Bilstein shock failure. What is wrong?

[Magikal]

79 k5, 4" lift. 52 front, 64 rear. D60/14ff. X-over/high steer.

So a few months ago I had the lower eye hole in my front drivers side bilstein 5125 12" travel shock fail. I chucked it up to wear and tear and replaced it. Then just recently the same thing happened to the other side. After some homework and measuring I came to the conclusion that I needed taller bump stops as I still had the factory ones on. My bad.

What I don't understand is when taking a closer look at the shock it doesn't appear to have broken. Looks more like the end came unscrewed and fell off? See pics.

Was hoping maybe someone can provide some more education and/or insight into this for me??

 

[Tnsejed]

Did it bottom out or hard extend without straps? Shafts are hardened and rod eyes most likely aren't. If it bottomed out you probably rolled all threads on the rod end leaving the hard shaft threads intact successfully pulling the rod end off the shaft?

I could see it while leaving that cir-clip in the body intact without damage when the piston hits full extension. What do the threads look like?

 

[Magikal]

See pic above. Threads look fine. The end doesn't appear to have been sheared off.

 

[frankin5]

Will it screw back on tight? What does the treads in the part that came off look like? Is it tight when screwed by on or is it possible to pull it back off with little effort?

 

[Magikal]

Will it screw back on tight? What does the treads in the part that came off look like? Is it tight when screwed by on or is it possible to pull it back off with little effort?

Both incidents the lower part is gone, lost in the woods somewhere. Both times the shock was attached with a grade 8 bolt and two nuts to form a lock nut.

 

[sreidmx]

That is very strange. I’ve never seen one do that.

 

[Magikal]

Me either...and not just once, but twice. What are the chances of the grade 8 bolt getting sheared off, and the lower part unscrewing itself off the shock? All in a matter of probably 20-30 miles of cruising forest service roads, not even off road.

 

[frankin5]

What does the mount on the axle or frame look like?

 

[sreidmx]

Me either...and not just once, but twice. What are the chances of the grade 8 bolt getting sheared off, and the lower part unscrewing itself off the shock? All in a matter of probably 20-30 miles of cruising forest service roads, not even off road.

If it’s on a washboard road I would say it’s more likely, the chatter is what would loosed that lower bolt.

 

[Magikal]

The axle mount is stock, single piece of 3/8 steel welded to the housing. Single hole in it. No damage to it.

Top mount is the all common ford shock tower.

I don't see how the bolt could have rattled loose. I saw that coming, hence the two nuts locked onto each other to prevent such a scenario

 

[sreidmx]

The axle mount is stock, single piece of 3/8 steel welded to the housing. Single hole in it. No damage to it.

Top mount is the all common ford shock tower.

I don't see how the bolt could have rattled loose. I saw that coming, hence the two nuts locked onto each other to prevent such a scenario

Pics of this mount setup? If it’s single shear I would bet my life on it shearing or coming loose

 

[blazinzuk]

Threads rip out of the eye. I have seen it before. Actually several times. I'm not sure that's what happened to you as the times I've seen it the evidence is clearly still attached.

I'd cycle the suspension and look for binding issues. The shock eyes really don't have enough travel to deal with a leaf spring suspension that is flexy

 

[sreidmx]

Threads rip out of the eye. I have seen it before. Actually several times. I'm not sure that's what happened to you as the times I've seen it the evidence is clearly still attached.

I'd cycle the suspension and look for binding issues. The shock eyes really don't have enough travel to deal with a leaf spring suspension that is flexy

Needs a heim rod end for that angle.

 

[natemc]

Pics of this mount setup? If it’s single shear I would bet my life on it shearing or coming loose

Yes. We need pics of the axle mount. Stock mount should be dual shear iirc

Threads rip out of the eye. I have seen it before. Actually several times. I'm not sure that's what happened to you as the times I've seen it the evidence is clearly still attached.

I'd cycle the suspension and look for binding issues. The shock eyes really don't have enough travel to deal with a leaf spring suspension that is flexy

Needs a heim rod end for that angle.

You need to measure the droop of the suspension before you determine where to mount the tower. Than build limiting straps to prevent the damage to a shock that's too short. 52" Springs will droop really well. Probably more than you realize. As far as the washboard roads go, continuous short stroke of the shock can cause a few irregular rotations of the piston itself. It does look possible that the rod eye, if it's a bushing not a heim, is unthreading as the rod rotates.
Good news is, you'll know what to check 10 miles down the road.

 

[Magikal]

In my head I have concluded that it us a result of either the shock bottoming out on the up travel or on the droop. I have been leaning more towards it bottoming out on the up travel. Ordering some new, taller, bump stops. Had it up with the Jack under the axle today to remove old shock and did some measuring while in that position and came to the conclusion that I need bump stops roughly three inches taller then what use on there now. This should stop the shock from bottoming out with around an inch extra for safety. At $80 a pop on these shocks I cannot afford to keep replacing them.

I will take some pics if the lower mount and probably and fab another. The idea of a double sided mount vs a single one makes much more sense in my head. Not having a shop here in north Idaho with cold temps and snow makes getting any progress very slow so be with me here everyone. am on the hunt for one to rent.

 

[campfire]

Looks like what happened to @AgDieseler?

But I don't understand how you would shear off the mounting bolt at the same time that you'd back out those threads.

 

[AgDieseler]

Looks a lot like what happened to me.

I don’t think the threads back out as much as they stripped apart. I tried to reassemble, only to have a come apart again, hence the weld.

David

 

[Magikal]

Looks a lot like what happened to me.

I don’t think the threads back out as much as they stripped apart. I tried to reassemble, only to have a come apart again, hence the weld.

David

I would think it would shear the bolt off, allowing the lower section to slowly rotate until it falls off...

Or, if it just plain ripped it out of the threads then wouldn't it be a flaw on Bilstiens part? Warranty? Sure wish I had the lower section still that came off....

 

[sreidmx]

No the threads ripping off are not a warranty claim. How’s that? If the travel is not limited by as strap the 600lbs of wheel and axle will stop because of the shock. Properly mounting limit straps and bump stops is what keeps the shocks and springs alive, contrary to what the internet might say lol

 

[Blue85]

Doesn't the shaft turn freely inside the shock? Then what would prompt "unscrewing" of the eye? With the lower bolt sheared, the bottom of a 12" shock should be near the ground. You would think the hit able to shear the bolt would have no problem pulling the eye threads out. The highest force seen on those threads should be the damping forces of the shock valving. It's probably designed to fail there instead of ripping the shock body open.

Have you contacted Bilstein? Maybe they can sell you just the eye, assuming the shock seems good otherwise. Or if somebody has junk shocks, maybe the eyes can be removed.