Break Failure

[Jfam]

Since I can’t use the search feature, have to ask since this is scary! Last week—at the recommendation of a TDR member some time ago—I had a set of “Iron Claw” pads installed on my 94 TD. Noticeably superior to former pads. About 5 days later, while pulling into a parking lot, brake pedal slowly goes to the floor. . no brakes! Apparently neither front nor back as I was in idle and could not stop the truck. Had to use neutral and then reverse to do it (automatic tyranny of course).



Towed her to my mechanic’s garage and all worked fine! Road tested and all fine! Noticeable smell from the left front. No fluid loss. Current thinking is that the old (205k) fluid could not handle the additional heat generated by the high performance pads. Also will replace caliper and hose. Any other thoughts?? As usual appreciate the help of the TDR crew.

 

[WyoJim]

Jfam... I will be very interested in the solution to your brake problem when you solve it... In the mean time if it happens again try the emergency brake.

 

[redramnc]

Sounds like you may have had fluid boil. As we all have been told, brake fluid absorbs water over time and suspends it in solution, thereby causing rust from the inside in steel brake lines. The water can boil if heated enough and when it does, it expands. The resultant gaseous mixture is much more compressible than the liquid brake fluid so it acts like a momentary bubble in the brake system, generating a soft pedal or, at worst case (as in your case), no braking whatsoever.



Had a friend years ago rearend somebody due to the same phenomena. I went over the system from front to back for him and all I found was contaminated fluid. Since it was a used Ford pickup and he had never touched the brakes it was possible that it had never been bled. There was no sign of failure anywhere with the mechanical systems and no air was found when I did a test bleed.



Just for peace of mind I would flush that system pronto. Questioning my brakes are not something I prefer to have to think about.



Hope everything comes out OK.

 

[Extreme1]

Chances are that the caliper was hanging up and creating the heat. A brake line plugged with rust will do the same thing: hold pressure and not release.



Before you replace the caliper, are you sure the piston is the culprit and not the mounting pins? Did you clean the pins and the rubber bushings they slide in and lube them with a high quality silicone based grease? That is usually the cause of a sticking caliper.



The second most likely cause is that the caliper can't slide in the knuckle due to rust build up. With the pistons retracted, no pads and the calipers installed, you should be able to slide the caliper the full range of its travel by hand. Sandpaper and a file will cure it if you can't.

 

[Joseph Donnelly]

You didn't post where you live. If a humid area, water vapor gets into the brake fluid, causing hydrolysis (breakdown) of the fluid and a lower boiling point. I found the IC brake pads good for "normal" use, excellent pedal feel. For high heat, heavy trailer use, I prefer the Performance Friction carbon metallic.

 

[BK]

I agree with redramnc and J. Donnelly.

If the calibers were hanging, I don't think they would have hung perfectly the same on both sides, front and back.

But with 205K miles and original fluid, if you live in most places but AZ, NM and such... there's some humidity. .



The boiling of the water in the fuild could have caused a bubble to rise to the master cylinder causing the complete failure.

The water is heavier than the brake fluid and settles into the calibers and wheel cylinders where they are exposed to the heat. The water will cause pedal fade. . when it turns to gas. . it wont compress at all but raise through the system.



While I agree with Extreme1 about the correct way to service the brakes once a year... I think the calibers hanging would have cause varing pulling or dragging and burning up of one pad or the other.



The lack of the pressure in the front brakes from the expansion of the water vapors can cause the pressure distribution valve to cut off the pressure to the front breaks and attempt to apply more pressure to the rear. If the rears weren't adjusted up manually (we all know these self adjusters suck. . like most), there' wont be much pedal todo anything with. (this is my experience with Ford brakes, not sure if the Dodge pressure distrubution valve works the same way. . should though)

 

[QRTRHRS]

Brake caliper, source for rebuilt.

I need an opinion on calipers. I have one either not sliding or hanging up. At 122k, should I go ahead and replace both if it is bad? New or rebuilt and does anyone have a good source. I also have some pulsation in my pedal. If I need to replace the rotors, where is a good source. Guess I should have been following the brake threads closer. TIA

 

[Extreme1]

A couple things here:



QTRHRS:

The brake pulsation is most likely a warped rotor from heat build up from a hanging caliper. I would really try cleaning the pins and lubing them and confirming the movement of the caliper in the knuckle. If you throw new calipers on, it might still bind. Since you will need to do the other work anyway, you might as well try this first (since it's free) and you might save yourself some $$.



The warped rotor will need to be cut. Some claim that a warped rotor will come back after a couple thousand miles and you are better off replacing it. I've always been able to have them stay flat after cutting, maybe I'm lucky.



Jfam:

Brake fluid is hydroscopic. That means tha it absorbs water which lowers the boiling point. If you had just completed a long hill decent or something similar, I would concur that the lower boiling point may be a factor. Either way, the fluid should be changed.



But since you were driving in town, I am pretty sure it was either the hanging caliper I described above I had it happen to me once, in town, no brakes. Like BK wrote, the rear adjuster suck and unless you are on top of that, the rears probably aren't working as well as they should. This would contribute to the no brakes when the front circuit boiled.



The other possibility is the when the pads were installed, a piece of crud became dislodged and got under a seal in the master cylinder. I have also had that happen, more than once.



