slightly sticking brakes

[Big Mike's Motor Pool]

when my clutch went bad my brakes were fine. the truck sat for about 7 months before i decided i wanted to fix it. well, its been fixed for a while now and i notice that the brakes will stick when applied. they dont stick to the point that that truck is completely immobilized, as if it had no air, but more along the lines of when i am braking for an upcoming stop sign and i let off the brakes the truck continues to brake for a bit and then loosens up. if i stay on the brakes till i stop all the way , when i go to take off its hard on the truck for a few feet until they release again. incase my description is cloudy, when i stomp the brakes on a hill and get out of the truck it wont roll away. not that i would think of doing that, but thats the symptom im talking about
im not sure where to start looking, any opinions or advice is greatly appreciated

 

[TheBuggyman]

Mike,
I don't know if this will help......
My five ton has a tiny bleed hole in one of the glad hand covers and if that gets clogged up then the airpak cannot release brake pressure. I had mud daubers build a nest over mine and my brakes would not release at all. Maybe if yours release over time then the hole is just restricted. I hope this helps but I don't know if it applies to the Deuce.

Eddie

 

[jatonka]

Pretty much the plugged pee hole on the 5 ton glad hand cover is not relevant to M35 2/12 ton trucks. You either have a sticking air pack release valve or you have a restriction in your master cylinder that isn't allowing brake fluid to return quickly enough. There is also a very slight chance that you have one or more failed brake hoses that are blocking the return of brake fluid. And a slight chance that some of your wheel cylinders are sticking. If you have access to a working air pack, change it for yours and see if the trouble is fixed, you can then rebuild your airpack, Bjorn did a story on it several years ago in MV magazine. JT out

 

[acetomatoco]

And to add to the excellent post above, make sure your MC vent is not clogged...just take off the fording line and put a differential vent in the hole and see if your problem is corrected...easier even, is just to take the fording line off for a while to see if the problem is fixed... and be sure to put some OHT in the air side of the booster...btw, JT sells OHT....

 

[DDoyle]

they dont stick to the point that that truck is completely immobilized, as if it had no air,

Please understand that the absence of air does not apply the brakes on a M35A2. These trucks do not have air brakes, nor the spring safety brakes associated with air brakes in most applications in the past 40 or so years, like over the road trucks. The brakes are hydraulic, air is there only to provide power assistance for the brakes - much as vacuum is used for the same purpose on most cars. As soon is the motor is running, you CAN drive away - but you won't have power brakes - only pure hydraulic - and this makes stopping somewhat slow.

You probably already know this, but a lot of new guys find posts on this site through google, etc - and I didn't want someone to go down a very wrong path.

The other guys have already given good diagnostic steps.

Regards,
David Doyle

 

[Big Mike's Motor Pool]

they dont stick to the point that that truck is completely immobilized, as if it had no air,

Please understand that the absence of air does not apply the brakes on a M35A2. These trucks do not have air brakes, nor the spring safety brakes associated with air brakes in most applications in the past 40 or so years, like over the road trucks. The brakes are hydraulic, air is there only to provide power assistance for the brakes - much as vacuum is used for the same purpose on most cars. As soon is the motor is running, you CAN drive away - but you won't have power brakes - only pure hydraulic - and this makes stopping somewhat slow.

You probably already know this, but a lot of new guys find posts on this site through google, etc - and I didn't want someone to go down a very wrong path.

The other guys have already given good diagnostic steps.

Regards,
David Doyle

hmmm, well, maybe this might have somthing to do also with my problem if no air wont immobilize the truck. before the clutch blew up i remember taking off from my house one day with a glad hand open and the valve on. it had no air when i got to the intersection near my house. the brakes were hard like you said but once i went to move the truck stalled. i had to put it in low range to get out of the way of traffic to close the glad hand because the brakes jammed and i couldnt move.

 

[Big Mike's Motor Pool]

And to add to the excellent post above, make sure your MC vent is not clogged...just take off the fording line and put a differential vent in the hole and see if your problem is corrected...easier even, is just to take the fording line off for a while to see if the problem is fixed... and be sure to put some OHT in the air side of the booster...btw, JT sells OHT....

i will try the vent trick tomorrow first because its simple. the last person who touched the MC cap and air line wasnt myself so there is a good possibility somthing may have been boogered when my friend checked the brake fluid for me. i may have access to a good airpak, i know i can get one though even if i have to rebuild it. actually, if i get another one that i dont know the history of its getting rebuilt before i even crawl under the truck because i hate doing a job twice and i would rather spend a few bucks and rebuild it beforehand.
dont mean to sound like a dummy, but whats OHT??

