Changed the front pads on a 98 Sahara, now the front brakes barely grab, pedal doesn't feel right, (too much travel), and the back brakes lock up when I try to stop. To fit the new pads, I pushed the caliper pistons back into the calipers, drained out some extra fluid from the master cylinder, put the new pads on, reinstalled the calipers, started it up, hit the brakes a couple times, then test drove it and discovered the problem. Bled both sides, topped off the fluid, same problem. When I jack up the front and spin the wheel, the brakes can stop it, but of course there is not much force to be stopped.
Did the Master cylinder coincidentally go bad? Proportioning valve?

I also took off the rear brakes to see if something was jamming them up but they seem fine.

I would pull the new pads and compare them very carefully with the ones you took out as far as dimension and exact match. If that doesn't work, put the old ones back in and see if they start working normally again, and go from there.

If you hear hoofbeats, think of horses.

I would pull the new pads and compare them very carefully with the ones you took out as far as dimension and exact match. If that doesn't work, put the old ones back in and see if they start working normally again, and go from there.

If you hear hoofbeats, think of horses.

Yeah, I was thinking of trying the old pads to see what happens. I was working at night in the dark, so who knows what I put in there :confused:

bleed the breaks start with the rear pass then the rear drive then the front pass then the front drive. get all the air out.

Holy crap did you bleed the brakes?!?!?!

Just pushing the pads back into the calipers doesn't introduce any air into the system-bleeding the brakes was neither the problem or the solution. You probably have the new pads in wrong-or the wrong pads. Not familiar with that type of calipers off hand-but you could also have the caliper sliders jammed up somehow. Don't work in the dark-at least buy a flashlight for a couple of bucks-drop lights aren't that expensive at the hardware store either, less than $10.

I agree, I would dfinitely redo the brake job in good lighting. Make sure the slides are not seized up and used some high temp silicone lube to keep them from sticking. Most likely you have assembled it wrong. I always say you shouldn't mess with brakes or steering if you are not confident that you can do it 100%. Both can get you killed it not done properly. Also check that you did not twist and kink the rubber brake hoses when you reassembled it.

I agree, I would dfinitely redo the brake job in good lighting. Make sure the slides are not seized up and used some high temp silicone lube to keep them from sticking. Most likely you have assembled it wrong. I always say you shouldn't mess with brakes or steering if you are not confident that you can do it 100%. Both can get you killed it not done properly. Also check that you did not twist and kink the rubber brake hoses when you reassembled it.
Agreed-people (for whatever reason) think they can do a brake job-when in reality they can't. There are alot of tricks of the trade that you won't know without experience-and brakes are a safety issue-don't dabble in brakes,leave it to an experienced person.

Thanks for all the replies. Just for the record, I've done many brake jobs and have never come across this problem. Replacing pads should not require bleeding, I did it in this case because I couldn't figure out what was going on.
The answer was actually pretty simple. When I went back and took off the new pads to check things out, I saw that they were only touching the rotors in a few high spots. The rotors were not evenly worn and of course the old pads had conformed to the rotors. Since the new pads were flat they barely had 10% of surface contact, hence no ability to stop, so more pedal pressure just locked up the rears. Continued low speed braking improved the problem enough that I took it out on the road and bed them in. Problem solved.

Thanks for all the replies. Just for the record, I've done many brake jobs and have never come across this problem. Replacing pads should not require bleeding, I did it in this case because I couldn't figure out what was going on.
The answer was actually pretty simple. When I went back and took off the new pads to check things out, I saw that they were only touching the rotors in a few high spots. The rotors were not evenly worn and of course the old pads had conformed to the rotors. Since the new pads were flat they barely had 10% of surface contact, hence no ability to stop, so more pedal pressure just locked up the rears. Continued low speed braking improved the problem enough that I took it out on the road and bed them in. Problem solved.Yea thats called break in.

No-actually he's correct-it's called "bedding in". Of course you would have been better off machining the rotors flat first-and they would still work better if you did it now. I used to not do that with my own vehicles until I realized what a difference it makes in stopping performance. There actually is more to bedding in pads than most people realize that will result in better braking performance-but i won't cover that here. And keep in mind that you waste some of those new brake pads making them conform to that used rotor.

I believe I am aware of the full "bedding in" procedure, or at least one of them. Basically a series of hard braking from 60 - 10 without stopping completely then driving around to allow the brakes to cool before stopping, as I recall.

I've had an ongoing debate with myself about machining or changing the rotors verses leaving them as is. My thought, possibly misguided, is the grooves and ridges create larger surface area and once the pads match the rotors you would have more braking power. Obviously you feel this is not the case. Why am I wrong?