Been toying with my nephew's truck... 79 F100 short bed, 6 cyl with manual OD, power steering. It never comes all the way back to center after a turn... usually have to give it a nudge to get that last half-turn of the wheel. This makes it tiresome to drive on the highway. You constantly have to correct... one way, then the other. I bet others around me thing I'm drunk! If I give it a nudge to the right and let go, it continues to the right. If I give it a nudge to the left and let go, it continues to the left. It never comes back on it's own. I can't find anything loose or sloppy under there.

I figured a front end alignment would help and took it to Modica Brothers... a reputable local business chain in our area. They showed me that it was certainly in need of adjustments. After I left, it seemed to drive a little better... but that was all. Nothing significant. Not enough to correct this issue.

My 77 F150 drives nice and straight. Let go of the wheel and it always tracks on center. But not this 79 F100. It continues to go in the direction where I last let go of the wheel.

Suggestions??

 

Have you checked to see if the king pins are seized,?, could be a lack of grease. Could be the box itself also.

 

most likely what JessyJ said above, but did they happen to give you a print out of the alignment values? The caster angle is what makes the wheel return to center, just curious what the caster angle was?

 

Ditto on seized king pin (s) . Do you know if they checked them out. In doing the caster check, we would turn the wheels by hand. If they had a hard time doing so it might indicate king pin problems. They also should have checked for play. Caster and camber are set by bending the axles.

 

Below is the Before/After on the alignment.

I personally greased everything up front before going up there. I know that doesn't mean something might not be in a bind, but I do know for sure there's grease in them there pins.

I had also asked them to check the wheel bearings and brakes... which they did and said that was all good... didn't need anything there. The only thing extra they did was rebalance all the wheels and rotated them. Said being out of alignment was already showing on those new tires so they moved those to the back.

Perhaps I will raise the front of the truck and see how easy it is to turn those wheels by hand. Then, I can do the same with my 77 F150 for comparison. I would think the steering components between the two trucks should be the same.

 

P/S pump is different 1977 vs 1978/79.

 

Okay... thanks, Bill.

 

I know on my F250 there is an adjustment on the power steering gear box that if adjusted wrong will cause the problem you describe. I don't know if the F100 has the same type of adjustment??

 

Yes, it is there. I considered that the previous owner might have tightened it up, so I backed it off 1/4 turn. I noticed no difference. I kinda don't like messing with that adjustment. I wouldn't want to find out the hard way that I over-adjusted it.

 

Tightening in my case made the problem worse. Another thing to check, that I think your alignment shop should have looked at is where the pitman arm attaches to the steering box. I had enough play between the pitman arm and the shaft from the steering box it required about a quarter turn of the steering wheel before there was any movement of the pitman arm.

 

That adjustment on the steering box has to be made with the wheels straight ahead.

 

Do not mess with that nut, it only sets the preload of the sector shaft. Over tighten it, the box could lock up. Backing the nut off after this occurs may not solve the problem.

 

Yeah... I do not like steering boxes when they lock up.... kinda really screws up your weekend!

The steering in this F100 really has very little slack... if any at all (my 92 Chevy has horrible slack compared to these Fords). My 77 F150 feels slightly different... but I think it's due to the 77 and earlier models having a larger diameter steering wheel compared to the 78/79 models.

Yesterday I spoke to a long-time Ford service tech from Gabriel/Jorden Ford in Livingston, TX. His opinion was replacing the steering box. So far, I haven't yet lifted the front to try turning the wheels. I've been dealing with my late-70s Ford 1600 tractor (a Japanese built diesel compact tractor). Shooting for getting this done by the weekend. Also, in the meantime, my 77 is in the shop getting a new clutch... YAY!!

 

An update... as Jim mentioned, it was indeed that adjustment on the top of the power steering box. It seems the previous owner cranked down on this nut... it was way too tight! Imagine the loading on the shaft being so much that it would not allow the steering to center on it's own. I am almost surprised nothing got broken since then.

Back when I started this thread, i had backed that adjustment off just a little and it didn't change anything. A couple of weeks ago, I went out there and started backing that adjustment off in quarter-turns, and then drove it. After finally backing the adjustment nearly TWO full turns, the steering in the truck felt normal! The wheel would come back to center on it's own and became a LOT easier to steer down the highway! Previously, it was somewhat tiresome to drive down the highway for any significant amount of time. So much better now!

As many people have mentioned, this adjustment is not for reducing slack. Yes, there's a wee bit of slack in the steering now, but nothing terrible... no more than I would expect for a truck from the 70's. Trucks from back then are not going to have the tight steering that a new modern truck will have today. The number of wheel turns from stop to stop are nearly double of a modern vehicle.

I am glad it's fixed now, as I have given the truck to my son-in-law and I wanted to make sure this was corrected before he took it.

 

CharlieXLT,
Good to hear you solved the issue and equally for bringing closure to this thread; what you had to do in order to resolve the original problem. That is helpful for most of us. Thank you