Yes it would cause a firm pedal, I mis-spoke. I was thinking of the piston that runs through the brake booster into the master. The seals on the piston could be shot causing soft pedal.

 

96 XJ Police Package with abs brakes

History: I believe I am having the same problem. My XJ only has 78,000 miles on it, but the insurance company totaled it in an accident. Because of this it sat for about 6 years. In the process of fixing it, I switched out the front axle and had the front brake lines open and exposed to the air and some rain for about 4 months. The brake fluid in the master cylinder was drained out front the brake lines.

Symptoms: Brakes do not engage until the peddle is 1/2 way to the floor. When the peddle is all the way to the floor, the brakes are very weak. The peddle can be pumped up until hard, and does NOT slowly sink to the floor (exception, the original Master Cylinder did allow the peddle to sink back once it was pumped up). When peddle has been pumped about 5-6 times rapidly, I can get reasonable braking.

Attempted repairs: 3 new master cylinders (not rebuilds) from 2 different manufacturers. Bench bled for a 1/2 hour 2x, and bled in XJ at least once. Brakes bled countless times by myself and so called professionals who gave up. However, I don't think they ever used a pressure bleeder. Slave cylinders checked 3 times. I inspected most of the brake lines. ABS pump has been scanned (and I think bled) by a computer. Brake booster has been inspected and the brake booster shaft thing that compresses the brake was checked for mal adjustment. Checked for leaks. All of these have been unsuccessful.

Now after all this, I suspect it could be a few things. The replacement master cylinders may have not been for an abs equipped XJ. Is there one kind of master for abs systems and another for non abs brake systems? Is there a cylinder, piston, or pump in the abs that could be broken and absorbing some of the braking pressure? Is there a brake line that is hidden in some place I may not have been able to see in my visual inspection that could be swelling, or leaking? Could there be air in some place that requires special bleeding? The second master cylinder's installation instructions seemed like they were written by an idiot, but it said you had to bleed the brake line distributor thing, I think it is called a proportioning valve, (it is located directly down steam of the master [both of the 2 lines go into it], and it is a gold colored, long, rectangular block metal block) with a special tool. Is this what gon4low is talking about when he sais combi valve?

Anyway, I do not know what to do next. If you have any theories or solutions or anything that may help, pleases leave a comment. 96rokee and I seem to have a big problem here.

Sorry about the epic post.

 

has either xjs with these issues rear brakes ever been adjusted ,thats were your pedal height comes from...???

 

Yah mine were adjusted. it helped a little bit, but it is still really bad. 60 to 0 would probably take 1/2 a mile if I didn't pump the brakes.
Also, my abs light will sometimes come on if I pump the brakes enough. It may just be metal shavings on the rear abs sensors, or a pocket of air in the proportioning valve that is turning the light on. If I pump the brakes enough, I can get the rear passenger side wheal to lock up when the abs light is on and I slam on the brakes going about 7mph.

 

well no.. didnt know bout that..

but dropping the front axle and putting back on shouldnt require pedal height adjustments should it?? it was working solid before this..

dont think i ever mentioned it but bout 500 miles before i dropped my front axle i changed my rotors calipers and pads. and bled after and they were solid!

 

Just to clarify, dropping the front axle had nothing to do with the rear drum brake adjustments. They were mal adjusted for other reasons, and it happened to help a tiny bit.

 

Turns out I put my front brake calipers were on upside down and the passenger's caliper on was on the driver's side and the driver's caliper was on the passenger's side! Oops!
Now that this is fixed, My brakes are very very good!

@96rokee, If it is possible you made this mistake to, I can post pictures of the calipers in the correct position. The bleeder valve on the calipers should be on the top end of the caliper.

/\ Top of caliper
° Bleeder valve

\/ Bottom of caliper


After fixing this, you may need to bleed the front on more time.



Or if if you still can't fix your brakes, just buy a louder horn.

 

Wow I'm surprised I let something so simple overpass me...
But thanks so much for sharing your solution cuz I'm sure once I switch em, they'll be fine.

 

I know! right? I thought the same thing.