Brakes dragging

[doc76016]

I finally bought a "deuce" yesterday. It was only around 180 miles
away and the seller assured me that it was "in great shape" and that he
"wouldn't hesitate to drive it anywhere".

Sooo... I started on the trip home. Around 60 miles into the trip
it started bogging down. A couple of miles later my wife (who was
following in the car) pulled up alongside and told me to stop. I
noticed that it really seemed to stop quickly as though something was
dragging. I got out and saw smoke coming from the rearmost driver's
side axle area. I deduced that the those brakes were binding. I called
the seller. After consulting with "his mechanic" he told me that
apparently the self-adjusting mechanism had gone TU. I was told that I
should loosen the two jam nuts at the bottom of the brake drum assembly
and then turn the smaller inner nut with the oval-shaped head until they
became loose and then to retighten the jam nuts. This, I was told would
disengage the self-adjustment feature and enable me to continue to my
house. It took me three trips several miles along the interstate to
find a hardware store and to purchase the correct size socket to do
this. Finally, I did as was told and when I started up the vehicle it
would indeed coast a bit between gear changes, indicating that the
binding was no longer present. I then continued on my journey. About
60 miles down the road (sound familiar?) I noted again a loss of speed
and a feeling that something was dragging. I once again pulled over and
I once again saw some smoke (although not nearly as intense) coming from
the rearmost driver's side brake area. I decided this time to
completely remove the jam nuts, leaving the adjuster? nuts free to turn.
I also rotated the adjuster? nuts until they felt "loose". As it was
late, the wife and I left the vehicle and had a dinner. Upon my return
it seemed that the dragging was greatly lessened, but I wasn't sure
that it was completely gone. We then completed the journey to our
house, a distance of approximately 60 miles (hmmm... there's that same
distance, again). When I shut down and got out I noticed a bit of smoke
once again coming from the same spot.

Now, it's been 40 years since I drove a deuce-and-a-half while in
the army. I rarely drove one then as I was actually assigned to an
M113a1 APC so my experience with the deuce is limited and long
ago. Could this be some sort of air pressure/regulator problem?
The distance for it to develop and the elapsed time between my
stops and resumptions of the trip make me think that it was slowly
developing within the air system while driving. Then, maybe
instead of my actions helping the malfunction was correcting itself as the air
pressure was lost during the prolonged time it took me to find tools the first
time and while we ate dinner and refueled the second time.

I just now read through the dash 20. Under the "brakes drag" section it
seems to indicate that I should replace the air-hydraulic cylinder. Does
this seem right to you guys? Anyone close to Arlington, Texas that could
come by and have a look?



Grateful for any insight,
mdh in Arlington, Texas

 

[tmbrwolf]

The brakes are NOT self adjusting on these, it could be improperly adjusted shoes, broken or missing parts inside that is causing them to drag, or a miss adjusted master cyl. I would first check break pedal freeplay, if there isn't enough freeplay it will retain pressure in the system and will cause the brakes to drag after several applications of the brake pedal, one way to check if this might be the cause is to crack the bleeder on the offending wheel when it starts locking up, if it's excessive pressure you'll know!

 

[Jake0147]

Agreed, start with the pedal free play adjustment. If the master cylinder doesn't release quite fully, it won't "vent" the fluid in the system properly to the resivoir. A brake dragging will warm the fluid. It then has no release, so the brakes apply a bit. This multiplies the heat issue, thus the expansion issue, thus the friction issue, and back to the heat issue, in a big snowball.
It's a single circuit, so if hydraulic pressure is present at any wheel, it's present at all of them. I might suspect oil or grease or brake fluid being present in the drum that's smoking. Visual inspection of the brakes in their entirety on a new to you deuce is never a bad plan anyhow. You can count on at least some parts being as old as the truck.

Lots of deuces seem to get lots of short trips, broken only by a very long trip when they change owners. This brings out troubles that wouldn't otherwise show. The search engine on this site is a PITA but is well worth your time to fool with, as well as the stickies at the top of the Deuce forum. There's a wealth of information here including the TMs for your truck, under the resources tab at the top of the page.

 

[doc76016]

Re: RE: Brakes dragging

The brakes are NOT self adjusting on these, it could be improperly adjusted shoes, broken or missing parts inside that is causing them to drag, or a miss adjusted master cyl. I would first check break pedal freeplay, if there isn't enough freeplay it will retain pressure in the system and will cause the brakes to drag after several applications of the brake pedal, one way to check if this might be the cause is to crack the bleeder on the offending wheel when it starts locking up, if it's excessive pressure you'll know!

Thank you for your reply. You know, I _thought_ the brakes weren't self-adjusting, but this is a 1985 model and I last drove a deuce in 1972 so I thought that maybe they had changed. I really didn't believe that the seller knew even the little I did about these vehicles. This confirms it.

