My truck is a 1991 F150 with a Bendix C-300N P.S. Gearbox.
It seems to need a Power Steering pressure Relief valve adjustment.

The steering is too sensative, even unintentional pressure on the steering wheel changes the direction of the vehicle. A new steering box did remove the 4- 6 inch dead spot in the steering wheel which has improved the situation beyond belief- speeds exceeding 55 mph have been attained!! Previous improvements: PS Box, pump & lines, ball joints, shocks.


The Service manual states the Power Steering Pressure Relief Valve is adjustable; by the shim pack that loads the valve. To improve the steering will removing shims in the relief valve assembly lower the bypass pressure; require more force/ and in turn desensitize the steering ?

 

I've complained about "hyper sensitive" steering about my 89 and my current 95. Like it was made to be steered by a 3 year old? It takes so little effort it is hard to keep steady sometimes.

I've wondered if lowering the pump pressure would increase the heaviness and make it a bit more stable. Both my trucks have tight suspensions, nothing worn out.

 

Yep I have about 3 FoMoCo -[all pre2k vehicles] with the same sensitivity- but not as bad as the F150. I've been reading/ looking at pictures in the manual and this seems like a cure- it is a simple job. My box is rebuilt/ new and I have learned to bleed the system of air, hope if there are possible ways to mess it up someone will let me know.

FYI- the adjustment would be to allow more of the pump's pressure to bypass the steering box - back to the pump resevoir

 

Freightrain I have found Info about adjusting the Saginaw pump @ :
Modifying your Power Steering Pump - GM Truck Central

Borgeson; Mullens; and maybe some other's make kits to adjust the Saginaw pump pretty cheap and adjustable.
Look at :
https://www.summitracing.com/search/part-type/power-steering-pump-pressure-regulator-kits?ibanner=SREPD1

 

Having owned dodges that infamously suffer from dead steering at slow speeds, a complaint that the steering is too good is a good complaint to have.