Catastrophic Knuckle Failure (1 Viewer)

[bloc]

The thing most people in the torque-the-studs camp seem to forget is there is no flange to stop further intrusion and all of the force gets transmitted to the first thread in the knuckle, deforming it. Toyota didn't provide a value on these because one isn't important. Common sense applies: Clean everything well, don't leave the stud hanging out, take extreme care when assembling the rest of this critical system. VERY few original assemblies had problems, and this is without loctite or a special rain dance during assembly.

that looks like a hub stud and cone washer, check you hubs

.....

I also chose to use red Loctite because as I would tighten the studs, there was a chance that the stud could turn as well and loosen.

Care to explain how that could happen? Both threaded sections on each stud are the same direction even if they don't share pitch.

To further my Loc-tite post, i truly believe that torque is important, but as stated before, eventually there is a chance that grease and gear oil can seep down the studs and loosen them. I believe that.

toyota might want to know they were doing it wrong from the beginning..

 

[icorradoi]

Sounds good. I had the new Torx head studs from @NLXTACY when I installed mine and went to 30 lb. ft. I cleaned and tapped the thread on every hole in the knuckle and used loctite on the studs. Will keep an eye on them after I get my diffs back and get everything back together.

 

[NLXTACY]

I thoroughly degrease the knuckle, use new hardware with each rebuild, chase each thread, use brake clean to blow it out and remove residual grease/oil. Then just tighten until snug. The shoulder prevents it from going into the knuckle too far. I do not bother with any type of loctite.

 

[concretejungle]

personally i don't know why you would go to all the trouble with new hardware and all that cleaning and NOT use loctite?! It cost a couple of dollars and adds about 30 seconds to the job.

 

[BILT4ME]

The thing most people in the torque-the-studs camp seem to forget is there is no flange to stop further intrusion and all of the force gets transmitted to the first thread in the knuckle, deforming it. Toyota didn't provide a value on these because one isn't important. Common sense applies: Clean everything well, don't leave the stud hanging out, take extreme care when assembling the rest of this critical system. VERY few original assemblies had problems, and this is without loctite or a special rain dance during assembly.



.....



Care to explain how that could happen? Both threaded sections on each stud are the same direction even if they don't share pitch.
g..

"I also chose to use red Loctite because as I would tighten the studs, there was a chance that the stud could turn as well and loosen."

Wow, I really worded that sentence poorly! Maybe that's why the wife and I don't communicate!

What I was TRYING to say:
I chose to use red Loctite because as I would tighten the NUTS, there was a chance that the stud could turn as well, CHANGING the torque value. Even that's not really clear.

I want ONLY the NUT to turn in order to get the torque CORRECT. If the STUD is turning as well, then the torque is different because now it is being affected by the threads on the opposite end of the stud (a coarse thread if I recall) and it is a twisting motion on the stud instead of a linear pull by the nut on the thread.

Someone else has stated it more eloquently than I above, but I don't want the stud to turn while I'm torquing the nut.

There are all sorts of theories on "proper" torque of bolts and studs, but none are 100% perfect. They are all related to some type of friction and external forces. This becomes drastically evident in grade A325 fasteners used in structures and how they are supposed to obtain the "perfect" torque, whether it is shear off bolts, turn-of-the-nut, or a limiting torque wrench.

I am not an expert, nor did I stay in a Holiday Inn Express last night.

No, Toyota did NOT spec these fasteners as a coated thread fastener, but perhaps they SHOULD have? Did they KNOW they were going to have an issue 15 years down the rad, 20 years? 22 years?

For the heck of it, I checked ARP's website, and they only recommend to tighten their studs "hand tight" (not finger-tight) whatever that means....... The head bolts use their special lube. Others use Loctite.

Again, no hard and fast rule.

I torqued. I Loctited. Deal with it. It's MY truck. You do what you want.

Did I mention flaming?

 

[midfat]

I thoroughly degrease the knuckle, use new hardware with each rebuild, chase each thread, use brake clean to blow it out and remove residual grease/oil. Then just tighten until snug. The shoulder prevents it from going into the knuckle too far. I do not bother with any type of loctite.

