I am in the process of welding up and gusseting my frame. I just had it sandblasted. The frame is very solid with no structural rust. I checked it for straightness and it it checked out very good.

What I did find when looking it over was cracks in welds on the upper and lower front suspension mounts. I found 8 different cracks.

The factory welds are less than stellar. Some of them are barely even burned into the part they are supposed to be holding to the frame.
I think this is why we see posts on here about suspensions on some cars tearing loose.

Anyway, after seeing this on a frame I originally thought was very nice, I'm thinking everyone should be checking these things closely, especially if you have gone to better tires, suspension and more power.

Mike

 

+1 for this advice. I noticed the same thing in the engine bay/cross member/control arm mounts on my 74 coupe. I had the welds cleaned up and reenforced. I didn't gusset the frame though; which was mainly due to lack of experience. I will do so on next project.

 

Where on the frame are you planning to add gussets? Are the gussets hand fabbed or purchased parts?

 

I'm hand fabbing the gussets. I'm doing all the high load areas of the front and rear suspension and a few other places I feel could use it.

Mike

 

Yea I have a weld repair on the front cross-member - I hear it's common there. Quality control was very poor on the production line those years IMO. Now that most cars are unibody its done by high tech robotic welders making spot welds. Who's to blame for that happening?



Try a google search for the Chevy Power Manual/Catalog for C3 frame improvements. I've seen it several times and it details all the reinforcements Chevy recommends for the C3.

 

I found 2 cracks in the upper frame differential mount today and 1 in the front frame differential mount.

I am very glad I decided to pull the body off and weld up the frame.

I made my gussets for the front lower suspension mounts a put one on the frame above the sway bar mount.

Im not a welder and this oil contaminated metal has been a struggle for me. Everything is burned in good, just hard to make pretty welds when it's spitting and popping at you.

Mike

 

Back over 30 years ago I saw the cradles have splits in them...and it seems that that is an area that I look at very carefully now due to the car is so much older now....and never really knowing how it is being used.

Also knowing that GM never intended for these Corvettes to last as long as many of us have helped keep them on the road and the brand alive...there is a point of failure due to fatigue.

Heck...even commercial airplanes get sent out to pasture due to the number of hours it has been in the air...so they do not fall apart in the sky.

So anything that can be done to help out the frame in the weak spots or giving it a 'freshen-up'...is wise.

DUB

 

What type of welder are you using Mike? If you have a MIG welder there is gas mix using CO2 and wire rod types that are designed to weld rusty and painted steels. But good MIG welding does sound like frying bacon. Ask your welding supply store especially if they supply your welding gas. Practice on scrap metal helps too.

 

It's a small Lincoln and I'm using CO2. Most of the welding I've done in the past was with a TIG and argon on new metal making parts for my Top Fuel bike. This Lincoln belongs to my friend at the shop he is also letting me use.

I'm getting good welds, just not so pretty in some places. This car was so oily and greasy underneath when I got it, that when I cleaned it off, a lot of the steel was still shiney. It must have leaked terribly right from the factory. It's good and bad, it saved the frame from rust, bit it is every nook and cranny of the frame still after being degrease, pressure washed and sandblasted. It is in seams and places where piece were attached to the frame. It makes the bead spit back at me, smokes and catches fire. Some places are OK and I get a good looking bead, but in the bad places I just have to stay at it and burn the crap out, then the bead burns in good. It isn't the prettiest bead, but it's still strong. Thank goodness for grinders!

Mike

 

Hey Mike.
Following this thread.

How did you check the frame for straightness?
I have 3 frames I'll be working on over the next year and I'd like to know how to do this, short of taking it to a frame shop.

I'll be starting on my first one later this week.

Anyone else knows how...please PM me or if Mike doesn't mind, post it here.

Txs
Dennis

 

I first checked the frame for square by measuring diagonally between body mounting points and between suspension mounting points. Everything checked within 1/16" inch. I can't imagine they were ever any closer than that. I also measured straight between suspension mounting points from front to rear and compared that measurement side to side.

