Aussie79

I have seen threads before about this but didnt think it would happen to me, it really is a weak spot on the Corvette chassis. 1 year ago I put new nylon bushes throughout the front end on a complete chassis rebuild, I had a 4 wheel alignment done and it has been great up until a few weeks ago when I noticed on braking and turning left at the same time my tire was rubbing on the inner guard, I even posted here about it and most said it happens on some cars and dont worry about it, well if yours starts rubbing you had better worry about it because here's the cause of mine. You will notice that this area has had a previous repair by the previous owner.



A break or tear along the cross member of the chassis where the bottom A arm bolts to the cross member, the whole A arm is about quarter inch lower than it should be at the front which translates to the wheel moving backwards (rubbing on guard). Here's a pick from the front where the metal has given way at the front A arm bolts.



Lucky I caught it before it became catastrophic, I believe it is repairable with some welding and extra gussets welded in but I would like to hear your opinions before I make a start. The crack starts at the front right side of the member at where the A arm bolts are, goes left across the top of the A arm bolts and then turn to the rear of the car for about 2 inches.

Comments on how best to fix this welcomed.

Thanks, Dennis.

AdamMeh

Wow... glad you found it before it got really bad - meaning that you didn't get hurt or have an accident. Thankful for that.

Hope it can be fixed without having to go to far into the car.

Adam

Procrastination Racing

I think I would start by pulling the body of the frame.

Drastic, I know, but with it off, you can flip the frame over and weld down on the bottom as opposed to welding overhead.

Get someone who really knows there stuff, because welding on a frame is not recommended due to stresses it creates.

Indiancreek

I would get the weight off of it, remove the "A" arm and anything else in the way. I'd have it TIG welded. That will make the crack the strongest part of the area.
The welder will know how to do it, but V it out a little, do a root pass and then lace back across a couple times. There is a very good welder on this site who would be the guy that can tell you best. I'll look his name up and post it in a few minutes.
"13brenova" is his deal. Check his prior post and look at his work.

vanice

More common than you may think. The nut is most likely the cause that set this crack in motion. When you fix it grind a radius on the side that will be pointing toward the back. The sharp edge stresses the metal and over time you wind up with a crack.

7T1vette

Call around to find a good welder that has portable equipment and can come to you to do that repair. Once you select a welder, have him come look at the problem and advise you of what needs to be removed for him to have adequate access to the break. (Body off to do a frame 'patch'? I don't think so...)

The welder will advise you of any prep cleaning required, protection of other parts in the area, and what to do about fuel concerns, etc. Then, get the car ready and call him back to do the repair.

Be prepared: The welder may find that there is more damage in that area than you have noticed. If he's good, he'll probably look the frame over in other areas (old frames rarely go bad in just one area!); and he may suggest that other areas be reinforced, as well.

billcarson

wow glad your ok as it could have been much worse.this smells like a situation well documented by many on this site regarding the use of anything but rubber bushings where movement is necessary in more than one plane.they warned against the use of poly solid or any other bushing that would not allow this movement.i just did mine and went all rubber on their advice.the frame looks solid otherwise which makes me believe a stress is being put where it doesn't belong.good luck on the repair.

GREGG-73

The welding to repair the issue by the prior owner is what has caused your fracture in the base metal. Its obvious to me that it was done improperly and the weldor over heated the material causing the HAZ (heat affected zone) adjacent to the repair to fail. Lots of great advice above....be sure to get experienced people involved in the repair, or you may not be this lucky the next time. And it ain't going to be cheap! JMO





Stay in tune....

Aussie79

Well I dropped my car in to the smash repairers today to have him look at the damage (yes I drove it, very carefully I might add, its only about 3 miles) and he didnt seem to disturbed by what he saw, he said that he has seen and repaired this kind of damage to many vehicles over the years. I have had work done by this guy's shop before and like his work, he is also a fellow C3 owner so he appreciates how much these cars mean to us. He couldnt give me an exact price as he will be charging by the hour but thinks it shouldnt exceed a few hundred dollars, he spoke about undoing some of the previous Bubba repairs and welding and redoing it properly with strengthening gussets and plates. I left the car with him and will be able to pick it up in a few days. I will post pictures of his repairs so you know how it worked out. I will obviously need to have another wheel alignment done when I get it back too.

Cheers, Dennis.

69 Chevy

Not funny that this happened. But funny that you don't think this amount of metal fatigue is NOT catastrophic!

I agree with GREGG-73 that this tear is in the heat-affected-zone of the previous weld repair.



I would be very surprised if your repair shop TIG welded those repairs.

This damage did NOT happen from hitting one pothole. It happened from neglect.
I also do not think non-rubber bushings had a thing to do with it.



All C3 owners would do well to crawl under their antiques and inspect them on a regular basis. Then this type of damage would be way less likely to happen.

Thanks Dennis for the good pics.

mrmagrath

Mate, Silvester V8's here in Christchurch have 3 C3 chassis for sale at the moment if you wanted to go down that route.
http://www.trademe.co.nz/motors/car-...-452910429.htm
Just across the ditch and with a favourable exchange rate.
Cheers

Aussie79

Thanks and worth noting but my chassis (except for this crack) is in much better shape than those on this website, in fact most of mine has still got the factory black paint on it, ex-Californian car and always garaged by its one previous owner, I think it is just bad luck, any frame could do this and many will, 69 Chevy said it best "All C3 owners would do well to crawl under their antiques and inspect them on a regular basis", the thing to remeber here is that our cars are in fact antiques, I work in the aircraft industry and if we neglected aircraft like we neglect our cars they'd be falling out of the skies like rain. No it's not catastrophic, catastrophic to me is when the frame completely lets go at 60MPH and the wheel assembly goes under the car and destroys it and probably you too.

mrmagrath

That's a chilling thought........

mrmagrath

BTW, love it up your way!

Indiancreek

It looks like the first fixer just layed the MIG to it for a volume of weld. That caused all the heat. TIG wouldn't have heated the area so much. Wondering, what engine mounts are you running?

Aussie79

I replaced the engine mounts a year ago along with the bushes, used stock rubber mounts from ZIP, considered poly but thought of the vibration transfer and stuck with rubber. Why?

Picked car up tonight, $200 and happy with the job, he didnt use any plates or gussets, he cut out all the old weld crap, used a porta power to close up the gap and re-welded all the broken bits back together, then for strength he welded the block that the two bolts go through for the control arm in to the chassis making it part of the chassis now. He sparayed black gloss everywhere to pretty it up so the pics have a lot of reflection, not as good as the first pics but you get the idea.

Indiancreek

Any weld behind the two bolt plate? I wonder, I doubt it, if he removed the plate/bar. Was the tear behind the plate/bar, looks like it but not sure from the pic?

69 Chevy

Doesn't look TIG welded to me.

Indiancreek

Not TIGed. Looks like MIGed to me. My only question is did he just weld the two ends of the tear and is the middle still there behind the two bolt plate/bar. Much more work to remove the bar weld the split the full length. Then grind weld to let the bar be replaced. I was guessing 3 to 4 hundred bucks when I first tried to figure out how I would get at it. If it were a job I was looking at doing.