Is that how they do it below the equator?

I would think all of that is just extra weight.
A properly stitch welded chassis would be plenty rigid.

I have some doubts, but without real testing, the results of either strategy are very subjective.

I did some stiching in various areas and I added about 45lbs of chassis reinforcements to my car. They lie very low on the car, not rotating, and are fairly centralized. I won't be a good enough driver that 45# is going to make or break my lap times anytime soon. I think most here would struggle to walk that line.

A consistent, non-compliant chassis can be tuned, hold more consistent kinematics and be more predicable to a driver...let alone it will aid in keeping the car eventually twisting itself apart. It's an old chassis and developed in a time where engineers could only dream of FEA. I feel that some areas need more that stitch welding. I'll take the weight "hit" to tie a few extra components together with some plate.

That's my methodology.

....oh and since I'm not a welder for a living, or well-trained, all my work is trash anyway. So who cares?

I think you should rethink this, especially the lower radiator support reinforcement. Think about it, the k member is reinforced, but what does it bolt to? The frame rails, which basically are flapping in the breeze out front. Hit a bump with one wheel, what's the front of the car gonna do? It's gonna twist if the bump is big enough.

Where are you in Northern CA? I'm in the south bay area. Maybe you should come take a ride in my Valiant. It has the lower rad support reinforced. The chassis does not flex. It also has the firewall tied to the frame rails. Better bang for the buck than stitch welding I would bet.

I'm not doubting you at all Goody I think you have very valid points! I just cringe on adding more weight to the car. The cage itself I figure is about 200 lbs.

That would be sweet to check out your Valiant lilcuda! Also you could compare the amount of flex on my car. Maybe it will sway me to get the lower rad support as well.

The lower radiator support "upgrade" is in my book right up there with LCA gussets, 11/16" TR, or monkey see, monkey do. To depend on a deep u shaped channel to stiffen anything is really being optimistic. Much better results can be found elsewhere/differently if, its important in the first place, but as goody wisely noted, without testing, we are just welding, adding weight, and going on our merry way. Seat of the pants testing always shows positive results, because that is what we want it to show for our time, hard efforts and utter brilliance. The problem is, it may not be the most efficient solution

And again IMO, torque boxes are band aid replacement compromises instead of going a true SFC. Doing both is nearly redundant.

Stitch welding body seams adds the least amount of weight, might beef up some poor/weak unnoticed OEM spot welds, can't hurt much, other then time/effort, and is IMO a good place to start.

I just checked out the US Car Tool radiator support again and remembered why I didn't get it when I got their inner fender braces.

http://store.uscartool.com/70-74-e-body-core-support-stiffener.html
For a $130 bucks that looks way too flimsy to me!
What supports the rear of it?

I would rather weld in a 2x2 square tubing above and across the K-frame to attach both frame rails together.
Thats how it is on the rear of my car with the fuel cell cage.

I agree with the conclusion on the US Car Tool support, I am not overly thrilled with it.


....However....I do foresee the part loading to be roll around the car's X-axis. As in the frame rails varying in the Z-axis slightly... in that case, the design would be suitable (trying to "open" the U).

I don't foresee much torsion loading through the Y-axis of that part (where boxing would be vital). The K-member would also have to to be twisting across the Y for that to happen as well.



Again, all these are assumptions. Without physical testing, I can't validate that much.

The Valiant has a XV Motorsports radiator support, not the US Car tool. It has no holes in it. See the link below.

http://www.hotrod.com/how-to/chassis-sus...-prep/#photo-14

Mine has 0 flex at the rad support.

Did you do something with the top too? I considered that

I added snout bars and sheeted the radiator opening back in.

This is my junk, mostly us car tool, but the brace for the core support needs to come out and a new one put in because it does not clear the radiator. Did this with the Lincoln...

I also did the K-frame, the material is thicker and easier to weld...

I suspect the US Cartools unit pictured above is supposed to be added to the existing radiator yoke to create a boxed structure. The box would be stronger than the single plane stamped sheet core support that is stock. Or you cut out the stock piece and add a boxed unit from XV or use your own fabrication talent. Back in my competition days, we always added a tubular support between the front of the frame rails either under the radiator or in front/behind based on radiator, engine, and set back allowances. We also welded caps to the end of any frame rails as well to reduce parallelograming of the tubes under load.

Regarding stitch welding, it has significant gains that are possible and is restricted or outlawed by some organizations because of the gains it produces using a stock based chassis with no other structure being added.

There used to be an extensive topic on it on protouring.com. An early 1st gen Mustang was the test bed. Using just stitch welding, no subframe connectors, no roll cage, or any other devices were installed. Torsional rigidity was improved 67% over the unwelded chassis. This was measured on an extensively well set up surface plate using dial indicators to conduct measurements. Further mods to include SFC, roll bar, etc got the chassis into some pretty stellar territory and total torsional deflection was under .06" from end to end when it was all finally done.

Doing stitch welding on a built car...couple of schools of thought there, which are no different than my opinion on installing SFC. The best way, IMO, is to have the car level, square, and plumb to ensure things are as close to ideal as is reasonably possible. However, most of us on here are not good enough drivers to really notice the impact this level of detail will produce. In that case, simply installing things to lock them in to reduce deflection may be more than adequate. If you are building a car to the level of detail of the former, continue with that, if the latter, continue with that. Its entirely possible to periodically stitch weld seams on your car, sitting in the garage on its tires. Will it help increase rigidity, yes. Will it lock in any deviation from ideal, yes. Will you notice, probably not. As I often point out, if you are tight enough with your car to notice under/over steer changes of half a tank of gas, then you may notice the difference of level, square, and plumb. Otherwise, you may be worrying about things that won't make a difference.

Frankly, on a running car, I'd be more worried about the welding current fragging an expensive ignition system, dash set up, or data system than I would be about noticing the chassis not being square.

If your only going to do it once, your going to be money (and quality) ahead to have a pro do the welding. It takes alot of practice to really be good. I have had a Mig welder and plasma cutter for many years, but really wanted to learn Tig and improve all my other welding skills, so I took the Welding classes at Lincoln Tech. This is a bit over a year of welding classes and is a bit pricy at $21K. For the non-pipe welding class we likely use up around 20'minimum or more of 3" wide by 1/4" or 3/8" steel (for each lesson like stick, mig, tig, etc.). Not sure how many pounds of filler materials we use, but it adds up.
The school is using the Dynasty 200/210 models and the seem to hold up very good to constant use.
I just posted in the General Section about the issue I'm having with my new Miller Dynasty 280 dx welder. I'm sure when it works it will be great? It should be for what it costs (over $7K.)

http://www.weldingsuppliesfromioc.com/mi...CFYVAaQodi_YDVA

by the time I added the gas cylinder (about $350), filler rod(s) (another $350), and other accessories I'm into it for around $8K total.
The specifications on the Dynasty 280 are really impressive and I can run it on 208 volt single phase. I think the Dynasty 350 requires three phase power?

Anyhow, for the $30K+ I now have invested in equipment and training I could have had someone do my welding, but where is the fun in that

So you spent 21K to learn something that a local community college would have cost 1200? I have about 3 days labor invested in my Lincoln precision Tig 225, and I learned to weld in High school. I maybe rusty but a lot is due to I shake when I weld. You must have wanted to learn how to weld real bad...Tim

I was expecting the course to be maybe 1/2 that too! Really I had the money and the night classes fit my schedule. Plus the school is not too far from house. If I knew then what I know now, wait - I actually learned something...