How to adjust brake bias

Take that trailer to the shop and have a certified technician adjust them.

A work around is to stomp your service air 7 times while sitting still and out of gear. But it's with auto adjusters.

If you have a manual trailer brakes, a half inch or 9/16th will do it. Get a ball peen hammer and adjust until ding ding becomes thud on drum, THEN BACK OFF one turn until you get a ding. Set brakes all drums should have the same thud thud. Any that dings reveals a weak brake.

DO NOT go running under there with automatic slack adjusters and start wrenching, they will simply lock it up and you will find that it will not move until a certified mechanic gets ahold of them. Which is why I tell you to go to a shop.

 

Interesting. Get rid of the trailer then. I don't see a solution. Smaller drums maybe?

 

The Freightliners we have where I work are the same way. I know they replaced the foot brake valve to fix it. I dunno if there was other items replaced though. But whatever they did worked

 

Tip: THE SIX PACK!

If you didn’t know already, you can adjust automatic slack adjusters while sitting in the driver’s seat!

All you have to do is charge up the entire system. (Tractor and Trailers) Give 6 – 100% brake applications using the foot valve.

Count to 5 each time before you release you may need to build up the air system in between. This will keep all functioning auto-slacks in adjustment, including the steering axle.

It is a good idea to do 100% brake applications periodically throughout the day, when stopped at lights, waiting for a train or at the customer’s waiting for a door. *Keep in mind an auto slack will only adjust when the brake application is 90 psi or higher, even then only one notch at a time*.

 

7/16 wrench on the slack adjusters with the brakes released, off. Make sure the truck won't roll over you, blocked or trailer brakes on.
Tighten up the adjusters with that 7/16 all the way, then back off 1 whole turn.
The adjusters will sound like it's braking off with a uncomfortable sound, this is normal.

 

Very bad for Rockwell auto slacks.

 

Do you always pull the same trailer?

 

If you own the trailer, could you not change the service brake relay valve to one with a lower cracking pressure? Might be able to gain 2 or 3 more PSI to the trailer brake chambers that way.