Check your bolts!!

[Hemling]

A bit of a close call the other day - actually quite a big deal now that I think back on it. Before heading out on our big camping trip from Miami to Door County, WI, I decided to install Bilstein 5100 rear shock absorbers on my Excursion. I had to get adaptors to mount the eyelet-style upper mounts. I finished the install, really straightforward, and off we went. We make about four stops, really take our time you know, and one of the longer pulls had us going from Northern AL into Indiana. On one of the inclines in the middle of TN, we hear a loud clunk, like we ran something over. I know we didn't - there was nothing in the road that large that could make that kind of sound that I would have missed. Felt like it bounced under the vehicle a few times (hard) and shot out behind. No clue what it was. Climbing moderate grades, nothing too bad, when the rear starts feeling spongy. By the time I look in the side mirror, the left rear is smoking. Dead flat and we were doing 65+ on an uphill climb. I manage to get us pulled over and changed. Back on the road a little sweaty and dirty but all ok. But something isn't right. Handling just isn't 'on' I don't know how to explain it. Have to baby it and slow down a lot for the remainder of the leg. We get in, and I look around, and the crossbolt for the upper rear left shock absorber is GONE. One of the mounting bolts is gone too. The new adaptor is hanging on by one bolt, while the shock itself has unsprung upward and wedged itself between the gas tank and body. I dismount the entire shock absorber, get new hardware, tighten everything up again, and just for fun check the other side. Sure enough, I can wiggle the crossbolt and the locknut is on the last few threads. The constant jarring of being loose has worked the two mounting bolts loose also, but everything is still there, so I tighten it all up again. I KNOW I tightened all this hardware up when installing!?!?! Blew a golfball sized hole in the inner sidewall of a 10 ply tire. All I can figure is you have to torque things up again like lug nuts after a few miles? I'm sure the stress of towing sped the effect, but I just can't believe it was that drastic!

[fj12ryder]

Turtle n Peeps wrote:
The bottom line is this. If you had bolts loosen up in a few weeks or months they were not taken to spec torque in the first place.

Again, read the article you posted. It explains why some, not all, but some bolts in some applications will loosen up if some kind of friction modifier isn't used. That may be Loctite, Nylock, castellated nut, jam nut, or some variation of that.

Many trailers recommend retightening lug nuts after being installed, even if tightened to the recommended torque.

[Turtle_n_Peeps]

How many rod bolts have you ever had loosen up over time?

The bottom line is this. If you had bolts loosen up in a few weeks or months they were not taken to spec torque in the first place.

[fj12ryder]

"Properly tightened bolts don't loosen. It really is that simple."

Uh, did you actually read that link you posted? It stated categorically that "Yes, properly tightened bolts can loosen over time". And it went on to explain why properly tightened bolts can become loose. And what you can do about it.

[Turtle_n_Peeps]

Properly tightened bolts don't loosen. It really is that simple.

Do you check main cap bolts in an engine? Do you check rod bolts in an engine after a few miles?

The reason that they don't loosen is because they meet the proper stretch point and torque.

Here is the science behind why bolts loosen.

[Dtank]

wa8yxm wrote:


Lost a engine mount bolt so went to pull the nut off the mate to make sure I got the right size.... Took it off not with a wrench but my fingers.. Put it back with locktite.

Appears the OP could add - Check your nuts!! - to the thread title?

:W

[wa8yxm]

On my first towed other things happned that resulted in damage to the front clip. so when we got to the body shop some of the mounting bolts for the base plat.. Gone The installer forgot the LOCKTITE instruction.

Lost a engine mount bolt so went to pull the nut off the mate to make sure I got the right size.... Took it off not with a wrench but my fingers.. Put it back with locktite.

Just two of the stories I have.

[bucky]

As the newest Excursion is 15 years old and you live in Miami I would suspect rust in that area. That could cause you thinking you were tightening the hardware when really you were crushing the mounting area.