Saw this referenced on a HAMB thread. Some of the C-notches I've seen on here really scare me, and this shows why! Note that the trucks modeled don't have leaf springs, so our trucks' frames are much more heavily loaded than these.

http://67-72chevytrucks.com/vboard/s...d.php?t=457037

(Yeah, it's on a Chevy forum, get over it. Steel is steel)

 

That's a good explanation of the advantages and disadvantages of different notch types. Some of those do appear much weaker than stock, but I would have never guessed how substantially weaker they really are.

 

BLASPHEMY!!! Thou shalt not pollute our forum with such vile filth!!!!!



Just kidding..... maybe.....

 

Good article Ross . I have seen a disturbing amount of examples of individuals who can afford a Mig Welder and a Plasma Cutter and make mods that put the rest of the driving public at risk through acts of gross incompetence . Sorry if I offend but it's a pet peeve.

 

Exactly how I feel. What's the worst thing is, if one guy does something poorly, posts pictures of it, others see it, and figure it must be OK, so they do it.

 

Great article Ross, you may have just saved someone's life.

 

I used to comment on this on the HAMB, but it was obvious that my views were not 'in' with the cool crowd.

In Australia, we MUST have a certified automotive engineer sign-off (ie - be legally resposible for) ANY mods to chassis, steering, brakes etc, etc. BEFORE you can drive on the road at all. Most folks cry & whinge about how they can't build what they want at home in their back sheds....sure beats families crying about their loved ones crying about their family & friends killed by an oncoming ratrod...

rant over.

mine was all done by a qualified professional, with Engineer approval;

 

It's also why I keep pushing the Jag IFS for these trucks.....it keeps all factory geometry and it's the hardest to stuff up the mounting!

 

It's been years and years since I used FEA software. But......isn't the loading being added incorrectly on those models? I guess it would depend on what suspension you were using. Certainly backwards in my mind if using leaf springs. A little more definition of the loading would sure be helpful. However, the premise is correct regardless. Trussing is the way to gain strength in these designs.

 

Much the same in Canada . You can build whatever you want but if it won't pass an interprovincial inspection then no plates , no insurance and no fun . Thats why you occasionally see a nearly complete truck for sale cheap a lot of times.

 

He explains in the article that all he's applying to the frame is deadweight of the box and contents in the bed, because the Chev coil spring/long arm suspension doesn't have any suspension loads behind the spring pocket (or airbag). In the HAMB thread several folks make comments that leaf springs would be a worse loading case on the frame, especially right over the axle.

Note also he doesn't make any judgement as to whether the frame would fail, just looks at % of stock strength.

The thread was actually a question from a guy with a fridge Ford who wanted to know if it was OK to make a 2" hole in the 5"-tall frame, right over the axle, to run a gas filler tube to a rear-mounted gas tank. He didn't like having the fill in the bed.

 

Excellent thread. Anytime we can improve the safety of the trucks we build, it is good. Also, knowledge is always welcome.

What HAMB thread did you find this reference?

Phil