What would be the best method that I should take, to convert armstrong steering in my 68 Merc dually one ton, to power steering. Already have a Ford P/S pump from "73" F250. One tons are hard to steer with one arm.

 

My 70 has power stearing and is fine to drive. I would just do a complete convertion. Pump, gearbox and the correct linkages.

 

Find a donor truck and take everything you need. You need the column also. I did this about 20 years ago and it's great. You will probably need seal kits for the steering box. I needed upper and lower kits.

 

Donor truck: There were two totally different types of P/S systems used in these trucks.

1967/68 F100/250 2WD & 1969 F100/250 2WD before serial number D96,001 used BENDIX P/S.

1969 F100/250 2WD's & F350's from serial number D96,001. 1970 and later F100/350 2WD used FORD P/S.

P/S was not available on any F350's prior to this 1969 serial number break.

The column's steering shaft is a different length with manual steering, a different length with Bendix P/S, a different length with Ford P/S.

Whatever 1969/79 Ford P/S is used, will require the column to be modified.

Ford P/S gearbox: There are two seal kits, one for the input (D7AZ3E502B) shaft, one for the sector (F3AZ3E501A) shaft.

These two Ford P/S kits were used in myriad 1965/2002 Passenger Cars and 1969/91 F100/350's (and etc). Are available from Ford and a gazillion autoparts stores for around 35 bucks for the pair.

But, all the Ford P/S gearboxes have a FLAW which causes them to begin leaking within a short time. Since only the seal kits are available, what autoparts sell are not "rebuilt" gearboxes, they are resealed gearboxes.

redheadsteeringgears.com (located in Seattle) machines the case to install the sector bearings that Ford omitted...on purpose.. Go to their website and read all about it.

 

does this problem exist with the 78-79 f250 4x4 power steering gear boxes? i'll be doing the power steering swap in my 71 4x4 and been wondering if it would be a good idea to send it to get rebuilt while it's out of the truck.

 

It exists with all types of Ford P/S gearboxes, none of which have the needle bearings, cuz Ford left them out...on purpose so they could sell replacement parts...once the warranty ran out.

Sooner or later...usually sooner, the little darlin's begin to leak. Replacing the seals...doesn't help much, the seals might last a year or two, before they start leaking again.

 

Redhead will machine the box for a 78-79 to accept the bearings? If you send them your box to be rebuilt how long do they last compared to the standard replacement seal kit only before they start leaking?

 

A long long time because the new bearings eliminate the load against the seal.
Withought the bearings the sector shaft pushes and pulls againt the housing as you steer. You can see it happen if you have someone turn the wheel wile you watch the pitman arm. Keep the tires on the ground though so there will be resistance. That action over many many cycles destroys the seals as well as wears things inside the box. The aditional bearing suport the shaft and eliminate the side to side movement.