Brake pedal question.

[Gonzo 1066]

I have had 2 near panic stops with my 04 Dodge Dually. Both times the brake pedal felt wierd. It did not pulse like the ABS was activating. Just seemed to go a bit soft nearly to the floor. This is with a very heavy trailer behind, and YES the trailer brakes are working properly. . Any input??

 

[NIsaacs]

ABS equipped trucks are an accident waiting to happen, they suck. My '91 brakes just quit in a panic stop, usually a last minute red light. They say you have to pump them to reset them... ... . who the heck can make your foot release the brake in this scenario... I can't.



My '01 will lock up with the upgrade larger rear brake cylinders, thats the way I like it.



Nick

 

[mwilson]

I have discovered the 4 wheel Chrysler ABS performs a lot better if you excersise the function on occasion.

I live on a road that is dirt in the summer and snow/ice in the winter so it is easy for me to cycle the ABS once a month or so in solitude without any worries about tires or oncoming traffic.

Give it two or three pedal pounding panic stops and see if that helps any.

Also gives you a chance to test all four wheels and to see if it stops in a straight line.



After any brake work involving bleeding you should do the same thing from what I have found.



I don't know if a little air gets trapped in the ABS pump or if the plungers stick but now that I excersise the system it works properly when needed.



When we bought our first van with 4 wheel ABS I make the wife do several panic stops on snow at 30mph or so so that she knew what to expect and to also understand she could still steer under full brake application.



I currently have 3 Chrysler products in the driveway with 4 wheel ABS and I am happy with the braking performance now that I know how to drive with it and it is working correctly.



Mike.

 

[Gibbs]

Gonzo, my pedal felt weird during a panic stop the other day in my new to me 04. 5. The pedal felt like it went into another stage or something and got soft and seemed like it was almost on the floor. But not like the ABS pulse like in other vehicles I've driven. I wasn't sure if I was going to stop and it scared me.



I figured I'd bleed out all the old fluid since it'd probably never been done and replace front brake pads with Hawks. The pedal felt a little better after this, but even after breaking in the new pads per the instructions, it still did the same weird thing with the pedal feel a couple different times. My 03 never felt like this.



mwilson, that's an interesting theory about the plungers or trapped air in the ABS system. I was wondering if there was still trapped air somewhere, so I have a Motive power bleeder en route to see if I can get a better bleed. The road I live on turns to dirt after my house, so after power bleeding I'm gonna do a few "death avoidance panic stops" to see how it responds.

 

[Prairie Dog]

I don't feel the ABS function like I did on older vehicles. I'm pretty sure it's because the pulsing is so fast - it's really just a buzz.

 

[Bernie]

My thought on the subject:

That "weird" feeling is probably due to poor maintenance.
-Fluid may have very small air bubbles that you don't feel daily. Change fluid annually, or at least every 50k miles.
-Fluid may be old, and as a result full of water. Again, change fluid annually.
-Flex hoses may be old. They tend to be fine, until a panic stop. I bet they stretch and expand dramatically under a panic stop.
-Brake pads off-gas at temp. During a panic stopped, that gas can actually create a small gap between the pad and the rotor. That pad float is probably what you felt. The alternative are pads of better material (like Hawk), or rotors that have relief for the gas (like slotted rotors).

 

[Bernie]

About ABS: I have to disagree with the previous post that ABS is an accident waiting to happen. ABS is a great tool. Like all tools, understanding it will help you get the most out of it. There are two ways to think about it:

Use it as an indicator:
-In the past, we learned a thing called threshold braking. That is applying as much brake pressure as possible, with out locking anything up. This was (and still is) the technique that will provide the best (shortest) braking distance.
-When the abs kick in, we have passed the threshold. The ABS is then trying to keep us from locking (and crashing).
-If you use the ABS as an indicator of passing the threshold braking point, and easy up slightly, your stops will be shorter than with ABS.
-This is the safest, shortest method. However, we are not teaching it to new drivers, as it requires some thought and, gasp, skill.

Stab and Steer:
-This is the method being taught.
-Stand on the pedal. Abs will be on.
-Remember to steer away from any problems. That is, after all, the point of abs (to keep wheels turning so they can steer).

Both these methods work. Threshold will be about 15% to 25% more effective (depending on how it is done). Stab and steer has the advantage of consistency (as the computer is making the decisions).

One poster said he prefers to lock the rear wheels. This is, in my opinion, disastrous advice.
-A locked wheel has little to no friction, making stopping distances longer.
-Not every stop will be on dry pavement in a straight line. Any other surface or with a bend, locked rear brakes equal a spin.
-This applies to trailer set up as well. All brakes should work the same, with the same bias. Too much in one area (rear axle, trailer, front axle, whatever) can only potentially introduce problems.

 

[Bernie]

Also, I agree that an "exercised" system is a better performing system. The ABS systems holds fluid, and moving that fluid can only be an advantage. Good advice about applying the ABS in a controlled situation periodically to exercise it.