View attachment 1550001

While the knuckle is clean, from within the birf cavity, I also squish some RTV down on top of the stud. Because the threaded stud hole goes all the way through the knuckle, this is just a little more insurance preventing birf soup from acting like a penetrating oil and lubricating the threads from the inside out.

 

[NLXTACY]

personally i don't know why you would go to all the trouble with new hardware and all that cleaning and NOT use loctite?! It cost a couple of dollars and adds about 30 seconds to the job.

Because I don’t see the need. It’s just more work when I need to rebuild next time.

 

[NLXTACY]

While the knuckle is clean, from within the birf cavity, I also squish some RTV down on top of the stud. Because the threaded stud hole goes all the way through the knuckle, this is just a little more insurance preventing birf soup from acting like a penetrating oil and lubricating the threads from the inside out.

The contact surfaces of the screw/stud prevent leaking if the studs are tight. Only leaks if they are loose. But I see your point.

 

[BILT4ME]

 

[dallen341]

I thoroughly degrease the knuckle, use new hardware with each rebuild, chase each thread, use brake clean to blow it out and remove residual grease/oil. Then just tighten until snug. The shoulder prevents it from going into the knuckle too far. I do not bother with any type of loctite.

View attachment 1550001

How many coats of wax on the paint?

 

[2fpower]

are you all still playing with your nuts??


Seriously, Larry Bird did less ball handling then you all!

 

[NLXTACY]

How many coats of wax on the paint?

I need to find a different carnuba/cocoa butter blend

 

[bloc]

I want ONLY the NUT to turn in order to get the torque CORRECT. If the STUD is turning as well, then the torque is different because now it is being affected by the threads on the opposite end of the stud (a coarse thread if I recall) and it is a twisting motion on the stud instead of a linear pull by the nut on the thread.

That is one cool thing about the way toyota set these up.. the more coarse pitch of the stud where it threads into the knuckle means that it effectively can't turn the stud as you tighten the nut. Clamping force would rise at an even greater rate than that of the nut. The finer thread at the nut means that is all that will turn. Also, as long as the nut hits torque spec with clean threads it can't be any less than the designed clamping force.. even if the stud isn't threaded into the knuckle all the way. (at which point it probably wouldn't stay at that clamping force for long) not that any of us would leave the stud hanging out on purpose. OR a scenario where a trunnion race isn't seated correctly during assembly then pulls all the way in during driving. This will impact clamping force.. and I suspect is a large part of the problems people have with these after rebuilds.

Point is, both of those scenarios involve improperly assembled knuckles, regardless of thread locking compound or torque values.

I torqued. I Loctited. Deal with it. It's MY truck. You do what you want.

Did I mention flaming?

Awwww...


People can do what they want with their rigs. I take issue with people on here using faulty logic to explain procedures to people that may impact what the less-informed of us do.. sometimes for the worse.

At the end of the day loc-tite is NOT needed on this fastener system, and can make a trail/roadside repair if someone does mangle something FAR more difficult.

Tightening the nut causing the stud to loosen just doesn't make sense, which is why I asked for clarification. Thanks for responding

 

[AutoCraft Aus]

Building super heavy trucks on big tyres and wheeling them long term over some of the worst highways, let alone offroad station tracks for a living, we do afew things that see us never have an issue with these.

And I like to drive my trucks hard too, so confidence and safety are paramount. Unloaded for this pic my truck was down to 7600 lb.
On a trip at 8200-9000lb we would do this 10-30 times in a week over cattle grids, wash aways and spoon drains.

And you can drive for 3-4 days on this track with these and worse. In a round trip you can do 6000 miles over 3 weeks on this type of tracks.

Lack of maintenance, and overtightening torque to yield bolts are the 2 biggest "organic component" errors that effect these and the axle studs with the same cone set up.

If they are leaking, they are loose, so if oil/grease comes out of them thats a warning sign.

The steering will become vague in the straight ahead position initially, then the steering will go off centre when they become loose and start breaking. Pay attention to this.


