Frame/A Arm failure
Thread Starter
Safety Car
Joined: Nov 2005
Posts: 3,960
Likes: 571
From: Lompoc, CA. Santa Barbara County
Frame/A Arm failure
While Autocross racing today, my right front suspension collapsed. This is what I found when I got the car home and on the lift. The lower A Arm welded on mount had torn away from the frame! I've never seen this before. My frame needs the A Arm mount re welded into place. Anyone have to do this?
Team Owner
Joined: Sep 2013
Posts: 36,415
Likes: 6,904
From: New Or-leens Loo-z-anna
WOW!
Will you do the repair yourself......or will you have a Shop repair it ?
(I have a small break in mine--but no separation yet/guess it's time to repair it after seeing what happened to your frame!)
Will you do the repair yourself......or will you have a Shop repair it ?
(I have a small break in mine--but no separation yet/guess it's time to repair it after seeing what happened to your frame!)
Melting Slicks
Joined: Aug 2012
Posts: 2,548
Likes: 379
From: Woodinville WA
yikes. A long while ago I was complaining about the crap welds GM put on that bracket - it devolved into a big argument - thanks for validating me? that doesn't too terribly hard to repair.... though doing a weld front to back might be in order (along with welding the bottom plate to the top hat of the cross member.)
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
Wow! How stiff are those springs??? I'm surprised because there is absolutely no rust or damage.
The good thing is nothing ripped and fell off! You can slowly heat bend and weld everything back. Then weld in some light re enforcement over the welded areas.
The good thing is nothing ripped and fell off! You can slowly heat bend and weld everything back. Then weld in some light re enforcement over the welded areas.
Burning Brakes
Joined: Sep 2012
Posts: 818
Likes: 0
From: coon rapids mn
Scary ,and the pre 1980s should have a little better frame then my 1980 .there was a great thread on welding up and strengthening the frame .maybe look into a after market frame ,they start at $4000.mite be cheaper then having a shop fix it .
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
That is some serious chit! You have been hammering that around the autoX I see. That is not going to be an easy one to fix. Anything can be done with enough time and money. Let us know the results. Looks sad on the flat bed 
Race Director
Joined: Apr 2000
Posts: 17,641
Likes: 187
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
That can be fixed by someone who knows what they are doing, pretty thin metal in that spot and others on our '80's. Was starting to prep mine for road courses, now I am a bit worried.
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Racer
Joined: Jan 2004
Posts: 303
Likes: 28
From: los angeles ca
If you drive a corvette the way it was meant to be driven the lower A arm attachments will crack and eventually fail.Not if but when.
Some of the worst of the many bad welds on a Corvette.
I check mine for cracks every time I am under the car after fixing it the first time.
It is a lot easier to weld cracks than fix a major failure.
All those parts are available new but you can probably straighten and re weld what you have. Not easy but doable.
Do both sides before the other side fails it is most likely cracked too.
Re weld all the weld slots in the mounting channel and stitch weld the out side to the cross member. Now is a good time to add the PM gussets.
I could not find frame dimensions for the A arm shafts to aid in repositioning them.
But mine ended up slightly wider in the rear C/L to C/L +1/16<.
That may or may not be right but it adds castor.
It looks ugly now but you can fix it and make sure it does not happen again.
Some of the worst of the many bad welds on a Corvette.
I check mine for cracks every time I am under the car after fixing it the first time.
It is a lot easier to weld cracks than fix a major failure.
All those parts are available new but you can probably straighten and re weld what you have. Not easy but doable.
Do both sides before the other side fails it is most likely cracked too.
Re weld all the weld slots in the mounting channel and stitch weld the out side to the cross member. Now is a good time to add the PM gussets.
I could not find frame dimensions for the A arm shafts to aid in repositioning them.
But mine ended up slightly wider in the rear C/L to C/L +1/16<.
That may or may not be right but it adds castor.
It looks ugly now but you can fix it and make sure it does not happen again.
Melting Slicks
Joined: Jul 2006
Posts: 2,253
Likes: 467
From: Salmon Arm, BC
I looks in that second pic, that it had been cracked for some time. A little rust on some of the crack it looks like. Just took some time and added stress for a fatigue failure to happen.
Are you going to fix it yourself, or have it done?
Are you going to fix it yourself, or have it done?
