Brake problem?

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Coyote Jack

Coyote Jack

Member #55, I'm old
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I have a 98 Ram1500 4X4. The brakes are acting a little wierd. There are no fluid leaks and the master is at the full mark and always has been. There are lots of pads and shoes left. Most of the time I have a nice high brake pedal. Every once in a while the pedal will go almost to the floor before any brakes start to take effect. Anybody got any idea what might be causing this?

Jack
 
Could be a problem in the master cyclinder bore with either a score mark on the bore, debris, or primary seal lip issue.
 
Rear drums? I've had wheel cylinders starting to go act this too, with just a drip wanting to start around the cup.
 
i would check rear drums sounds like maybe adjusters are working right and i know that if brake fluid in master cyl.. is brown looking the brakes will be alot different if you do alot of towing.that's been my experience with them..
 
Morning Jack, When my son was building houses the contractors son had the same issue with his Dodge Truck, I am not sure what year it was but I think Creed " my son" changed out the rear wheel cylinders for him in his stock car shop. I will call him about 9 am and ask.
It does sound like it's sucking air some where.
 
Usually when the pedal hits the floor and mysteriously returns to normal it's the master cylinder.... but give it all a check. Look for leaks coming out from behind the drum backing plates for the signs of a leak. Also check to make sure the caliper slide pins aren't sticking and that those rear adjusters are correctly operating.

But I'll put $10 on the master cylinder being the culprit..... 8)
 
All right John, I'll see your ten bucks and raise you another five with my bet that it's a little vacuum leak on the booster.

Good luck chasing your gremlins Jack.
 
My 99 caravan does the exact same thing as what you describe. I have been trying any trying to diagnose the problem. The rear brakes and lines have been completely replaced (and I mean completely) and fronts inspected without finding anything wrong. I can only think of 3 remaining factors;

1 - master cylinder
2 - vacuum assist can
3 - anti-lock brake controller crap (I hate anti-loc) never had any warning lights or anything.

I'll follow this thread as I'm curious and if I find my problem I'll post it too.

Thanks
 
master cylinder bypassing internally. That fact that a master cylinder will fire off a few warning shots before it kills
is one of our little blessings.
 
CudaChick1968 said:
All right John, I'll see your ten bucks and raise you another five with my bet that it's a little vacuum leak on the booster.

Good luck chasing your gremlins Jack.
Click to expand...


..... and I'll raise YOU a Root Beer Float!

Vacuum leak usually gives a very hard pedal... but I never rule anything out.

Keep throwing out ideas gang, we'll fix it. And I'll see if I have to go to Tennessee.... with a Root Beer! 8)
 
My bet is your Master cylinder is crapping out Jack, the truck is old enough that I'd just replace it to be on the safe side Jack.

Terry
 
I agree with John that a vac leak will usually give you a hard pedal. And as I said, no leaks of any sort. So, I think I will start with a new master. It sure won't hurt other than in the wallet.

Jack
 
Jack,

I am leaning with the master cylinder diagnosis but the link that 6pk2goDemon posted :cheers: for your ABS system will help you isolate the problem for sure, great info there. It always feels good to me if I go through all the steps and know 100% what the cause is before I open my wallet.

A lot of brake problems are due to moisture in the system and a fluid flush is something most people never do. I think everyone should read that diagnostic page just for the info on brake fluid contamination.

When you change out the master, buy and use new bottle of fluid or an sealed one you already have. Never buy the econo size unless you do a lot of brake work or your going to flush your system and will need a lot. Brake fluid will go bad sitting on the shelf, once the seal is broken it will start to absorb moisture ever so slowly by the cap.
After 30+ years or wrenching I'm still learning too. :read2:

John
 
If I read that article correctly, it only applies to antilock brakes. I don't have them, so I guess I am back to the master cylinder.

Jack
 
I am such a dumbass. I am ashamed to say I even tried to build a car.

I went out tonight and had another go at the truck. I started looking at the tires. WTF is going on with the front left, it just didn't look right. Camber was way off, in at the top. Got the jack out, lifted up the truck, checked the wheel and low and behold, the thing wobbled something fierce. You got it, the hub was shot. I have seen bad hubs before and even replaced a few but nothing like this. There were no bearing rollers left in it. What surprises me the most is there was no sound and the truck didn't drive any different. I replaced the hub and went for a drive. Bingo, no more brake problem. To top it all off, the truck didn't feel any different other than the brakes. I have never seen anything like it and hope I never do again.

I am such a dumbass at times.

Jack
 
I'm glad you found the problem. You would have only been a dumbass if you would have replaced the master and not noticed the hub. :-D

I just did the wheel bearings, shoes and cylinders on my 74 Duster, they were the original stuff of coarse. My warning came from a severe vibration on the highway and a nasty shudder when I took the exit, I thought the front end was coming apart. Turns out my 47K original mile car had a right inner bearing race that was a pretty dark blue and my bearing rollers fell out of the race, it has a very shiny spindle too. The original grease was the consistency of roofing tar. Mine gave me warning enough to make it home without siezing up on the hub, yours gave you a different warning but got your attention just the same.
 
Kernel Sanders said:
My 99 caravan does the exact same thing as what you describe. I have been trying any trying to diagnose the problem. The rear brakes and lines have been completely replaced (and I mean completely) and fronts inspected without finding anything wrong. I can only think of 3 remaining factors;

1 - master cylinder
2 - vacuum assist can
3 - anti-lock brake controller crap (I hate anti-loc) never had any warning lights or anything.

I'll follow this thread as I'm curious and if I find my problem I'll post it too.

Thanks
Click to expand...

I know this an old thread now but wanted to tie up my loose ended post

Well last weekend I replaced the master cylinder and now have absolutely no issues now so definately was the master crappin out.

Cheers!
 
been there Jack. my 2002 had the abs light lit at 8k. took it to the dealer and rear axle bearing was shot cocking the rotor setting off the abs light. i never knew
 
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