Track Bar Bolts Upgrade!

[AnnDee4444]

I mean, there's only so much force you can put into it. At 190 ft lb your front LCA bushings still do this. You've got 2-3 tons of Jeep yanking and pushing and pulling on that bushing, especially when off road, so if 190 ft lb ain't doing it, how much more you willing to try and put in? Personally, I'd rather solve it with a better fit via a bolt vs torque.

You can increase clamping force without increasing bolt/nut torque by using thread lubricant.





Edit: Also grade 9/12.9 bolts have higher tensile strength than grade 8/10.9 (180,000 PSI vs. 150,000 PSI). If you're going to the effort of changing bolts, might as well get one you can torque higher.

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[Remorseless]

You can increase clamping force without increasing bolt/nut torque by using thread lubricant.

That's a little misleading - the bolt is still experiencing the same amount of force on the threads, which carry the clamping load, and your bolt isn't capable of carrying extra clamping load than it was when dry. You reduce the torque to rotate the bolt when lubricated, for sure, but not the load the bolt threads are carrying. You'd end up having to upsize the bolt anyway to have a stronger thread surface to carry the higher load if you wanted higher clamping forces than the current bolt spec allows for without stretching (which, ironically, makes the fitment issue worse). The dry torque spec is what it is in order to fall within the proper safe range for "good enough" clamping but having overhead for thread/bolt strength.

So, if you've got a dry torque at 190 ft lb and you introduce antisieze, and knock 20% off the torque value to have the same clamping force at 152 ft lb, but then you go up to 190+ ft lb to increase the amount of clamp you're getting for the torque value, you're really just stressing the bolt threads, pushing roughly 240 ft lbs of rotational torque's worth of clamping force.

Even then, the question is - Is it enough? Does 240ish ft lb of clamping force not break or stretch the bolt and does that absolutely stop the movement?

My experience - not likely. 2-3 tons of Jeep is just an absolute monster on bushings over time, especially with articulation loads.

 

[GATORB8]

You can increase clamping force without increasing bolt/nut torque by using thread lubricant.





Edit: Also grade 9/12.9 bolts have higher tensile strength than grade 8/10.9 (180,000 PSI vs. 150,000 PSI). If you're going to the effort of changing bolts, might as well get one you can torque higher.

Have to be careful there. I think max torque is around 70% of yield, and lubricated increases tension by 30%, so if you lubricate and torque to spec, you may be nearing yield.

 

[AnnDee4444]

That's a little misleading - the bolt is still experiencing the same amount of force on the threads, which carry the clamping load, and your bolt isn't capable of carrying extra clamping load than it was when dry. You reduce the torque to rotate the bolt when lubricated, for sure, but not the load the bolt threads are carrying. You'd end up having to upsize the bolt anyway to have a stronger thread surface to carry the higher load if you wanted higher clamping forces than the current bolt spec allows for without stretching (which, ironically, makes the fitment issue worse). The dry torque spec is what it is in order to fall within the proper safe range for "good enough" clamping but having overhead for thread/bolt strength.

So, if you've got a dry torque at 190 ft lb and you introduce antisieze, and knock 20% off the torque value to have the same clamping force at 152 ft lb, but then you go up to 190+ ft lb to increase the amount of clamp you're getting for the torque value, you're really just stressing the bolt threads, pushing roughly 240 ft lbs of rotational torque's worth of clamping force.

Even then, the question is - Is it enough? Does 240ish ft lb of clamping force not break or stretch the bolt and does that absolutely stop the movement?

My experience - not likely. 2-3 tons of Jeep is just an absolute monster on bushings over time, especially with articulation loads.

Agreed. Upsizing or up-grading (as in grade 9/12.9 bolt) would be the two real ways to increase clamping force. Lube just changes the torque required to get the clamping force.

And I have no idea what is or isn't enough to prevent movement.

 

[Remorseless]

And I have no idea what is or isn't enough to prevent movement.

Me neither lol, why I take the easy path and just throw hardware at it.

 

[JEEP4U]

 

[AnnDee4444]

$22.29 before shipping for one bolt/nut/washer set

https://boltsandnuts.com/shop/9-16-18x3-hex-cap-screws-grade-l-9-bolts-usa-zinc-yellow-433558
https://boltsandnuts.com/shop/9-16-sae-grade-l-9-flat-washers-usa-zinc-yellow-433954
https://boltsandnuts.com/shop/9-16-18-grade-l-9-hex-collar-locknuts-usa-zinc-yellow-437316


From this chart:

Bolt Grade	Thread	Torque (dry, zinc)	Clamp Load	PSI Increase
Grade 9 (above)	9/16-18	171 lb.ft.	21,412 PSI	32.5%
Grade 12.9	M14-2	147.4 lb.ft.	18,879 PSI	16.9%
Grade 8 fine	9/16-18	146 lb.ft.	18,268 PSI	13.1%
Grade 8 course (OP)	9/16-12	130 lb.ft.	16,375 PSI	1.4%
Grade 10.9 (not stock)	M14-2	126 lb.ft.	16,154 PSI

 

[GATORB8]

$22.29 before shipping for one bolt/nut/washer set

https://boltsandnuts.com/shop/9-16-18x3-hex-cap-screws-grade-l-9-bolts-usa-zinc-yellow-433558
https://boltsandnuts.com/shop/9-16-sae-grade-l-9-flat-washers-usa-zinc-yellow-433954
https://boltsandnuts.com/shop/9-16-18-grade-l-9-hex-collar-locknuts-usa-zinc-yellow-437316


From this chart:

Bolt Grade	Thread	Torque (dry, zinc)	Clamp Load	PSI Increase vs. Stock
Grade 9 (above)	9/16-18	171 lb.ft.	21,412 PSI	32.5%
Grade 12.9	14mm-2	147.4 lb.ft.	18,879 PSI	16.9%
Grade 8 fine	9/16-18	146 lb.ft.	18,268 PSI	13.1%
Grade 8 course (OP)	9/16-12	130 lb.ft.	16,375 PSI	1.4%
Grade 10.9 (stock?)	14mm-2	126 lb.ft.	16,154 PSI

Stock is M14-1.5

 

[AnnDee4444]

Stock is M14-1.5

Crap.

