Rear Brakes hainging up

[Dsl_Dog_Treat]

Ok for those that didn't find my secret mod on the not so Gold one.

I installed a micro brake system on the truck in lieu of the conventional parking brake system.
I have noticed a viration on the truck at around 60 mph and thought it may have been a u-joint issue.
Not so says my freshly singed fingers from brake drum contact last evening investigating the issue.
I also had concerns of a not so much of a power gain from the turbo but all has become quite clear now.

The micro brake is setting and releasing fine but am wondering if it is causing the slack adjusters to go a little too far.

A little insight.

The rear cables are still attached to the drums and secured to the framerail.
Micro brake system plumbed in place of the Rabs module.

Is there a desired / required amount of pressure needed to maintain the adjusters to keep them in place?

Do I just need to remove the e-brake cable assemble to alleviate this occurrence (planned to do but haven't made it yet)?

Or is there a possiblilty that the micro brake system is restricting fluid flow?

Calvin I know ya have some more experience with these systems than I do, but I would think it should be almost overkill as this system was setup for an International R-190 Firetruck.

Any thoughts?

 

[Mr_Roboto]

OK, I gotta say it. It's "Mico" brake, which is a popular manufacturer of line locks. There is no "R".

I suggest jacking up the rear end and seeing if the brakes are really dragging. A brake drum will be hot just from normal use.

The slack adjusters work from applying the brakes in reverse. There is no way for them to "overadjust" automatically. It is possible that the parking brake cables are pulled and making the brakes drag. Pull off the drum, and use a prybar or large screwdriver to pry between the axle flange and the parking brake arm. This will pull the brake cable back into the drum if it is pulled and stuck.

As an aside, a line lock should not be used as a parking brake. They are for short term use only and will leak pressure down. The older and more worn they are, the faster they leak.

 

[towcat]

ron-
the mico brake in simple terms is nothing more than a gate valve. there is no restriction when off. like we talked earlier, they do tend to leak down when in the "on" position, so do not go long term without a working parking brake or blocking the wheels after setting the mico.
check your brake adjustments, chances are the drums got a little rusty or flatspotted when the axle was removed from the frame.
at 60mph and the vibration is consistent with engine load and road speed, there is a high chance your driveshaft is out of balance if not bad u-joints.

 

[tonkadoctor]

Towcat, I'm really having a hard time reading your posts since you put up that new Avatar. Everytime my eyes go back to the left to start reading the next line my eyes get stuck and I lose my spot and have to start over. Damn she's pretty to say the least.

Towcat has a valid point on the driveshaft balance. Did you get it correctly back in the phase since it was pulled out. Being out of phase will cause a vibration too.

If your brakes are dragging you would usually smell them just like a burnt clutch, smells like burnt BBQ sauce to me.

 

[Dsl_Dog_Treat]

OK, Let me defend/explain myself here a bit.

The line lock brake was an quick fix to a more expensive problem.
$7.00 cable versus $125.00 for all 3 cables.
Money has become an issue with the project and chose the lesser of the 2 to get by as I'm not a big user of the parking brake.
Small kiddies around and flat ground, I tend to make sure they are not around when working on the truck if it needs to be running and I usually chock the wheels even then.
For the most part, the truck is off and in gear if they are around or I'm working under it.
The decision of removing the e-brake assembly was first thoughts but not sure if I wanted to as to why they were still attached and contemplated the spending of money on the cables that may/not get used much before they rust up again.
Michigan winters here are tough on cables and if not used on a daily occurrence, which I would be fault at, they tend to rust up purdy quick.
I also live on a dirt road and keeping them greased up would also just add to dirt buildup and possible failure also.
Hence the need for something with less maintenance and can rely on it to hold the truck when needed for me would be about 5% of total time in/on the truck.
I have used this system on our firetrucks for many years and have only dealt with one problem with them and is when the engine runs for an extended time while on a scene, they tend to become overpressured and have to bleed them off to get the system to release if someone sets the brakes too hard.
That is why I chose to use the system as I already had a new valve assembly in my posession.

Now last evening I backed the adjusters off 1 1/2 turns and the brakes are no longer dragging.
Noting the left rear having a now cooked axle seal.

The axles remained on the truck to keep it as a rolling chassis for ease of moving it around.

The driveline was kept in one piece when I took the truck down and was even marked it just in case.
I had to have a new driveline built for it last year as the PO had bent it somehow.
Only good pieces left were the u-joints.
Prolly 12k on the driveline since it was built.

I went thru and replaced everything on the rear brakes except the wheel cylinders last summer as one of the rears had come apart.

One other factor is the newly installed urethane bushings which now amplify things more in the cab due to a more rigid mount.
The vibration is still there but so far the brakes have seemed to stay backed off so far.
Tonight I will be investigating further as I will have more than 20 minutes to work on it and will prolly also look to see if any tire weight may have fallen off.