Should I replace these suspension parts?

[derf]

Yeah, AMC in the 80s was so random on SAE vs Metric on pretty much every fastener.

 

They used whatever was the cheapest when the contract was signed.  If SAE saved them a dollar on every million fasteners, they would pick that.  If the metric was cheaper that day, that's what they picked.

[llhat]

metric or sae,   do not use a cheep bolt !!   ensure they are grade marked,   grade 8 for sae,  corresponding for metric and are of the same design,  shoulder, thread length,  head style ( integral washer ) 

[derf]

Metric would be 10.9, for a similar to grade 8 SAE.

[AnotherOldJeepGuy]

Yep, metric.  The bolts holding the sway bar to the frame came out in good shape.  I did work them back/forth along the way being mindful of the force and soaked them good with penetrating oil.  The other two bolts fastening the link to the frame were completely trashed, as were the threads at the top of the old link, sure glad I got the suggestions to just replace these!  I managed to get them out, it took breaking loose force the entire way for all 4 of them, no way I wanted to put them back in.  For the ones at the bottom of the link, which did not come with the new links, I matched it up at Napa to M12-1.75 bolts.  Added washers since the original nut was a nut/washer combo.  The washers they had were not optimal but they will work.  I managed to get get 27Ft-Lb on new link top nut, but I stopped short of 75 for the bottom link bolts, at under 50 they seemed to already be 500-lb gorilla tight so I stopped.  (I never used a torque wrench from the 70s or so until a couple years ago and the target numbers always seem to take a lot more force than I am comfortable with anyway to click, so I'm calling my intuition good enough).  The smaller bolts on the bottom I tightened them until the seemed plenty tight, tighter than they were when I removed them and called it good.

 

The result seems good.  Test drive good.  I don't know how much effect this has on actual sway, but several of the loud "clunks" I was hearing when I went over a bump now sound like a new truck, I'll take that!

[AnotherOldJeepGuy]

1 hour ago, llhat said:

metric or sae,   do not use a cheep bolt !!   ensure they are grade marked,   grade 8 for sae,  corresponding for metric and are of the same design,  shoulder, thread length,  head style ( integral washer ) 

The bolts I got were pricy Napa back room stock for what that's worth.  I had already headed out to do the work before I saw this, so I'll double check for a grade.  They seemed heavy duty, not the economical home depot stock.  They felt as heavy as what I took out.  If I can't verify a grade, I'll look for replacements that are graded and swap them in.

[AnotherOldJeepGuy]

Based on the part numbers on the receipt these are what I got.  It looks like the part number on the receipt is not correct for the nut because I know it was also M12-1.75 and it fit the bolt.  The nut that matched the bolt, of course they only had one, that's why I went with the lock nut version because that is what they had.

[AnotherOldJeepGuy]

Anyone used this online bolt seller?  Looks legit.

 

I am assuming that a certain amount of unthreaded length is OK as long as it is fully inside the link body?

 

[JZLAJeep]

2 minutes ago, AnotherOldJeepGuy said:

Anyone used this online bolt seller?  Looks legit.

I've had success buying bolts from fellow club member @boxyjeep. https://boxyjeep.com/pages/bolts-fasteners

[derf]

7 minutes ago, AnotherOldJeepGuy said:

Anyone used this online bolt seller?  Looks legit.

 

I am assuming that a certain amount of unthreaded length is OK as long as it is fully inside the link body?

 

For suspension bolts, I prefer shouldered bolts like that.  So long as the shoulder (unthreaded part) ends just short of where the nut needs to be.

 

The threads on a fully threaded bolt can dig into the steel sleeve of a bushing.

 

My JL Wrangler had fully threaded bolts from the factory.  I bought a kit of shouldered bolts to replace the factory hardware.

 

I don't know about that particular website.  I do like the idea of buying from a forum member like Boxy Jeep.

 

For a lot of my specialty hardware needs, I order from https://boltdepot.com/ most of the time.

[AnotherOldJeepGuy]

Mine were also fully threaded originals but too damaged to reuse.  I like your opinion that a non-threaded part inside the sleeve is less destructive.

 

I looked at boxy jeep link but I didn't find a listing just for these bolts, but I'll try a direct contact and see what happens.

[AnotherOldJeepGuy]

Well the more I look the farther down the rabbit hole I go!  I would have never dreamed how much of a research project this would turn into for a stinkin bolt!

 

Rabbit Hole #1

I put my digital caliper to work trying to measure how much thread I need to make sure the threaded part goes at least partially into the hole so that the nut can be tightened / torqued.  It looks like any bolt with an un-threaded part  (shoulder) longer than about 37mm would expose some of the shoulder, meaning you could not tighten it.

 

The original bolt measures 70mm, but it was fully threaded so this rabbit hole doesn't  come in to play for the original or any other fully threaded bolt.  The full thread class 8.8 bolt I put in before knowing about this rabbit hole is 65mm long and that total length looks good, but 5mm less than that starts to look  too short.  Meaning I need something  65mm or longer.

 

A bit further down the rabbit hole on bolt specs and it seems  that any length from 65mm up has a MIN thread LENGTH spec of 30mm (based on Bolt Depot and Bolt Barn info), so that means the MAX length of the shoulder is [spec-ed length] - 30mm (MIN length).  There is also a transition area identified between the non-threaded area and the threaded area but I don't see numbers spec-ed for that so I have to allow for that in the answer.

 

So rabbit hole 1 of 2 concludes that the only size of a shouldered bolt that works is a 65mm.

 

Rabbit Hole #2

The M12-1.75 bolts I see online seem to be paired with lock nuts, although the don't look like lock nuts to me because I am used to seeing a filler of some type in the nut, nylon I think, to turn the nut into a lock nut.  The nut I took off had no such filling, so are there lock nuts that don't have this filling, and, do I need a lock nut?

[llhat]

there are different types of lock nuts,  some with the nylon insert that locks,  others use some type of deformation to the nut to create interference either as a deformation at the 'top' of the nut where the bolt would stick through,   or  there could be some type of knurl or 'teeth' on the face of the nut flange.... 

[AnotherOldJeepGuy]

It's not obvious [to me] that there is anything special about the old nut, but it was very hard to remove and seemed to remain tight all the way until it was within a turn or two of coming off.  Any nutty experts here that can say for certain just by looking if this is or is not a lock nut?

 

And the plot thickens, I do know for a fact that the new top nuts that came with the new Mevotech links were lock nuts, the nylon insert type.

[llhat]

i cannot tell in the image...  but by your description of the actions on removal,  the nut was of the thread distortion / deformation type, and a lock nut.   typically these nuts have some pressure placed on them after threading to 'smoosh' the top few threads.   to me,  if the new nuts have nyloc design, use them.  I do not think they are vastly superior or anything, but will work, and you've got them.

[AnotherOldJeepGuy]

41 minutes ago, llhat said:

i cannot tell in the image...  but by your description of the actions on removal,  the nut was of the thread distortion / deformation type, and a lock nut.   typically these nuts have some pressure placed on them after threading to 'smoosh' the top few threads.   to me,  if the new nuts have nyloc design, use them.  I do not think they are vastly superior or anything, but will work, and you've got them.

Makes sense!