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Unread 04-30-2011, 10:05 PM   #1
JedK89
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2001 TJ Wrangler 
 
Join Date: Apr 2011
Location: Killarney, Manitoba, Canada
Posts: 2
Abnormal momentary brake failure

So i got a real puzzler for all you gear heads...problem started today just doing some mild off roading in some mud and snow. Went over a small embankment, came down off of it and turned a sharp left and then pressed the brake. However, when i pressed the brake it went right to the floor and i had no brakes what so ever. So I realesed the brake and re-applied and the brake applied as usual. So I drove a mile back to the house testing the brakes every oncein a while and everything was perfectly fine. Went to pull into my parking space (which requires a full-lock turn to the left), hit the brakes and once again the pedal went right to the floor.

So after having this happen twice I started to get a little worried about the brakes on the jeep. And after a little driving around and hitting the brakes the ONLY way, and I mean the ONLY way the jeep losses its brakes is if i take a slow, hard left turn then apply the brakes. Checked the brake fluid, and its right where it has been since i bought the jeep, the fluid looks a little brown but not dark by any means.

There is some snow and ice build up on the bottom of the jeep, wondering if i possibly pinched a line or something stupid, either than that I have no idea. Going to take a better look when all the snow and ice melts off.

Looking for idea's...anyone???

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Unread 05-01-2011, 01:29 AM   #2
sxysouthtx
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1993 YJ Wrangler 
 
Join Date: Oct 2009
Location: Baton Rouge, Horrible LA
Posts: 877
Man, that is a tricky one I've never heard of. You could have punctured one of your brake lines. But I doubt it. Could be bad vacuum from your booster to your intake manifold. But the secondary seal on the primary piston in your brake master cylinder could be a culprit. Secondary seal is an outer leak. The primary seal on the primary or secondary piston would be an internal leak. You could have those symptoms if one of those goes bad. Pop the top off of your master cylinder and have someone apply the brakes. If you seen anything but normal, replace the piston. But I could be wrong.
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Unread 05-01-2011, 03:48 AM   #3
chmo
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2006 TJ Wrangler 
 
Join Date: Nov 2009
Location: Abu Dhabi, United Arab Emirates
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Had the same problem after the shop welded C-Gussets to the inner C's.
A full steering lock and the caliper (brake line bolt) was touching the gusset.
Once it touched, brake pressure was gone momentarily.

The shop had to grind the gussets and to put some washers under the steering stop screws. Everything fine now.

In your case I would really check if there is no ice/mud gunk build up around the calipers which gets squeezed against the inner Cs when turning sharp.
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Unread 05-02-2011, 12:27 AM   #4
mrblaine
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1999 TJ Wrangler 
 
Join Date: Dec 2004
Location: Quail Valley, California
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Quote:
Originally Posted by chmo View Post
Had the same problem after the shop welded C-Gussets to the inner C's.
A full steering lock and the caliper (brake line bolt) was touching the gusset.
Once it touched, brake pressure was gone momentarily.

The shop had to grind the gussets and to put some washers under the steering stop screws. Everything fine now.

In your case I would really check if there is no ice/mud gunk build up around the calipers which gets squeezed against the inner Cs when turning sharp.
Yep, you got it. There is something interfering with the caliper when the steering is turned all the way that's pushing on it and pushing the caliper against the inner pad which compresses the caliper piston. It takes a few to several pedal pumps to get full braking back.
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Unread 01-27-2013, 04:39 PM   #5
laddie
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2003 TJ Wrangler 
 
Join Date: Dec 2005
Location: , Illinois
Posts: 74
Quote:
Originally Posted by chmo View Post
Had the same problem after the shop welded C-Gussets to the inner C's.
A full steering lock and the caliper (brake line bolt) was touching the gusset.
Once it touched, brake pressure was gone momentarily.

The shop had to grind the gussets and to put some washers under the steering stop screws. Everything fine now.

In your case I would really check if there is no ice/mud gunk build up around the calipers which gets squeezed against the inner Cs when turning sharp.
Quote:
Originally Posted by mrblaine View Post
Yep, you got it. There is something interfering with the caliper when the steering is turned all the way that's pushing on it and pushing the caliper against the inner pad which compresses the caliper piston. It takes a few to several pedal pumps to get full braking back.
Son of a gun, Jeepforum just saved me from buying a new vacuum booster. I was having this occasional soft pedal which I was convinced was the booster going bad. Did a little searching related to the booster and found this thread......I put "C" gussets on several months ago, I checked the clearance, did some grinding and thought I had it. Well, I either didn't quite get it or the clearance changed due to a new rotor and caliper I put on recently. Anyway, just went out to the garage - cranked the steering all the way left, no problems, all the way right - pedal goes soft. Pump it back up and try again for good measure - same result. My intermittent mysterious problem solved and will only cost a little electricity and wear on a grinding wheel to fix. Thanks, jeepforum
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