Carlton, you may consider doing a sticky on this one.

I know of two Gen 1 LCAs that have failed catastrophically in the past few weeks. Cracks developed around where the lower ball joints are pressed in, and the arms failed, sending the wheel up into the fender well and separating the steering knuckle away from the lower control arm.

Both failures were on '98 Frontiers, which, as you know, share parts with the Xterra. On another 2002 Xterra I know of, the owner caught the developing cracks before they failed and replaced the LCAs.

If this happens at any sort of speed, you're going to crash.

Check your LCA's often guys...at least with every oil change. You don't want this to happen on the road, as the damage could be severe, and someone might get hurt.

Andy,
NOAS had three members with this "issue" last year, myself being one of them. The cracks will develop into full-blown tears in a hurry.

So I second the "check them regularly". They may be expensive to replace, but better than dying.

Here's a shock mount failure.. I think it was Axel who had the ball joint issues..

Could the torsion bar cranks be helping to cause this?

T bars have nothing to do w/ that at all..

Alittle dissconcerting to say the least. Most of the other issues just an inconvenience i.e. exhaust man.. This a real safety issue.

Dan, I think he thought there might be extra stress added to the BJ' via the PML.

You are correct. The ball joint issue is already touchy w/ me..

Assuming this is an issue with an owner who frequently off roads is one thing, but I wonder If an X that sees nothing but hardball would/has the same prob.? Because if indeed an X that, God for bid does not go offroad has this issue, SCARY!!!

I just replaced one that had a big tear in it. I think once they start going, they get going quickly as I didn't remember seeing that thing cracking over time.

It's not a cheap thing to replace and it's kind of a PITA, but in this case it's definitely not worth it to be penny-wise and pound-foolish.

Hell yeah worthy mentioning again or made a sticky; really been a long-standing problem on the 1st Gen X’s that are wheeled regularly going back 5 yrs or so when they first started showing up.

Ian (OG XOC) was one of the first ones that posted about the shock mount problem in 02; he had his welded/reinforced I recall. Both my LCA's had already cracked by then and getting worse (see inline from 02' drivers side when they 1st showed up) so I had my local muffler shop weld my shock mount and around the LCA ball joint also but it didn’t last very long ~ 3 months before the drivers side failed and the scenario described pretty much happen to me and it was very difficult to steer; I blew a tire and crashed. In hindsight would have been much better getting a new replacement.

DR…didn’t T weld Muds LCA up at the start of Paytee Draw on the last AZ run? I know at least half a dozen in our club that had the cracks over the years.

Brian

Thanks for the warning..

The ball joints are subjected to less force, rather than more force, when you do a PML.

Remember, the weight being supported is not changing...the height change is simply from where the T-Bar starts from...and has no impact on the down force on the ground at the tire contact patch.

Remember, the ground stays still, and the truck goes up...and the reason the truck goes up, is because its merely starting its exact same weight support at a new position.

The longer the effective leverage, the more force is applied, but the less force is required to apply it....

So, a stock tire sits further out than a pml's tire, as the IFS has swung the tire down and inwards.

If you've ever done a push up, or had to build a support for something....you'd notice that maximum support is provided parallel to the line of force...like a post holds up something if its straight up and down...but a post at a 45 degree angle would require a lot more bracing to hold the same weight up, etc.

The PML tire is closer to the center of the truck...and therefore less perpendicular, and subjected to slightly less leverage.

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The suspension starts with the t-bar adjuster...a pole stuck at a particular position at one end....inserted into the LCA outboard of ITS pivot point, twisting the LCA down.

The T-Bar leverage is twisting the LCA down...which applies a downward force to the tire.

ALL of the downward force is from the tension of the torsion of the t-bar.

As tension is added to the t-bar...it twists slightly...and, then, when it reaches the point where the spring rate of the bar matches the resistance, it simply rotates, rather than twists, as the adjuster finger is drawn up into the cross member.

A stiffer bar will commence rotation sooner, for the same weight, than a softer bar.

As the weight remains constant...the bar does not twist more, it merely continues to rotate...and, it continues to remain in the same state of tension for that weight....the weight may rise, but the bar is as twisted as it was going to get.



