Yep those trailing arms will split, rip, snap and break! My right one broke and the left one bent pretty good! Y would chevy use something along the lines of a cheap metal when so much of rear end depends on it?

 

FYI - Nilahs MCSS, this is a 3 year old thread.

Those bends are typically the result of:
1 - Someone jacking the car up on the trailing arm, as they were not designed to support the weight of the car on the center of the arm.
2 - Resting a jackstand under the trailing arm, again, they were not designed to support the weight of the car on the center of the arm.
3 - Having some form of an impact to the wheel to force the arm to bend. This would be expected more to a lateral arm then a trailing arm though.

I've worked on a bunch of these W-Body cars (Grand Prixs, Montes, Impalas, etc) and even other cars that GM uses the same type of design, they have survived salt covered roads and crazy driving just fine. Sure, they can be designed better (such as I have full tubular UMI trailing arms on my Monte), but unless you are performance driving or have horrible roads, the stock ones are just fine.

 

FYI The_Maniac, allow me to apologize for simply stating that my trailing arms are bent as well as cracked, along with asking a retorical question. But since you commented on my question, don't attempt to insult my intelligence.

Now let me correct you on 3 things As far as #1&2 goes I know you were not referring to me, and good ole #3...The point of impact does NOT have to be on wheel itself to cause such damage, you should know that since you have worked on X amount of Chevys. Also the only way that salt corrosion will and has done damage...well you know the answer now don't you.

Crazy driving NOT an option, no bumpy roads where I reside, performance driving...on the same street that "normal" driving is done, sounds like a total waste of money and parts to me, I personally get down at the raceway...FYI

One other thing before I head out like a baby...These threads can be 10 years old, they are here for a reason, such as troubleshooting, advice you know things of that nature. Why not keep in mind the next time you decide to answer anothers post or reply to a post...maybe the answer a I looked for wasn't there and I'm gonna ask! If you have to be a _____ (fill in the blanks) in how you answer posts I prefer don't waste your time with my questions please because you seriously come off like a total jerk like you are mr. better than me. I dont like that at all.

Have a nice day

 

First Nilahs, you make a post like this and claim for it to be "rhetorical", I can hardly let it go with out a chance to first apologize. My intent was never to even try and insult your intelligence or anyone else's for that matter.

Your original statement sounds like you are with the belief that these trailing arms are poorly designed and bending/snapping is a common problem as a result. In reality, based through my personal knowledge/experience and reading a lot on this car forum and a few others, very few people have ever had problems with their trailing arms. For that matter, most people who do find a problem with their trailing arms did not know how it happened (hence why I listed some common causes I've seen first hand or read about).

I am a driveway mechanic, I wrench on my own cars and help other friends and family with their cars (and reading a lot of what people have to say on forums like this really does help, I've learned a lot from these Internet communities).

Related story:
For example, I know a family member who took a car for a simple alignment, walked out with the car to bent lateral arms (similar to the problem you commented on about bent trailing arms). He confronted the shop and they insisted they could not have done the damage, it was the result of something else (such as, they tried to say he must have jacked the car up on the arm). Eventually he got them to demonstrate how they prep a car for an alignment with the damaged car, by placing the car back on the alignment machine. He caught them red handed re-performing the steps that damaged the rear laterals (down to where paint marks were left on the lateral arms were lining up with what the shop mechanic was re-doing). As a result, the show did apologize and replace the laterals they damaged.
End related story.

I was not referring to any person specifically with items 1-3. Simply common causes. You could have dropped your car off for a simple service and the service shop could have done the issues noted in points 1-2. They may not have made a significant bend at the time, but once they kink the design, they have then created a weak spot where flex can occur. In the example I listed above about the rear laterals, it was noticed because the car now had a banging noise going over bumps and sometimes you would go over a bump and it felt like the rear end would hop to the left or right (I personally drove the car myself and felt what my family member was mentioning). Currently, my winter car I bought last October has bent laterals thanks to the previous owner (and the way they are bent clearly looks like the problems I noted in points 1 and 2). I don't have the wheel hop, but I do have the noise going over big bumps. I completely intend to replace them in the spring (the car was a cheap fixer-upper and I ran out of time and want to mess with it before winter). If I don't replace them, eventually the weak spot from that bend will fail completely and the metal will split from too much flexing.

I do understand that impact to the wheel is not the only point of impact to bend these arms. Heck, I bent a trailing arm on my '84 Camaro back in '99. It had impact to the rear quart panel. I smashed the side of the car against a telephone pole after I made some bad wheel corrections while slipping on some ice. But, those other points of impact typically leave distinct tell-tale signs.

And as for salt/corrosion damage, those things happen to any part on a car. I had a lower control arm on my former winter car break loose due to corroding a couple years ago (which in turn resulted in a damaged fender). It would be the same way salt/corrosion damage could weaken the metal of these trailing arms. I'm not sure I've ever heard or read of one case of corrosion damage to these parts (not saying it never does, I'm sure service shops get those situations here and there). It's just not common.

I'm not trying to accuse you of crazy driving or any mis-doings with your car. I've had a tendency to like to tweak and make changes to my rides. I have also been known to take my cars to autocross meets and once in a rare while down the quarter mile. I made upgrades like the UMI trailing arms not to waste money, but because even on a street driven car, some of these performance parts improve the feel and handle of the ride.
For example, why do many people who never race a Corvette buy one? A Cavalier serves you just as well for a street car. Some people like the feel and handle of a Vette. By the same, there are those who have no interest in modding their cars, they like them just the way they are (and sometimes, I wish I never got the "mod bug", people have trouble stopping once they get it).

I understand these threads can be ages old. And they are still out there to provide information to people. If you look at most forums, if the thread has been cold for a couple of years, no one wants to begin a discussion on a thread that has been stagnant for that long (a good portion of the time people part of the original thread have been long gone when the thread is over a couple of years in age). From what I've seen in my time on various forums, it's usually best practice that if you are having a problem and seek advice to start a new thread (possibly reference a link to the old one, but start a new one so not to intermingle your problem specifics or resolutions with someone else's thread).

Again, I want to apologize, I was not trying to insult you and I was not trying to give a "I am better then you" attitude. As I read your reply, I really feel you were trying to insult me. But hey, that's life, I'm not going to take offense to it. But what I hope is that in my lengthy response, I provided better clarity to my original reply. I was simply trying to provide information that I have not seen these arms fail as a result of a design flaw but I am aware of some common causes for failure. I was never trying to accuse anyone of anything.

 

TL;DR

Had one of the lateral arms break on my Grand Prix the other day going 60 down the highway. That was a pretty fun experience.

 

I just want to say assumptions cause a lot of riff. I'm apologizing for taking what you said on a personal level... I shouldn't have snaped back at you the way I did.

Thanks so much for your imput, it helped me understand somethings I had not thought about. No hard feelings this way and I hope I can bug you if I need some troubleshooting experience?

Thanks,
nilah

 

I hope it wasnt bad...

 

And sometimes it's tough to read the tone/intent behind an Internet message. Thanks for the taking the time to read my long reply. Apology completely accepted

No problem on the input. That's what we're all on here for. Don't hesitate to bug me or start some threads of your own up. Chibi can a tell you, I had many a question in the realm of modding my Monte, I had a bunch of threads on here and a couple other places. It helps to consult people who KNOW the car your working on (and there are plenty of us here)