Hino 500 intermittent braking one wheel

[Chris8]

Long story shorter, a truck from our own fleet has had multiple reports stating 'truck intermittently pulls hard left (or right) under braking'. I experienced the truck pull to the left under low - medium braking coming into a roundabout, turning left. It had no pedal feel and minimum brake force until I pushed to a medium brake, where it than mainly applied brake force to the left front wheel and near pulled me into the next lane.

Another statement form my co-worker saying that he experienced the right front wheel lock up coming into a roundabout turning right.

Just to state the vehicle has new front linings and cylinders fitted with machined drums. Rear brakes are good at about half life.

Could this possibly be the result of a by-passing master cylinder ? As this truck has two master cylinders, I'm guessing one is main and the other some sort of secondary purpose or backup ?

 

[greasytshirt]

That model isn't sold in the states, so I'm not familiar with it. It sounds like it has the air over hydraulic system on our cabover trucks prior to 2005. Each master cylinder is given a pair of brakes to activate.

I'd maybe have a good look at things like the leaf spring bushings. The front axle can shift under certain circumstances so that could potentially upset braking performance.

I don't know which brakes are tied to each master. You'd need to follow them back to see what they connect to.