Is anyone able to find a chart that shows M14-1.5?

 

[GATORB8]

Crap.

Is anyone able to find a chart that shows M14-1.5?

I've only found torque so far, none of the ones with clamping load.

 

[richk225]

Interesting article on torque plus degrees

https://www.norbar.in/About/What-is-Torque

https://www.norbar.in/News-Events/Blog/ArticleID/65/Torque-Angle-Explained

https://static.nhtsa.gov/odi/tsbs/2015/MC-10137258-9999.pdf

https://arpinstructions.com/generaltorque.html

14mm https://arpcatalog.com/36/

Confused yet?

 

[AnnDee4444]

After arguing with ChatGTP for too long (and losing), I'm going to take an educated guess. This chart shows M14-1.5 as being about 7.9% higher than M14-2... which is close enough for me. Just don't use any of the numbers as absolute values... it's just for comparison purposes.

I'm still assuming grade 10.9 on the stock hardware.

Bolt Grade	Thread	Torque (dry, zinc)	Clamp Load	PSI Increase vs. stock assumption
Grade 9	9/16-18	171 lb.ft.	21,412 PSI	22.8%
Class 12.9	M14-1.5	~159 lb.ft.	~20,370 PSI	16.9%
Grade 9	9/16-12	153 lb.ft.	19,193 PSI	10.1%
Class 12.9	M14-2	147.4 lb.ft.	18,879 PSI	8.3%
Grade 8	9/16-18	146 lb.ft.	18,268 PSI	4.8%
Class 10.9 (stock?)	M14-1.5	~136 lb.ft.	~17,430 PSI
Grade 8 (OP)	9/16-12	130 lb.ft.	16,375 PSI	-6.1%
Class 10.9	M14-2	126 lb.ft.	16,154 PSI	-7.3%
Grade 5	3/4-10	227 lb.ft.	21,322 PSI	22.3%
Grade 2	1-8	232 lf.ft.	16,355 PSI	-6.1%

 

[GATORB8]

After arguing with ChatGTP for too long (and losing), I'm going to take an educated guess. This chart shows M14-1.5 as being about 7.9% higher than M14-2... which is close enough for me. Just don't use any of the numbers as absolute values... it's just for comparison purposes.

I'm still assuming grade 10.9 on the stock hardware.

Bolt Grade	Thread	Torque (dry, zinc)	Clamp Load	PSI Increase vs. stock assumption
Grade 9	9/16-18	171 lb.ft.	21,412 PSI	22.8%
Class 12.9	M14-1.5	~159 lb.ft.	~20,370 PSI	16.9%
Grade 9	9/16-12	153 lb.ft.	19,193 PSI	10.1%
Class 12.9	M14-2	147.4 lb.ft.	18,879 PSI	8.3%
Grade 8	9/16-18	146 lb.ft.	18,268 PSI	4.8%
Class 10.9 (stock?)	M14-1.5	~136 lb.ft.	~17,430 PSI
Grade 8 (OP)	9/16-12	130 lb.ft.	16,375 PSI	-6.1%
Class 10.9	M14-2	126 lb.ft.	16,154 PSI	-7.3%
Grade 5	3/4-10	227 lb.ft.	21,322 PSI	22.3%
Grade 2	1-8	232 lf.ft.	16,355 PSI	-6.1%

I think it might be an 8.8:

 

[AnnDee4444]

I think it might be an 8.8:

OK, let's give this another shot. I know the torque values are going to be different depending on lube/coating, so don't take those as absolute values or torque recommendations.

Bolt Grade	Thread	Torque (dry, zinc)	Clamp Load	PSI Increase vs. stock assumption
Grade 9	9/16-18	171 lb.ft.	21,412 PSI	75.8%
Class 12.9	M14-1.5	~159 lb.ft.	~20,370 PSI	67.2%
Grade 9	9/16-12	153 lb.ft.	19,193 PSI	57.6%
Class 12.9	M14-2	147.4 lb.ft.	18,879 PSI	55.0%
Grade 8	9/16-18	146 lb.ft.	18,268 PSI	50.0%
Class 10.9	M14-1.5	~136 lb.ft.	~17,430 PSI	43.1%
Grade 8 (OP)	9/16-12	130 lb.ft.	16,375 PSI	34.4%
Class 10.9	M14-2	126 lb.ft.	16,154 PSI	32.6%
Class 8.8 (stock?)	M14-1.5	~95 lb.ft.	~12,181 PSI	0.0%
Class 8.8	M14-2	88.1 lb.ft.	11,289 PSI	-7.3%

So back to my original question... is the benefit of changing the bolt really from the diameter increase, or ~50% clamping load increase (assuming torqued adequately)?

From what I've read, most shear connections consider any slip to be failure. I'm not sure it's something I want to allow here.

 

[JLfromCA]

Fine threads ?

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