Everything You Always Wanted About Lower Ball Joint Bolts

The bolts are high strength steel, heat treated to the 150,000 to 180,000 psi strength range. The knuckle is forged steel, so its strength is likely to be less than half of the bolts' strengths.

 

will be watching this thread.

 

While we're collecting data from the torque tests, here's a little more info about the bolts we're testing. Although commonly used for the 3rd Gen Toyota 4Runner, these bolts are also used for Tacoma and Sequoia trucks, so the results are applicable across various platforms:

“GREEN” – Toyota 90080-10066 (replaces 90105-10406); Flanged Head Bolt. This bolt is specified for the 1996–2000 4Runner. It’s a flanged head bolt, with “two dot two hash” head marking, which Toyota classifies as Class 11T bolt.

“RED” – Toyota 90105-10505; Flanged Head Bolt; This bolt is specified for the 2001-2002 4Runner, at locations without the protector boot. It is identical in appearance to the Green bolt, with the same Class 11T head markings. However, the red color code suggests that there is a difference between this bolt and the green bolt.

“BLACK” – Toyota 90119-10933; Bolt with Washer. This bolt is specified for the 2001-2002 4Runner, at locations with the protector boot. It is longer than the other bolts, to accommodate the extra thickness of the protector boot. The “11” head markings also classify it as a Class 11T bolt. The captive washer makes this bolt quite different from the flanged heads of all the other bolts.

“ZINC” – This is a Class 10.9 Yellow Zinc plated bolt, often used as a replacement for OEM Toyota bolts. It’s also a flanged head bolt. Purchased from Belmetric, BF10X1.25X30YLW.

“ARP” – This bolt is made by Automotive Racing Products, Part Number 663-1003. It’s an 8740 Chrome Moly steel bolt, with a flanged head, and supplied with an optional washer.

We should hopefully have some initial test results next week!

 

A lot of bolts fail from becoming loose and having side loads put on the bolts as well as a shock from play looseness.
For example a wheel is very unlikely to sheer off 6 studs if tight. Loosen the lugs a turn each and they'll break off. Seen it many of times.

 

Two reds and two blacks with some blue loctite for my LBJ jobs. So far so good. Interested to see more regardless.

 

OP,
Your post is of interest to many including myself. I retrofitted the Lower Ball Joint (LBJ) Protectors to my '97 Taco 4X4 last year. We looked at the different bolt lengths/applications last summer on this board: lower ball joint bolts why so many | Page 2 | Tacoma World. But the different torque spec on the different bolts was a bit confusing. The 2001 FSM called for a different torque value depending on whether or not you had the LBJ Protectors (2001 FSM below). FSMs from later years when the Protectors were standard equipment only gave a single torque value for all of the LBJ bolts. All that left the subject of which torque value to use on which bolt about as clear as mud.

 

I remember these discrepancies too. I went with 59 foot pounds for all four bolts. I was trying to "feel" the tension through the wrench as I was approaching the click and I didn't feel any questionable over tightness occurring.

 

It seems to me that some sort of tensile strength evaluation has to be made. Is the "11T" designation simply a geometric assignment (nominal diameter and thread pitch) or does it have a strength spec as well? If you file the head flat on the green, red and black variants - do they check the same hardness? I was wondering if green = 8.8 (SAE Gr5), red = 10.9 (SAE Gr8) and black = 12.9 (170K tensile) in material strength - or something like that and 11T was the size.

I'm also interested in Toyota's recommendations of thread lubrication. Since all of the torque/tension relationships depend on the lubrication factor - are the torques listed in the above chart "dry" values (simply plated and oiled) or do they imply use of a "thread lubricant"? If an assembler installs a fastener to a dry torque spec - but has used a "for real" extreme pressure thread lubricant - they could easily be pushing the limits of the fastener's capacity. As an engineer I have "fenced" with Loctite a couple of times over the friction coefficient of their products - and they usually just bail and say test it yourself...... So with no time or budget to experiment, I have assumed it is like water - used the dry torque spec. This was the recommendation of engineering superiors at a couple of mining equipment manufacturers as well.

On the chart, the high lighted torque values for the LBJ fasteners are suspiciously close to the difference between 8.8 (37 ft-lbs) and 12.9 (59 ft-lbs) commercial fasteners - applied "dry".