The brake pedal freeplay is only about 1/4". If I read the TM correctly that's correct. Seems far too little to me. Is that correct?

Later,
mdh

 

[doc76016]

Re: RE: Brakes dragging

Agreed, start with the pedal free play adjustment. If the master cylinder doesn't release quite fully, it won't "vent" the fluid in the system properly to the resivoir. A brake dragging will warm the fluid. It then has no release, so the brakes apply a bit. This multiplies the heat issue, thus the expansion issue, thus the friction issue, and back to the heat issue, in a big snowball.
It's a single circuit, so if hydraulic pressure is present at any wheel, it's present at all of them. I might suspect oil or grease or brake fluid being present in the drum that's smoking. Visual inspection of the brakes in their entirety on a new to you deuce is never a bad plan anyhow. You can count on at least some parts being as old as the truck.

This theory has merit. Only the rearmost driver's side axle had smoke, though. I guess a visual inspection for broken parts, etc. is in order.

Thank you,
mdh

 

[Floridianson]

I just now read through the dash 20. Under the "brakes drag" section it
seems to indicate that I should replace the air-hydraulic cylinder. Does
this seem right to you guys?

Yes the air-pack can be a problem. If you did not have to pay for the parts then it is faster to grab a new part and be done with it per TM.
You could try and lube it up and keep it lubed or take it off and inspect and make your decision as what you find.
In this case I would think that a complete brake system check is in order so that you know where you are with your new truck.
To replace or rebuild that is the question.

 

[doc76016]

Yes the air-pack can be a problem. If you did not have to pay for the parts then it is faster to grab a new part and be done with it per TM.
You could try and lube it up and keep it lubed or take it off and inspect and make your decision as what you find.
In this case I would think that a complete brake system check is in order so that you know where you are with your new truck.
To replace or rebuild that is the question.

Thank you for the kind reply. It seems that the most likely cuplrit is the air-pack with the brake master cylinder/pedal travel misalignment also a possibility. However, I found a link to a PS article which lends even more creedence to the air-pack. The little gremlin says, "Brake fluid coming from the breather means there's a bad seal in the air/hydraulic cylinder." I do have a small amount coming from that point. Looks like that's probably it.

 

[cranetruck]

RE: Re: Brakes dragging

Welcome to the site Doc, glad you are getting some help.

 

[rizzo]

RE: Re: Brakes dragging

I had a problem with mine dragging and it was compressed air in the lines. bleeding fixed that.


Thanks for posting the PS article. I am having a problem and that might help

 

[rizzo]

Re: RE: Brakes dragging

The brakes are NOT self adjusting on these, it could be improperly adjusted shoes, broken or missing parts inside that is causing them to drag, or a miss adjusted master cyl. I would first check break pedal freeplay, if there isn't enough freeplay it will retain pressure in the system and will cause the brakes to drag after several applications of the brake pedal, one way to check if this might be the cause is to crack the bleeder on the offending wheel when it starts locking up, if it's excessive pressure you'll know!

Thank you for your reply. You know, I _thought_ the brakes weren't self-adjusting, but this is a 1985 model and I last drove a deuce in 1972 so I thought that maybe they had changed. I really didn't believe that the seller knew even the little I did about these vehicles. This confirms it.

The brake pedal freeplay is only about 1/4". If I read the TM correctly that's correct. Seems far too little to me. Is that correct?

Later,
mdh

the adjusters are two bolts on the backing plate at each wheel

 

[doc76016]

Re: RE: Brakes dragging

[quote="rizzothe adjusters are two bolts on the backing plate at each wheel[/quote]

That is correct. The point is that they aren't SELF or AUTO adjusting.

mdh

 

[Big Mike's Motor Pool]

RE: Re: RE: Brakes dragging

if you ever start driving your truck in the mud alot like i do you will get to become really good friends with those adjusters

 

[tmbrwolf]

RE: Re: RE: Brakes dragging

There are 4 points to adjust the brakes, two near the top and the two at the bottom, to properly adjust the brakes you'll need to remove the wheel, on the drum there is a small access plate bolted to the face, remove the plate to access the shoes, You'll need a .010 and .020 feeler guage to adjust the brake shoes, the top adjustment is .020 at approx the 2 & 10 o'clock positions and .010 at the bottom of the shoe, move the adjusters a little at a time until you get them set, it can be a little frustrating to get them adjusted, the -20 TM has the info needed. If you are getting any brake fluid from the draft tube DO NOT drive the thing until it's fixed, the fluid can get into the air portion of the booster and cause it to hydrolock, I had this happen to me in a convoy in Germany, I was pulling canvas out of my rear for a week after that one! Another good thing to do if it hasn't been done is the breather mod on the master cly, if the breather line is still hooked up remove it and the elbow, replace it with an axle vent, this will keep the brake fluid from getting contaminated with junk in the breather system.