NW Challenge Trip Report!!!

[blackforestham]

 

[blackforestham]

 

[Houm_WA]

Yeah I wouldn't worry about the boot, it's just a debris trap. They didn't even put 'em on the fronts!

I have searched and searched and cannot find an uprated bolt that is not a socket-head cap screw. I've got some people at fastener shops looking for one for me.

BFH: By your description, sounds like this bolt threads into the control arm and torques down. So there is no nut or anything like that....supid question, huh?

...does that spindle rod or whatever just stay up there? Do I need to use something to prop it up? Does anything come undone when you remove the bolt? That's really my only nightmare in working on this rig....taking out a bolt and having a bunch of $hit "come unglued" and be unable to put it back together!

 

[blackforestham]

Houm - the bolt threads into the spindle assembly, not the control arm. The arm is just a passive component of this assembly. It does have a steel bushing which mates up to the "washer" of the bolt to prevent over compressing during the torque procedure. When the bolt is pulled out, the arm is somewhat free to move down if you force it. The other end is connected to the frame and the length is controlled by the jamb nut on the threaded end. You have to loosen the jamb nut to really screw things up - so don't. The arm just sits in the same position unless you play with it - so don't. ROFL!

 

[Houm_WA]

so it's a simple unscrew, replace, torque down?

I have found a 12.9 but it's a partially-threaded bolt (40 mm of threads) and it is a socket-head type of cap screw. Would that be better than the factory? It IS stronger.

 

[jesus_man]

so it's a simple unscrew, replace, torque down?

I have found a 12.9 but it's a partially-threaded bolt (40 mm of threads) and it is a socket-head type of cap screw. Would that be better than the factory? It IS stronger.

That's what it appears to me. Pretty simple operation. It sounds like only 25mm of threads are used, so if you have at least 30mm of threads, you should be fine! Make sure you get an extra HD washer too.

J.D.

 

[blackforestham]

Here's the scoop - uprating this bolt may be actually cause more issues than it solves. In talking to my specialty guy, there is a 12.9 special ordered bolt available. He recommends staying away from the 12.9 for a good reason. Yes, the 12.9 does have a higher Tensile Strength rating than a 10.9, but the type of application we are using it for creates issues.
The strength rating is based on pull out values which are applied to the bolt along it's longitudinal axis. The force being applied to the bolt in our application is a shear condition, which lays 90* to that same axis. The 12.9 is more "brittle" than lower rated bolts and will deform less than say a Grade 5, 8 or 10.9 when being subjected to side or shear forces prior to failure. Yes, the Grade 12.9 has higher hold down values, but our application has little to do with true "holding power". We're just locating a suspension link.
I'm sticking to the OEM 10.9. LR Part# RYG500073 - 5 bucks each. Done.

 

[Houm_WA]

Good argument, BFH. Keep in mind that "tensile strength" is indeed determined by putting a test specimen (shaped like a dog bone) in "axial tension" like you describe above...but the bending strength of a material and/or component made of said material is also directly tied to the tensile strength. Sheer is indeed a different thing, imagine the stress coming across the bolt instead of along its long axis.

So since the 12.9 and the 10.9 are geometrically the same (so the same applied shear stress across the bolt) what you are implying is that they don't have the same shear modulus. I wonder where we can get a comparison of the shear modulus of the two bolts.

...oh, and one more thing, Dave. If this is a question of STATIC strength (whether it's axial tension or shear) why change the bolt? If you are just replacing the stock bolt with a new stock bolt....what's the point?

 

[Houm_WA]

I think I'm gonna shove a Johnson Rod into the spindle assembly and duct tape it down. That ought to hold it!


...just joking around here, Greg. Let's have fun with it.

 

[blackforestham]

Good argument, BFH. Keep in mind that "tensile strength" is indeed determined by putting a test specimen (shaped like a dog bone) in "axial tension" like you describe above...but the bending strength of a material and/or component made of said material is also directly tied to the tensile strength. Sheer is indeed a different thing, imagine the stress coming across the bolt instead of along its long axis.

So since the 12.9 and the 10.9 are geometrically the same (so the same applied shear stress across the bolt) what you are implying is that they don't have the same shear modulus. I wonder where we can get a comparison of the shear modulus of the two bolts.

...oh, and one more thing, Dave. If this is a question of STATIC strength (whether it's axial tension or shear) why change the bolt? If you are just replacing the stock bolt with a new stock bolt....what's the point?

I get where you're coming from. As explained to me, the lower grade will deform and deflect more than a higher grade in the same situation. It's more "malleable" per se. Since I removed my bolt, I'll replace it with new bolts - it was not recommended to re-use these bolts after the initial torque application. I'm just chalking it up to a 10 dollar education and an excuse to wrench. Now I also have emergency spares - win/win.