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Registered
Join Date: Oct 2021
Posts: 4
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Rear Brakes sticking on
Hi I have a 1998 996 3.4 C2 tiptronic, First of all when I bought the car after it has been standing for about 5 years I think, It had no brakes, after inspecting the system the brake pipes where very rusty, so I have now replaced the complete system, Then I had problems with the bleeding, so I fitted a new master cylinder, and eventually I got the brakes to work. The brakes seemed ok, Yesterday I took it for mot and all was well, Until it went on the brake roller tester, the brakes where ok , But when I wend to drive it away from the Mot station the rear brakes had locked on, I left it for a few minutes and it released, I managed to get it home without using the brakes hard, So when I was on the drive I pressed the brakes hard and the rears lock solid again, left it a while and got it on the ramp, I pressed it hard again while on the ramp, and I tried to get the pads out. no way stuck in with the pressure still on. I then cracked open the bleed nipple and the pads came out, The caliper pistons seem free and fine, So I am going to go after the brake booster, I think it it holding back.
Any thoughts?. Paul |
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12-11-2021, 10:36 PM
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Registered
Join Date: Jan 2004
Location: Pittsford, NY
Posts: 3,721
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Stop guessing and throwing parts at the car. Have it checked by a Porsche indie mechanic. This could be a software issue that needs to be managed with the PIWIS software.
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Tony G 10 Porsches come & gone! 1962 Morgan Plus 4 
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12-14-2021, 03:20 AM
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Porsche 911 Carrera S
Join Date: Sep 2015
Posts: 71
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I would wonder about the brake booster diagnosis. It is there to assist the pedal braking effort not really hold or let-go-of brake hydraulic pressure. Is it possible the brake pedal linkage is binding? Perhaps it's the ABS unit. Perhaps it's something wrong the caliper (binding?). Are you sure the other rear is locked? Do the fronts lock? When you did the master cylinder, did you bleed the ABS unit? Did you pressure bleed or use the old-school two-person method? Tony's suggestion to take to an experienced Porsche shop (with brake experience too) is appropriate.
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________________________________ John - 2005 C2S 997.1 at ~82k mi |
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12-14-2021, 11:48 AM
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Registered
Join Date: Jan 2008
Location: NJ
Posts: 1,186
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Early 996 brake boosters had a bleed hole on the bottom. ( redesigned in 2000? 2002?) It would let water into the booster when the cowl drains were blocked. The internal corrosion would cause the brakes to stick. Do a Google for water in the booster.
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2013 991.1 Carrera S Cab 2004 996 Turbo CAB X50 sold 2003 996 cab 6 speed Sold 1972 RS 3.2 twin plug short stroke crank fire, roll bar, sold DE instructor since 1985 |
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12-14-2021, 07:00 PM
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Porsche 911 Carrera S
Join Date: Sep 2015
Posts: 71
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OP, is your brake pedal getting stuck when you take your foot off of it? (Not returning to its topmost position)
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12-14-2021, 08:23 PM
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Registered
Join Date: Oct 2014
Location: NW Arkansas
Posts: 1,349
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This is not likely your problem but free and easy to inspect.
We had issues with the brakes sticking on our 930. The culprit was thick paint on our new Textar causing the brake pads to stick and not return with the caliper pistons.
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SWB 912 - G50 Carrera - 986 Boxster - 997.2 911 Turbo - 958.2 Cayenne SOLD: 9Y3 Cayenne GTS - 958 Cayenne Turbo S - 997 Carrera 4S - 957 Cayenne Turbo Workshop Coordinator at Ehrlich Motorwerks instagram.com/patrickossenkop ehrlichmotorwerks.com |
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12-15-2021, 07:34 AM
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