So - interestingly, as the tires get closer together...the amount of force required to lift the weight decreases...as the leverage advantage builds as the tires move closer to the leverage points...which means that the T-bar may actually UNTWIST slightly as the tire gets closer inboard.

This is why, all else being equal, a wider tracked rig needs a stiffer t-bar, even if the rig's weight stays the same....the further out the tire is, the longer the lever the t-bar is trying to force down.

So - What it all means, is that a suspension lift, including a PML....does not place more stress on the t-bars, or the LCA's....and in fact, it can marginally REDUCE the stress.

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For those of you who believe that if all the passengers picked up their feet, the plane could take off easier....just skip the entire topic and go to the Phat Chic thread or something, there's pictures.

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Most of the failures on suspensions that crash into rocks, etc....are from crashing into rocks, etc.

People with tears in their underhood sheet metal, typically get that from the body flexing repeatedly...after metal gets bent back and forth a few times, it can tear, etc.

If the suspension does all the flexing, the body can remain perfectly serene and level. We have IFS though, so the body up front tends to twist quite a bit....hence the gaps we leave in the aftermarket bumpers so they don't hit the fenders under flex, etc.

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And so forth...

So, modifying the suspension doesn't really stress the parts in question, but NOT modifying the suspension MIGHT.

TJ, sometimes you remind me of this one professor that I had....

Obviously, this is an offhand observation...but, it LOOKS like the shock mount is bowed, like from over compression...and the crack is where an over compression crack would be expected....

Is it possible that the people with cracks like this had shocks a tad too long for full uptravel?

TJ you always find a way to make me feel better about things which leads me to believe one of two things.. Either A. Your a bullshit artist. or B. You know what your talking about.

I just stayed at a Holiday Inn Express....the rest is history.

I welded small steel plates onto the LCA then added gussets on both sides of the shock mounts and they held up well.

what color did you paint them?

Toolbox, the shock mount cracks and the balljoint issues are two separate things. Losing a shock mount won't get anyone killed. Having the LCA bust out completely where the balljoint is pressed in might!

I think Mud broke his upper mount, actually.

He has a new set of LCAs installed on his truck right now because his was cracking out around the balljoints.

On the two trucks this happened to a few weeks back, one is lifted (JW's truck for those of you who know him), and a non lifted truck. Both are in the 100k mile range and both have been used fairly hard - well, JW's has been flat out abused, but still...)

Definitely worth keeping an eye on though. Would hate to see anyone get hurt over something that a visual inspection here and there can prevent.

Yeah I hear you in my case I had both crack; the shock mount first and around the ball joint later on the drivers side when my truck had only 55k and was less than 3 yrs old.

Axle's LCA around the ball joint cracked and 3 or four other did also way back in 02-03. The shock mounts on some of the those trucks where ok and others not. Its not pretty when the shock moount comes off on the dirt at any speed.

Mud broke off his lower shock mount according to T and its intresting that he cracked around the BJ's just like mine did afterwords.

You guys don't see the potential connection for a stress fracture in the vicinity of the shock mount then changing the ball joint angle/strees on the location, or the appearance of a stress fracture any where on the LCA indicating forces exceeding the part's tolerances, when the LCA is flexed?

Considering that one of the ones that broke recently was an unlifted truck, no, I don't see the connection.

I don't remember saying a lift had anything to do with it either...?

Stress fractures of the metal....weak metal, metal that's been failing on a small number of X's...a potential safety issue....

It looks like we might have some parts with weaker metal...just like some t-bars sagged like hell, and some leaf springs, etc.

:rolleyes:

>> DR…didn’t T weld Muds LCA up at the start of Paytee Draw on the last AZ run?

Yes he did. Then the shock mounts broke driving out of camp and John welded them up again after the run. Then they started to tear again. I replaced the LCAs. Mine were mostly ok out at the balljoints but tore up at the shock mounts and were tearing through top and bottom.

I wouldn't expect a mall crawler (other than Cody) to ever have a problem with them but it is worth eyeballing the LCAs occasionally.