Yo!
I have a good one that has stumped me for about 3-4 months
I have a 1993 Wrangler and it Had ABS brakes before I changed the axle's 4-5 years ago. I changed to 4-wheel disc brakes dana 44 front chevy calipers, Currie hi-pin rear with explorer disc brakes

I removed all of the ABS system. and stayed with the stock master cyl. that came with the ABS brake system. For 4 plus years the brakes have worked great , But a few months ago on the Rubicon I was climbing a boulder with the right front tire and had to stop. When i steped on the brake it went to the floor.
I checked the fluid level OK, no leaks anywhere. Backed down pressed peddle and had brakes agian, this happened a few more times on this trip.
Fluid level is not the problem even in the extream angles ..no air in system.. pads good.

I went thru the brakes and checked all the calipers, lines,pads
figured it had to be the master. So I replaced it just befor running the Swamp lake trail. Drove it and brakes were great!! took it on the trail and had to pull a broken jeep out (Dist. broke) and I was pulling him up a 6' ledge and he hit a rock and the sterring wheel whiped out of his hand and I had to stop! steped on brake and down to the floor it went OH!! $hit!! clutch out engine off##@%&$* and a few words later. This is getting re-dick-u-lus

I have a friend with a 1992 and he is starting to have the same problems once in a while.
Anybody got any ideas

GOT BRAKES???? MAYBE!!!!!!

there was a thread awhile back on this same prob. i don't recall the solution though. do a search and see what you come up with.

I've been having similar problems, but I'm convinced that it only happens when I turn just right and flex up some, I found that my caliper is hitting my shock at certain angles due to my super loose buggy leaf setup up front, I think it is compressing the piston and the pedal goes to the floor to get the piston back out to where it should be.

This is actually quite a common problem...though I do not have an answer for it.

It's been my experience that it happens most, for some reason, with (vacuum) power brakes.

It happened to my too, once and on the trail. I wonder if the booster looses vacuum for a second and then no brakes. once the pinched hose or lost vacuum returns brakes work again.

That's my guess.

I wound up changing my master and booster with an new corvet type unit and the problem has gone away I did have one time that it ocurred since but it at least stoped the jeep

something to do with the engine rpm's being low? it sounds really strange.

well this post is really old, BUT.........
A couple years ago, I bought a Rubicon Express SOA kit, I know, I know :rolleyes: , wish I had that money back.
Anyways, the kit specified to run the shocks upside down because of something like this. It said something about the caliper and shock tube hit and somehow causes you to lose your brakes. Well, since I swapped axles and put my shocks where I want them, or they freakin rip off :mad: , I have never had a problem with this. So, just thought I'd add my $.02 in case it might help someone else when they search.