An omega or bell curve would be best, but it's a difficult shape to build, the shape I drew is much easier to fabricate and is nearly as good if the angles on the ends are somewhere between 60 and 45 degrees. It is also a tried and true standard frame notching reinforcement method.
I also believe in using like thickness material for boxing plates and kickups as the original frame to reduce the likelyhood of creating stress risers. If I use a doubler I never end it in a straight vertical line but end it by either angling it ~ 45*, fish mouthing it or ending in a V or football shape.

 

Gary -

I thought this might be of interest. It is a pretty complete article about C-notching.
http://www.classicperform.com/tech_a...-Notch-Kit.htm

 

Yes thats a good one Randy Jack, I read that one and pretty much did the exact same thing, their notch is just as deep as mine Maybe I should email them and see if they are still alive All kidding aside I will do something to beef them up, no reason not to the fab is what I like.


Bobby here is a better pic, you are right everything disapears when its all black, it took 3 pics and some photoshoping to get it to show up as good as this. I should of taken some pics of the oilspots for you too

 

Gary,
Thanks for the pic. The frame looks good.
I read through the article that Randy posted also and it sure looks like you followed the same process. I don't think I would worry too much if I were you, there are countless vehicles running around with this very modification done to them. I think what we had here is a classic case of over analyzing (we're good at that...lol)

If you are really worried you could eithe fishmouth the boxing plate a pit to help avoid the stress risers. or you could extend the boxing plate up to the next x-member.

I myself would probably fishmouth the boxing plate a little bit (easy enough with a cut off wheel and a few minutes of free time) and call it good.

Carry on my good man! I'll overlook the clean garage for the time being
Bobby

 

Gary,
I caught a potential problem in your picture. The top mounting of the shocks has a bolt oreintation in the vertical plane when it should be in the horizontal plane or 90 degrees from were it is. The bolt oreintation you have would allow fore and aft movement, where as, the frame moves up and down and the shock is supposed to rotate around the bolt. I think you are going to end up with a bent shock rod.

 

Good catch Bruce! I also worry about the swaybar mounting, looks like it just goes thru the lower frame flange without reinforcement. The swaybar will put a significant load on that mount, should at least add a triangular gusset to either side with a doubler past the gussets or carry the boxing past the swaybar mounts with a doubler for the flange.

 

Good catch Bruce, will fix it. I will just add a single shear bolt instead of the bracket. Like the factory style. And Ax the mount is allready gusseted

As far as the swaybar I will keep my eye on it but I have the sneaky suspicion Ax wants my frame to weigh 3500 lbs by itself I am building a cruiser not a demolition derby car. I checked my superduty and the front swaybar is mounted on a bracket off of the frame rail in such a way that it applys the same type of force just with a moment arm 3 times that of the f100 swaybar mount, and thats on the front swaybar that works much harder and under a big ole heavy diesel engine.

Ax not trying to attack you just having some fun. I appreciate your input and know you are a standup guy. You previously offered me some free parts that turns out I didn't need. Thats just the kind of guy Ax is.

 

No, actually I believe in adding lightness wherever possible, but as a national autocross racer (the AX in my user name stands for autocross) I regularly see what the forces a vehicle can generate while manuevering can do to parts, even on the smooth surfaces we race on. We totally destroyed the stock swaybar mounts on our Miata two years ago, And it weighed < 1/2 what our truck weighs with a much lower center of gravity, and very stiff shocks thus much less body roll. I have seen plenty of swaybar endlink mounts and even upper strut mounts ripped right out. I do however believe in erring on the side of safety when a failure could have deadly consquences. Gusseting and bracing does not need to be heavy to add a lot of strength, just needs to be properly engineered. Take for example with boxing a frame, 1/8" material will be nearly as strong as 1/4" and you could cut 3" holes 9" on centers down the whole length for lightening and internal access and reduce the weight of the plate by an additional ~ 25%. two triangular gussets like I described for the swaybar endlink attachment could be cut from 1/8" plate, have a good sized lightening hole drilled in the center and add < 1/4 # to the frame. Doing that to both sides of the frame would add about the same weight as a fast food carryout lunch.