Total brake failure during a panic stop

[Kaiserjeeps]

I just had a panic stop go awry. I was pulling into a fuel station to get some diesel to haul a load to my new place. A guy darts in front of me early on in my approach and me really not seeing him hit the brakes hard to stop in time. Since there was a now a pick up in my path where there was none seconds before, I needed to stop way sooner. It made pressure for a 1/4 second and went straight to the floor. I grabbed the emergency brake while headed right for the pumps and this pick up. I came to a chattering stop. Everybody was oblivious to the excitement that almost took place. My friend and I were grateful we were not on the pass we were just headed for. I took it apart today and was really surprised at what I found.
I am not sure why it failed. I really romped the brakes a week earlier for a deer. I think I may have started the problem then?

Today I rebuilt the master with a kit as it seemed sticky. It was new last year. I got a nice smooth hone inside it. It functions well when bench bleeding. The airpack is less than a year old. I am having trouble bleeding all of it. I am building a bleeder tomorrow from the stickey. I feel like I should look at all of them now. Thank you 503m715 for the extra parts to get me going.

I see every reason to up grade to more modern brakes. A dual system. What works as a good conversion?

This is failure number two. Hence the reason for all the new parts earlier.
I love my hobby, but I don't want to die doing it.

 

[gimpyrobb]

Wow AL! That looks to me (as much as I hate to say it) like the brakes might have been out of adjustment. If all the wheel cyls(left and right cups) were moving, there shouldn't have been THAT much pressure on that one pad assembly. I know you take good care of your trucks, could it have just been a bad weld on the metal? Kinda looks like the weld didn't have good penetration. Maybe a little on the cold side. Its hard to tell from just a few pics. Seems like the master and booster are in good shape if they made enough pressure to do that. Let me know if you need more parts.

 

[Kaiserjeeps]

I had a pretty high pedal before. I know that axle had the most worn shoes. I let some stuff slide a couple years ago when I ran a little slim on money. I think you are right though. Mike set me up with piles of brake parts. Drums, cylinders, shoes, hardware. Thanks Mike. I have what I need I think.
What a bad feeling when there is nothing there. Both times I was doing under 25. Both times I had just driven the curvy pass or was heading there. I have an angel.

 

[wsucougarx]

Indeed you definately have someone watching over you my friend. Wow, I haven't seen brake failure like that one. Who would have thunk.

 

[rosco]

My suspicion is that there has been a problem there for sometime. All that goop and accumulation didn't happen/accumulate because of the panic stop. There has been a slow leak/seep there for sometime. It let go during the panic stop. Was the assembly proper? Did you find the piece from the failed plunger? Was it a new break? The failed weld - was it a new break?

Good no one was hurt. Lots of worse things could have happened. I have often thought that these vehicles run, and continue to run, despite deferred maintenance and incompetent maintenance. Many are subjected to that kind of treatment. One should carefully go over them, to insure they are roadworthy.

 

[Deuce_and_a_Half_Dragon]

I will never understand what posses people in small vehicles to dart infront of largeer ones, I think that it might have to do with a lack of knowledge about weight and such . I would never think of darting my 6,000lbs bronco infront of a 13,000+ deuce or anything else for that matter, I had a short stint as a fuel truck driver (before anyone asks I left because of a schedule conflict) and I know what happens when a large vehicle tries to panic stop, usually ends bad, glad to hear this was one of the times it went okay.


Btw, i probly would have hopped out and been a bit more than unfriendly with that, ahem, gentleman

 

[bratpackdad]

Thats a whole lotta gunk there. Proper cleaning and alignment should solve the problem. If you're still concerned you can switch to air brakes.

 

[ALFA2]

All that bent metal and wear shavings point to at least two things: First, the hydraulic system worked well up until the final failure, ( bent parts, extended wheel cylinder cup) and a preexisting condition, misadjustment, possibly a slight leak, may be a missing return spring.

You got lucky, that you stopped as you did, up on the finishing of your rebuild of the break system, please check the run out in the drums, especially the one where the mechanical failure occurred, if the drum was overheated or very hot when the wheel cylinder blew, it may have warped the drum a little out of round, when the breaks cool off with the shoes /pressure applied, from emergency breaks locked in, and also from hydro system breakage in applied position, it is rare, but it does happen.

Hope it helps.