I had the frame on a nice flat and level spot on a concrete floor. Not as good as a frame table, but close enough. I took measurements from each suspension mounting points and spots on the frame. From the frame to the floor was again within 1/16" to the floor from side to side.

The measurement between the upper a-arm mounts was within 1/8" of the 26 3/8" original spec, being at 26 1/4.

I was more worried about the frame checking square and straight then matching original specs. Door gaps were pretty good on the car, as were height side to side before I lifted the body off.

Mike

 

THANKS Mike!

Appreciate the response and the details.

Good luck with your project.

Dennis

 

When I restored my 83 GMC 4x4 I called several shops and only found one who could check the frame and had a rack to pull it back into specs if needed. Most racks now days are computer programmed and if the shops don't purchase the programs for the older frames they can't check or straighten them. There is a great guy in Yuba City, CA. who has been doing full frame off custom and classic cars for years if anyone needs someone in Nor Cal.
I played with some welding years ago so I'm planning to take a class at my local college before I pull the body on my 73.

 

Dennis,

Not sure what year you are working on but I have these posted on my tech page for all C3 cars... and 1963. I've not had time to add the 1964-1967 charts. But if you need a better pic you know how to reach me.

Ernie

http://repairs.willcoxcorvette.com/1...mension-chart/

 

Mike on dirty metal I was taught to use a propane torch or even better MAP gas and heat up the whole area to be attacked. It burns away oil and paint then hit it with a wire brush just before welding. Welding on pre heated metal will also prevent cooling stress cracks.

My 79 frame developed cracks right around the lower a-arm connection point. I attributed it to 700# front springs and my 295 width front road racing slicks.

I welded right over the cracks and then ground them down flat and "fish" plated over the whole area. The upper area was done like the chevy power book suggested 20 years ago.

 

THANKS Ernie......appreciate that.

Dennis

 

Dennis..

Just right click on the pictures, select copy and paste them into your paint program. They'll be larger than what you see on the tech page and easier to read.

E

 

Not that this matters but on my MIG welder I use a CO2/Argon mix gas ...which I am not mistaken is a 75% CO2 and 25% argon.....and not just CO2. I know when I tried to use strictly CO2...it would not weld correctly.

'cardo0' is also correct..at least in my opinion..when I am welding... I preheat the area of I feel the welder will not penetrate the steel well enough due to the thickness of the metal and I want to hear my welding process sound like frying bacon.

ALSO..be aware of the welders 'duty cycle'. If it is not 100% duty cycle...then it will only weld effectively for the amount of duty cycle it is rated at. Check into that...because it does make a difference.

And not that this matters also...but the BEST weld is one where gravity is aiding in pulling/drawing the weld into the metal. So vertical and upside down welds may not be as good as welding horizontally. And how I know this even though am not a certified welder...is that my old roommate was ..and worked for a company who built huge compactors in really thick plate steel...and the fixture that hold all the parts for welding ....could fully rotated 360 degrees so that EVERY weld was always horizontal.

DUB

 

Thanks Dub,

The CO2 is what my buddy has and so I use it. I know it would do better with argon, which is what I was used to when I did any amount of welding 25 years ago. I've modded and built frames, I just didn't do much of the actual welding, but was side by side with several very good welders over the years. I've done a ton of fabrication though.

I have been welding mostly horizontal welds on top I don't need to weld upside down, because I can just flip the frame over. A little bit of vertical welding is all there is. The welds are burned in good, the small Lincoln welder is a 230 volt unit, not a little 110 volt. It can burn through the thin steel used on our frames If you turn it all the way up.

I made gussets for the top differential and suspension mount today. There are gussets for the side under the frame rail too that I will weld in after i flip the frame over.

I pressed out the sombrero bushings and am going to weld in disks to raise the differential in the frame or lower the frame over the differential and rear suspension, whichever you prefer to call it.

 

I pressed out the sombrero bushings and am going to weld in disks to raise the differential in the frame or lower the frame over the differential and rear suspension, whichever you prefer to call it.


Van Steel has a kit for this.