 

[doghead]

OHT info... http://www.steelsoldiers.com/index.php?name=PNphpBB2&file=viewtopic&t=14487&highlight=oht

 

[DDoyle]

[quote="MUDLORD"
hmmm, well, maybe this might have somthing to do also with my problem if no air wont immobilize the truck. before the clutch blew up i remember taking off from my house one day with a glad hand open and the valve on. it had no air when i got to the intersection near my house. the brakes were hard like you said but once i went to move the truck stalled. i had to put it in low range to get out of the way of traffic to close the glad hand because the brakes jammed and i couldnt move.[/quote]

Sounds more and more like a sticking valve in the air pack - if removing the MC vent line does not solve the problem, I'd add the OHT and work the brakes repeatedly before spending money on hardware.

One caveat though - how often do you drain your air tanks - and what are the temps where you are?

Regards,
David

 

[gimpyrobb]

RE: Re: slightly sticking brakes

Yup, could be frozen.

 

[Big Mike's Motor Pool]

RE: Re: slightly sticking brakes

i prolly dont drain the tanks as often as i should, maybe once every couple months. i live in souther new jersey, its pretty cold here but nothing drastic. i would imagine that ice could form and then stay even when we get a few days of warmer weather. i have had ice in my cooler for more than a month if its kept out of the sun i guess this same thing could happen in an air system

 

[gimpyrobb]

RE: Re: slightly sticking brakes

Well, I think he was getting more at the brake fluid. If your running dot3 it will collect water. Once the cold rolls in it can/will freeze. Thats why he was wondering about the last time you bled the brakes and what the temp was. I didn't think about water in the air lines too.

 

[DDoyle]

RE: Re: slightly sticking brakes

Nah, I was thinking about the air lines.

DD

 

[Big Mike's Motor Pool]

Re: RE: Re: slightly sticking brakes

Well, I think he was getting more at the brake fluid. If your running dot3 it will collect water. Once the cold rolls in it can/will freeze. Thats why he was wondering about the last time you bled the brakes and what the temp was. I didn't think about water in the air lines too.

i only run the recommended dot 5 in it even though its really expensive

 

[Big Mike's Motor Pool]

RE: Re: RE: Re: slightly sticking brakes

well, i tried the trick with the vent line, i even took the MC cap off and blew air through it and made sure it was free of obstruction and tried again with out the vent line. same deal. i had a friend over today and i would get the brakes to lock up in the driveway and then had him open the service side glad hand. nothing came out but the brakes would release. im guessing its the airpak now. im goig to go to napa and get some airline antifreeze and get it into my system and see if it helps. if nothing comes of that im going to try the OHT. would there be anywhere i can get that local to me or is JT the only way to get it??

 

[doghead]

RE: Re: RE: Re: slightly sticking brakes

Light hydraulic oil(hy-trans) or marvel mystery oil or whatever you can find can be substituted. Use airline antifreeze only on the air side.(probably not needed)

 

[Big Mike's Motor Pool]

RE: Re: RE: Re: slightly sticking brakes

thanks, i think i have some hy trans at work. approx how much should i put in it?

 

[doghead]

RE: Re: RE: Re: slightly sticking brakes

Just an ounce.

PS mag page on adding OHT. http://www.steelsoldiers.com/index....rpak_lube&name=gallery&include=view_photo.php

 

[Big Mike's Motor Pool]

RE: Re: RE: Re: slightly sticking brakes

well, i shot the air pack up with some marvel mystery oil today. since the brakes seemed to work with the service side open in the back, i worked it in for a bit with the valve open in my yard. i closed the valve and the brakes were still was sticking. i took it for a ride down the road and did a panic stop. the brakes seemed to be freeing up, i then decided to go to this paved forestry road near my house that nobody would be at for more working in. i got the brakes to work decently, almost back to normal. sometimes the pedal is light and almost floors, other times its hard and high. im just going to try to make it throught the winter like this. i only really use it for transporting pallets to the woods party spots when i go out, and for off road stuff. in the spring time i'm going to replace the airpack for one im gonna rebuild. i think im also going to freshen up the master cylinder, all rubber brake lines, wheel cylinders, and finally fix my brake switch. since im going to be bleeding atleast one thing, why not go a little further and make it all right. thanks for the info guys!!