You get there. There is a sticky in the top of the 3rd gen thread to help folks search for post. Some users are very grumpy. They get wound up if users can't search effectively. Not realizing everyone skill set is different..

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The google site specific search that Brian linked you is the best way to search the forum.

Go X-Large or go home, right?

Sheesh!!

For the metric impaired that’s >65 tons of force. I think it can break an LBJ bolt with ease.

Time for some updates on the project. I made a few changes to the test setup - I switched from using a nut to represent the tapped threads in the knuckle to a 7/16" thick stainless bar, which I drilled and tapped for M10x1.25 threads. The hard stainless material is a better match to the forged knuckle, and the tapped threads stood up well to repeated use, unlike the nut.


I also upgraded the load cell to a 10K unit, which allowed me to gather data without having to extrapolate, which I had to do with the 2K load cell:


Finally, I changed the top spacer that represents the ball joint flange from a piece of 1/8" angle iron I used originally to a 1/4" thick stainless bar, because I noticed that the angle iron was distorting slightly over the load cell barrel. The harder and thicker stainless bar did not flex, and represented the ball joint flange much better:


As for the actual tests, I tested a bunch of bolts (thanks @rickashay , @brillo_76 , @jross20 , and @octanejunkie ). I torqued each bolt to 20, 37, and 59 ft-lbs - 20 ft-lbs to give me some idea of how linear the data was, and 37 and 59 ft-lbs to represent the two commonly cited torque values for LBJ bolts. I used three bolts of each type to account for unit to unit variability. Each bolt was torqued and loosened four times, to determine how preload changed with repeated installation cycles.

So here is some preliminary data. I say preliminary because I am still doing some data reduction, and I need to run some more tests on the ARP bolts (I ended up being one short, so I only had two to test). So please do not quote the data yet, as it is likely to change a little. But the overall conclusions should not change, and they are very interesting.

First, here is the plot of torque vs preload for a brand new bolt of each type. This plot shows the average preload value generated by the three bolts for a given torque, on the first installation:


One thing jumps out right away - the Black bolt (aka "Bolt with Washer", 90119-10933), generates a lot more preload at any torque value than all the other bolts. At 59 ft-lbs, it would generate around 15,000 lbs, which is higher than the safe limit for these bolts (I drew in a red dashed line at 12,000 lbs as the upper limit for now, but we will confirm this later, during the destructive tests).

This chart alone explains why Toyota specified a torque of 37 ft-lbs for the Black bolts, as opposed to 59 ft-lbs for the others - it's not that the bolt is weaker, as some have speculated, but that it reaches the same preload (or higher) at 37 ft-lbs as other bolts do at 59 ft-lbs. So, conclusion number 1 - if you use the Black bolt, do NOT torque it to 59 ft-lbs, you will yield the bolt. Torque it 37 ft-lbs and be happy.

The variation between all the other bolts is smaller, but still significant. The Zinc plated 10.9 bolt has about 10% more preload at 59 ft-lbs than the updated OEM LBJ Red bolt (90105-10505). The original OEM LBJ Green bolt (90080-10066) generates only 75% of the preload that the Zinc bolt does.

I tried to reverse engineer Toyota's design, although of course these are just assumptions. The original Green bolt generates about 7,300 lbs at the specified 59 ft-lbs torque, while the updated Red bolt generates closer to 8,700 lbs. So I am assuming that Toyota thought the 7,300 lb preload was a bit low, and in 2001 changed to the Red bolt with a different coating material, to bump the preload up to over 8,000 lbs. That is also consistent with the Black bolt, which generates over 9,000 lbs at its specified torque of 37 ft-lbs. So from this, I took the liberty to assume that the lower safe limit for these installations is around 5,000 lbs (it may be closer to 6,000 or 7,000 lbs for all I know). That is shown by the lower dashed red line in the chart.

