DO NOT TIGHTEN YOUR DIFF BOLTS TO 33 LB FT (READ THIS FIRST)

That's a bummer.

It almost looks like if you removed the flat washer that there might be enough to grab on to the end of the stud with a pair of vice grips, and maybe be able to get it out, but you will want to first heat up the end of the bolt enough with a propane torch to loosen any thread locker that on the threads.

If that doesn't work, sand the end of the stud flat and drill it for an easy out and try that along with heating up the stud to soften any thread locker, and lucking it looks like it's one of the studs that you can get to with a hand drill.[/QUOTE]

DON'T DESTROY THE EVIDENCE!!!

Try to get as close a magnified shot of the broken surface of that bolt, or even better the other half that came off with the nut. Clean it real good without scratching the surface, such as soaking in solvent and using a fiber or soft plastic brush (NOT a wire brush). Then dry any oil or solvent off it with alcohol or air duster before shooting the pics. If part of the surface appears flatter than the rest, and also has markings resembling curved lines, then it's a FATIGUE CRACK. Thread roots in a bolt are great stress concentrators. Cyclic stresses can build up there to the point where the material starts to yield on a microscopic level and form a tiny crack. As the stresses continue, the crack continues to grow larger as the cycles increase. When the crack reaches a "critical" size, the material can no longer hold itself together, and FAST FRACTURE happens. That's when it breaks. My guess is that bolt was already cracked and near it critical size when you attempted to check its torque. If so, then Toyota cannot blame you for the broken stud, as it was already cracked. My other concern would be WHY did it crack in the first place. Those bolts should be designed for the application (proper material and hardness/heat treat). They should never break like that if the specs are correct, and should be able to withstand any cyclic loading (where ever that may be coming from). It's also very possible that when assembled, it was over-torqued and pre-cracked and continued to grow by fatigue. But I'd still be suspicious of the materials hardness. Hold on to the broken parts and try to get good pics for your defense if Toyota tries to blame you. FYI: I've been in the metallurgy/failure analysis field for 40 years, and have seen countless broken bolts from all industries.

 

DON'T DESTROY THE EVIDENCE!!!

Try to get as close a magnified shot of the broken surface of that bolt, or even better the other half that came off with the nut. Clean it real good without scratching the surface, such as soaking in solvent and using a fiber or soft plastic brush (NOT a wire brush). Then dry any oil or solvent off it with alcohol or air duster before shooting the pics. If part of the surface appears flatter than the rest, and also has markings resembling curved lines, then it's a FATIGUE CRACK. Thread roots in a bolt are great stress concentrators. Cyclic stresses can build up there to the point where the material starts to yield on a microscopic level and form a tiny crack. As the stresses continue, the crack continues to grow larger as the cycles increase. When the crack reaches a "critical" size, the material can no longer hold itself together, and FAST FRACTURE happens. That's when it breaks. My guess is that bolt was already cracked and near it critical size when you attempted to check its torque. If so, then Toyota cannot blame you for the broken stud, as it was already cracked. My other concern would be WHY did it crack in the first place. Those bolts should be designed for the application (proper material and hardness/heat treat). They should never break like that if the specs are correct, and should be able to withstand any cyclic loading (where ever that may be coming from). It's also very possible that when assembled, it was over-torqued and pre-cracked and continued to grow by fatigue. But I'd still be suspicious of the materials hardness. Hold on to the broken parts and try to get good pics for your defense if Toyota tries to blame you. FYI: I've been in the metallurgy/failure analysis field for 40 years, and have seen countless broken bolts from all industries.[/QUOTE]

Yes, when a bolt or stud has been in the process of failing for a long enough time, when it finally does fail you will usually will be able to see a larger area of older looking discolored metal as well as a smaller area of fresh bright looking metal where it finally separates.

We would see this on studs on large productions machines where I worked, and from what I can see of the end of the broken stud, the material all has the same fresh looking color, and being in a location on the truck where its going to water and dirt, it shows no sign of corrosion if in fact this the stud had started to fracture over a period of time, but then again it's hard to tell for sure by not being able to see it in person.

 

I'd also venture a guess that one or more of the remaining bolts are also cracked to some extent. Especially if they don't meet hardness specs. It's a scary thought that perhaps tens of thousands of bolts in our tacos are cracked because of out of spec hardness. Lets hope not.

 

Bro, it's Newtons Meters, not ft lbs.

18 N m = 13.3 ft lb

 

Most assuredly not brother, that's the first column. 25 N m = 17.7 ft lb (call it 18).

 

A lot of Aisian bolts are garbage.

 

Better tell the dealer you saw the recall on the news and were worried about your families safety and you couldn't wait for the recall notice. Cause that looks like a big warranty claim refusal.

Regardless, that stud should never of failed at that low of torque.

 

Not necessarily bolt strength issue. Could have been cross threaded at factory and forced on and left just before breakage. I have had wheel studs do that after inspection stations air wrench lugs back on before.

 

Well, I guess ^that explains this:

 

Are all the affected trucks the Mexican built ones? I'm guessing yes. Then the bolts are likely sourced from Mexico.

 

No.

 

How about no one touches their diffs except Toyota.

 

I don't know if this makes any difference, but I recently took my truck in about 3 weeks ago letting them know that I was experiencing a bit of seeping from my third-member. On the work order they put that they tightened the bolts to the factory spec of 33ft lbs and it should be good to go. Now with this recall that just came out, I will keep an eye on it and see if it persists. If it does I will take it back in and have them figure this out once and for all. BTW - My truck was not on the VIN list of affected trucks.

 

off-roads torque spec is 18ft lbs

 

Yup. They tightened them to 33ft lbs on my TRD OR. So if there is a bolt stretching issue, I'm definitely not asking them to loosen them to 18ft lbs. I'll just keep an eye on it and see what happens. It's all documented so I am good with it.

 

2016 TRD 4x4 sport on the recall list.... out of town for work but will look at this as soon as I get home.

 

That's nuts. I'll be mortified if all of this stems from poor quality metal resulting in fatigue cracking or failure due too inconsistent elasticity yield.

If Toyota cut costs and can't even get their hardware right....

Guess we will just have to wait and see. And I'll be watching the highest milage thread like a hawk. Haha. Hope everyone's issues get remedied as pain free as possible!

 

http://www.lowrangeoffroad.com/trail-gear-toyota-differential-stud-eliminator-kit-140056-1-kit.html alternative

 

Interesting. Normally, I would take studs 1000 times over bolts. I am curious how the studs are coming out; as they say. I hope the rearv no studs are not press fit??!!..