UPDATE: Ball joint preload question...not the same old question

[jamesroney]

Not a rant, a frustrated observation of manufacturers compromises, that we end up having to deal with.

After sleeping on this issue, and contemplating the death wobble I experienced after cut n' turn of inner Cs, with new ball joint installation, this is how I am going to re-adjust ball joints . . . maybe.

1) Install ball joints in knuckle, verify they are seated with .0015 shim.
Axle housing is supported on jack stands.

2) Install knuckle in axle, torque lower ball joint to 70 ft-lbs.
At this point weight of knuckle is hanging on non load supporting crimp of lower ball joint.

3) Using bottle jack, lift knuckle until lower ball is fully seated in socket.
4) Install tapered sleeve in upper joint and tighten till upper ball is fully seated in upper socket.
Instuctions mention 30 to 70 ft-lbs.
Is this to much, or to little?
We want enough pre load so that when tapered stud pulls into tapered sleeve, during final torque of top nut, we don't create a gap in upper joint.
5) Torque top nut.

This should split the load between upper & lower joints, and not have one doing all the work.

When complete we want no play in ball joints, and not so tight that we are binding upper ball against it's crimp.

If there is play, ball joint crimp may be suspect.

The manufacturer wants to verify no binding from excessivepre-load with a "fish scale".
Fishing is to inactive for me, so I don't own a fish scale.

I'm going to say "yes" to your technique. Fish scale is over-rated. you have a pretty good idea of what a fish weighs.
30 lb-ft vs 70 lb-ft is not relevant once the slack is taken up. I'll bet you don't even get 1/4 turn difference. It's a huge difference if you are trying to create a clamp force...like for a cylinder head bolt. But for setting a zero-lash condition...30, 50, 70...it's all the same.

I'm going to say that there's a lot of overthinking here. I've seen worn out used ball joints with tons of slop, wiggle, and play. Those trucks didn't wobble, shimmy, or misbehave. I've seen trucks with perfect, brand new ball joints that will shake out your liver. So there's that.

In a perfect world, both joints would support both loads so that the ball is in constant contact with the lower socket.

When is that Bronco going to drive???

 

[DirtDonk]

And I’m going to get back on my soapbox and say that your parts installation probably didn’t have much, if anything to do with it that wobble.
Sure, a wobble can be exaggerated by loose parts, but it usually doesn’t start there.

So that wobble, if a true Death Wobble, is coming from a tire, or tires.
Was it a real earth shaking, seat upholstery pinching, underwear soiling event?
You described the speed at which it took place, which is consistent with many DW’s, but what other details can you share?

 

[DirtDonk]

I take back part of that. If your knuckles are loose and floppy, then even a tire that’s just starting to go down the wobble road can go over the edge.
But the actual dynamics of a wobble start with a tire.

 

[Yeller]

I take back part of that. If your knuckles are loose and floppy, then even a tire that’s just starting to go down the wobble road can go over the edge.
But the actual dynamics of a wobble start with a tire.

X100. Bad tire will make wabble regardless of the parts supporting it.

10 degrees of caster all new everything including hydro assist….. death wabble bad….. rotated the tires, all good, but had a vibration in the rear.

 

[67sport]

Isn't there a saying about surrounding yourself with people smarter than you?
Great read. Excellent info in this thread.

 

[Lando375]

Okay here's an update. I was using all the wisdom the internet had to provide. I know the Dana 44 was used by several vehicle manufacturers so I began looking their ball joint procedures. They were all the same except the adjuster inital torque. I used new Moog ball joints and the instructions said 70lbs for the adjuster. I started over because of piece of mind and I was chasing that number.

I torqued the adjuster to 70 lbs and the castle nut to 100lbs. The pull force was about 37 lbs. I did it a few more times with lower and lower torque; checking the adjuster for damage each time. At about 55 lbs of torque and the castle nut at 100 lbs, I was at 23-24 lbs of pull force. Just for reference before the castle was torqued the pull force was in about 36-38.

I followed the same YT videos mentioned and was able to replicate the results but the final torque changed after I tightened it all up. I was unable to find a mention of when to check the pull force but every picture of the knuckle was complete with hub and rotor. I can only assume the pull test is when it's completely reassembled.

Both sides are perfect now. I'm wondering how many people check the final pull force.

Thanks for all the replies and help with this.

 

[ba123]

thanks for the update.

I did pull force before and after final top nut…I think you have to at the very least do after.

Totally agree with James and whoever that it’s prob overthought, but still do it. My feeling is that it needs to be somewhat tight and then it loosens with break in, but that’s just my guess.