My 1986 diesel never quite drove properly and after a less than successful attempt at replacing one of the king pins the poor steering feel has slowly gotten worse. It never returned all the way to center when coming out of a turn and now it is very tiring on longer drives.

I'm so fed up with this situation that I am thinking of swapping I beams and spindles out of an 87 or up truck to get the ball joints instead. My F150 has ball joints and has always had a nice gentle but accurate steering feel. I did see a rather expensive kit that uses needle bearings instead of bushings (no machining required), but those were for hot rods and they probably would not fit my truck. I'm not too worried about cost at this point, I just want the thing to drive a little easier instead of having to constantly heard the truck down the road. Engine torque and wind were a real challenge on the last trip. The truck is used almost exclusively on pavement.

What do you guys think, should I still try and get another king pin kit and make it work as per OEM or should I go with something else? Am I alone in having this problem?

 

You didn't say if it was 2wd or 4wd and what do you mean by unsucessful kingpin replacement? Did you change them or not?

In any case, check your caster. You should shoot for about 5-8 degrees for good return to center.

 

I replaced it myself. Its a 2wd. How can the caster be adjusted?

 

Worn axle pivot bushings and radius arm bushings can cause poor steering characteristics. Ride height and toe-in need to be within specs, too. If the steering is loose check the usual suspects- flexible steering (rag joint) coupler, tie rod ends, etc. for play. Caster is not adjustable on kingpin equipped trucks but can be affected by the above problems. My '83 F350 with heavy duty forged kingpin axles steers very well except for a slight bit of play in the steering box.

 

King pins will hold more weight than balljoints. All of the 18 wheelers use them, with no problems.

You really can't do the whole job by yourself. You can take it apart, get the old bushings out, and install the new ones, but unless you have the special reamer to ream the new bushings, you can't complete the job. The bushings are undersized, and after they are pressed in, the reamer cuts them for perfect alignment and fit with the new pin. I have done everything to the point of reaming the bushings, and at that point I take the spindles down to the local machine shop to have them reamed.

I have heard also of certain situations where the axle on big trucks needs to be bent to get it in alignment. The big shops are set up for this, with chains and a large bottle jack on their alignment lift. I am not sure though, if they can bend a twin I beam axle or not.

 

I found a shop up in Gloucester County Virginia a number of years ago who had the equipment to bend the beams. He did my 77 F150 and my 86 F350. Properly set up and lubricated, king pins will out last the ball joints by a large margin. Unfortunately, I just scrapped the remainder of the 90 F250 parts donor truck, it had the axle halves you need for ball joints.

 

I just want to make sure that its even possible to get the kingpins to have a nice light driving feel instead feeling like I'm trying to drive a container ship down the highway. If it is possible than I'll try again this time having the bushings sized by a machine shop. Another kingpin kit is not that much cost since this truck is the main company vehicle and needs to be perfect.

 

My alignment man (family business for ~65 yrs) said these trucks with kingpins never need to have the axles bent for alignment unless they have been wrecked or otherwise have had the suspension altered.

 

Well, mystery solved.

I pulled everything apart and found lots of rust on the king pin in addition to excessive play (about 1/8" at the tire).

I called the machine shop and hopefully I can get it done (properly this time!!!!!!!!!!!!!) on monday. I ended up putting it all back together filled with gear oil for now so I can still use the truck just in case I need it (or the shop). There was already an improvement in steering though it still doesn't return to center, at least its drivable again.

Goes to show it doesn't pay to cut corners........