broke 2 lower control arm bolts torquing to spec - JeepForum.com
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  • 1 Post By 2005JGC
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post #1 of 8 Old 05-14-2019, 05:33 PM Thread Starter
sqlb3rn
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broke 2 lower control arm bolts torquing to spec

Hi all, I installed a new lower control arm, and have twisted 2 bolts in half torquing them down to spec. From what I read, the rear bolts should be tightened to 105 ft pounds... but on one side, it just twists in half around 90 ft pounds. The frame holes are shaped like an oval race track, so the control arm bolts could be adjusted left/right. I don't know if maybe it's not lining up, and putting shear stress on the bolt... but it looks straight and the head, washer, and nut are fully seated. And I can easily insert/remove the bolt without any sideways stress.

One bolt torqued down fine, but the other used bolt twisted in half, and when I replaced it with a new one it also twisted in half... so the 2 bolts breaking in the same hole makes me question if there is a problem with the alignment or something of the holes. Also I noticed the tab on the flag nut is bent in and it felt like the entire bolt and nut were spinning when I broke the last one.

Should I torque it to 105 as the service manual says, or a little less like 90? It doesn't seem right if the bolt can't handle the torque. I have to wait several days for new nuts and bolts, so I really don't want to break another one (I bought 2 this time for a spare). The picture is the new bolt with old flag nut twisted in half. My best guess is, I didn't notice the bent tab and reused the old nut, which allowed the bolt to spin and spin and spin until the metal got weak and it stretched and broke.

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Last edited by sqlb3rn; 05-14-2019 at 05:55 PM.
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post #2 of 8 Old 05-14-2019, 06:43 PM
2005JGC
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Hmmm... According to my specs, the front bolt/nut is to be torqued to 125ft lbs. The rear bolts appear to be 105 ft lbs. It makes me wonder if your torque wrench is broken. It is not a torque to yield bolt/application and the fact that the threads are stretched way out near the break suggests the bolt was over torqued. I have had the torque wrench that never clicks scenario. Maybe this happened to you?
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post #3 of 8 Old 05-14-2019, 07:00 PM
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Are you sure you have the right bolts? I think the part number changed and this 06101984 is the newest part number. The nut should be 06508257AA.
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post #4 of 8 Old 05-14-2019, 07:33 PM
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Sounds to me like you're using inferior bolts. Be it the wrong grade of new bolts or rusted old bolts.

I found a couple of mine rotting a while ago, bought good 12.9 grade bolts and nuts from McMaster and torqued them to 90-100 as per standard industry practice for a bolt that size/grade.
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post #5 of 8 Old 05-14-2019, 10:19 PM Thread Starter
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I picked up a brand new 50-250 Kobalt torque wrench for this project, and it feels about right. Yes I got the 06101984 bolt last time, and just ordered 2 more of those with the nuts. It has 10.9 stamped on it, but it's from Mopar. I suppose I could try a 12.9 if a third one breaks. Hopefully the new nut fixes the problem.

Thanks for the replies.
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post #6 of 8 Old 05-15-2019, 04:54 AM
caulk04
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Was on mobile last night, didn't see the picture that it was a brand new bolt. Not sure what those cost, but I just checked my McMaster history and I paid $26.55 shipped for 10 bolts and 25 nuts. They are 10.9 grade, not 12.9 as I thought.

98093A773
94942A104
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post #7 of 8 Old 05-15-2019, 12:51 PM
badgerwithhands
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I had the same thing happen. Replaced the bolts and they went in fine and torqued fine. Aligned fine also.
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post #8 of 8 Old 05-16-2019, 10:42 AM Thread Starter
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Quote:
Originally Posted by caulk04 View Post
Was on mobile last night, didn't see the picture that it was a brand new bolt. Not sure what those cost, but I just checked my McMaster history and I paid $26.55 shipped for 10 bolts and 25 nuts. They are 10.9 grade, not 12.9 as I thought.

98093A773
94942A104
Whoa, thanks for that info. I paid $26 and some change for 2 nuts bolts and washers from Mopar.

Just an update, the new bolt went in and torqued down fine. I am taking it in for an alignment today... the toe is way out of whack.
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