Everything You Always Wanted About Lower Ball Joint Bolts

I posted this on the 4Runner forum, but reposting here since it applies to the early Tacomas as well!

Which LBJ bolts are the strongest, how much torque should be applied during installation, and can the bolts be reused?

These questions are the subject of some controversy on the Toyota forums, but the answers are often speculation and opinion - until now. We are starting a series of tests over the next few weeks to gather data on bolt strength, torque vs preload, and torque to failure, to answer these questions (and more) about LBJ bolts.

We will be posting periodic updates here, but the majority of the details will be on our webpage - https://spikerengineering.com/lower-ball-joint-bolts

We will test five different OEM and aftermarket Lower Ball Joint (LBJ) bolts commonly used for the 3rd Gen 4Runner and early 1st Gen Tacoma trucks:

1. Toyota 90080-10066 (replaces 90105-10406); Flanged Head Bolt; Green
2. Toyota 90105-10505; Flanged Head Bolt; Red
3. Toyota 90119-10933; Bolt with Washer
   
4. Belmetric BF10X1.25X30YLW Grade 10.9 Zinc Plated Bolt
5. ARP 663-1003 Bolt (8740 Chrome Moly)

In Part 1 of the test series, we will measure the torque vs. preload relationship for each bolt type. This will determine how much preload is generated at a given torque level, to see if some bolts are more "slippery" than others, and if a lower or higher installation torque value is warranted to obtain the required preload.

In Part 2, we will subject the bolts to destructive testing by measuring the torque needed to fail the bolts during installation. We will measure the actual torque required to fail the bolt, and document the failure mode (thread shear, tensile failure, etc).

Finally, in Part 3, we will test each bolt in an Instron machine to measure its tensile strength - the definitive indicator of bolt strength.

So stay tuned - this will be fun!

 

Great idea, but don't take too long... I need to buy new bolts and want to make sure I'm getting the right ones

 

Will do the best we can, but you can't rush genius! Not to mention the Instron folks. But we should have all results in a few weeks.

 

Sub’d. Great idea!

 

Nice,
Thanks for doing the research for us.

 

How often do the stock bolts fail?

 

Right, while the tests are interesting, its the BJ’s that usually fail first. And many times, the bolts ate designed to fail first to prevent excessive damage to other parts. Higher strength bolts are also more susceptible to embrittlement.
https://www.boltscience.com/pages/t...is-not-necessarily-the-case-for-fasteners.pdf

 

Also I noticed that there is only about 1/4" thread engagement on my 98 so I would not tighten beyond spec. I already thought I pulled the threads out once because torque wrench felt light at the end but luckily it was Ok.

I suspect there is a reason for small thread engagement because there is no reason that they could not have more, plenty of room there and it seems highly unusual - probably related to what Chuy is saying.

 

I think the research is cool but even the best bolt in the world would be no better than whatever threads it engages in the steering knuckle.

 

I love science for the sake of science. Subbed for that.

In real world practice, as long as the wheels don't fall off, it's good enough for me.

 

Epic

 

Probably depends how you drive it. Not very often on the pavement, but more so offroad. Many of the comments to this post from only two weeks ago were "happened to me too":

 

You may be surprised - some of the preliminary testing is showing the bolt itself breaking, before shearing the threads in the knuckle. That was a surprise to me.

 

This is awesome. SFS - Subbed for Science.

 

ARP as in the bolts everyone buys for engine upgrades, suspension, etc? If so then I put my money on those being the best.

 

Torque to failure of the bolt is one thing (and probably in a spec sheet somewhere), but all that really tells you is how bad it can get if you don't follow the recommended torque setting.

I think what would be more telling, and more relevant to the lower ball joint controversy, is which is more likely to fail given a certain load on the "system" (spindle + ball joint), the ball joint or the bolts (properly torqued)? It's hard to picture how you'd set up a rig to test that, though.

It seems like a majority of the posts I see on ball joint failures are more likely related to user error. I've seen a lot of "bailjoint finally failed at 250k miles" posts.

Dude you should have way more than a 1/4" engagement.

Be sure you put the bolts in the right place, there are two different length bolts.

 

Stress analysis usually shows that internal threads are always capable of breaking external threads made of identical materials. Simple arithmetic explanation - root of the female thread (at the stress concentration) has a larger circumference than the root of the male thread. I like to use metric 12.9 capscrews in place of 10.9's - then torque them to the 10.9 spec. There is data that shows this adds fatigue resistance.

 

The tests we are doing are only designed to tell us about the bolts. No doubt that higher fidelity test could be conducted, which would consider the entire LBJ/knuckle combo, simulate dynamic loading, fatigue, side loads, etc. That's not our purpose (nor do we have the equipment to do those tests).

We'll do Instron tests to determine which bolts are the strongest. That's half the battle. We'll also see how much preload is generated by each bolt for a given torque. Finally, we'll see how preload for a given torque degrades with use, so you will know if you should reuse a bolt or not, and if you do, what torque to apply to it.

I don't believe such data exists anywhere, so I think this will be quite useful.

 

Yes, but . Like you said, that's true for identical materials. In reality, the bolts are higher strength than the knuckle, so its male threads are stronger than the knuckle's female threads.

What I am seeing so far is that when torqued to failure, the bolt breaks in tension/torsion, not in thread shear. But the threads do show severe yielding and deformation:

 

Do you have hardness data for the knuckle? Very good indicator of tensile strength..... The ratio of the strength of the internal thread to that of the male part is useful.

Torque is dependent on finish and lubricant. What is going to be the test lubricant?