretty sweet! I used to have a pad spreader, but it appears that someone borrowed it and never returned it. That's why I hate loaning out tools.

I am a charter member of the long fat screwdriver club. 🪛

The worst brake job I can remember was on my Zupra, putting on track pads. The factory pads are glued on, probably to reduce noise and perhaps simplify installation at the factory. But what a pain to get them off! And yes, I damaged the finish on the calipers. Grrrrrr.
 

DarkHorsePremium

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Are you a Tech, or a very learned DIY'er? This is golden.
@Lou G,
That's very kind of you. I'm just a car enthusiast, a learned DIY'er 👨‍🔧

My Dad started the boys with mini bikes and dirt bikes when I was eight or nine. He taught us how to wrench and ride. That turned into cars. We had a marine dealership for 16 years too so I saw my share of motors. I've never stopped learning. I'm no expert, cars are just a hobby. The 7G forum is great. I've learned so much from everyone. Lots of friendly helpful people here. After coming from Subaru, the Mustang was exactly what I needed. Looking forward to learning my DH. 👍
 


GrabThatBlue

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I found a video on how to replace the rotos yourself.

I miss the part where he compressed the pistons. Can someone tell me why and when you have to do that? In thos video everything looks so easy.
 

DarkHorsePremium

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I miss the part where he compressed the pistons. Can someone tell me why and when you have to do that? In thos video everything looks so easy.
When you replace the rotors on your car, it's recommended that you put new pads on to. You'll need to compress the pistons to get the loaded caliper back on the new rotor. Then go through the bedding process unless you buy pre-bedded pads. You're still going to need to get the surfaces properly mated for best performance. In the old days we used to turn rotors but not anymore.

Brakes are one of the most important components on your car. They need to work right, so I never skimp. You should be able to get several pad changes on new rotors. It depends on driving habits and use. You can measure the run out regularly and change if necessary, but always put new pads on with new rotors. It's the best and safest way to go.

Nice video BTW. My rotor preference is for slotted only, but some people like drilled and slotted.
 
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he compressed the pistons. Can someone tell me why
As the pads wear out and get thinner, each time you step on the brake, the pistons come out of the caliper a little bit further.

If this was not true, and the piston retracted all the way, then you would have to pump your brakes two or three times every time you wanted to stop on the thin, old pads.

So when you remove those pads, and you put the new, thicker pads in, there will not be enough clearance between them to fit them over the rotor.

Accordingly, you need to push the pistons back into the caliper to spread the pads further apart to make room for the rotor.
 

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I found a video on how to replace the rotos yourself.

I miss the part where he compressed the pistons. Can someone tell me why and when you have to do that? In thos video everything looks so easy.
When replacing old pads with new... In other words, the new pads won't fit into the space left by the old worn pads, and the pistons need to be pushed into the calipers to fit the new thicker pads.
 

LouG

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Bedding in is also a must. I was told 4 or 5 hard stops from 100kmh (or more if there's no cops around)
I noticed on the Mustang that initial bite and modulation improved out of sight once properly bedded.
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