I have always used the 105 studs that now supercede the 80 version so you can use the star drive to insert them.

Be surgically clean.

Use loctite on the studs [not the nuts]

Use a brass drift and mallet to ensure the steering arm gets seated correctly while doing the torque up procedure properly.

If the studs are unknown to you, always replace them, as the last guy may have overtensioned them and you wont know until they work loose.

They snap off because they become loose and the side thrust snaps them. Its not stud quality or load that does it, if they are done correctly, its coming loose.

Carry a spare set of studs nuts and cones and washers in your tool kit for axles and steering.

Normally the ones you replaced when maintaining the steering, with new ones, carrying the 2nd hand set as spares.

No use carrying new ones and driving on unmaintained, unknown old ones really.

Check the tensions every time you service the truck.

 

[Rifleman]

For the heck of it, I checked ARP's website, and they only recommend to tighten their studs "hand tight" (not finger-tight) whatever that means....... The head bolts use their special lube. Others use Loctite.

This info is from Milodon web site, they make studs for racing engines, and is what they recommend as the correct "hand tight" torque amount.
http://www.milodon.com/2012 Milodon Catalog/Head Bolts & Head Studs.pdf
SUGGESTED TORQUE SPECIFICATIONS :
Always
clean up block threads with a bottom tap
(chasing tap)
before installing studs. Install head
studs with non-hardening thread sealer and use
Locite on mains. All nuts are torqued using oil as
lubricant. Lightly seat studs into block at 10 ft./
lbs (hand tight).
Then torque nuts as follows:
• 7/16” @ 65 ft./lbs.
• 1/2” @ 85 ft./lbs.
• 9/16” @ 115 ft./lbs.

 

[Dave 2000]

Different application but good info all the same.

Regards

Dave

 

[concretejungle]

Darren pointed out another big thing to watch is that when you are seating the steering arm, make damn sure that you are slowly and methodically ensuring it is going on straight. Same with the cap on top of the knuckle. I've had mine go in just every so slightly off and it will never torque correctly and ruin your trunion bearings. It's very easy to torque those down and have them sitting fractionally crooked.

 

[Cruiserdrew]

So i pulled mine apart and cleaned them in the parts washer, then sand blasted them to like new. I used air and brake cleaner to ensure the knuckle threads were perfectly clean and dry. Then i replaced with new studs with blue loc-tite. After torquing them down, i let them sit 24 hours just to ensure the loc-tite had time to dry. Then i added the grease and finished the job.

Knock-on-wood, my studs have never come loose with this technique. Not even a little.

This is exactly my practice. Blue locktite on the stud/knuckle thread only. And blue so that if I ever do have to get out a broken stud, I can.

But since doing it this way starting 10 years ago in 3 trucks and thousands of miles, I've not had a failure.

Regarding torque into the knuckle threads, I put them in firmly but not super tight, I'd estimate 20 foot pounds at most.

 

[Rifleman]

Darren pointed out another big thing to watch is that when you are seating the steering arm, make damn sure that you are slowly and methodically ensuring it is going on straight. Same with the cap on top of the knuckle. I've had mine go in just every so slightly off and it will never torque correctly and ruin your trunion bearings. It's very easy to torque those down and have them sitting fractionally crooked.

The way I check to make sure that the caps and steering arms are seated all the way is to check them with a feeler gauge. If you can slip a .002 or .003 feeler gauge between the cap/steering arm, and the knuckle housing after you've bolted it down, then that means it's not on straight, or seated all the way down.

 

[bloc]

Darren pointed out another big thing to watch is that when you are seating the steering arm, make damn sure that you are slowly and methodically ensuring it is going on straight. Same with the cap on top of the knuckle. I've had mine go in just every so slightly off and it will never torque correctly and ruin your trunion bearings. It's very easy to torque those down and have them sitting fractionally crooked.

This is why I assemble everything as far as possible by hand, then use a small dead-blow mallet to push in the arm and upper cap before even turning a wrench on the bolts. All that gets done with the bolts/nuts is pre-load the trunion bearings then set torque on everything.