Advanced
Joined: Aug 2012
Posts: 95
Likes: 0
From: Woodstock Alabama
the lower a arm mounts are the weak link of the stock front suspension. I bought a junk yard coupe to get a good frame , but then I found this. so I took it to a frame shop and they repaired it all. no sweat for those guys, but as you can see, it's not a repair that you want bubba to do for you.
the arm mounts had been ripped off both sides and the bottom of the crossmember torn out. bubba did the best he could but overhead welding was not his strong suit. notice the square tubing added to try and fix it.
the arm mounts had been ripped off both sides and the bottom of the crossmember torn out. bubba did the best he could but overhead welding was not his strong suit. notice the square tubing added to try and fix it.
Last edited by beautimus; Oct 5, 2014 at 07:36 PM.
Advanced
Joined: Aug 2012
Posts: 95
Likes: 0
From: Woodstock Alabama
this why they cut all that metal out, but yours will not be anything near that bad. I just put these pics up so you can see that its not as bad as it seems. if mine can be repaired to the point that it looks like it was never damaged, yours will be a snap for the right guys to repair.
Burning Brakes
Joined: Aug 2004
Posts: 802
Likes: 1
I did a frame off restoration on a 73 to fix rusted areas. I was shocked when I saw the quality and lack of welds on that A arm bracket. Plus it is welded to a flimsy sheet metal belly pan.
The real structure is at the big bolts at the front and rear of the bracket, but that is sheet metal as well.
If you hit the wheels at a curb stop, you are placing a lot of torque load on that A arm bracket.
During frame restoration, there is some people that add a lot of gussets to support this area of the frame with good reason. But it deviates from stock.
In my opionion, the C3's have outlived there usefulness as platforms for performance builds.
Steve L
73 coupe since new
The real structure is at the big bolts at the front and rear of the bracket, but that is sheet metal as well.
If you hit the wheels at a curb stop, you are placing a lot of torque load on that A arm bracket.
During frame restoration, there is some people that add a lot of gussets to support this area of the frame with good reason. But it deviates from stock.
In my opionion, the C3's have outlived there usefulness as platforms for performance builds.
Steve L
73 coupe since new
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Wow, from the pix it looks like both sides ripped out from the frame. The chevy power manual used to have reinforcement details for the C3 (1969).
http://www.corvettefaq.com/c3/ChevyPower.pdf
They recommend gussets on both upper and lower control arms but your crossmember looks trashed also. Sorry i know its late now but if u seek repairs then this is another source for reinforcement of the front suspension. I share your loss as i know how much a corvette enthusiast you are as it will be a tough repair from underneath the car and pretty much the entire front end will need to be stripped - including removing the engine.
Thx for sharing as it helps us all.
http://www.corvettefaq.com/c3/ChevyPower.pdf
They recommend gussets on both upper and lower control arms but your crossmember looks trashed also. Sorry i know its late now but if u seek repairs then this is another source for reinforcement of the front suspension. I share your loss as i know how much a corvette enthusiast you are as it will be a tough repair from underneath the car and pretty much the entire front end will need to be stripped - including removing the engine.
Thx for sharing as it helps us all.
Burning Brakes
Joined: Dec 2008
Posts: 971
Likes: 45
From: Middlesex NJ
I have seen this in several posts very ugly for sure. Most seem to happen when someone slams the front wheel into a curb and bends it back. This doesn't appear to be you case and your frame looks pretty clean and rust free. I also see poly bushings.
Did you happen to tighten the lower control arm bushings when the front end was suspended in the air instead of with the front end loaded down on the ground after settling in?
I see you have poly bushings as well. It just looks to me that the metal just fatigued and then ripped out in the (circular) direction of how the control arm swings under compression load and that the bushings (both front and back) appear to have ripped the metal attachment points (front and back) due to stress loading in the direction the bushing was turning?
Do you have the lower control arm bump stop bushing on the lower control arms?
If you had tightened the lower bushing while the front end was suspended in the air you would have imputed a preload on the bushings for when the car was lowered and if the lower control arm bumpers are missing then you could really over turn the bushing on compression travel?
Did you happen to tighten the lower control arm bushings when the front end was suspended in the air instead of with the front end loaded down on the ground after settling in?
I see you have poly bushings as well. It just looks to me that the metal just fatigued and then ripped out in the (circular) direction of how the control arm swings under compression load and that the bushings (both front and back) appear to have ripped the metal attachment points (front and back) due to stress loading in the direction the bushing was turning?
Do you have the lower control arm bump stop bushing on the lower control arms?
If you had tightened the lower bushing while the front end was suspended in the air you would have imputed a preload on the bushings for when the car was lowered and if the lower control arm bumpers are missing then you could really over turn the bushing on compression travel?
Last edited by mysixtynine; Oct 6, 2014 at 01:56 PM.