Track Bar Bolts Upgrade!

[GATORB8]

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.

There was a question? I thought we were just researching bolts for fun.

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[AnnDee4444]

There was a question? I thought we were just researching bolts for fun.

LOL... I had to go back and check just to make sure I actually asked something and it wasn't all in my head.

Here's what started the bolt information quest. https://www.jlwranglerforums.com/fo...d bolt diameter change anything?,-I know many

 

[AnnDee4444]

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.

Sorry to bump an old thread... I have some random thoughts.

I've got the Metalcloak Front Track Bar Reinforcement Bracket, and have noticed that I have a hard time keeping the frame-side track bar bolt tightened. The instructions specify this bolt as "M14-2.0 x80L STL C10.9 Zinc" (126 lb.ft. on the chart above. While this does appear to be an upgrade from stock, I've been thinking about how flange size or the lack of a washer could factor into any slippage.

I found this M14-2.0 x 80mm grade 12.9 partially threaded flanged head (147 lb.ft. on the chart above). I think this might be the best metric bolt somewhat readily available unless I decide that non-flanged + washer could work. Then a socket-head or 12-point could be used if I find a less expensive option.

Another thought was using thread locker (red?) and/or a cotter pin on the bolt/nut.

 

[cosmokenney]

Sorry to bump an old thread... I have some random thoughts.

I've got the Metalcloak Front Track Bar Reinforcement Bracket, and have noticed that I have a hard time keeping the frame-side track bar bolt tightened. The instructions specify this bolt as "M14-2.0 x80L STL C10.9 Zinc" (126 lb.ft. on the chart above. While this does appear to be an upgrade from stock, I've been thinking about how flange size or the lack of a washer could factor into any slippage.

I found this M14-2.0 x 80mm grade 12.9 partially threaded flanged head (147 lb.ft. on the chart above). I think this might be the best metric bolt somewhat readily available unless I decide that non-flanged + washer could work. Then a socket-head or 12-point could be used if I find a less expensive option.

Another thought was using thread locker (red?) and/or a cotter pin on the bolt/nut.

Blue Loctite or the wire trick.

 

[jadmt]

stock front track bar bolts are 10.9 not 8.8

 

[JeepinPete]

The clamp load units in table posted is incorrect. Clamp load isn't going to be in psi (pounds per square inch). It will simply be pounds. PSI infers stress in the bolt as stress is measured in psi but those values are far too low for a high strength steel.

Digging in a bit more, those number agree relatively close with other tables for tensile strength. The units should just be pounds, not psi.

In the case of the MC bracket, it is subtracting load from the track bar bushing as it requires force to deflect the ears. Stepping up to a higher class bolt is how they work around it. From the sounds of it, it isn't enough.

Flanged/non-flanged make no difference in the clamp force. If you are seeing deformation of the steel of the MC bracket under the bolt head then a flanged bolt might be necessary, though a equal strength washer will do the same.

Pete

 

[AnnDee4444]

stock front track bar bolts are 10.9 not 8.8

So if the stock bolt is really a M14-1.5, is it actually slightly better than the longer one that came in the Metalcloak kit? Due to the finer thread pitch and same 10.9 grade.

The clamp load units in table posted is incorrect. Clamp load isn't going to be in psi (pounds per square inch).

Of course

In the case of the MC bracket, it is subtracting load from the track bar bushing as it requires force to deflect the ears. Stepping up to a higher class bolt is how they work around it. From the sounds of it, it isn't enough.

I hadn't considered this... I wonder if Metalcloak did either.

 

[jadmt]

So if the stock bolt is really a M14-1.5, is it actually slightly better than the longer one that came in the Metalcloak kit? Due to the finer thread pitch and same 10.9 grade.


Of course


I hadn't considered this... I wonder if Metalcloak did either.

I have done work on 3 of them in the last couple weeks a 23, 24 and 25 and all had 10.9. both ends of the track bar..this is from the axle end removed when I did a ss relocate.

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