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The handbrake on my car is too weak. By that I mean that, when I pull the handbrake as hard as I can, it still doesn't brake the car if I park steeply enough. The handbrake lever does, however, still tighten up normally when I pull it, rather than bottom out, so I assume it isn't just that it needs tightening.

It's a BMW E39, so it uses the inside of the rear brake discs as a drum brake for the purposes of the handbrake. However, I've checked the brake shoes, and they seem fine. Checking pictures of new brake shoes, they don't seem to have visibly more lining.

If it isn't the brake wire, and the brake shoes aren't worn, what can it be? Can the brake shoes get "old"?

  • Could the inside of the brake "drum" be rusted? – Pᴀᴜʟsᴛᴇʀ2 Nov 26 '17 at 1:21
  • There was some rust inside the drum, of course, but it didn't seem particularly excessive, and there was a band around it that seemed to match the brake shoes that seemed clean enough. I'll certainly admit it wasn't exactly sparkling clean, though. Perhaps it might help if I try braking the drum in a bit? – Dolda2000 Nov 26 '17 at 2:55
  • You could try that ... put the e-brake on just enough so it would rub, then drive it a bit. Not much, though, or you'll overheat it and cause other issues. A 100 yards or so should help it out if that's the reason why. It's at least worth a try. – Pᴀᴜʟsᴛᴇʀ2 Nov 26 '17 at 3:37
  • Some cars have rubbish handbrakes. Have you checked this isn't a common issue with that model? I had a Vauxhall Corsa that wouldn't hold on many of the hills near home (anything over about 25% required parking with the wheels turned into the kerb). This was despite the best efforts of the main dealer. A back-street garage improved things a little, probably by roughing up the braking surfaces. Hill starts on similar roads could be interesting too. – Chris H Nov 27 '17 at 16:05
  • @ChrisH: Well, the reason I'm on it is because it was too weak to pass inspection, so I'd like to think it's not just this weak by default. :) – Dolda2000 Nov 27 '17 at 16:12
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As you say that the handbrake mechanism is working, perhaps the shoes have just become hard and glazed due to their age and thus less effective. If this is the case there will be far less braking friction if the shoes and drums are not binding against each other as they should during operation.

If you're doing the work yourself, and if possible, remove the handbrake cable from the shoes before full disassembly and pull the handbrake on gradually making sure that the inner cable is actually pulling up properly and smoothly inside its outer sleeve.. I have known many handbrake cables to seize up at a point inside giving the feeling that the handbrake is working, when in fact you're just pulling the handbrake lever against a seized point in the cable, and so the shoes are only partially operating.

Now onto the shoes... You can try roughing up the top surfaces of the shoes and drums with some emery cloth or sand paper. Whilst your there make sure any pins and levers are floating properly and are lubricated were necessary. If the shoes are really old you could be wasting your time trying to revive the old surfaces, and if this is the case replacements may be the better option.

  • Good ideas all around that I'll certainly have to try, but one question: Can brake lining really get bad just by old age? I've never heard about it previously, and Googling for it doesn't seem to get any meaningful results outside of bike break pads. – Dolda2000 Nov 26 '17 at 12:20
  • The linings don't degrade much if unused in a clean environment unless they are very very old. However the linings when inside a drum are subjected to extreme temperature changes, temperature cycles and extreme pressures. They also don't live in the nicest of environments with an atmosphere of dust, rust, moisture and perhaps even fluid and grease particles in some cases. It's all this stuff that can cause degradation, cracking and general breakdown of the materials. – Orb Nov 27 '17 at 0:23

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