Steering knuckle stud failure. (1 Viewer)

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Jan 12, 2017
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Clovis, CA
I have been wheeling on 35's for 8 years and just last week i installed 37" tires and drove up coyote ridge. Its not a difficult trail, however i manages to break off my steering knuckle studs and left my truck stranded. I had to drive 2.5 hours with my friend truck into Bishop and pickup up some bolts at Napa and drove back out to my truck. I was able to recover some of the cone washers on the trail and was able to secure the steering arm back on the knuckle and drive 6 hours home without issue. I was suffering from altitude sickness and was feeling miserable so i wasn't thinking about taking pictures of the carnage. I find the breakage timing questionable since I have been wheeling harder and more technical trails for over 8 years on 35"s without failure.
Questions;
Are 37" the breaking point of the stock steering and without upgrade failure to inevitable?
Was the breakage directly a result of failure to recheck the torque on the steering studs?
As long and the steering studs are constantly re-torqued with stronger upgraded studs is it safe to run 37"s on hard trails.

I know the best answer is Hellfire, Slee arms, for Front range, however that is not an option at this time, but definitely in the future.
Im just considering to going back to 35's (315's) if steering breakage is common with 37's
Input appreciated...
 

landtank

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I've had a few stud failures and some backing out. I put these together with a stronger stud and longer shoulder and so far so good.

 
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South west utah
I have been wheeling on 35's for 8 years and just last week i installed 37" tires and drove up coyote ridge. Its not a difficult trail, however i manages to break off my steering knuckle studs and left my truck stranded. I had to drive 2.5 hours with my friend truck into Bishop and pickup up some bolts at Napa and drove back out to my truck. I was able to recover some of the cone washers on the trail and was able to secure the steering arm back on the knuckle and drive 6 hours home without issue. I was suffering from altitude sickness and was feeling miserable so i wasn't thinking about taking pictures of the carnage. I find the breakage timing questionable since I have been wheeling harder and more technical trails for over 8 years on 35"s without failure.
Questions;
Are 37" the breaking point of the stock steering and without upgrade failure to inevitable?
Was the breakage directly a result of failure to recheck the torque on the steering studs?
As long and the steering studs are constantly re-torqued with stronger upgraded studs is it safe to run 37"s on hard trails.

I know the best answer is Hellfire, Slee arms, for Front range, however that is not an option at this time, but definitely in the future.
Im just considering to going back to 35's (315's) if steering breakage is common with 37's
Input appreciated...


Had you been using a front locker on the trip.

I ask because I personally believe front lockers are hard on the knuckle studs. All my knuckle stud issues involved trips where I was using the front locker. Just think about how much harder it is to turn with the front locked up, that just means more stress on those studs. I always try to turn the front off when turning, especially in high traction situations like my local slick rock sandstone.
 

JunkCrzr89

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Are 37" the breaking point of the stock steering and without upgrade failure to inevitable?
NO.

I have been wheeling harder and more technical trails for over 8 years on 35"s without failure.
☝🏾 That’s why they broke. You beat on them for years and probably never or rarely ever checked them. They died from age, neglect, and abuse. Were probably already cracked before you put 37s on.
 
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Clovis, CA
Ive rebuilt the axle and replaced the seals and birfield joint with longfields in the axle about a year ago and i remember torquing everything down properly. I guess it was my failure to recheck after a couple outings that worked them loose. Ive been considering these welded gussets for added strength.
 

COYS

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I check the knuckle nut torque every time I'm about to wheel. Pretty easy to do. Sometimes they loosen up a little. Loose nuts break studs.
How are you getting a wrench to the bolts that abuts the brake rotor shield? There’s no room. Thanks.
 
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Removed the shields long ago no issues, before that snap on wobble socket or wrench. I have ran 37s since 09 only once have I had the knuckle studs loosen. Was right after metal masher, checked um after the trail found three loose, tightened back up and finished out the week no issues. Once I got back home only hr away swapped in new hardware and have always been tight. I changed them again last time I rebuilt the front end just cause. Check um after every trip and always tight, no added thread locker factory studs and cones nutS 🥜

image.jpg
 

landtank

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It’s my opinion that since it seems to be exclusively the passenger side that fails it’s just a situation where a previous design falls short.

The studs Toyota uses were first designed for the FJ40 were the steering design was a tie rod that independently steered each wheel. So the load on those studs was that of turning 1 wheel. On our 80s the steering box turns the passenger wheel which in turns steers the drivers wheel. Basically doubling the load on the passenger knuckle.

We have seen this before with the event of AWD where the current successful design of the birfield subcomed to the riggers of AWD and Toyota had to redesign the spline length.

Woody’s mom’s 80 dropped the passenger steering arm and it was her daily driver. That tells you something.
 

cruiseroutfit

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They break/fail/loosen on stock rigs, daily drivers and certainly anything with larger tires, more stress and severe off-road use.

We've sold tens of thousands of OEM, aftermarket and ARP variant studs over the past 3 decades. Sometimes preemptively, sometimes for trail spares and dozens and dozens of times to repair a knuckle that dropped the arm (80) or sheered studs on a standard top-arm setup. I lost a steering arm on my 40 a decade ago on a mountain trail. Sucked but I fortunately had spare studs. Personally, I think it's a combination of stress and over-torque, once that clamping force is lost, they can't hold the steering just on their cross-section.

