Originally Posted by SCOTI (Post 3898411)

DWright,

Sorry about pirating your thread. I hope the info shared w/my combo helps others avoid the same mistake.

Originally Posted by Malibob (Post 3899102)

Wow, does a step notch help any of this? I am thinking about notching my rear to get the frame down (want to lay rockers), guessing this is a little OT but, is a step notch better? Can you get to the ground with a pipe notch or an aftermarket "kit"?

Originally Posted by Malibob (Post 3899186)

Got the bug now

Originally Posted by gopokes (Post 3899413)

I was just doing some searches for low budget c-notch ideas when I came across this thread, this is great information. I do have one question though. When cutting the frame do you need to make the cut as large as shown? The line in red in the pic below is what I'm a little confused about. I was thinking it would be easier to only cut as much as necessary to fit the pipe in and leave the part of the original frame in and put the reinforcement over it. Hopefully this makes sense.

Originally Posted by Malibob (Post 3899102)

Wow, does a step notch help any of this? I am thinking about notching my rear to get the frame down (want to lay rockers), guessing this is a little OT but, is a step notch better? Can you get to the ground with a pipe notch or an aftermarket "kit"?

Originally Posted by lakeroadster (Post 3886471)

Yep, from a "calculation standpoint" adding the structural steel member is about the same as welding in a boxing plate. Most of the bolt on kits use a steel plate that is considerably thicker than the stock truck frame thickness. That helps but I still would like to run the numbers on one of the kits to see if it is as strong as the original uncut frame when all is said and done.

As for the bolt holes, they don't effect the strength very much as long as they are spaced away from each other.

I took a little time this morning and made a solid model using Inventor Cad software. (See attachments below)

First I made a model of a stock frame rail.

Second a model of a c-notched rail using 4 inch pipe (0.237 wall) as the notch. This configuration is about 75% weeker than the stock frame.

Third was the c-notch with a 1/4" thick boxing plate. This configuration is about 25% weeker than the stock frame.

Using FEA is more realistic than the simple channel and tube calculations that were discussed in the previous posts because it looks at how all the parts work together as a system. And the cool thing about this type of analysis is it gives you a warm fuzzy feeling about how different modifications effect the strength of a part.

Kind of neat, don't ya think?

Originally Posted by lakeroadster (Post 3899788)

The "best" way from a stress and corrosion perspective is to cut the entire frame side piece out and replace it with the reinforcing disc, as shown in the diagram. This allows a full penetration weld to be made at the o.d. of the reinforcing pad and the pad becomes integral with the frame. This also eliminates the corrosion that can occur when materials are sandwiched together.

That being said, adding the repad without cutting the frame is still a good compromise and a huge improvement in strengthening the frame.

Originally Posted by lakeroadster (Post 3899788)

The "best" way from a stress and corrosion perspective is to cut the entire frame side piece out and replace it with the reinforcing disc, as shown in the diagram. This allows a full penetration weld to be made at the o.d. of the reinforcing pad and the pad becomes integral with the frame. This also eliminates the corrosion that can occur when materials are sandwiched together.

That being said, adding the repad without cutting the frame is still a good compromise and a huge improvement in strengthening the frame.



I would need detailed dimensional data of the off the shelf kit to do an analysis. I am curious, does the information you got from them say anything about how strong the kit is or have any "legal" stuff about not being legally responsible for damages, etc., etc?

The reality of the situation is the bolt on kits I have seen just don't add the needed sectional strength back into the frame.

Originally Posted by darkhorse970 (Post 3900671)

I have them in a storage unit away from my house. I will go take some pics and measurements and let you know what I've got. They were purchased from Early Classic Enterprises over 5 years ago. I will look at the paperwork that came with them.

Originally Posted by lakeroadster (Post 3906875)

OK guys, the bed is off my 65 C10 SWB right now so I can make a model of the actual frame configuration, instead of the straight configuration I did for the previous FEA.

Then if you guys could make a sketch with enough information such that you could build a set of "bolt on notch brackets" then I would have what I need.

This should result in a real world CAD Model and thus the FEA results should be pretty dog gone accurate.

Now that we have this discussion and I have done a bit of surfing, looking at some of the kits being marketed, they don't appear to have enough height. Based on the previous results we have already discussed I am betting these bolt on bracket kits will be weaker, much weaker, than the original frame.

Lets put it to the test and find out. What do ya think?

Originally Posted by Malibob (Post 3984951)

Anyone got any pics of the CPP notch and how their truck sits with it? I am trying to decide which way to go and don't want to buy things twice like I have this whole build.

Originally Posted by 8mpg (Post 3985075)

In my opinion it fits well...but please weld the inside seams:
http://67-72chevytrucks.com/vboard/s...d.php?t=402527