Hello. Several years ago, I found this interesting article from a metallurgical engineer on how to properly splice a truck frame and other frame info. It was difficult to find again as the original article is apparently unavailable. This is the same method endorsed by Ford: Tips on truck frames This method being employed with pictures are published, download-able as a PDF here: http://www.morryde.com/pdfs/Chassis Stretch.pdf
Was that aimed at me? Here, I'll make a useful comment for this thread. It's a GREAT piece of information and I hope that people read it and pay attention to it. Thanks to torchmann for posting it up.
nope not aimed at you scoot And i second your quote! "It's a GREAT piece of information and I hope that people read it and pay attention to it. Thanks to torchmann for posting it up."
Okay. Cool then. XOXO Modified my initial reaction to reduce long term drama... HAHA! So I'll re-raise my question... Why is this? Something wrong with engineers??
Great article. There is more to subframing and clipping frames than just looking at it and saying, "yeah, that looks like it'll hold".
Totally! Recently I helped another HAMBer redo the clip on his 55 Chevy PU. It had a Camaro clip on it and when we started cleaning things up it was the scariest thing I had ever seen!!! We redid it and even lowered the clip a tad in the process. Clipping always made me a little nervous, but guidance, like the above article, is a good thing to put out there for the masses.
Aside from yield strength, it is also important to remember the effects of welding, heat, and the dynamic loads that pieces go through. It sounds real impressive to hear that mild steel has a strength of 35,000 psi, but once you're actually building a piece and understand the loads exerted on it, you'd be astonished how easily things break. For example, when pieces are not only in a tension/compression, but when a sideways load is exerted. When I ran the U of Delaware FSAE team, we fabricated our control arms out of the thinnest chromoly tube we could use, which was at the time .037, that was slit, and a insert pressed in which was drilled for the rod end. Then the insert was welded into the tube. We wanted to test the strength of the insert and tube, so we put one into an Instron machine, which tests strength in tension force. The tube necked and snapped at 6230 lbs of tension force. Since our car was only 400 lbs, we figured this was plenty strong. WRONG. A toe link bar was welded to the middle of the lower control arm, which was a poor design. It created a heat affected area and put a sideways force on the lower arm. That 400 lb car and 160 lb driver, moving at 50 mph, hit the brakes, and tore the rear control arms in half, sending the car out of the practice lot, across a street, and through a split rail fence. Never take your chances when it comes to frames
I use to have that attitude towards engineers when I was machining parts. Now that I am going back to school for my engineering degree it was a rude awakening on what is involved in the engineering field. 57JoeFoMoPar, we did the kidda the same thing on our SAE Baja car this yea. We oped to use titanium in as many places as possible. We did weld samples and pulled them apart on the instron. Then we modeled the part in solidworks and did the FEA with a safety factor of 12 and the parts should have worked in theory.... We tested the car in dry conditions with a good outcome, but when it came time for comp the place was a mud fest and failures galore. Moral of my rant is engineers may not look like they do much but when you're put in their shoes your in for a huge surprise. Machinist, welder, engineer.... I am in a daily conflicted with myself!