Hey guys and gals. This is my first post here and yes I did search before posting.

I have a 1998 XJ base model and have owned it for about a year. I have always had a few hard stops after my xj has been out in the wet for awhile...what I mean by that is the first few slow stops will feel like wet pads and I will stop quick (going under 5MPH).

Well, a week ago I pulled my jeep out of my garage for a short drive and as I approached the stop sign (going less than 10 MPH) I applied the brakes on a dry road and I come to a HARD stop and the tires screech, it felt like the front driver side tire.

I was able to slowly drive and coast to stops while making my way to the auto store for new front pads and calipers. The rotors were fine and only the front passenger side rotor had the slightest ridges. Anyways, I was able to change all of those parts out and my buddy and I bled the brake lines. We did plenty of tests and they seemed to be working perfectly. I was able to make it to my families thanksgiving 30 miles away and back 30 miles with no issues. Everything was great until today...

I hop into my xj to run to the store and screech!!!It felt like the front brakes again...but worse than the a week ago. I honestly never had this issue, so I am just assuming it is the front because it felt like I was stopping hard and not dragging the rear tires.

*Maybe other info that might help*

I am not sure if I have ABS and if I am pressing the brake pedal down at a stop light and slightly take pressure off it makes a weird sound...

Any help would be great! Could it be the booster? Rear brakes? I have even read something about a valve within the brake lines that is meant to distribute equal pressure to all four brakes.

Thanks for the help!

 

When you swapped everything out the first time, did any of the pads look wet (like a brake fluid leak)?
Does it pull to one side when you are slowing down?
When you take your foot off the brake pedal after a stop, does your vehicle roll easily? Or does it feel like a caliper is locked up?
Is there any visible wetness around any of the brake calipers?
If the pads get any fluid contamination on them, they will grab and cause symptoms like you are describing...........

The "Proportioning Valve" that you referred to, sends equal pressure to both front calipers, and considerably less pressure to the rear wheel cylinders.
Drum brakes operate on a much lower hydraulic pressure than disc brakes do....
Most proportioning valves (in a disc/drum brake system) also incorporate a "Residual Pressure Check Valve" that holds a slight amount of pressure to the rear half of the system to overcome the force of the return springs attached to the shoes.........

 

It could be a bad front brake hose. Replace them both.
If the hose is coming apart internally, it will let fluid move into the caliper but block it from freely retuning. Next time you hit the brakes that caliper is already slightly pressurized and the additional pressure causes lockup.

 

First thing you need to do is to isolate the issue between front and rear. One thing I've noticed in mine is that the rear brakes tend to be overly sensitive during the first couple of applications with the car outside after a rainy night. Not sure if it's a normal behavior for drum brakes but the brakes work normally afterwards.

 

OP, first of all. Even if you think its the fronts, have you opened the rears to inspect. Have you adjusted rears recently. Had you greased the slide pin in the front calipers when you changed the pads.

When I still ha rear dumb brakes, I had a leaky cylinder. This would cause the rear brake to lock up when stopping from 20mph and other speeds too. Best thing I ever did was the rear brake swap out. Do some noggin pokin on your jeep and then report back. Dot change your lines yet or do anything drastic. Inspect first everything. Also changing all the brakes fluid via bleeding is a good thing to do as general maintainance

 

Thanks for all of the info guys. I will report back after I poke around with your suggestions. I did drive it today, which is a sunny and dry one...and I had no issues. Standby to Standby!

-Sarge

 

Is the brake fluid clean & clear? The slightest amount of moisture in the hydraulic fluid will cause the seals to swell.

 

I took it to Les Shwab this morning for their free brake inspection. They concluded that the front ones are fine and the rear ones were "glazed" which they sanded down and they adjusted something in the rear for free...I am not sure what all was done, but it feels fixed. They said that the glaze was causing the locking up issues. Like I said, I don't know exactly what they did, but it seems fixed!