King pin adjustment

[Freightrain]

Replaced them13 yrs ago to start with. Truck always steers nice, but gets a random bounce/wobble at about 55 mph. Not slower, not faster. I did notice this past weekend the right front tire was getting some strange cupping on the outside edge. Never had that before.

I got to poking around Sunday morning. Jacked it up and got a board under the tire and low-behold the thrust was loose on the king pin. Near 1/8" or so. I got my book out and it called for .005. Yowza. I couldn't get the cotterpin out easily so had to pull wheel, hub and backing plate. Pulled the pin and used a piece of 1/8" steel as a lever to adjust the cup and set it for the .005 it calls for. The hard part was being on the far end of my wedge board and be at the pin to look/measure. Monkey and a football comes to mind LOL! I got the RH side done and went to the LH side. It was much tighter, but still adjusted it.

Once I got it all back together and wheels running true I took it for a quick spin. Got it up to 55 mph and WOW...so much smoother. No wobble to the steering wheel or bouncing action to the front end. I think my trip to PIttsburgh will be much nicer next week. I'm not too concerned with the condition of the tire as they are going to get replaced for next year anyway. They are 14 yrs old and I just noticed a slight weather checking starting on the sidewall. Not horrible-barely visible, but don't want the possibility of problems. The thought of spending $800 just doesn't thrill me, but what are ya gunno do??

[j hancock]

Good info. Pretty tight specification!

[Glensts]

I've had that issue too with the wobble and I swapped tires from side to side and that seemed to help it out. May not be right thing to do but it worked, It had Dayton 5 spokes

[macattack]

took a look at my king pins today and my pass side needs adjustment. calls for .005 to .027 for upper knuckle clearence mine on the pass side is much more than that. gonna try adjusting it.

the king pins were replaced a little over a year ago.

[Freightrain]

I know you had/have a random "shake" going on with your truck. This could be part of it. With the chassis being stiff enough, the wheel will get to oscillating up/down on that pin and will really rattle the truck and steering wheel. I never would have thought it would cause the problems it did. You would think with all the weight on it that it would just sit on the thrust bearing. Nope. The tire gets some harmonics going on, it would shake that spindle and rattle it from the slop. It transmits it through the whole truck. If you only check it for side/side play that is not enough. The up/down is just as important(as I found out).