911 brakes dragging - rebuild calipers? New rotors?

[Alexandphoto]

Hi all

Having an issue with my brakes unfortunately.

Background
- Brake master cylinder rebuilt, lines replaced, bleeders replaced, and system bled about a year ago.
- Car sat for about a year after this due to fuel system issue.
- Don’t believe the brake issue existed before this.

With the car now back on the road, the brake warning light is on and some of the brakes are dragging.

IMPORTANT - The car drives dead straight and brakes in a straight line.

Issue with rear left caliper

- Rear Right wheel spins fine.
- Rear left is much harder to spin, and at certain points of the rotation it is even harder to spin
- I’ve tried adjusting the handbrake in that corner and that did not resolve the issue. I pried the pad closest to the rim off and the wheel would then spin freely. After I turned the car on, pushed the brakes, it would go back to the old behaviour.
- When in gear, the RR turns fine . RL locks up frequently
- 2 videos of this:

https://youtube.com/shorts/4lyZT82YXOk?feature=share

https://youtube.com/shorts/BZ_d7sMNh7Y?feature=share


On the fronts
- front right spins very free, and will rotate a little bit more even after I stop spinning it
- Front left spins ok, but not as free as the front right. If I stop spinning it by hand, it will stop almost straight away.


Any thoughts on what it could be? I suspect at a minimum that the rear left rotor is warped.

Could I have too much fluid in the system causing the brakes to drag?

Could the calipers need a rebuild? (Since the RL caliper piston seems to be able to move fine, I don’t think this would be the issue)

Does the front sound like a concerning issue?

[deemsriddle]

A common reason for dragging brakes is the pedal cluster bushing on the drivers floor board has gone bad and the drag wont allow the brake master cylinder to fully disengage. If this bushing is bad, it will not release the master cylinder fully. In addition, a bad bushing and will negatively effect clutch action which might shorten clutch life.

This is easily diagnosed by getting on your hands and knees, and pushing in on the brake pedal manually. If the brake pedal doesn't return to its original position on its own, or the pedal can be pulled out manually, then you need to have it rebuilt. There are many people on this site that can do it for you. It's also a great way of gaining "sweat equity" as the bushing is inexpensive and can be done by a skillful shade tree mechanic. Check the Pelican forums and YouTube.

Your rotors are dragging and then loosening only to drag again like that because of uneven rotor wear. The rotors either need to be replaced with new, or trued if there is enough material on the existing rotor. Also, spend the bucks to have your calipers rebuilt or, rebuild them yourself. It's a great investment.

You don't give the year and model, but the air cooled cars are all old and need to have a lot of service done to them. The 1998 993 is 24 years old. Everything else is older that that. Our air cooled Porsches are worth an unbelievable amount of money and will likely retain much of their value, if history repeats itself. The A list cars will probably appreciate. A little preventative maintenance and repair can potentially save you in the long run and will add to the value of your "investment."

Plus the value of your life and the lives of your passengers and others on the road deserve the greatest of respect (NO, I am not a tree-hugger or liberal.)

Remember, the life you save may be mine, or owe you money.

Good luck. Your problems seem to be age and service related.

[blucille]

A common reason for brake dragging is deteriorating rubber brake lines.

If you are in doubt, a full rebuild isn’t very hard. Plan on going over the calipers and replacing the rubber lines. I suggest new rotors at this point as well as pads since the car has been sitting for a while.

[manbridge 74]

Had a guy once accuse me of “milking his wallet” when I recommended rear lines that were dated 1970. I saved one, cut it in half to show him complete blockage.

[SCadaddle]

In your second video with the right rear spinning with the engine running and in gear, unless you've got a LSD I would imagine you could either chock that right rear or put it on the ground and the left rear would spin. Somebody else can chime in on that.

Easiest way to determine a sticky caliper is to go for a drive then get out and put your open hand/fingers on the wheels near the center of the wheel. The dragging ones will be considerably warmer than the ones that aren't.

The Ate caliper rebuild kits are very inexpensive and you can use the tutorial from the PMB website to clean them up and put the kits in them yourself. Of course the tutorial is going to take subtle jabs at you for being cheap and not using their services, but it is what it is. I recently refurbished the calipers on my SC and it is a wonderful thing to have a car that actually rolls. The one deviation to the PMB tutorial/videos that I made is that I used the permatex silicone based caliper grease in the bores that is orange in appearance vs. PMB using the permatex synthetic based grease that is purple. I surmise this is due to dated material and the silicone grease is supposedly a newer product. I spent the majority of the time in really cleaning up that 1/4" or so of the bores that is outboard of the piston seal. That is where things get corroded and hangs up the pistons under the dust boots. Some may argue and suggest just using brake fluid as a lube to get the pistons back in the caliper, but this is the one spot you don't want brake fluid because 1) it is outside of the hydraulic brake system and 2) it will just promote corrosion leading to sticky calipers......again. My rear left caliper had got to the point of holding the car on an incline.

[deemsriddle]

Under "background" he says replaced brake lines. These brake problems should be looked at with the idea that any car with 25 year or older braking system needs a complete overhaul and not done a little at a time.

[Bill Douglas]

I had one caliper dragging recently. I pulled it off the rotor and took the pads out. shoved a bit of wood in where the rotor would have been and stood on the brake. One side wasn't moving. I put a g-clamp/c-clamp holding the good side in and stood on the brake again. forced the caliper back in, brake pedal etc. I did this about 15 times. I cleaned the two pins that hold the pads in place. Got the mnor surface rust off them. The stuck caliper now moves freely. That was a month ago and it's been fine since.

[Gadsby]

I restored 2 brake systems this year, not bad just time consuming. Always nice to know it will stop.

I got a car last fall came out of trailer with no brakes, fluid on trailer floor!

[Alexandphoto]

Thank you all for the tips and advice. As mentioned, I’ve replaced the lines already so should be good in that department.

I’ve picked up new rear pads and rotors, as well as a hardware kit. I’ll be trying that first, and closely looking at the seals on the caliper.

Similarly for the fronts, I’ll give the calipers a good clean and inspect for damage.

Fingers crossed. I’d just got the car back after a year off the road, itching to drive again!

[2.7RS]

Refresh calipers with new seals
New rubber lines.
Plenty of elbow grease. Cheap though.
Only use ATE seals.

[mrdstr]

@Gadsby - what was the process to refinish the calipers? About to start on rear caliper rebuild as I had a sticking piston. Would love to bring the color back.