Spongy Brake Pedal

[jkexplorer]

Your symptoms seem to be very similar to mine. However, I am not sure that I agree with your explanation that the pads are grabbing much higher in the pedal than before brake replacement. The difference in the thickness of the brakes is compensated for by piston extension in the caliper. So regardless of brake thickness, the distance between the caliper piston and the pads should be the same. Therefore pedal travel should not change. Somebody please correct me if I am wrong.

 

[410Fortune]

pad and rotor thickness is simply compensated in the system bu using more/less fluid from the resevoir.

teh pedal continues to go down after you are stopped because of the vacuum booster, not because of the hydraulic pressure. Obviously if you keep pushing you can keep compressing the brake fluid until it cant compress or extend the calipers anymore, but while the engine is at idle it does not supply the booster with as much vacuum as higher RPM's. So it is a combo of all those things....at least thats how I understand it

 

[spta97]

I like that explination...less work

jkexplorer - how is the actual performance of the brakes? The reason I'm not too concerned is that my brake performance is 1000% than it was before. Spongey, but I can stop much quicker than it did. I guess one way to test the above theory is to have someone look at the fluid level as you depress the pedal. You could also rev the engine at the same time.

 

[jkexplorer]

The actual brake performance is on par with what it was before pad replacement. Certainly no braking improvements, just spongier brakes and feels like pedal travel is greater then what it was before. Sounds like you've experienced the performance improvement due to usage of ceramic pads in the front. I've used Raybestos semi-metallic pads on all 4 wheels. No prior experience with ceramic pads, so next time around it may be interesting to try ceramics.

 

[spta97]

Well it could be that or the fact I had no more material left on my rears and they were grooved to hell. I have been happy with the ceramics but the complaints I have heard is they get hot and can warp rotors. They are pretty much noise free too which is nice.

I haven't decided if I'm going to put the rears on yet. The dust I got could have been break-in related. Typically, the rears do not generate as much dust as the fronts. I'll give it another week or two and decide then.

 

[jkexplorer]

One of my rear rotors was grooved and had to be replaced. What I found interesting is that the original rear disk pads had no wearout indicators. So I was caught completely by surprise when the damage occurred. The replacement pads did have wearout indicators.

 

[markie_g]

I have a 1999 x and read this thread before tackling my "spongy pedal".Going into the repair job I also knew that e-brake was not working, and wanted to investigate as to why. I started with the rears first. When I pulled off the rotor/e-brake drum off on pass.side the brake lining was no longer adhered to the shoe.Bought the new shoes and comenced to replace mode.Ran into trouble with the placement of the shoes,Took off drivers side for reference and found NO lining on drivers side!Now I found why E-brake was not working.Tonight I tackeled the fronts after confirming that the rears were 100%.
Found that there was a stuck/frozen caliper pin. Went to two parts stores of different names "ie: Napa/kragen".put some heat on pin/slider. Did not work. Soaked slider with PB blaster and heat wrench and BFH.Did not work.Borrowed neighbors air chisel,used heat,Now thatsomebitch is beginning to move. After replaceing parts, Big difference. Hard to believe that one stuck slider can effect the brake performance.This forum is Great.I was versed into what to watch out for and tips on what to do. Keep explorer forum going!

 

[Mr_Baskett]

Hey I have a similar problem. I have a 1992 with RABS. I replaced my rotors, pads, drums, shoes and there was no issue. I then replaced my brake lines with steel braded skyjacker extended lines. I proceeded to bleed everything but forgot to bleed the master cylinder so I broke it. I replaced the master cylinder about two months ago and I set the adjuster in the shoes to the correct spot. When I put in the new cylinder, I bench bled it before I put it on (and am unsure if I did it correctly) then bled the whole system.
Now the car stops when the brake pedal is near the bottom. I have bled the system several times and I think that I messed up the new master cylinder. I am going to take the master cylinder back and warranty it for a new one and check if that works.