Brake Pedal Won't Release |
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Brake Pedal Won't Release |
sdthomas |
Aug 8 2018, 09:31 AM
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#1
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Member Group: Members Posts: 64 Joined: 14-June 11 From: Seattle Member No.: 13,193 Region Association: Pacific Northwest |
As I was driving home from work yesterday, I noticed my brake pedal seemed to get firmer and firmer. It got the point where just tapping it slightly would engage the brakes, as though there was no more travel in the pedal. When I got home I noticed all four wheels were very hot to the touch so the brakes had clearly not been fully releasing. I let it cool down and checked the pedal and it felt normal but now I'm worried about driving it.
What could cause this? |
Tbrown4x4 |
Aug 10 2018, 08:57 AM
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#2
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Senior Member Group: Members Posts: 703 Joined: 13-May 14 From: Port Orchard, WA Member No.: 17,338 Region Association: None |
If all 4 brakes are dragging, the last thing I would suspect is a hose or stuck caliper.
Your brake master cylinder has two rubber cups inside (primary and secondary) that seal inside the bore and build pressure when you push on the brake pedal. Just in front of these cups is a small inlet port. As you use the brakes and heat up the fluid, it expands, and travels back to the reservoir through the ports. If there is not enough pedal free play, these ports can be blocked by the rubber cups. The fluid has no where to go when it expands, and the brakes drag. The first thing I would check is pedal free play (as suggested above), and make sure the pedal returns to the stop every time. That said, your master cylinder looks a little crusty. There should be a rubber boot on the end to keep dirt and moisture out. I would suggest replacing it and bleeding the brakes. Might be a good time to replace the hoses too. (Also suggested above.) I would recommend PMB for all the replacement parts. 914 rubber has a nice M/C for sale as well. I just rebuilt my front calipers, and replaced the M/C and hoses. A little challenging to bleed, but the results are worth it. |
sdthomas |
Aug 10 2018, 11:41 AM
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#3
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Member Group: Members Posts: 64 Joined: 14-June 11 From: Seattle Member No.: 13,193 Region Association: Pacific Northwest |
Thanks for all the advice; it's super helpful. First things first though: how do I free up the brakes? If I just open up a caliper bleeder and let out some fluid will it relieve pressure in the system?
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wndsrfr |
Aug 10 2018, 07:06 PM
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#4
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Senior Member Group: Members Posts: 1,428 Joined: 30-April 09 From: Rescue, Virginia Member No.: 10,318 Region Association: MidAtlantic Region |
Thanks for all the advice; it's super helpful. First things first though: how do I free up the brakes? If I just open up a caliper bleeder and let out some fluid will it relieve pressure in the system? It certainly should...and if the wheel won't rotate then it's a stuck caliper piston.. |
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