 

I did pretty much the same thing. Even took a spare new 90119-10933 black bolt that I had measure then installed at 59 ft./lbs. It only stretched by a few 0.001"s. A spare new 90080-10066 Green bolt stretched about the same amount. More importantly, the black bolt stretched 0.0065" when torqued to 37 ft./lbs. Then the same black bolt only stretched a single 0.001" more when further torqued to 59 ft./lbs. After that little backyard experiment, I felt comfortable torquing all the LBJ bolts to the high value of 59 ft./lbs. Just finished doing my yearly inspection on the LBJs. After putting approx. 150 days of hard wheeling on them over the past year, all appears well with the LBJs and bolts at this time.

 

According to Toyota, the Green, Red, and Black head markings all indicate a Class 11T strength (it is independent of bolt size). However, no one seems to know (not speculate, know) what Grade or tensile strength that corresponds to. That's what we will find out.

My understanding is that unless specified otherwise, all torques are for dry installations. And yes, adding any lubricant will affect the required torques, I would not do that without some testing to back it up.

As for Loctite, we are testing some samples with Loctite. It has some effect on the threads, but keep in mind that a lot of the resistance is under the bolt head, and that part is unaffected.

That theory has often been speculated, but given the same Class designation, I would say not.

 

Thank you, I think you will find the results extremely educational and helpful.

I am very familiar with that discussion, as well as that Mighty90's post that has been the source of so much misinformation. All I can say is that those tests had some basic shortcomings (which I believe the author acknowledged), and as a result, the information presented may do more harm than good.

My expectation is that the reason for the different torque levels for the two bolts (with or without the boot) is not at all what some folks are speculating it to be.

 

OP, still finding time to make progress on your testing?

 

For real. This is very interesting

 

Good timing, I just completed my post with the updates .

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.

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

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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:

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As for the actual tests, I tested a bunch of bolts. I torqued each bolt to 20, 37, and 59 ft-lbs. The 20 ft-lbs point was intended 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:

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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).

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 for all the bolts except Black; the Black bolt friction coefficient is likely below 0.1. That puts it squarely into dry film coating territory.

This chart also 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 intent, 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 decided that 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 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:

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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):

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

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

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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).

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 (like I said, I think that it is dry-film lubricated). 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.

 

Gonna schedule some vacation time to read this. Anyone else hear Toyota taking notes?

 

This is the kind of rigorous scientific testing this forum needs in order to settle old debates. Kudos, Leon!

 

So the variable seems to be the coefficient of friction - and how that value increases with successive applications. The black capscrews certainly must have a very effective coating! I have run across some coated machinery bolts that had a specified U.S. mil spec - and an odd torque requirement to match. Must have been a similar sort of coating.....

Did each of the screw sets have their own tapped block?

Thanks for your efforts with this - makes me more of a believer in cleaning up fasteners for re-use and uniformly applying a known thread lubricant.

 

Saved for later knowledge consumption
Very interesting test

 

I received an interesting lesson in that just yesterday while disassembling a Taco 7.5" front clamshell diff. I needed to remove the pass side axle shaft/diff tube which is held in place by (4) 17mm head bolts. Toyota had assembled the diff tube with their orange FIPG sealant. They even got a large amount of FIPG on the threads of the bolts. The big Dewalt impact gun was bogging down significantly even after the bolts were broken loose which seemed very strange, almost as if the bolts were slightly cross threaded. So I backed them out more slowly. The (4) bolts all finally came out but were not just warm to the touch but blistering hot! I will definitely be cleaning that FIPG off those bolts before reassembly in order to get a true torque value when assembling the new diff. If I were reusing the old diff, I would also feel the need to clean the threads with carb cleaner then chase the threads to remove the FIPG. I normally clean then lubricate all the fasteners I use/reuse on the Taco in order to keep them from galling/freezing up. Some people use antiseize on their LBJ bolts. But I don't want mine backing out so install with blue Loctite.

 

Yes, the difference in performance of all these bolts is due to the coatings/finishes. They are all high carbon steel bolts, likely with a zinc plating, and then some other coating, which is what affects the friction coefficient. I'm still not sure what the coating on the Black bolt is - we threw it into an FTIR machine but did not pick up any traces of moly.

I reused the same tapped hole for all the torque tests, constantly monitoring it for wear. It's a hard stainless block, and I didn't see any wear with all these cycles.