Front cross member crack
Thread Starter
Intermediate
Joined: Aug 2014
Posts: 26
Likes: 0
Front cross member crack
I have a 1979 C-3 that I was having some brake problems and the Driver side tire would rub. It has the 350 with a 700R4 tranny. I have searched and found some good info about the repair. I am going back with black poly bushings, I know I know use the rubber well it had the rubber in it so I guess it couldn't go to bad. I was going to hire a certified weld to come over and repair it, I can weld but I would feel better with a expert. My question is has anyone had the repair done and how has it lasted no more problems? more problems? I am going to take the motor out so I have good access to the area top bottom sides. any advise?
Melting Slicks
Joined: Sep 2011
Posts: 3,372
Likes: 215
From: Peoria Arizona
I have read posts on here about this exact thing. Try doing a search on the forums for it. Not sure if there were follow up posts about the durability etc., but it has happened to others as well.
I think you're on the right track with hiring a pro to do it. This is a MAJOR structure on the car. Do it right the first time.
Good luck with you project!
Adam
I think you're on the right track with hiring a pro to do it. This is a MAJOR structure on the car. Do it right the first time.
Good luck with you project!
Adam
Le Mans Master
Joined: Aug 2010
Posts: 8,519
Likes: 505
From: Bussey, IA
I have read posts on here about this exact thing. Try doing a search on the forums for it. Not sure if there were follow up posts about the durability etc., but it has happened to others as well.
I think you're on the right track with hiring a pro to do it. This is a MAJOR structure on the car. Do it right the first time.
Good luck with you project!
Adam
I think you're on the right track with hiring a pro to do it. This is a MAJOR structure on the car. Do it right the first time.
Good luck with you project!
Adam
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
I weld in the frame cracks from time to time....and honestly...I do not remove the engine in 99.999% of the cases. I do remove what I can and NEED to gain access...but rarely need to remove the engine due to it being further back that the lower control arm perch. With no photos of what you have for cracks...who knows.
DUB
DUB
Team Owner
Joined: Feb 2003
Posts: 54,120
Likes: 9,428
From: Sitting in his Nowhere land Hanover Pa
2024 C2 of the Year Finalist - Unmodified
2015 C2 of Year Finalist
I would be more concerned as what caused the crack. It's going to have to take some hard abuse to crack a frame
Thread Starter
Intermediate
Joined: Aug 2014
Posts: 26
Likes: 0
Thanks, I think I am using the crack as a excuse! The numbers on the car do not match. The 350 numbers do not match and it has chev performance fast burn heads on it, I have a LS 6.0 that needs a home and I am sure its is calling for the Vette. It just happens that around the corner on the other street the guy is a certified welder and I had he come by this after noon. He said he has done some of these??? is this a common problem? He said he would only Tig the repair then for added support he would fish plate ( I think that what he said ). He didn't give me a price yet he just asked if I wanted him to do it, I want to just get some other est or ideas. does this seem the way to go? for the reason why it cracked I can only guess, the front end was worn out. no or VERY little rubber bushings in the control arms upper and lower, when I took it apart the springs were broken just past the 1st coil. the rubber stops look good they have not been smacked they look good I am hoping it was just neglect that caused the crack. I have tried to attach pics but its not working I am sure its the comp not the operator??
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
I have seen cracks and splits in the steel near a factory pi$$ poor weld....and also some of the spot welds letting loose...and YES..it can be attributed to the car having a ROUGH life..and also can be due to road conditions and just the design. Some cars have no problems...others have spot welds and splits in the frame by a weld.
I have no idea what 'fish plate' means.
DUB
I have no idea what 'fish plate' means.
DUB
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
A fish plate is a plate of steel resting over the crack and welded to the good part of the frame. The plate is generally square and positioned so the pointy ends of the plate run past the top to the bottom of the crack (assuming a vertical crack) with the other pointy ends running a couple inches to either side. Obviously, crack length and location dictate the final shape of the plate. You prep and weld the crack, grind down the weld, lay the plate over the crack area and weld the fish plate to the frame. This way, the crack isn't coming back since the plate is providing most of the integrity of the repair.
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Verdad Gallardo
Instructor
Joined: Feb 2013
Posts: 193
Likes: 2
From: Illinois
I had read more than once here on CF about the engine cradle area of the frame and how much flex occours. Over the decades this can lead to metal fatiging of some of the welds and actual frame components especially if the car has been driven alot.
When I had my engine out for a build (and after cleaning the entire cradle to paint), I did a detailed inspection. Sure enough I found some partially cracked welds and some torn metal. I mig welded all up even adding some beads where ther weren't any and continued to prime and paint.
After the engine re-install I also made my own spreader bar and installed it between the upper A-Arm mounts. The benefit of this is better handeling and a much stronger cradle, greatly reduced flex and fatigue. Something to think about as well when your welder finishes up.
Pic of spreader bar:
When I had my engine out for a build (and after cleaning the entire cradle to paint), I did a detailed inspection. Sure enough I found some partially cracked welds and some torn metal. I mig welded all up even adding some beads where ther weren't any and continued to prime and paint.
After the engine re-install I also made my own spreader bar and installed it between the upper A-Arm mounts. The benefit of this is better handeling and a much stronger cradle, greatly reduced flex and fatigue. Something to think about as well when your welder finishes up.
Pic of spreader bar:
Burning Brakes
Joined: May 2013
Posts: 789
Likes: 129
From: Los Banos CA
Here is the thread for my 79 cross member crack and repair. It's holding up good after at least 1000 miles or more....
https://www.corvetteforum.com/forums...me-advice.html
https://www.corvetteforum.com/forums...me-advice.html
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
A fish plate is a plate of steel resting over the crack and welded to the good part of the frame. The plate is generally square and positioned so the pointy ends of the plate run past the top to the bottom of the crack (assuming a vertical crack) with the other pointy ends running a couple inches to either side. Obviously, crack length and location dictate the final shape of the plate. You prep and weld the crack, grind down the weld, lay the plate over the crack area and weld the fish plate to the frame. This way, the crack isn't coming back since the plate is providing most of the integrity of the repair.
I never called it that. Learned a new term. Here is the thread for my 79 cross member crack and repair. It's holding up good after at least 1000 miles or more....
https://www.corvetteforum.com/forums...me-advice.html
https://www.corvetteforum.com/forums...me-advice.html
DUB