Torque Specs and a broken M16 bolt

[Joe S]

I installed the 2" Mopar JL lift and as I was torquing the rear upper control arm, the bolt snapped. I torqued other M16 bolts to 185 and 190 foot pounds with no issue. In the instructions, the rear control arm to frame bolts are supposed to be 200 foot pounds. Any ideas? Defective bolt? Incorrect specs? Torque wrench issue?

Instructions I used. http://starparts.chrysler.com/info/default/K6862546AH.pdf See page 21 for the torque specs RR UCA to Frame.

I found this reference for 185 foot pounds in the posters spread sheet. https://offroadpassport.com/forums/topic/6480-torque-specs-crazy-inconsistencies/

Luckily the bolt is only $21...

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[jadmt]

rear uppers to frame should be 120 ft/lbs rear uppers to axle 90 ft/lbs only bolts that are 190 ft/lbs are the front lowers....I think mopar screwed up on instructions.

 

[BetterThanMine]

It happens. They snap coming out, going in and just looking at em. I wouldnt think on it too much aside from being sure you were using new hardware from the get go, never reuse torque yielding bolts, and that your Toqur Wrench was indeed set right.

 

[Terrymo]

IDK Here’s a screen shot of the original Mopar 2” lift torque specs and hardware sizes. It notes the hardware as M14 with lower torque. The newer instructions you reference show M16 at a higher torque which seems reasonable. I have no first hand knowledge but keep the original lift instruction torque specs as a cheat sheet.

More recent version

 

[BDinTX]

Just a general question... how could they change the bolts?
My understanding is M14, or M16 references the diameter of the bolt in mm at the threads (14mm or 16mm diameter bolt).

Even if the lift kit replaced all the control arms (not just front LCAs), the holes where the upper control arm attaches to the frame and the axle aren't changing.

I wouldn't think there would be that much slop in the holes.
Am I missing something?

It almost looks like somebody messed up the documentation on the second one.
How would you use an M16 nut on an M14 bolt?

The bolt description seems to be incorrect in the above snip:

 

[Terrymo]

@Joe S did you get this sorted? Any updates on the conflicting hardware sizes and torque specs?

 

[Joe S]

The bolts are definitely M16, 10.9 and $21 at the dealership. I’m going to torque them to 185# and send it. I had the torque wrench tested and if was off by 16#, but even at 216# the bolt should not have broke. I tried to bring it up with Jeep Customer Care, but they kept transferring me and I eventually gave up when they mentioned I needed to talk to a technician at the local Jeep dealership. Other than that issue it was smooth sailing.

 

[Joe S]

Today I went to Goodyear to have new tires put on and asked them to verify the torque on the rear control arm bolts. I asked them to torque all 8 bolts to 185 foot pounds as that was a value I had managed to get the upper control arm bolts to prior to breaking the lower one. They verified the torque values online and agreed they should be torqued to 185. They decided to torque to 160 prior to the reaching the final value. They broke the lower control arm to axle bolt at 160 pounds on the opposite side of the bolt I had replaced.

When they went to the Jeep Dealership to pick up a new bolt, they asked for the torque specs and were given the attached instructions for the rear control arms. Nowhere close to 185 let alone 200 foot pounds, but 74 pounds + 80 degrees

Now I am concerned all of the other bolts that were torqued to the values in the instructions, are they all compromised now? Are they going to break on the trail?

I tried to talk to Jeep Customer Care to no avail. I have now sent an email to the dealership I purchased the kit from. I'll update if I hear back from them.

 

[Pape]

190 that would be tbe shit I'll pull on my previous jeep and crushed the sleeve ended up cutting the bolts when it was time to remove them they rarely go over 120 ont suspension

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