 

[Bob4x4]

The abs needs to be bled using a scanner or alternatively panic stops repeatedly until air free then bleed the base syst again

 

[mwilson]

Gonzo, my pedal felt weird during a panic stop the other day in my new to me 04. 5. The pedal felt like it went into another stage or something and got soft and seemed like it was almost on the floor. But not like the ABS pulse like in other vehicles I've driven. I wasn't sure if I was going to stop and it scared me.



I figured I'd bleed out all the old fluid since it'd probably never been done and replace front brake pads with Hawks. The pedal felt a little better after this, but even after breaking in the new pads per the instructions, it still did the same weird thing with the pedal feel a couple different times. My 03 never felt like this.



mwilson, that's an interesting theory about the plungers or trapped air in the ABS system. I was wondering if there was still trapped air somewhere, so I have a Motive power bleeder en route to see if I can get a better bleed. The road I live on turns to dirt after my house, so after power bleeding I'm gonna do a few "death avoidance panic stops" to see how it responds.

If you have air trapped in the ABS you will feel the pedal rise after a hard ABS engaged stop or two.

Then all wheels should be bled again as Bob 4x4 mentions. (I forgot to put that in my previous post).



By making the ABS pump activate during a hard stop you are doing the same thing that the scan tool does when bleeding the system in a shop.



Kind of a DIY way to properly bleed the system.



Mike.

 

[Gonzo 1066]

Thanks for the input, I have replaced brake fluid 2x so far in the 120,000 miles of towing. I will do it again and try a couple of panic stops. .

 

[NIsaacs]

About ABS: I have to disagree with the previous post that ABS is an accident waiting to happen. ABS is a great tool.



One poster said he prefers to lock the rear wheels. This is, in my opinion, disastrous advice.





If an ABS system does not perform flawlessly every single time, than it's an accident waiting to happen. If we use 100% as the point of lock up, then ABS needs to work at 99% every single time, if needed. It does not and never will. I will admit the systems are getting better, however this has taken years to develop. What about the early antique systems like my '91 Dodge pickup that is junk?? You can't blame it on a maintenance issue because it was junk since day one. How many wrecks have occurred needlessly??



I will use my right foot as my ABS, thank you.



Nick

 

[mwilson]

I agree that the early ABS systems simply sucked.....



My BIL had a 2001 GM pick-up that was downright frightening to drive,was that way from new.



I think from 2003 or so on that the ABS systems began to be reliable from all makers.



It is a learning curve for all, remember the 1980 ABS debaucle on the big trucks... .



The first attempt at air disc brakes and tubeless truck tires????



It gets there after a while...



Mike.

 

[Bernie]

I will use my right foot as my ABS, thank you.



Nick

-That was my first suggest, in the form of threshold breaking. These systems do not replace good driving. If you are threshold breaking, you are going to stop better than any ABS system, modern or ancient.

-Locked wheels is not threshold breaking. Locked wheels are not in control, and they have about 25% of the friction (and therefore, stopping power) of an unlocked wheel.

-I agree, your best stopping tool is your right foot. However, if you are using it to lock your rear wheels you are a danger on the road, and you are not using your foot as ABS. The A stands for Antilock.



And, so you know, I have had (and current do have) many late eighties / early nineties ABS systems on my race cars. I leave the systems in place. Yes, modern systems kick their *** when in ABS, but I would still rather have it compared to locking up unexpected.

 

[Bill Stockard]

I agree that the early ABS systems simply sucked.....





Remember the 1980 ABS debaucle on the big trucks... .



The first attempt at air disc brakes and tubeless truck tires????



It gets there after a while...



Mike.

Yep, I remember them well...



Bill

 

[NIsaacs]

I agree that the early ABS systems simply sucked.....



My BIL had a 2001 GM pick-up that was downright frightening to drive,was that way from new.



I think from 2003 or so on that the ABS systems began to be reliable from all makers.



It is a learning curve for all, remember the 1980 ABS debaucle on the big trucks... .



The first attempt at air disc brakes and tubeless truck tires????



It gets there after a while...



Mike.

Yup! My first big truck with ABS was a new IHC Glider Kit with that mess. It was my first exposure and first delete:-laf



Nick

 

[Gonzo 1066]

I changed brake fluid today after some panic stops. Seems to have improved the pedal feel. Will know more when I tow the big trailer.

 

[JeffBob]

I recommend you get your truck's brake system inspected by a certified technician immediately. In the absense of a diagnosis you should assume you've suffered a primary brake circuit failure.



Options include:

1. Inner brake line wall failure; outer wall failure would then be catastrophic.
   
2. Master cyclinder failure
   
3. Vacuum booster failure
   
4. Vacuum line failure
   
5. Hydraulic leak - piston seal failure
   

Most likely, old brake lines or master cyclinder internal seal failure.



My truck only has 60k on it, so that leaves age causing this, and it sounds like "they're all doing this" at this age.



Don't put your life or others at risk, get a solid diagnosis before u drive it!



I'm sure the next shoe to drop with mine would be near or total brake loss.



And that will ruin your day every time.