ALFA2

 

[TechMav]

Judging by the pictures, I'm going to hazard a guess that it was a bad weld on the shoe. When you hit the brakes hard, it was enough to push the flange out and that is what broke the tab on the wheel cylinder, since that seems to be a shiny, fresh break. I agree that it looks like you had a slow leak already, as the brake dust/fluid goop build up. So... combination of manufacturing fault and luck.

Glad no one was hurt, and Deuce and a Half Dragon is right... people just don't think anymore. "I can stop on a dime, everyone else can too."

 

[maddawg308]

That happened to NewMVGuy at the first Rausch Creek rally in Oct. 2007. It's not common, but it happens occasionally. Nothing you can do to prevent it other than check your brakes once a year.

It is also one of the reasons I choose to resistance brake with the engine and downshifting. Takes a lot of strain off the brake use if you aren't using them too often in panic stops.

 

[No.2Diesel]

Not the first time...

Hi,

Haha Maddawg beat me to it! Talk about a double post!! edited....
I'm glad that no impact(s) took place. Yeah most people do not operate their vehicles defensively.

Back at camp we were able to scrounge some little pieces of scrap metal and we were able to use the arc welder provided by the RC Office Staff and we bent back the shoe and welded it. The little clevis rod on the wheel cylinder also broke so we needed to weld that to. I carried extra wheel cylinders, fluid etc. and everything was up and running in no time.

The round part of the shoe is welded to the vertical portion by small cheesy welds that look like a robot carries out in a nano-second providing for very little weld area and penetration. So if there is a leaky wheel cylinder and schmageggy gets on a portion of the lining it may grab on only side creating a twisting motion. The weak and lack of welded area does not help creating the situation. So don't allow for leaky wheel cylinders. It looks like in both of these cases there were leaky wheel cylinders present when the drum was pulled.

Enjoy the pictures!

 

[deuceman51]

I'm wondering where the brake shoes came from? Are they after market or US made NOS. I have never seen anything like that before. I had an incident a few years back driving an M916 carrying a D7 dozer driving on snowpacked streets. A small blazer cut me off right off my front bumper changing lanes and then puts his turn signal on to make a right hand turn. I never thought that rig would stop in time, but a few people had angels that day also. People just don't think anymore!!!!!!! Glad everything turned out as good as it did.

 

[Barrman]

Glad you are ok Al. Not much you can do to prevent a bad weld besides TIGing all of them before you install. Get new shoes in there, adjust them up and keep being on the look out for idiots while driving.

 

[Kaiserjeeps]

I know it is messy in there. It was not last time I was working on it. I think that worn shoes help cause this. As for who made the shoes, I don't know.
I am cleaning up and replacing everything. I am never going to run brake shoes that low again. Not if this can happen. I never even had time to get mad. I had enough adrenaline to drop an elephant when it happened. Then it was how to limp home and not have an accident. In my shorts.

I am off to go build a power bleeder.

 

[Recovry4x4]

Another consideration worth considering is the depth of the piston. It for some reason you had a cheap copy wheel cylinder, it may have pistons that are too short to compensate for a worn out shoe. Might also mic the drums. If it's been turned oversize too many times, it could cause this. Also for you folks with the old gassers, the hold downs that use a hitch type pin are prone to failure. I had one do that and the shoe rubbed against the drum until it cut right through it like a lathe.

http://www.steelsoldiers.com/deuce/5140-whoa-no-brakes-20-000-deuce.html

http://www.steelsoldiers.com/deuce/5149-brake-inspections-warnings.html

 

[USAFSS-ColdWarrior]

Glad you didn't "stop on the dime" that was in the little-car-driver's pocket.

Thank God for the happy ending.

 

[Maverick1701]

phew!!! close call

glad all ended well

 

[503m715]

Al, glad you were not hurt and could make use of the spare parts.

 

[Kaiserjeeps]

I am glad they were here. I actually had all of it in the back to take up to the property. Thanks for giving me all that. I found a near new pair of shoes to get me mobile right away. I made a pressure bleeder like the one in the stickey up above. Talk about brakes. A nice solid pedal and ready to go. I'm going to make a dot 3 one for my other smaller jeeps. Talk about easy and quick.

I think my general rule of thumb for stopping distance now is about a 1/4 mile.

 

[Kaiserjeeps]

It drove well today. Or should I say it stopped fine. I still drove like a little old lady.
I want to start looking for new brake shoes. I have some that are close to the ones that failed. And it looks like I need some seals.
Of course I intend to search way past my bed time however comma I wonder if anyone knows of a good source that is reasonable for brake shoes that is worth mentioning.

Do they take the old cores? Or should I toss em?