Steering box, drag link end failure modes?

[mrldcty]

I have read a couple of things that indicate there are one or two catastrophic steering failure modes related to the steering box and to the drag link (pitman arm) end. I'm chasing a little shock vibration coming through my steering wheel... can someone tell me what these failure modes are and if they have any pre-failure behaviors that might match what I'm feeling through the wheel?

 

[charliemeyer007]

I'd start with the tires - rotate front to back see if any thing changes.
While the front wheels are jacked up, check for loose wheel bearing top/bottom play and the ball joints side to side. Then pull/push all the rod ends looking for play. Have someone move the steering wheel lock to lock the center arm should pivot not move up and down.
Are your tires balanced and show even wear plus are the rims straight. What about your hubs are they releasing.

Know any local car people that can help you - it really is a hands on thing. Watch a lot of youtube on front end work.

 

[mrldcty]

I'd start with the tires - rotate front to back see if any thing changes.
While the front wheels are jacked up, check for loose wheel bearing top/bottom play and the ball joints side to side. Then pull/push all the rod ends looking for play. Have someone move the steering wheel lock to lock the center arm should pivot not move up and down.
Are your tires balanced and show even wear plus are the rims straight. What about your hubs are they releasing.

Know any local car people that can help you - it really is a hands on thing. Watch a lot of youtube on front end work.

Yep, done all of that. Completely rebuilt the entire front end from diffs to knuckles to brakes to springs. I have shims in the front and back to correct my pinion angles after and EMU lift as well. What I'm feeling is not that type of vibration and the steering is not sloppy. It feels like something is just a little loose and clunky. Not terrible, but it's a new thing and it's bugging me. I double checked my U-Bolt torques last night, thinking maybe the shims had compressed (steel) and all is well there (flip kit). I check my the steering knuckles a few times a season, so all good there. When I first got the truck, I tried to tighten the "adjustment" screw on the steering box, but not sure I actually ended up adjusting it much. Also, I recently adjusted the drag link end, which took a couple of whole turns to tighten up. Backed it off a half turn per the FSM. There is a tiny bit of play in the rag joint... so that is my next target. I tried snugging the bolts on it but nothing turns. Will soak in PB Blaster and try to snug that up today.

Mostly I just wanted to know if this is a warning sign of something going out in steering box or drag link end because I have seen people imply there are some bad failure modes that can happen in those. The truck only has 50K original miles... but it's 44 years old, so maybe the rag joint can shrink over time and get some play in it? Living under the hood is a harsh environment to be in for 44 years!

 

[45Dougal]

Everything pumped up with grease?

 

[charliemeyer007]

50K is like virgin. FJ40's aren't the softest, smoothest on the pavement rides - they do however work well off road where you will never notice some minor clunk or vibration.
If it ain't broke don't fix it can be an expensive lesson to learn at times.

 

[Mr. Green]

A rag joint sounds like cheap insurance I’d do that if original. Play vs vibration are very different. Anything speed dependent? Driveshaft?

 

[mrldcty]

Thanks for the input so far! The clunkyness I'm feeling is not rotational in nature IMO and is not speed dependent. If my steering damper wasn't brand new, I would suspect that... so that might be a clue that the issue is between the steering wheel and the damper. I also went through a very complete process to remove drive train vibration after my lift which included drive shaft balancing and new drive shaft bushings along with complete diff rebuild (to add lockers). Everything is well greased.

I was able to snug up my rag joint today, as well as the steering box input shaft collar, but I still feel the clunk.

My next theory is that my steering box input shaft preload is loose, which may mean my bearings are going out? Not sure how this could happen with just 50K miles, but who knows. I made this video to show the play I'm talking about:

It doesn't bother me off road, I mostly notice it on the tarmac.