My Brakes Seized up on the Trail |
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captianpattson
Member Joined: 07 Apr. 2010 Location: ST GEORGE, UT Status: Offline Points: 770 |
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Posted: 18 Mar. 2018 at 4:48am |
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Hey everyone, I took my jeep out on a trail for the first time today with a buddy of mine. We got about a mile down the road and realized that when I tried to shift into second gear it would stall because the jeep would suddenly come to a stop before I could even shift. We got out and realized that all the brakes were seized up, even the brake light was on. I did a disc brake conversion on all four wheels so it isn't stock but the MC is stock. The rotors were super hot. I crawled under and loosened one of the bleeder nuts and everything let go. It shot a bit of fluid out. Luckily we were on a pretty flat ground otherwise the jeep would have rolled over me underneath it (I've never claimed to be smart). my rig doesn't have a master cylinder heatshield in between the exhaust, do you think this could have been a contributing factor? I loosened the cap on the MC so it couldn't build up pressure in the system on the way back and I didn't have any problems. Anyone had a similar problem? Any suggestions? I can either get a heat shield or wrap the exhaust?...
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ndnchf
Member Sponsor Member x 2 Joined: 22 Sep. 2017 Location: Virginia Status: Offline Points: 2177 |
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is your brake pedal adjusted from proper free play? If not, the internal port in the MC may not be uncovered by the piston. This allows pressure to be equalized or relieved in the system. Heat wrap would be a good idea if you don't have a heat shield.
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1948 CJ2A - It goes nowhere fast, but anywhere slow.
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SE Kansas 46 CJ-2A
Member Sponsor Member x 3 Joined: 22 Jan. 2016 Location: S.E. Kansas Status: Offline Points: 3192 |
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46 CJ-2A #64462 "Ol' Red" (bought April 1969)(second owner)(12 V, 11" brakes, M-38 frame, MD Juan tub)
U.S. Coast Guard Chief Petty Officer(ret.) U.S. Army Vietnam veteran and damned proud of it. |
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Lee MN
Member Joined: 13 Aug. 2008 Location: Harris, MN Status: Offline Points: 4955 |
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X3 on the free play!
Lee |
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LEE
44 GPW-The Perfected Willys 49 2A “If you wait, you only get older” 67 M715 American Made Rolling History |
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captianpattson
Member Joined: 07 Apr. 2010 Location: ST GEORGE, UT Status: Offline Points: 770 |
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I haven't adjusted them at all, so that's most likely the culprit. I'll do some reading. Thanks!
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Rick G
Member Joined: 17 May 2015 Location: Amarillo, TX Status: Offline Points: 1468 |
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I had the exact same problem with my 4 wheel disc conversion. I struggled with this problem for weeks. I built a heat shield for the master cylinder, wrapped the exhaust, wrapped the brake lines, even had the exhaust rerouted. I had built my disc brake system with a new Wilwood dual reservoir master cylinder in the original location. I was FRUSTRATED beyond comprehension. I took heat readings all over trying to find a hot spot and it didn’t exist. I even thought I was going to have to use that special high temp brake fluid. When I drove mine about 3 miles it would lock the brakes up so tight, I couldn’t get the jeep to move even in 4wheel drive low range!
Finally, I called Wilwood for help. I told him the temps I was seeing in the brake system and he said that was not hot at all. He said I didn’t have enough pedal play. I ended up having to cut about a 1/2” off my brake rod because of how I built my mounting bracket. Voila’! Problem solved! Brakes work perfect now.
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Bruce W
Member Joined: 29 July 2005 Location: Northeast Colorado Status: Offline Points: 9653 |
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X5 on the lack of free play being the culprit, minus one on the lack of a heat shield being the culprit.
You say you are using the stock master cylinder - if you did not remove the residual pressure check valve, the disc brakes will not release completely. If you do remove it, the rear wheel cylinders will leak. BW
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It is NOT a Jeep Willys! It is a Willys jeep.
Happy Trails! Good-bye, Good Luck, and May the Good Lord Take a Likin' to You! We Have Miles to Jeep, Before We Sleep. |
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captianpattson
Member Joined: 07 Apr. 2010 Location: ST GEORGE, UT Status: Offline Points: 770 |
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I'm going to readjust the brakes this weekend. I did remove the rpv prior to installation. I haven't had any issues with the rear cylinders leaking. What would cause this issue? I haven't installed a proportioning valve yet.
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Rick G
Member Joined: 17 May 2015 Location: Amarillo, TX Status: Offline Points: 1468 |
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I originally installed Wilwood 2 psi residual valves, one for the front and one for the rear (4wheel disc). I have since gutted both valves and have had zero issues without them. Bruce, I’m not sure I understand why the rear wheel cylinders will leak if you remove the pressure residual valve(s)?
