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Has anyone seen a trailing arm fail like this? This is on my 77 L48 original drive train. I drive it a couple of times a week and never drive it too aggressively. It's an Arizona car since new so no rust issues.
what is the piece on the bottom end of the bolt, it should be a rubber cushion but I see no sign of compression like the cushion on the top of the bolt?
Hi S,
????
In looking at the remains of the T-arm it appears it tore through the hole for the bolt….but the bright silver areas seem small and it appears there were rusted 'cracks'?
Were these now rusted cracks the beginning of the failure?
Regards,
Alan
Something doesn't look correct in that picture. The area where the spring bolt passes through the arm should be a complete open-end box. It looks like the only support was from a single plate extending from the arm (the shiny edge). It's as though the top and sides of the "box" were cut or had been broken for some time. Am I seeing things?
Looking at your picture, the trailing arm is formed by two separate "U" shaped pieces, where one slips inside of the other and is then welded forming a "box" open in the center. At the rear of your arm you can see at the top where the two pieces overlap (the horizontal red and blue lines). The bottom of these "U" shaped pieces has broken away from the rest of the arm. This would not be so unusual, except that you say it is a life-long Arizona car and there is no rust otherwise.
Also there are areas in your picture (yellow lines) that are not ragged as you might expect to see from a fatigue crack which might otherwise explain the failure.
Perhaps if you were to remove the separated piece from the spring bolt and take a close up picture of it and one holding it in proximity of where it came from in the arm it might give us a different perspective and provide you additional feed back.
Regardless, you'll be needing a new (refurbished or otherwise) trailing arm to mount your bearing support in and replace the one you have. There have been a few recent posts that recommended vendors such as Bair's of Pennsylvania or Vansteel out of Florida for refurbishing trailing arms. Both of them should be able to supply you what you need. Also depending on the mileage on your car and it's maintenance history, this might be a good time (certainly a convenient time) to consider refurbishing the rear bearings as well. On the C2's and C3's it is only a matter of time before they will fail and a failure on the road would likely double the cost of refurbishment now.
what is the piece on the bottom end of the bolt, it should be a rubber cushion but I see no sign of compression like the cushion on the top of the bolt?
There is a rubber cushion on the bottom. The previous owner replaced them before I bought the car. I can't attest to the quality of the parts used or the correctness of his work. It's been trouble free for nearly five years. I'll start looking at vendors for a replacement and I will check the other sid too. Thanks guys.
I'll be doing a closer inspection of my T/A now....but I will repair/reinforce them if they are weak, since I rebuilt the assemblies about 1500 miles ago (didn't notice any problems).
It is strange that the bottom rubber shows no sign of compression.
Better safe than sorry.
Last edited by doorgunner; Feb 6, 2017 at 05:47 PM.
I'll be doing a closer inspection of my T/A now....but I will repair/reinforce them if they are weak, since I rebuilt the assemblies about 1500 miles ago (didn't notice any problems).
It is strange that the bottom rubber shows no sign of compression.
Better safe than sorry.
I took apart the bolt and put the broken piece back in the trailing arm. Very strange how it tore. I checked the passenger side and that one is ok.
it looks like the only thing holding the top together is your sway bar bracket, I think if it was me and the rest of the arm looked good I would take it off and find someone to weld it and add some reinforcement
I took apart the bolt and put the broken piece back in the trailing arm. Very strange how it tore. I checked the passenger side and that one is ok.
Patrick, thank you for posting that picture. It is very illuminating and clearly shows a fatigue type failure. The crack started at the back and worked it's way forward where it ultimately failed. It also shows that both longitudinal cracks are rusted which means that it started a while back, perhaps a year or more.
I have never seen a crack like that before in a trailing arm, but I've seen arms that were so rusty that it is a wonder they were still holding together at all. Since your control arm appears otherwise to be in good condition, it makes me wonder if a vibration type fatigue could have led to the cracks that were then aggravated by being so close to the spring attachment point.
What is the condition of the rear wheel bearing on that side? When you begin to disassemble it, after the half shaft is unbolted, pay close attention to how smoothly the spindle turns on that side. It is conceivable that a high frequency vibration form a failing wheel bearing could create a fatigue crack. Although more often than not once a bearing begins to fail, they progress rather rapidly and that looks like it had been cracked or at least started to crack, some time ago.
Good luck, and let us know what you discover... GUSTO
The road that leads to my house is dirt and often very washboarded. I suppose this could be a contributing factor as to the vibration. On the highway the car was very quiet in the rear with no noticeable noises or vibration. I'll let you know what I find when I get into the teardown.
Looks like aftermarket bolt and poly bushings. Those bolts are usually longer than stock to lower the rear of the car. I don't see any threads showing so they may have been cranked all the up. No sure if that is an issue or not. Just an observation.
Is it possible the end spring bolt struck something in the past and damaged the TA?
I was thinking the same thing. We have a place in Tucson and have to go through a wildly rutted up road with large rocks. Hell I just had to put in new tires on the Honda Pilot bc they were all chewed up. I have never seen a failure like this but have seen frame cracks. You didn't Dukes of Hazard this baby did you?
Something was definitely striking the sway bar brace-the imprint can be seen. But my question remains, where is the remainder of the "box"? All that is shown is the bottom part that is held in by the spring bolt. And as far as the construction of the arm, didn't GM at least spot weld the area where the two layers overlap? I'd like to see a profile picture of this fracture.
Something was definitely striking the sway bar brace-the imprint can be seen. But my question remains, where is the remainder of the "box"? All that is shown is the bottom part that is held in by the spring bolt. And as far as the construction of the arm, didn't GM at least spot weld the area where the two layers overlap? I'd like to see a profile picture of this fracture.
This is the passenger side. It looks like it's spot welded only on the bottom.
Trailing arm failure
It is very illuminating and clearly shows a fatigue type failure. The crack started at the back and worked it's way forward where it ultimately failed. It also shows that both longitudinal cracks are rusted which means that it started a while back, perhaps a year or more.
