got a 76 f 100 4x that has a bent drag link . I've done some research on this board and understand I can UPGRADE TO 78/79 stuff --just bolt on . However I am not clear on whether I need to include the pitman arm in the swap or not . Also What are some sources for a np435 2wd to dana 20 adapter? Novak and Advance Adpt seem to have only for 4wd tranny. Thanks

 

No need to swap pitman arms... same same.

Dunno about the trans adapter... I 'm swapping to an NP205 and 4wd 435.

 

F100/150 4WD Pitman Arm is different 1976/77 vs 1978/79 F150 4WD. Drag link is different 1976/77 F100/150 4WD vs. 1978/79 F150 4WD. With/without P/S makes a difference.

There were no F100 4WD's after 1976, so you'll be using 1978/79 F150 4WD parts, except: 1978/79 F150 4WD Super Cabs use different parts as they have leaf spring front suspension.

 

Besides the cast engineering number and catalog part number, what is the physical difference in 76/77 and 78/79 PS pitman arms?

 

Dunno, haven't seen these parts in decades, so I can only go by the parts catalog. Note that with/without P/S also makes a difference.

3590 = Pitman Arm / 1973/75 F100 4WD & 1975 F150 4WD have Garrison Power Assist P/S / 1976/79's have Ford/Saginaw integral P/S.

 

mine has power steering but not that silly ram thing ford had in some of these older rigs. Just that long necked box bolted to the outside of the frame. Guess it would be the Ford/Saginaw. I too would be interested in the significant differences between years. Big thing in my mind is the size and direction of the taper in the end of the pitman arm. And perhaps length. And of course spline count and orientation.

 

'76/'77 pittman arm has a splined hole in one end where it goes on steering box and the other end is a ball jointed stud made to it where the drag link attaches. When that ball joint wears, you replace the whole pittman arm.

'78/'79 pittman arm has the same splined hole on end that goes to steering box .... but the other end is just a hole where the stud of the upper ball jointed end of the '78/'79 drag link's ball jointed end attaches. The '78/'79 drag link has two ball jointed ends. As long as the nuts are tight, a '78/'79 style pittman arm will never wear out as it has no moving parts itself. When slack developes in either ball joint end of '78/79 drag link, you simply replace the link itself.


To swap a '76/'77 steering linkage to the better driving '78/'79 style requires '78/'79 pittman arm, '78/'79 drag link, both '78/'79 tie rod ends (long one to RF knuckle, short one to LF knuckle), '78/'79 adjustment sleeve and the two clamps.

The '78/'79 style tie rod ends will last longer as they only "move" when the truck is steered left or right. The tie rod, once adjusted, does not change length and toe does not change with bumps because the axle itself is of fixed length .....
..... but the older '76/'77 style "inverted Y" style where the drag link goes from pittman arm to RF knuckle at an angle, then part way down the LF tie rod end attaches and goes to LF knuckle and both swing through different arcs while the axle is fixed in length, results in constant toe changes and a wandering truck. Every bump and steering input moves the tie rod ends as well.

Below is my '77 on a lift (not loaded, axle is hanging), it has '78/'79 steering since 1986, I've replaced the drag link once in 70 plus thousand miles since .... tie rod ends are still tight. She also has poly bushings with a few extra degrees in the C-bushings and a Red Head Steering Box. When I bought the truck with oem steering, it was all over the road it seemed, the "upgrade" was a huge improvement and it only had 35,000 miles on it.



Below is a picture I found of the linkage as originaly installed on a '76/'77 F150 (not mine, this one is on the ground). You can see that when the suspension is compressed the wheels would point apart. Likewise when one when suddenly encountered a bump and is pushed up that wheel would turn outward and you, the driver would have to steer back to offset it temporarily. Call it "bump steer".

 

Whoa... that's strange. I stand corrected. Thanks for the info.... Found a pic:

 

that's exactly the kind of info I'm looking for !! Thanks tbear !

 

Subscribed for future awesome information. And to move some of this to the compilation thread.

 

maybe make a note in the compilation that 77.5 F250 4x4 is same as 78/79? The 76/77 and 78/79 references may be confusing to new readers

 

D7TZ-3590-C .. Pitman Arm / Marked: D7TA-3590-GA / Obsolete

1977 F250 4WD from serial number Y20,001 (not a High Boy) & 1978/79 F250 4WD / 1978/79 F150 4WD Super Cab / 1979 F350 4WD

 

I should have put up pics ....

You are very welcomed!

 

Great info, thanks, we're about to do this upgrade, as well!