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Stev
Member Sponsor Member Joined: 27 July 2016 Location: Cincinnati Status: Offline Points: 2391 |
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Something else to consider: If this system has rubber flex lines hoses, they can also act like check valves when they get old. The hoses can collapse once you take you foot off of the break - trapping the fluid in the wheel cylinders / pistons - keeping the breaks engaged.
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Stev
1946 CJ2A Trail Jeep (The Saint), 1948 CJ2A Lefty Restored |
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SE Kansas 46 CJ-2A
Member Sponsor Member x 3 Joined: 22 Jan. 2016 Location: S.E. Kansas Status: Offline Points: 3192 |
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46 CJ-2A #64462 "Ol' Red" (bought April 1969)(second owner)(12 V, 11" brakes, M-38 frame, MD Juan tub)
U.S. Coast Guard Chief Petty Officer(ret.) U.S. Army Vietnam veteran and damned proud of it. |
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Bruce W
Member Joined: 29 July 2005 Location: Northeast Colorado Status: Offline Points: 9653 |
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The reason (or one of) for the residual pressure valve is to keep a small amount of pressure in the wheel cylinders so that the lips of the rubber cups will be pressed against the wall of the cylinder, making a good seal. This helps to keep the brake fluid in where it belongs, and helps to keep air, water, and dirt out. Maybe I should have said they may leak, or will eventually leak. BW
Edited by Bruce W - 20 Mar. 2018 at 4:49am |
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It is NOT a Jeep Willys! It is a Willys jeep.
Happy Trails! Good-bye, Good Luck, and May the Good Lord Take a Likin' to You! We Have Miles to Jeep, Before We Sleep. |
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captianpattson
Member Joined: 07 Apr. 2010 Location: ST GEORGE, UT Status: Offline Points: 770 |
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I shortened the rod and adjusted it so there was a very slight amount of movement before the rod begins to move the piston and confirmed that the piston now rests on the snap ring. I've driven it around the neighborhood a couple of miles and no sign of the brakes retaining any pressure. Thanks guys! I would have chased the exhaust heat issue had it not been for your suggestions.
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ndnchf
Member Sponsor Member x 2 Joined: 22 Sep. 2017 Location: Virginia Status: Offline Points: 2177 |
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Good news - glad it was something simple.
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1948 CJ2A - It goes nowhere fast, but anywhere slow.
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47heater
Member Joined: 17 July 2014 Location: Lee's Summit,MO Status: Offline Points: 717 |
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Help ! I'm having the same problem with my brakes. Front disc brake conversion with 11" rear drum brakes, Dual reservoir MC, New brake lines , new rubber hoses. The front Disc Brakes seized up & won't release. If I loosen up the bleeder valve they release. I have shortened the brake rod & adjusted the free play. It still seizes up. Where should I look next?
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Baker6x6
Member Joined: 27 July 2016 Location: WinstonSalem NC Status: Offline Points: 34 |
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You MUST use a master cylinder for front disc brakes- OR defeat the- internal residual check valve- built into the Master Cylinder (for the front line only). Drum brakes require the check valves- Disc systems do not need them. You can take the MC apart, and drill/remove the rubber flap from the check valve for the section you are using for the front brakes. *I don't know what MC you are using- and some use the front reservoir, others use the rear, some are interchangeable. The checkvalve in most MC's Ive seen is a stamped "cap" looking thing with a rubber flap inside it. It is usually made to fit on the end of one of the internal springs. Usually- nearest the outlet for that reservoir. That checkvalve does not allow the pressure to bleed back into the reservoir for disc brake systems. ALSO- on your OEM cylinder, there is a smaller "port"- usually just in front of a larger "hole". This port allows excess pressure back into the reservoir, when the pedal returns to it's at-rest position. (This is why you need the correct freeplay- so that port is uncovered when the pedal returns) Sometimes- especially if you (or someone) has HONED the cylinder- that port will be blocked with crud. It MUST be open- or you will eventually build up too much system pressure, and your brakes will lock up. You can clear the blockage with a pin, needle, or a welding tip cleaning tool.
Edited by Baker6x6 - 21 May 2018 at 9:09pm |
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captianpattson
Member Joined: 07 Apr. 2010 Location: ST GEORGE, UT Status: Offline Points: 770 |
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Basically either your piston is not returning to the rest position or you still have some sort of residual pressure valve present. Is your MC new?
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47heater
Member Joined: 17 July 2014 Location: Lee's Summit,MO Status: Offline Points: 717 |
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It's a new MC sold as a MC for disc brakes in the front & rear drum brakes
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