1998 Brake Problem

[soylentgreen]

Hi, guys. This is my first post. I'm a Mustang guy, but my old Expedition is my daily driver (actually the Expedition is newer than my Mustang...hahaha). I've never owned a truck before and I love it. I didn't know what I was missing. I hope to make a meaningful contribution here. I plan on keeping the truck for a LOOONG time. It has 190k miles and shows no signs of slowing down.

In any case, I'm having some trouble with my brakes (BTW, the truck is 2WD/ 4-wheel disc/ with cruise). At driving speeds, everything is fine. Stops normally and has good pedal feel. However, when at low speed such as turning into my driveway, the pedal gets very hard. It feels as though you're not going to stop, but if you stand on it, the brakes kick in. I also feel the pulsing of the ABS when I push the brakes hard under this condition.

It never happens when I leave my driveway in the morning. It only happens right after coming down from speed.

The pads & rotors look great. I don't think the problem is there. I replaced the passenger side caliper last summer (locked up). Is it the booster or master cylinder? I'd think if it were the booster, it would be more likely to act up at higher engine speeds (less vacuum). If it were the master cylinder, I'd expect it to act this way all the time or just at random.

Has anyone had this problem before? What was the fix? Any help would be appreciated. Thanks!

 

[soylentgreen]

Anyone????

 

[ELVATO]

Just to get it straight:

Normal speed -> Everything alright
Already driving slow -> Everything alright
Slowing down (possibly only when turning?) -> Pedal gets hard, ABS activates

From a quick search, it seems like it might possibly be rust in the hub messing with the ABS sensor. I'll see if I can find the instructions on how to clean the ABS sensor when I get home (have to take a look in the manual.)

 

[tonydiv]

I've asked some of my tech buddies, and they are all kind of stumped. The ideas ranged from bad abs pump/accumulator to a vacuum leak at the booster.

They did agree on this - have the dealer check it out soon.

 

[soylentgreen]

Thanks guys.

I think the caliper on the driver's side is sticking. When I parked the truck at work the other day, I could hear the caliper making a creaking sound after I exited the vehicle. I think it is releasing, but very slowly. So, when I brake and then immediately brake again, I think that caliper is grabbing the disc tighter than the others. To stop, I have to really step in it, which makes it lock up which makes the ABS kick in.

I will also check the ABS sensors. And, I agree...brakes are not something to be unconcerned about.

I'm going to get a caliper and replace it tonight. I'll let you know how it goes.

 

[JUST4FUN]

i was going to say calipers should be replaced in pairs. also going down the vacuume line
pinch the line between your fingers to see if the line is brittle or soft. replace if bad

 

[RedRanger91XLT]

ABS sounds like the culprit to me... you can get the ABS computer checked using a special ABS computer reader.

 

[soylentgreen]

Guys,
Sorry I didn't get back here sooner to update. I replaced the caliper and the brake hose. I recommend doing this anytime you're going to replace a caliper...it's cheap and you're there anyway.

In any case, that seems to have fixed the problem. I've been driving it now for about two months and all symptoms are completely gone.

Thanks again for everyone's insight and assistance. I hope my experience can help somlve someone else's problems too.