At any rate, bleed the brakes to change the fluid. Start by getting all you can out of the master cylinder and wiping it out. Add some new fluid and then start at the right rear corner and work your way back to the left front, bleeding one at a time.



When that is done, jack up the fron and spin the wheels by hand. They should be even (except a 4x4 will turn easier on the rt side) and the pads shouldn't drag. If that checks out OK, start the engine (to get power assist) and have someone stand on the brakes HARD. Release the brakes and check for brake friction. There should be NO residual brake force left on the rotor.



If one is dragging, try cleaning/lubing the pins and cleaning the caliper/knuckle interface.

 

[BK]

QRTRHRS ,

you should alway replace calibers in pairs.

rebuilt is fine... just know the shop you bought the stuff from.

If you hardware is rough, you can replace the pins and stuff. It's not a lot of money. . so along with the calibers. . change the hardware. What's your life worth?

Extreme1 has a point about cleaning and such. . doing brakes is much more than replacing pads and maybe cutting rotors or drums. the contact surfaces that the calibers and rear shoes ride on need to be clean and very lightly lubed correctly to work correctly.



The reason some say that warped rotors that are cut just come back can happen for a few reasons... (I've had some good luck cutting rotors too, it also depends on the shop cutting them)

Their braking habits are such that they warped the rotors when they were thicker. . now that they are thinner they are more prone to warping.

2nd, if the rears are not adjusted and operating correctly , the fronts can work twice as hard. . twice as much heat... easily warped. Also a rotor that is badly warped probably has heat cracks. . that in no way should be reused in my experience.

If the rotors are cheap. . I'm all for chucking them for new ones. . Even new ones need to be checked for flatness.

The last is that some folks just dont take care when tightening their lug nuts, you can warp a rotor by improperly and over tightening your lug nuts.

 

[dan_gilson]

What casue the no brakes situation and subsequent "good" test was probably a boil over. What was the last time you have the brake fluid replaced? It should be done every 2 years at least.



Brake fluid absorb water over time. If it is in there long enough you can reduce boiling temp to at 212F. If does not take a lot of stop and go to get the brakes up to that temp.



My suggestion would be to replace the fluid first with a good grade. I am partial to Motul 600. It is little more expensive. You will probably have to go to a racing shop to find it. The difference in price is about $20 extra over the standard stuff. What is $20 more when it comes to stopping?



Inspecting everything is next. I would pull each pin (one at a time) on the front calibers check for scoring. If it has any you might want to consider replacing the caliber. Also check for any signed of leakage from the pistons. Replace anything that has leaked!!! Pull drums and check for adjustment and leakage. If everything looks good put it all pack together and give it a good cleaning with brake cleaner. If rear shoes are not close to the same thickness over the length of the shoe you should probably replace. Otherwise you have a lot less braking comming from the rear axle.

 

[QRTRHRS]

Thanks for the replies. I should know better than to ask about changing both calipers. Going through a money and time crunch at the moment. I went to get the wife's "Z" out after sitting all winter and have no brakes on that. Then I have my tractor all dismembered while repainting. Can't even get the Ram in the barn and we are finally getting rain.



Anytime I ever cut the rotors on my Ford's, seemed like one good panic stop and they would warp right out. Should be dry enough tomorrow, I'll pull the wheel and see what things look like, maybe call NAPA for some prices.

 

[Eric_77]

You problenm sounds like a bad master cylinder very hard to detect and does not leave any good warning signs prior to failure, but you had the ONE that I have seen in the pat no brakes, no loss of fluid then braking comes back normal. When the piston in the master cylinder "leaks" the fluid goes back in the reservoir.



On the brake fluid Motul is very good stuff but is more of a racing nature, and is more hydroscopic than many others. What this means is it has very high heat range but absorbs water easier thus needing to be replaced more often.

Best choice for brake fluid would be a DOT 5. 1 do not be confused with DOT 5 which is BAD for anything other than Harley and Corvettes. I use Valvoline DOT4 Synthetic because it is easy to find and has high temp range and even "wet" it is higher than many brands "dry" and it is not very hydroscopic.

Brake fluid should be almost colorless if it is at all brown it has water in it. This is in general for 90+% of fluids as there are red adn blue and other asorted colors for racing applications but as mentioned earlier racing fluids are expensive AND more hydroscopic some to the point that they only last 24 hours before replacement is needed.

 

[dan_gilson]

Eric_77 is correct. You should change Motul more often. Motul also has a 5. 1. I prefer the Motul 600. The difference is about 100F in the high end temp. Also as Motul 600 gets wet its boiling point drops to around 400F which is much better than 212F. This choice comes down to a personal preference.



I change my fluid out every two years or so and have not had a problem with it.

 

[Jfam]

Thanks to all for the helpful responses!



Based on the evolution of the problem, the conclusion, without hard evidence other than the brownish brake fluid, is that boiling of contaminated fluid was the problem. This was probably brought on by a hanging left caliper. Though there was no smoke observed from the left front wheel area, there was a noticeably strong odor from that side which has not reoccurred since the initial failure.



Both front calipers and hoses replaced as well as flushing the brake system and replacing with dot 4 fluid. Cost = $216.