Took a wheel off. Hub and rotor seems to have quite a but of surface rust. Concluded that the parking brake is in fact released, so it's something at the wheels.

Either the caliper is partially clamped down on the rotor or the surface rust on the rotor is enough to barely rub the pad and slow it down. I can't think of other explanations.

Thoughts?

https://farm4.staticflickr.com/3745/...ec9cd8b8_b.jpg

Might be worth taking the calipers off to check if they are causing your issues..

Rebuild the calipers. Replace the rotors.

JR

Finally had a chance to take apart the right rear brake. Had some trouble with the caliper bolts. But was finally able to get the pads out and the caliper off the rotor.

I can report that the pads were making contact with the rotor, which explains why I was barely able to spin the wheel and the hub. When I removed the pads, it spins fairly freely, with certainly not as much resistance as there used to be. So that's good, and if think I could push the car if I did that on all four wheels.

But it still doesn't really tell me what the problem is.

I had a look at the rotors. There is quite a bit of surface rust, but they aren't grooved. The rotors themselves I think still have a lot of life in them and as far as I know, once the car is rolling, the pads should wear the surface rust right off them.

So that being said, I'd rather not replace the rotors at the moment. I'm operating on a semi-restricted budget every month for this thing and if I can get life out of these rotors, I'd rather try that.

Now, the real issue is why the heck the pads were clamping down on the rotor to begin with. With no pressure in the system (I don't think), why would the pads be compressed against the rotor? I mean, I guess its possible the brake pedal could have been pumped over the past few years when it was in storage and not running, but surely the pads wouldn't stay locked up against the rotor once the pressure was gone? Honestly, I don't know how the whole brake system works. All I know is that brake fluid pumps into the caliper, which squeezes the pads against the rotor which creates friction and stops the car. Why wouldn't the calipers release the clamp on the rotor when the brake is released or pressure dissipates?

The calipers themselves have lots of rust on them, but they look functional. I'm going to order new brake pads for the whole car and swap those out.

Thoughts on why this could be happening or ways to solve it? Yeah I know I could rebuild the calipers, flush the brake fluid, reprime and bleed the lines, and install new rotors and pads, but as I say, I don't want to throw hundreds at the system at the moment if its not desperately needed.

Calipers can get to the point where the pistons are more or less frozen in place. The hydraulic pressure from the master cylinder can push the pistons towards the rotor but there isn't enough pressure to push them back the other way when you let off of the pedal. Open one up and you'll find it looks like crap inside.

Rebuild them, or replace them. Money better spent than replacing the pads which will not solve your problem...

JR

Where does the pressure the other way come from? Remember, the car has been stationary for probably over 10 years and the brake system hasn't been used since then.

The car only has 55000 miles on it, so it's not like the calipers are worn out. Unless the seals and everything are toast from age, etc. which I admit might be problematic.

The fluid absorbs water over the years causing the parts inside to seize.
Replace the rubber lines, rebuild the calipers or have them done for you, change the fluid. Good to go. (sounds easy, but do some research)

Replace the rubber brake lines. They czm swell inside and keep the fluid from flowing back when you release the brakes.

As other noted, you may need to rebuild your calipers. You czm do it your self or many local parts stores can get you rebuilt units on an exchange basis (I think Cardone does them). If you want the best, PMB will restore them to better than new.

Sadly, a 911 than sits unused degrades much faster than one driven regularly. As a result many parts may look new but have failed or will soon.

So I looked up PMB. If I turn in my calipers to them, restored ones are like $279 for a pair, so around $540 for the complete set. Doesn't sound like a horrific deal, honestly.

The question is if I can really do this by myself without going insane or screwing up a critical part. How difficult is rebuilding these, really? I read the 101 projects book section about it.

It notes that if you take them completely apart, they'll likely leak thereafter because most kits don't include the gasket required or something. These things are pretty rusted as it is, which probably means I have to disassemble each completely.

It looks like to do it myself is going to be like $60-75. Is it just worth the additional 450 or so to get it done right and have them completely restored?

The lines I think I can do myself...I have to read up on it, but I don't see a tremendous problem doing that.

PMB does much more than rebuilding them with new seals. Read his explanation about what he does. I think it's a smoking good deal, for what you get.

There's no guarantee that yours are even rebuildable. There's a point at which they become junk.

I generally don't skimp on brakes. They are pretty important.

JR

The "pressure" is not really pressure. Your caliper pistons are saying, "I can move with foot pressure applied, but it's kinda hard to slide back to where I was before the foot pressure was applied".

I say pads and rotors are ok. Pop your pistons and take a look at the bore. It will be obvious if you have some creeping crud in there. Worst case is pitted bores, probably a strong chance on top of the crud and corrosion not allowing the piston to retract.

Try a DIY rebuild if the bores/pistons are smooth. If not, relax, cough it up, and pay for the rebuilt calipers and be done with it. This is more than likely your problem.