I sent a used RH 80 knuckle and double steering arm (PS) to a new home last weekend, he lost his on the trail and had to limp home. That was Saturday. Sunday I got a note from friends in Colorado Offroad Recovery about yet another 8x that lost their PS knuckle studs/arm. I suspect there are 10X I don't here about in the west :D This was a super common issue in the 90's-2000's on PU/4R and 4x/6x axles... it's no surprise that it's ramped up as an issue for the 80 over the the last decade.

We stock the OEM and aftermarket studs by the pound and keep a thousand in stock at any given time. :cool:

FB_IMG_1656028759048.jpg

Field triage

received_433029418696129.jpeg

Colorado frowny face day
 

2000cruiser

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I have been wheeling on 35's for 8 years and just last week i installed 37" tires and drove up coyote ridge. Its not a difficult trail, however i manages to break off my steering knuckle studs and left my truck stranded. I had to drive 2.5 hours with my friend truck into Bishop and pickup up some bolts at Napa and drove back out to my truck. I was able to recover some of the cone washers on the trail and was able to secure the steering arm back on the knuckle and drive 6 hours home without issue. I was suffering from altitude sickness and was feeling miserable so i wasn't thinking about taking pictures of the carnage. I find the breakage timing questionable since I have been wheeling harder and more technical trails for over 8 years on 35"s without failure.
Questions;
Are 37" the breaking point of the stock steering and without upgrade failure to inevitable?
Was the breakage directly a result of failure to recheck the torque on the steering studs?
As long and the steering studs are constantly re-torqued with stronger upgraded studs is it safe to run 37"s on hard trails.

I know the best answer is Hellfire, Slee arms, for Front range, however that is not an option at this time, but definitely in the future.
Im just considering to going back to 35's (315's) if steering breakage is common with 37's
Input appreciated...

Is it size or total weight of the wheels+tires?

I'm currently running Nitto MT 315x75x16's on the stock alloy wheels and the total weight of each wheel is about 105lbs, going to be moving to 17" Volk TE37XT's which are 17lbs each, and BFG TA 37x12.5x17 and my new total weight per wheel will be around 82lbs running a larger setup - hoping this puts less stress around steering, braking, diffs, etc and maaaaaybe get better gas mileage since I'm already on 4.88s lol.
 

cruiseroutfit

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...The studs Toyota uses were first designed for the FJ40 were the steering design was a tie rod that independently steered each wheel....

Interestingly the BJx and 2X Series Cruiser had retention devices for the bolt/nut on the knuckles from the factory. I wish Toyota would have stuck with that. I've had customer cross-drill and safety-wire their studs, obviously prevents them from loosening but fails to help with stretch. The better option imo for the 8x Passenger side steering arm is to add tabs to tie into the steering stops.

Screenshot_20220623-175736_Facebook.jpg

(Brennan Metcalf's 80 knuckle)
 

landtank

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Interestingly the BJx and 2X Series Cruiser had retention devices for the bolt/nut on the knuckles from the factory. I wish Toyota would have stuck with that. I've had customer cross-drill and safety-wire their studs, obviously prevents them from loosening but fails to help with stretch. The better option imo for the 8x Passenger side steering arm is to add tabs to tie into the steering stops.

View attachment 3041533
(Brennan Metcalf's 80 knuckle)
One of my bigger issues is with thread engagement. The studs that I offer are “cut” and at the max size for tolerance. That means there is some resistance when threading them into the knuckle. That resistance equates to less movement under stress. When you can finger thread a stud or bolt into place that equates to less engagement and less strength.

ARP hot rolls it’s fasteners with the idea of when it cools its within tolerance. It can be loose and still be within tolerance.
 
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Is it size or total weight of the wheels+tires?

I'm currently running Nitto MT 315x75x16's on the stock alloy wheels and the total weight of each wheel is about 105lbs, going to be moving to 17" Volk TE37XT's which are 17lbs each, and BFG TA 37x12.5x17 and my new total weight per wheel will be around 82lbs running a larger setup - hoping this puts less stress around steering, braking, diffs, etc and maaaaaybe get better gas mileage since I'm already on 4.88s lol.
I run a 37" 150 lb wheel and tire combo, two long days every week on average, with no major knuckle stud issues. I have broken a couple of studs over the years, usually when I hit something hard with the passenger wheel. I run stock studs.

I don't check my studs all that often as they have proven to be reliably tight, unless I abuse them. When I do check them, they are at or very near spec, or broken. I attribute the couple of breakages that I have experienced to the steering arm twisting slightly under shock load, which stretches the stud to the breaking point. It's very possible that a lower shock load could stretch the bolt, thus making it loose and weakening it. If discovered, the operator might tighten it and call it good, but the next shock could break it, and any others that are also weak. Or if not discovered, the other bolts are taking a higher load, leading to eventual failure. Some breakage is probably attributable to incorrect installation, but I've seen too many issues on trucks maintained by people who know what they are doing to blame it all on poor installation or maintenance.

The best fix I've heard of is simply welding the steering arm to the knuckle. In theory, it never needs to be removed, and I know that there are some people who have done it this way. I haven't had enough problems with it to justify the job, but it's an option I would pursue if I did.
 

Dirt Ferguson

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I only do a quick test with a wrench, takes like 60 seconds. I only do the ones I can get to easily with a wrench. The inside ones I check when I'm doing a service.

Same, flare wrench check before any big road trip or hitting trails, takes no time and good peace of mind. But I also always carry a spare set of studs with me when running trails. Cheap insurance, just like a fusible link.
 
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