spongy brake pedal (2001 merc sable)

Hi - I have a 2001 mercury sable (ABS front and rear) – has front disc/rear drums

I replaced the pads and shoes this weekend. Everything went well.
- Brakes have good stopping power
- Emergency brake works well
- takes very little pressure on the pedal to stop

The problem is that the pedal feels too soft. It has a spongy feel. I examined the calipers and wheel cylinders and they are not leaking, plus there are no leaks in the system. I bled the system even though I never opened up any lines. This didn’t help.

Any ideas on what could be going on here? Could the master cylinder be damaged? The only thing that I did that really effected the hydraulic system is to push the pistons back in.

Thanks

 

Often, new brakes will feell spongy for a few hundred miles. But if it goes beyond that, something is wrong. It sounds like you did things correctly, although I am not a modern Ford expert. Some calipers have a screw mechanism that requires unscrewing when pads are replaced, not sure if that is Ford. A service manual would definitely be of use.

 

I think Bill is right. The rotor or drums probably had some light scoring. The pads and shoes will have to bed in until they conforms to the old surfaces. Until then the brakes will feel soft. It's more pronounced when all four corners need to bed in.

 

rob,

Try doing some hard stops to seat new pads.

 

I actually used a manual, and there wasn't a "screw mechanism" listed on the calipers, plus I didn't see anything like that. They were really simple, which I like.

There was an extremely small amount of scoring. I broke the glazing with sandpaper and that was it.

I will drive it for a while and see how it goes!

thx again,
Rob

 

I was just reading a magazine article about choosing brake pads. They mentioned that the higher end pads have built-in shims.

When I replaced my pads (I used the higher end ones) and I wasn't sure if those built-in shims took the place of the loose shims, and there weren't any instructions, so I put the loose shims on over the built-in shims. I wasn't sure, and I figured it wouldn't hurt. Now I'm thinking about taking them off.

Do you think it makes any difference?

thx

 

It could make some difference since there will be a gap (although it will be very slight) between the old and new shims that will need to be compressed before you have braking action. This could possibly cause some sponginess.

I agree with the break in period as well though. Try some very firm braking. Repeat it several times. THat will tend to help.

 

Just re-bleed the entire system starting from the brake farthest from the master clyinder first. and work foreword.
That should be it.

 

Hi - I still haven't been able to resolve this. Took it to a shop owned by a mechanic with 10 years of Ford experience and 16 years total working on cars. All I was left with was a $100 less in my bank account. Anyway, the good news is I think I have diagnosed this with the help of an article:
http://www.asashop.org/autoinc/dec99/techtips.htm


I followed the directions, and removed the line and plugged the port on the master cylinder that goes to the rear brakes. Started the car and had hard pedal again! Great! This isolates the problem to the rear brakes, and most likely, the RABS valve. I suppose that there is a chance that there is something else going on with the rear brakes, but I don't think so...

Is there an RABS valve on this car (or something similar?) and how do I get to it. It looks like I need to remove the left wheel and fender well, but I thought I'd ask since it's too cold out and I don't want to rip stuff apart if there is an easier way. Is it possible that cleaning this valve out is all that is needed, and not a new one?. It worked fine until I pushed the caliper pistons back in.

thx