Broken Knuckle studs with >35s & How to prevent it (1 Viewer)

How many have broken knuckle studs while wheeling with 35"+ tires

  • I busted those studs!

    Votes: 6 17.6%
  • Mine are still holding up

    Votes: 27 79.4%
  • I broke something else related to the knuckle, but not the studs

    Votes: 1 2.9%
  • I wheel with 33s or smaller, but I've broken too

    Votes: 0 0.0%

  • Total voters
    34

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Joined
Jul 11, 2014
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On the way back from Coyote Lake last weekend, I broke the passenger knuckle studs, forcing the knuckle and wheel off the truck (destroying the knuckle bearings (SPC 3 degree bearings) and leaving me stranded. I ended up being able to load the truck onto a trailer and get it home.

Now I am planning to rebuild and want to figure out how to help prevent this in the future. My budget doesn't include Hellfire knuckles btw...

In my case, I believe the failure was due to the following:
  • I bent my drag link a few months back
  • On the trail this past weekend, going down hill slowly, I tried to climb a vertical 2-3' rock with the driver's front wheel. The truck didn't go up, it just shot the wheel hard left, SEVERLY bending the drag link
  • After another mile of huge boulders, the drag link was bending all over the place and I couldn't even steer right.
  • When we got back to the fire road, we straightened the drag link as best as possible and tried to take it easy. A few miles later, the knuckle studs sheared and the knuckle ripped off the axle.
I assume from all of this that multiple miles of the rocks deflecting the tires every which way placed significant loads on the passenger knuckle studs until the point of failure, at which point the knuckle destroyed the knuckle bearings as well as it was forced off the axle. Does that sound reasonable?

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My plan is to install the following:
  • New heavy duty tie rod and drag link (slee/marlin/trail gear/etc)
  • New passenger knuckle bearings with either the same (SPC 3 degree) or factory
  • New ARP knuckle studs
  • New seals and other associated misc items
I'm also considering running one or more small stitches of weld between the steering arm and the knuckle.

Does anybody have any experience and feedback with any of the above items?

Thanks!
 
Assemble clean and re-torque before and after you hit the trail.

Thank you, Dougas. This reminds me that I didn't mention that I had checked the torque of the knuckle stud nuts multiple times over the past few months and they were always right on.
 
I am interested In this as well. It would be a easy upgrade to replARB studs with ARB if they really any stronger.
 
An Uncalibrated torque wrench x multiple torquing sessions = fastener stretch and failure... Maybe I'm using the wrong equation , however, there are several of us running stock knuckle studs on 40's who beat on our 80's off-road and haven't had reports of this. Now having those damn things fall out after years of being trouble free wheeling and being perfectly fine... That seems to happen more than most would like to admit.
 
Don't forget you choice in wheels. Looking at your pictures, your wheels have a pretty healthy offset. That is going to increase the loading on everything the wheels are attached to.

I've read plenty on the forum about the need for hydro assist in the steering when running larger tires. I'm running a 37" x 14" tire on stock wheels. No issue with steering power, even on rocks. Also no issue with kickback in the wheel. It seems running a wheel with close to 0 offset mitigates a lot of the steering issues when running larger tires.

Now that I've written that, I am sure I'll rip a tire off at Rausch Creek in a couple weeks ;)
 
Thank you, Dougas. This reminds me that I didn't mention that I had checked the torque of the knuckle stud nuts multiple times over the past few months and they were always right on.

I was hoping to avoid this problem by checking my torque regularly but maybe not:eek: I do carry replacements...

You biggest challenge will be making sure the threads are super clean and dry prior to installing the new studs using lock-tight
 
Wheel spacers put a lot of extra stress on the steering components.. i tacod the drag link in the same way - tire was trying to climb a rock while I was coming down a hill. Rather than climb, it forced a left turn into the rock and the steering box wasnt having it so the drag link gave.

Anyway i run stock knuckles and steering arm(s) with hydro assist but i have had the nuts loosen up on me. Never broken like you have though.
 
I'm running 37s on 4.25 bs, I had the knuckle studs loosen after one trip, tightened them back up, then got home and replaced them with new Toyota studs and cones and nuts. Never had an issue since then. Id carefully look over the threads on your knuckle and probably replace that knuckle and steering arm if it was bent at all. Then replace with new knuckle studs from Yota. I also run heavy duty steering links
 
Easiest way to prevent this issue: Don'the run 35" or larger tires on a vehicle that wasn't designed for them. Also, check torque regularly.
 
Easiest way to prevent this issue: Don'the run 35" or larger tires on a vehicle that wasn't designed for them. Also, check torque regularly.

But this is 'mud. That's just not going to happen. 35" is considered small here.
 
Easiest way to prevent this issue: Don'the run 35" or larger tires on a vehicle that wasn't designed for them. Also, check torque regularly.

Great suggestion.
 
It may be worth it to carry a spare knuckle which has studs already in it ready to go. Are the knuckles interchangeable from side to side? I'm wondering about abs sensors.
 
No they aren't, the brake calipers bolt onto the knuckles so they are side specific
 
Easiest way to prevent this issue: Don'the run 35" or larger tires on a vehicle that wasn't designed for them. Also, check torque regularly.
Also not owning a land cruiser will prevent this issue... uhhhh
 
Sorry, couldn't not post it...
 
Swap 2.5 ton Rockwells in, problem solved.

I think it is likely that you just were unlucky. You had a badly bent steering component and likely 20 year old studs. These trucks are getting pretty old, all parts on even the most robust vehicle still have a lifetime.
 
Oh look, it's this subject again!

The drag link bending had nothing to do with snapping the studs. Sure, you could upgrade to a heavy duty one, that's a great way to snap a sector shaft. How good is your AAA coverage? Will they get you in the middle of a trail? Maybe your buddies are willing to help you kick the tires on either side of the rig to steer it back to a trailer?

Easiest way I've seen to prevent this is to check the torque on a regular basis. Just because you checked them a few weeks ago and they hadn't moved, doesn't mean they haven't moved since. Especially if you've been wheeling the truck.

Mine were always spot on, then I dragged ass on checking them before a trip, had been wheeling the truck often and during said trip, in Utah, one stud snapped. Pain in the ass, freaked out on repair options on the trail much more than I should have, then drove another six days of dirt on three studs, checking them from time to time.

The problem comes from not checking the torque, at least one of the studs loosens, the movement either causes it to fall out or snap, then the other three are that much more vulnerable. Continuing on makes another one let go by falling out or snapping and then the whole steering arm is walking around on the knuckle. If given enough time and opportunity, the knuckle falls off and you're the guy stuck on the trail with a truck that won't get you home.

You could carry a spare knuckle, but a torque wrench takes up a lot less space and can even be left home if you check them before you go out for a short trip. It's also a lot less messy.

I've seen rigs on 35s make it out under their own power with two studs put back in the holes, a bumper bolt jammed into one hole to stop it from puking birf soup everywhere, then a stick, whittled to the approximate size jammed into the fourth hole to also stop leaking. Sure, we checked the two good studs several times on the way out, in the dark, but it made it out, into Superior for Mexican food and pie, then home to Chandler, then over to Tools R Us' shop for repair later in the week.

I've also seen rigs on 37s limp home with one or more snapped. Mine included.

I've seen it happen three or four times now. You can come up with all the crackpot ideas you want, but a torque wrench on a regular basis is the best way I've found.

I suppose if you really want to, you could weld and gusset the knuckle. Or order those Mark's knuckles that have the steering arm cast in.
 

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