MarcusAOB

My 94 F 150 truck has a 5.0 and AODE/W setup.


When I turn the steering wheel hard over in either direction, I feel the brake pedal drop noticeably to the floor, when i'm in a straight line it pulls up fine.


It got me when I was turning round in my yard, and again in a parking lot. otherwise the brakes work as they are supposed to, no sign of fluid leakage no sign of a problem with the booster, if I disconnect it from the intake, then the pedal gets much harder, not softer.


Any ideas what might cause it ?

kd3pc

Might be that one (or both) flex lines from the chassis to the caliper is "stretching" or pulling enough to affect your brakes...you might have a helper watch as you turn lock to lock and see what happens to those lines.

MarcusAOB

I checked these flexible lines that run to the front wheels and they are in good condition, no kinks or loose connections. and the brake fluid is full, its not low, and the level does not drop when the wheel is turned.

techrep

iTrader: (1)

Lifted ?

seschenburg

Does the engine RPM drop some when you do this? It could be that your maximum swing is stressing the power steering pump creating greater drag on the engine causing it to decelerate.

Sudden engine deceleration causes an increase in vacuum which could explain the extra assist you are getting with your brakes.

MarcusAOB

Hi there's no drop in RPMs, the engine is pretty strong and runs very smoothly and steady - truck is not lifted is totally stock save for a better exhaust system.

seschenburg

k. Well, that was my only idea about this one. I'm out...

MarcusAOB

Its a weird one, its got all the mechanics at my local shop scratching their heads too,

MarcusAOB

So we just tore through everything, flushed and bled the whole system, changed all the springs and rear shoes as we went through them and they were worn down to the rivets, and checked the PS pump. Seems OK now.

techrep

iTrader: (1)

One of those ... replaced everything and it fixed it..