Brake Proportion Valve, and slow reation from the brakes.

I’m glad this came up. I just bought a 98 FLD120 and it does same thing. I haven’t picked up my trailer yet so I wasn’t sure how it would be then. Bobtailed from LA to PA and back and forth to a few shops. Have to get hard on the brakes and the rear axle starts to lock up.

 

Connect both your red and blue glad hands together and release both red and yellow brake valves when bobtailing as a bandaid until you decide what to do about it.

 

I have a Fleetpride 20 miles away and 29 miles the other way so I may just do this. It’s most likely the original valve so I wouldn’t mind putting a fresh one in.

 

http://www.truckt.com Bobtail Proportioning Valves

 

So take that small line off (control port) and cap it and move the larger one that's next to into the smaller (control) port where the smaller line was?

 

That looks like the rear service valve

 

The picture i posted was just a generic valve.

 

That's the only valve I have other then the small on the front axle that I know of.

 

The one you want will have two "hot" lines in. One constant and one supplied by releasing the trailer brakes. You want to "fool" the valve that the trailer brakes are released all the time. The other line is the "control" line from the pedal.

 

Can't tell from the picture if there are 2 hot lines.