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After watching a number of tutorials, I wanted to make sure it wasn't absolutely necessary to replace drums when I replace shoes and springs etc (I'm on a budget). Can someone confirm this and/or recommend best practice? Safety is obviously important, but maybe this question is rooted in misunderstanding.

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  • Chamfer the new shoes before fitting them, 1mm is more than enough. It will prevent them from squeeling and makes them adjust better right away. Otherwise the first brake attempts may require you to push in the brake pedal rather far.
    – Bart
    Commented Feb 20, 2018 at 19:16
  • @Bart Do you have an online resource that explains what chamfering the new shoes means and looks like? I'm unfamiliar. Thanks for the tip! Commented Feb 23, 2018 at 17:14
  • No I don't. It's just personal experience that proved this little trick very useful. Especially with older drums where old shoes have made an embedding. That embedding has rounded edges, chamfering new shoes will make 'em fit right in. But it also applies to new drums.
    – Bart
    Commented Feb 24, 2018 at 15:46

2 Answers 2

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You don't need to necessarily change out the drums, but there are a couple of caveats to this as an answer.

  • If the drum is in good shape and meets minimum thickness, you could just put the old ones back on there. They will not work as well as if you did one of the following two routes. You'll still need to bust the glaze on the wear surface of the drum using some sand paper or something similar.

  • If the wear surface of the drum is rough (you can feel ridges when you run your fingernail over it), you'll at a minimum need to get it machined so a fresh surface is there. You can do this as long as the drum meets the minimum thickness needed for it to work correctly.

  • If you cannot machine the inner surface, you'll need to replace it. Most drums have the maximum diameter the machine surface can be. When you take it into get it machined, the place where you get it done can check this for you.

Whether you use a freshly turned drum or a brand new one, you'll find they will work better and your brakes will last longer than using a used one. Even minor blemishes on the machined surface will wear the brake shoes faster than if you just bust the glaze off of it.

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  • Thank you @Paulster2. That's exactly what I needed to figure out. My car is a 2000 Hyundai Accent at 207k miles now and I'm guessing the drums might be quite old at this point, so I'll probably take the savings from DIY and put it into new drums. Thanks for the direction on this! Commented Feb 20, 2018 at 2:21
  • @MarkWitmer, I always price the drums/disks. Often a new part is so cheap its just not worth the hassle of dealing with the old part. I'm not going to machine a rotor if i can get a new one for less than $20.
    – JPhi1618
    Commented Feb 22, 2018 at 16:05
  • Yeah. I do see what you mean. After seeing how easy it is to get affordable parts online, I didn't see a reason not to do this. Any idea what it would cost to replace 2 drum brakes with wheel cylinders? So far, all of my parts costed me 126 dollars, so assuming the repair goes smoothly, I should still be saving money. Commented Feb 23, 2018 at 17:03
  • @MarkWitmer - Just check wherever you can online. Check Amazon and RockAuto. 126 seems about ballpark for what you've listed, depending your vehicle. Commented Feb 23, 2018 at 17:59
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The drums only need replacing if they are deeply cracked or oversize.

Properly adjusted drums last for several sets of shoes.

The inner edge will need to be cleaned and gently chamfered off to allow the drum to slide back on easily when refitting.

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