fld120 steering problem ! pls someone help me !

Perth amboy spring

 

Yes, it can and will also be overworking your steering assist and gearbox causing heat.

 

your problem is caster but I'm sure is way too much caster, when you have negative caster the steering wheel gets lighter, but when you have way too much is totally the opposite, the perfect caster should be 6 degree.

you have a car carrier which means that a lot has been done to get that truck lower, which leads me to believe that a lot of so called technician have been working on it, and by this I mean that a lot of people can turn wrenches but may of them have no clue of what they're fixing they know how to replace parts, no wonder you have totally done everything on your steering system.
go get some one that knows what they're doing and come back here and tell us what was it.

ask questions if they are going to replace something, ask why? then think about it if it doesn't make sense to you walk away, until you find some one that is not afraid to tell you what's wrong with your truck and what he's going to do to correct it and ask for warranty, I know it's getting harder and harder to find real technicians, any body can get a certificate but many have no clue.

good luck and let us know, when you find a good shop get the technicians name and spread the word, but do the same when some one made you throw expensive parts to the truck and no fix to the problem,

I'm sick and tired of ripoff shops.

 

Did you replace the hoses? The inner liner on the suction hose could be collapsing internally, starving the pump for oil. I would say you've definitely limited your problem to the box, pump, steering column.

 

With the pitman arm removed and no load on the gearbox output shaft, there wouldn't be much if any difference as it isn't required to do anything.

Gearboxes have been set up tight causing steering wheel to stay at last position steered, not retuning to center and the need to continuously correct the wheel while driving a straight road. Each correction of the wheel causes oversteer the other direction and you are herding the truck down the road, same as lack of caster, constantly correcting to stay on top of it, exhausting!

 

I had the return line replaced on my fld several years ago. Then
I could not steer it or turn. Was worse than armstrong steering.
Found out they put the wrong style return hose on it..

 

Gearbox set too tight and or lack of caster.
Correct caster eases steering effort and makes the truck track well.
I've had to make adjustments to steering gearboxes on new trucks due to them being too snug. They didn't steer correctly until I did. Many were aligned multiple times before I got them. When I would find that the gear was tight they would call me a liar, until the drivers jumped for joy that it was finally fixed. There is some great input here, use it all.