It started out yesterday when some friends came over to wrench on their Jeeps. One of the guys wanted to go through and torque his control arm and track bar bolts as it had been a while since he last did it. If you've driven a TJ off-road very much, I'm sure you can appreciate how annoying (and possibly damaging) a loose bolt can be.
We broke out the torque wrench and some sockets and went to town. All was going well until we got back to the driver side, frame end, lower control arm bolt. With the torque wrench set to 130 ft. lbs, Jake put the wrench on the nut while I held the head of the bolt with another wrench. He proceeded to torque the bolt. It turned, and it turned, and it turned. I could clearly see that the nut (with a shoulder washer on it) was turning and I could certainly feel the force acting on my wrench.
All of a sudden it snapped, simple as that. The bolt simply twisted in two, along the area where the threads are. The nut never moved off the end of the threads....it never turned a bit, from what we could tell. It was as though the nut was welded to the bolt itself. As we discussed this rather odd situation, Jake told me about the same think happening to his buddy's TJ. In fact, it was the same end of the control arm bracket.
Fast forward to this afternoon. I have a grease zirk that is not taking grease properly. It is on my RE lower control arm. With a wrench and ratchet in hand, I proceeded to remove the bolt that holds the lower control arm bracket in place at the axle.
Although mine did not twist in half, it took considerable effort to remove the nut....I mean considerable effort....and for the entire length of the threads. Enough effort that the nut was hot to the touch....not so hot that you could not hang onto it, but it was pretty darn warm at the least. You can see the nut and bolt above. The last 1/2" of the bolt...note the threads are all chewed up. When I started, there was not a ding in the threads....they were pristine, so to speak. There was a tiny amount of rust about and inch down the threads, but as you can see, the threads there are not damage. This rust may have been on that portion of the bolt that rests just inside of the bracket, now that I think about it and look at the picture.
A close-up of the nut. You can see, inside, where the threads were actually torn from the body of the nut. Yes, I did say torn. I peeled them out of the thread bolts with great effort, by the way.
Here is the end of the bolt. As you can see, it is pretty bad off. I did not even want to consider trying to get the nut back on that puppy. The threads are pretty much trashed as far as I am concerned.
So...what is with these control arm bolts? This one had been in its current setup for one year, to the month. I installed it last March when I did the 2nd lift and the RE arms went on.
Have you ever had stainless steel gall on you? It is as though some of the material from both parts exchange sides and makes for a really messy situation. When I took the nut off, this time, it felt as though this was what had happened. And in the case of Jake's bolt, the nut was seized on the bolt.
I've no idea what is causing this. By the way, the above nut and bolt costs about $9 from the dealer and the truth be know, makes for a sloppy fit in a RE control arms because of the shoulder that is right up next to the bolt head. I stopped by my local ACE hardware and picked up some 14mm x 100mm bolts and nuts today, to replace the one I took out of the control arm. They were metric grade 8.8 instead of the 10.9 that was stamped on the factory bolt. I did some checking on-line and found that tensile strength wise, a 10.9 metric is pretty much the equivalent to a Grade 8 SAE bolt and the 8.8 metric is equivalent to a Grade 5. (again, this is based on tensile strength ratings of both grading systems) I plan on replacing the 8.8 with a 10.9 as soon as I can get down to the local fastener store here in Phoenix.
So, I just though I would pass this along. I've not experienced this with any of the other factory bolts on my TJ, albeit there are some that I have not attempted to remove in the past year either. Maybe it is time to check them and round up some spares, just in case!
I realized that it has been a while since I updated this page and decided it was time to get that taken care of. I replaced all of my existing lower control arm bolts with a batch of 9/16" Grade 8 bolts, lock washers, and nuts. The fit is perfect and hopefully I will be rid of these troublesome factory bolts. Since this write-up was posted on my web site, I've received a number of e-mails from other TJ owners who have experienced the same problems. I've also talked with owners that have repeatedly removed and installed the same factory bolt/nut over and over again (as in like a dozen times). Anyway, I've not seen any more issues since switching mine to 9/16" and I do not believe I will.
4x4 Off-Road Homestead Firearms RC Flying