M35A3 Parking Brake adjustment

[DownRange762]

Can someone direct me to the TM and Work Package reference for the proper adjustment of the A3 parking brake? I get the concept that many just crank down on the adjustment by the parking brake drum until it feels good, but I'm looking for some actual reference measurements and diagrams. I've toured 24-1-1 and either missed it or it is in another TM that I haven't gotten to yet.

Also, it is correct that on a slope with the engine off the truck will roll regardless of it being in any of the Drive or Reverse gear, right? The day I took possession of my A3 I had to back it up the ramp into my shop (with the mirrors folded in to clear the door opening) and it would have been nice to stop the truck occasionally with or without the engine running to confirm I wasn't about to hit anything.

My parking brake, even with the in-cab adjusting knob fully turned, won't even come close to holding this truck on a slight slope, let alone pass the test of holding the truck in Drive.

 

[glcaines]

You first need to confirm that someone hasn't burned up the brake shoes on the parking brake and at the same time confirm that the parking brake assembly is complete and installed properly. Sometimes springs are missing or broken. It is quite common that drivers forget to release the parking brake, even though the A3 has a warning light for the parking brake. The parking brake on the A3 works very well if in good condition and adjusted properly. The test for function of the parking brake is to put the truck in drive and increase engine speed to 2,000 RPM with the parking brake engaged. The truck should not move. If the parking brake is adjusted too tight, the parking brake will drag and burn up the shoes. Also, if adjusted too tight, the parking brake will sometimes not release properly, especially in reverse. The way I adjust mine is to back off on the knurled knob on the parking brake lever. I then get under the truck and adjust the nut. I tighten it down and then back off a reasonable amount, making sure the shoes don't drag. I then adjust the knurled knob on the lever until the brake works satisfactorily without causing drag and releases properly. It will stay in adjustment a long time if everything is correct and you don't forget to release it before driving.

 

[michaelpilot1]

There is no park provision in the Allison transmission and the truck will roll freely in any gear with the engine off. The adjustment procedure is located in the A2 maintenance manual section 8, the incab adjustment is for cable tension. There is a clearance adjustment on the shoes at the rear of the transfercase. The manual is downloadable from Jatonkam35s and the number is TM 9-2320-361-20
JATONKA's M35 TM  download page Link to jatoka's

The manual is to large to upload here so I gave you a link but uploaded the scanned pages on the adjustment procedure. Good luck.

 

[gringeltaube]

Can someone direct me to the TM and Work Package reference for the proper adjustment of the A3 parking brake?....................................... I've toured 24-1-1 and either missed it or it is in another TM that I haven't gotten to yet..........

You already have Gary's excellent explanation above.... better than any Operator's-TM!

Regarding proper parking brake maintenance; yes, TM 9-2320-361-20; chapter 8, section I; pages 575 to 591. That is about all a guy needs to know!
That manual can also be found in our own library, under Resources - Technical Manuals for the Deuce...
Since the parking brake is the same for ALL 2.5ton M44 series trucks, that may be the reason it is not included in the A3's TM 9-2320-386-24-1-1 .



G.

 

[DownRange762]

Thanks for the explainations, the TM reference and most of all, the diagram. Everyone in the other posts mentions adjusting the "screw" but as seen, there are actually two threaded adjustments and I was about to crank on the wrong one. That would compensate just for cable stretch I'm guessing?

As for the amount of brake lining left, I have 3/16" to a 1/4" left on both the inner and outer shoe, the wear is even on both. Any thoughts on how much service life is left at this point if properly adjusted?

 

[gringeltaube]

.............................................................
As for the amount of brake lining left, I have 3/16" to a 1/4" left on both the inner and outer shoe, the wear is even on both. Any thoughts on how much service life is left at this point if properly adjusted?

That's why we have (and read) TM's...!

G.

 

[Hoefler]

Its difficult to adjust the nut on the braker lever. After wrestling and contorting I found that using a deep socket and several extensions and a ratchet allowed me to get it dialed in perfectly. The ratchet extensions need to extend up past the rear cargo box. Crank away and the truck will stay!
Watch for sticking of the brake in cold weather.
Pete

 

[DownRange762]

Out parking brake shoe return spring install?

I've adjusted the parking brake but need to replace the outer parking brake shoe return spring as pictured in the center. It's the rusty one in the middle that had a broken end you can't see in the picture.

I have the new replacement but was wondering if there was any trick someone else has used successful to get a new spring in position. Because of other components and very limited accesss, this is turning out to be a bear to re-install. Surely someone else out there has fought this and found a workable way to do it?

 

[Hoefler]

Agree-its in a bad spot. I have adjusted the nut on mine. After much contorting, I found a deep socket with several extensions on it and a ratchet allowed me to adjust the tension. My box has a removable panel on the front of the box-look to see if yours does. Take it off and see if you can get your hand through and to spring area. There must be a reason for this access panel-maybe its for the spring.
Pete

 

[DownRange762]

Hmm...never noticed a panel but without three or more elbows/wrists on my arm I can't get enough grip on the spring with pliers to pull it into position. I've never noticed the panel you mentioned, but I'll be looking for it now. Thanks for the tip.

 

[3dAngus]

Also, put a double nut on item #3, post number 3, second drawing.

It will keep your adjustment from vibrating off to a new setting.

I could turn mine with fingers. No wrench required. Backing a second nut to it kept it from coming undone. After every trip, I had no E brake at all.