I then ran tests to see how preload changes with repeated usage. It is often speculated on the forums that the LBJ bolts should only be used once, sometimes with the argument that the bolts yield during installation and thus should not be reused. My data refutes that suggestion - 7,300 to 8,700 lbs at 59 ft-lbs for the flanged OEM bolts, and 9,500 lbs at 37 ft-lbs for the Black bolt is nowhere near the yield point. So from that standpoint, the bolts can be safely reused. Unless you torque the Black bolt to 59 ft-lbs, which is guaranteed to yield it.

But the other concern with reusing a bolt is the reduction in preload with repeated cycles, due to coating wear. The chart below shows the percent reduction in preload as a function of repeated cycles, starting with a brand new bolt, and torquing it four times:


Three of the bolts (Black, Zinc, and ARP) maintain above 90% of original preload after the first cycle. Interesting to note that the two OEM flanged bolts (Red and Green) do not, they drop below 90% and 80%, respectively. By the fourth installation, the Green bolt has only half the preload of the first installation. The Black and ARP bolts still maintain 80% of original preload even after four installations.

The wide flange of the flange bolts degrades significantly with installation cycles (new on left, four cycles on right):


Compare that to the wear on the Black bolt, which is almost imperceptible:


Here's a more useful way to process this data, looking at the actual preload as a function of installation cycles:


Now we can see the effect of repeated installations on preload. In the worst example, the Green bolt drops to our assumed lower safe limit of 5,000 lbs with just one reuse. Additional cycles get the bolt to only about 4,000 lbs of preload.

So how much preload do we need (not so much as to yield the bolts, and not so little as to allow gapping during use), and how much torque should be applied to achieve that desired preload?

I think we can answer some of these questions using this data. Any of these bolts, torqued to 37 ft-lbs for Black, and 59 ft-lbs for all others, will generate the needed preload on the first installation cycle without damage (7,000 to 10,000 lbs). Don't torque the Black bolt to 59 ft-lbs, and don't torque the other bolts to 37 ft-lbs, and you should be fine.

On the other side, I think that most LBJ bolt failures occur due to insufficient preload, which allows gapping. This subsequently allows movement between the LBJ and the knuckle, likely leading to bolt loosening and breakage. Unfortunately we don't know the lower preload limit at which gapping can occur. My suspicion still is that 5,000-7,000 lbs is the low safe limit (especially for offroading), based on the fact that Toyota changed the bolt design to bump the nominal preload up from 7,300 to 8,700 lbs.

If you are going to reuse the bolts, especially more than once, I would recommend doing that only with the Black, ARP, or Zinc bolts. The two flanged OEM bolts simply have too much degradation after a few cycles. I suppose you could try to compensate for the preload degradation by bumping up the installation torque level, but without a load cell you will be doing guesswork (although with this data, it would be educated guesswork).

Using my spreadsheet for estimating torque to preload ratio as a function of bolt geometry and friction coefficient, the data above suggests that the friction coefficient is about 0.15 to 0.2 in all the bolts except Black; the Black bolt friction coefficient is likely below 0.1. That puts it squarely into dry film coating territory, which I think explains why it performs so well, wears so little, and has the smoothest rotation (by far) of them all.

There is one other element that is not reflected in this data, and that is "feel". As I torqued these bolts, the difference between the Black bolt and all the others (but especially Green and Red) was incredible. The Black bolt was smooth as silk - it rotated effortlessly, reaching the torque wrench's click point easily. In contrast, the flanged bolts, especially on repeated cycles, bucked during torquing, leading to jerky stick-slip type of motion. The clicking of the torque wrench was not nearly as pronounced as with the Black bolt.

Like I said, I am still processing the data and trying to make sense of it all. And I'm still awaiting the results of the destructive testing - but for now, I am a huge fanboy of the Black bolt.

A small aside - for these tests, I used the ARP bolts with their supplied washers, because the bolts did not behave as repeatably and smoothly without the washer as with the washer. However, the commonly used 30 mm length ARP bolt, when used with washer, leads to only about 2-3 thread engagement when installed in the LBJ assembly. It seems to be adequate at 59 ft-lbs, but I would not recommend such a small engagement. I would recommend stepping up to the 35 mm version of that bolt. The 30 mm bolt, while holding fine at 59 ft-lbs, stripped at much lower torque levels in destructive testing than the other bolts. In fact, it is the only bolt that failed by thread stripping, rather than bolt breakage. More on this in the destructive testing section.

