welding on frames?

a few people may know I'm building a prewar '30 roadster. I have two frames, one is rusty but straight, the is really nice except for a ft. and a half section on the passenger side, right about at the rear engine mounts thats bent, causing that frame rail to raise up about an inch. My idea was to cut out the twisted part of the nice frame, cut the same place (which happens to not be rusty) out my other frame, and weld it into the nice frame.
Someone recently told me its not good to weld on frames, because the heat sort of anneals the metal near the weld, which, next to the normally hardened frame metal, cracks.

is this true?????



thanks in advance for any help!

Joe

 

my daily driver is a nearly new Ford pickup.....the frame on it is welded all to shit. Should I quit driving it?

 

No, frames are not heat treated. You can weld them, using good welding technique and it will be fine. Yes there is a small difference in the weld vs heat affected zone vs the base metal, but they are all near "annealed" strength level. It is good to put a reinforcement doubler piece over any splice, especially where the splice is completely through the frame. Doubler can be a diamond plate or just a rectangular plate. Either will prevent any problems.

 

Generally, no. Only frames that are 6000 GVW or greater are hardened and that is a problem for welding. Your issue will likely be getting beneath the oxidation for good fusion and going slowly to guard against warpage.

 

Weld away. I can assure you that your frame is probably not hardened. I wouldn't want to ride on it if it was. If anything, you may want to warm it up a little before you commence to weld.

 

Why not straghten the good frame?

 

Yes, but not for the reasons stated.

 

That's true.....what can I say?

 

Weld it,I do i all the time

 

How do you think people do kick-ups and boxing and engine mounts and crossmembers and brackets etc etc etc.

 

Yes, but not for the reasons stated.........

Now that was funny...!

 

If you weld the new piece,is it better yo cut the frame straight down at a 90 degree or is it better to cut it at an angle like at 45 degree to get more welding surface???
I have kind of the same problem.

 

Depends on the location and the reason for the repair. The longer the weld, the greater chance for problems. A plate behind the weld is good insurance.

 

Stick or MIG?

 

Welding on a frame? I've been doing it my whole life. Not a problem yet. Bevel both sides a bit. Weld both sides. No plate on the back side is required, as you will be next BOXING that Model A frame. Model A frames are NOT strong enough for added horsepower and todays roads. I have been around A's my whole life. I have seen what happens when you don't box your frame. It ain't pretty.

 

thank for the comments guys!

 

Depends on the location. But with frames, its usually better to make the cut at an angle, or do a step cut. It's easier to keep the frame square with an angle or step cut, as the angle or step will help control one of the axises. The longer weld will make it easier to warp the area if you're not careful, but the increased surface area will make the weld area stronger if done properly. Also, a 90 degree cut and weld (again, depending on where its at) will not usually perform as well under torsional loads, they tend to fatigue at the upper and lower corners. A longer angle weld will spread the torsional load over a larger area, making fatigue and fracture less likely.

In either case a gusset or backing plate will help strengthen the area, and the model A frame should definitely be boxed for a more modern drive train anyway.

 

sorry scaterman dont want to high jack your thread...
Its going to be welded with stick.
I have an ugly step notch on my f1 frame courtesy of the PO.
Its ugly and it steals a lot of room in my bed.
I dont have rest of the stock frame,he made the notch with tubing and the rest of the frame as well.
I want to cut my frame right before the stock kick up part and add straight channel with a c notch right where the axle is and box it.

 

"Box that frame, Bluebear!"

 

I hate the term welding "ON" the frame. It gives the young guys the idea that welds are on top of the parent metal.

Any welding of thick metal like a frame should include the beveling of the parent metal so that the weld goes entirely through the thick metal and is built back up to the surface. It is not like gluing wood together which leaves the joint. A properly executed weld will leave no sign of the original joint.

If your welds are merely scabs bridging the joint ON the frame then you need to get it fixed correctly and there will be no problems.

I know it's only semantics but it can leave a mental picture that is not correct.

 

I would not weld my frame I having a welder do it.
I am just going to tell him how I want it done.

 

You can weld the frame just don't put water on it to cool the weld. let it air cool. Water will harden the weld and the steel around the weld

 

Not really true unless you cool the weld from red hot. As long as the weld is less than red (say 1300F for discussion as less than red), you can cool it any way you want. Air cooling is best, but helping it cool with a cool rag won't hurt. Slower cooling does let some of the residual heat to give some stress relief, but in reality it is not enough to worry about.

The important thing as several have suggested is to get full penetration, beveling the surfaces is a good idea.

 

This is the best answer to your frame problem. Knock it apart and stick teh bent rail into a 20 ton press and it'll straighten right out. When you get welding on a frame it is going to do some things on its own that you may not anticipate - i guarantee. I have welded on a bunch of them and your next post may well be looking for advice how to get a twist out of your frame as when you weld on just one rail in a smallish, local spot it will bite you in the ass.

 

Regarding the Boxing of a frame. Do you need to do a weld on the entire mating surface, or is a can you weld , leave a space, weld , space, Etc?? I ask because my frame has been partially boxed sometime in its life, but it has spaces between the welds. I want to complete the boxing job and correct the previous work if needed.

 

Alternating segments of weld allow for more flex. I always fully weld, but slowly, a section at-a-time, so as not to distort.

 

So stitch welding is ok to do when boxing a Model A frame?

My question is where the plates meet the crossmembers, you don't weld the plate to the crossmember correct?

 

Stitch welding is ok, as long as you keep stitchhing until it is fully welded. Weld the boxing plates to the cross members too. There should be no unwelded seams.

 

if you were to do a stitch welding job when boxing your frame it would crack right at the end of one of the welds, wherever the frame flexed the most, might not happen right away but down the road it would.

 

Just replace the bent piece and weld in and go on about your business.