I purchased a 96 Discovery about a month ago. The brakes were in bad shape. I could push the pedal to the floor and it would gently slow down and make grinding noises. I replaced all the pads and rotors. That fixed the grinding sound but the the brakes were still very weak. The previous owner recommended adjusting the pushrod between the brake servo and master cylinder. It's strange that this rod is not mentioned in the Haynes or RAVE repair manual and searching the internet forums found very little info on it either. I've adjusted the pushrod a few times today and have gained some braking strength but not enough. The adjustment screw on the pushrod was showing about 2mm of threads. I changed it to 3.00mm, reattached the MC and bled the MC and all four calipers. Very little improvement. I then changed the adjustment screw to show 5.15mm of threads, reinstalled the MC and bled the MC and all calipers again. The brakes are better but still very weak. I can put the pedal to the floor and the truck gently stops. I have the fuse removed for the ABS (It was removed when I bought it and I'm not sure why). I will work on fixing the ABS later.

My question is what to try next. Here are my thoughts.

1. Old rubber brake lines are ballooning. Replace with stainless steel lines.
2. Master Cylinder is bad. Autozone has a rebuilt one for fairly cheap. Should I avoid the Autozone one?
3. Adjust pushrod in the brake servo again.

Pumping the brakes does not seem to help. I can press down on the pedal and maintain constant pressure so I'm thinking there isn't a leak in a line anywhere. Thanks in advance for any help!

Also, the o-ring between the brake booster/servo and the master cylinder was missing. I used a universal o-ring from Advance Auto and it fit very well. It was size 44mm I.D/52mm O.D.

 

It sounds like you are pretty competent, and would have already caught this, But... I had leaky piston seals on my calipers that made my brakes mushy.

 

I hadn't thought of that. Thanks for the tip. Did you notice if you were losing brake fluid when you had those leaky seals?

 

Also, You will see plenty of articles on here that justify disabling your ABS. Mine had the ABS light on and the brakes worked fine. Every once in a while I would start the car and the ABS light would be off, and if I didn't notice... Trouble. I blew through a stop sign with my brake pedal pushed down to the floor!

 

Yes, but it seemed to be evaporating due to the heat, it wasn't super obvious, but then again, I was less knowledgeable then.

Good luck

 

You may be on the right track with the brake lines, just one ballooning would be enough to affect pedal feel. I had a similar issue with ours when we purchased it, but it was the front pads being worn almost to the backing plates so only the rears were providing braking. New front pads, problem solved. I was lucky.

 

I got stainless steel braided brake lines. It did help a little. The brakes on the Discos aren't very good even when they are working right. I have heard that you can get Defender calipers and they bolt on. I haven't tried that, but it might be worth looking into.

 

Yes these are rolling behemoths, but both my '96 and '97' will lock the wheels (ABS disabled). Remove your master cylinder and bench bleed it. Make sure you have good flow from both circuits. I've had the rear circuits go bad on both of mine. They would only spurt fluid out of the rear circuit at the very end of the stroke. (It took me three new master cylinders when I did the '97 to get one that would bench bleed properly) Also, be careful adjusting the rod too far. It should only be used to set pedal free play. You can adjust it out too far which will keep just enough pressure on the piston to partially block the port timing hole in the master cylinder. Sporadic brake application it will act normal, but pumping the brakes (like going down a steep grade) will cause the brakes to drag, heat up and they will lock.

 

I test drove a D1 with the defender brake upgrade and I instantly had brake envy! I just bought a set. It looks like the only difference is that the rotors are thicker with venting in the middle and the calipers are wider to fit them.

 

Let us know how it goes. It sounds like a nice upgrade.