Awesome info! I will be switching to OEM black bolts next time I do LBJ's.

Quick question - were you using the ARP 'torque assembly lube' on their bolts?

Thank you so much for doing this Leon! What great data.

A few questions:

ARP recommends 54 pounds feet of torque for their 663 (and SS 763) bolts. Did you test at that spec? Would the reuse theory change with the correct torque spec?

How long is the Tacoma "black bolt" 90119-10933 with washer? Total clamping length is what I'm after.

When does the shear test happen and will you be doing that with both first use, and successive reused bolts?
The thought is to determine the maximum number of reuse cycles before retiring the bolts. I'm at 4 cycles on my current ARP bolts and I use thread locker.

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The black bolt 90119-10933 is for 01/02 4Runners with the lbj boot/protector thing that most people don't reuse. It could also be for Tacoma's too.

Well, I took the plunge and upgraded to the black bolts since I had the LBJs off anyway. I also put the dust boot on there too -- seemed like a good idea. The boot is overmolded onto the two mounting washers so there is a no rubber in the way of the bolt joint itself. I also did not have any issues with the longer black bolts. Torqued to 37 ft-lb with some medium loctite.

Good question - I did not apply any lube to the bolts for these tests, partly because that's a whole new can of worms, and also because I'd need to use a different nut for every single test, and possibly a new spacer plate, since the lube would contaminate the thread and flange surfaces and affect all subsequent tests.

I plan to run some more tests with loctite, so I could try the ARP lube as well.

Thanks Mike, nice to see folks appreciate this labor of love .

I torqued them to 37 and 59 ft-lbs, just like all the others. 54 ft-lbs is going to be just a few percent below the 59 ft-lb value, you can just read it off the plot - around 7,400 lbs. That is nowhere near the yield point for these bolts, so ARP is being extremely conservative with the 54 ft-lbs callout.

The clamping length is exactly 35 mm long. The flanged bolts are 32 mm long, and the ARP (with washer) is only 28 mm.

I plan to torque one new bolt of each type to failure (I already did some tests in the junkyard and got some preliminary results, but the "juju" was less than ideal in the junkyard (laying in puddles of transmission fluid, people looking at me a little funny as to why I am installing bolts), and also there were not enough 3rd Gens for me to finish the tests (I could not reuse any tapped holes because the broken bolt segments were seized in place). So I'll do some more tests at home, using a double nut to represent the knuckle. I'll probably do this just for a new bolt, not for reused ones (not sure how many fresh nuts I have on hand, and they will be single use only for these tests).

I think the preload degradation curves already address this question, although of course no one knows for sure what the acceptable lower preload limit is. If it were me, I'd try really hard to make sure it stays above 7,000 lbs, which an ARP bolt with 4 reuses would not meet at 59 ft-lbs. You'd have to bump it up to about 65 ft-lbs, which you can safely do (the one that stripped at the junkyard did so at over 90 ft-lbs).

Way to go, you are my hero and I plan to follow in your footsteps on this one.

Assuming they are torqued to the correct spec, it would seem there's no reason they can't be used on 2000 and earlier.
Are you suggesting otherwise?

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I don't see a reason why they wouldn't work at the recommended 37 ft/lbs for 96-00 or without the dust cover. I was more of clarifying vehicle application of those bolts than disagreeing with you. I made a note to use these bolts next time the lower ball joints need replaced or the bolts get removed.

This is incredible work, Leon. This deep-dive technical analysis is so fun and interesting for a forum full of smart and creative people. I know that projects like this rapidly take on increasing numbers of variables, things to try, etc. I appreciate you powering through it and using your skillset and resources to develop such useful information for us.

Go Leon!!