Pipe Notch

[Hottrucks]

thanx..I guess I'll go with it ( kida a PIA to get under it now) I do regular inspections though the wheel opening and whe ever I get it up in the air

thanx Agian great info

[Chris65GMC]

Originally Posted by lakeroadster

Whenever someone starts talking about adding thicker plates to the sides of the frame rails and saying that this makes the frame stronger than it was in its original condition, yet they are and not adding vertical height, they do not understand beam analysis.

Thanks for all the great info! I was hoping you could further elaborate on the above fact.

Also, I was curious of the effect of welding thicker metal to thinner in a structural concept e.g. 1/4 inch wall sub-frame to chassis with factory spec frame. Does the lack of flexibility in the thicker metal create more stress at the meeting point causing undue stress?

Thanks!

Chris

[8mpg]

Originally Posted by lakeroadster

Wow, just read the link that was posted above, what a mess. I think 8mpg was on the mark as far as his technical comments related to the parts he bought.

There is a problem, IMHO, on this site when vendors weigh in on a topic such as this. They are biased, as they are selling product. The way other members then jumped on 8mpg is pretty ridiculous.

I would like to thank the 60-66 gang who were a part of our thread here concerning c-notching. Our discussion has been civil and interesting.

Thanks again guys.

I just wanted to say thank you for running the numbers and getting us an idea on how strong it truly is. My honest intention on the whole thing was not to start a war but merely ask about the strength and the welding. No one seemed to understand, regardless of the results, the CPP notch was going to be what I was running. They are sending me a 3/8" thick version for peace of mind.

I think ultimately though, to do as you want to do (as do I) and keep a baseline as a stock frame strength with a notch, we will have to build our own, or modify a prebuilt one. Adding a truss or adding height to the prebuilt notch wouldnt be hard, but not as good as it would be with a solid steel piece. Im going to run the 3/8" version and just not go crazy with towing. If I build a long wheel base later on, I will probably just end up building a whole box tube chassis for peace of mind.

[SCOTI]

Originally Posted by lakeroadster

I am just glad I could help. Good to hear CPP is getting you a 3/8" version.

And for the record I fully understand your concern and am in agreement with your taking points. I for one will be genuinely surprised if any vendor states their c-notch kits are as strong, or stronger than, stock and then actually prove it with FEA and then back it up with actual destructive testing data.

From what I have seen thus far Bell Tech has the strongest kit. It would be great to get an actual test of all of these kits to see who is the strongest.

For those of us that want to use our trucks for hauling and pulling heavy loads that match the trucks rated capacities this is really important.

To be fair, I don't recall any advertisements that full OE capacity is available after the installation of a bolt-in c-notch. I guess the general thought is "it's now a 'sport truck' & no longer used like a work vehicle". That's great if you can afford a new or secondary tow/work vehicle.

I do like CPP's reaction to the concerns.

Another idea would be to increase the height of the C'd portion of the notch on the thinner notches available. It might require cutting into the bed runners (or something similar), but it would be stronger.

[SCOTI]

Originally Posted by lakeroadster

I really didn't mean to imply that any kits are indeed rated.

That being said, they should be.. IMHO. But then again I ran the numbers and the strength reductions are pretty scary, also IMHO.

I wasn't calling anyone out. It was more of a disclaimer since it's easy to focus on what our concerns were vs. what these kits are advertised to do. I also agree the c-notches should completely restore the strength of the frame to OE stats.

[ol_skool_chevy]

Originally Posted by chevytrucknut

When my truck was in the process of having the notch welded up I stepped onto the back of the frame (all 280 lbs. of me) and could see it flex. So we then decided to add the boxed inner sides and that helped a ton. That being said .....I wouldn't tow or haul anything of serious size and weight,with any form of notch. Nor would I expect it to hold up being rear ended. They probally just fold up.So I do agree with what Lakeroaster has said. Thankfully the biggest thing I am haulin...is me.

280lbs....
I'm 230lbs.....Catchin' up with ya....
Did ya go to Beaches opening weds last week....I saw it rained

[71'tahoe]

Wow! What a great thread! I have to chime in on a few things. I have used belltech c-notch kits for years on my own personal projects as well as customers. I have never had those inside plates in any of the kits. I have used them on 1 ton chevy duallies as well as standard cab 1/2 ton trucks.

I wonder how weak the frame is now. I have a kit installed on a frame off project so I will measure the thickness of the notch tomorrow.

I agree with Scoti on they now consider these modified trucks as "Sport Trucks" and lose towing capacity. But Belltech has there Air Jack kits to restore lost capacity. Wonder how that effects the frame strength? As I said I have never had the inside frame plates in any of the kits I have installed.

One last note. Alot of people dislike Chassis tech but they have a notch kit that is a bolt on and has a piece of 2"x2" steel welded to the notch with the ability to weld to the top of the frame..wonder how those fair?

Lake roadster. I have taking all you info and will be using it in the near future.
I know What you are saying about comparing ONLY modified to stock frames in strength. I just wanted to add my 2 cents about using bell tech stuff as well as other products out there.

Greg "GT" Tholen

[SCOTI]

I only recall Bell tech having 'reinforcement' plates on the 88-up kits; nothing for year models prior.

[SCOTI]

Originally Posted by lakeroadster

Glad to do it for the members of the site.

Ya'll see this thread ? http://67-72chevytrucks.com/vboard/s...d.php?t=436943

That c-notch stress failure did make me think of this discussion.

[kieth]

The information we usually thought was most important was

RBM (Resistance to bend moment)

What is the RBM for the std chevy frame ? By using this number wouldn't we have a quick and ready number that we could judge the frame strength and compare it to a modification. ??? Kieth

[6doggie3]

Here's 62Bowtie's truck being pipe notch by my co-worker Johnny B good

[drewskiren]

I have a question or two.

I am installing a 72 body on a 2001 Silverado frame. The frame drops the cab pretty low, which is nice, but the rear of the frame kicks up a lot.

In my hot rod truck situation, I am needing to lower the bed down over the wheels. Not really any different than raising the wheels up into the bed wheel well, just looking at it from a different perspective. I can channel the 2.5 inch bed cross mounts that are underneath the bed floor. I will remake them with 1.25 inch tall channel iron (2 inch wide). I can install as many of these as needed. (How many would I need?).
I still need 1 inch more, Can I section the height of the 5.25 inch tall frame by 1 inch? Making the bed area of the frame 4.25 inches tall, would I get back to original strength by boxing the inside of the frame rails?

MANY thanks in advance!

[blown240]

Wow, what an amazing thread! I have leaf springs,(66 GMC Suburban) so strength is even more important. I am thinking of doing a 2 1/2 inch notch with 1/4 plate inside and out. Hopefully I will still be able to tow and carry a load.

[lakeroadster]

Originally Posted by drewskiren

I have a question or two.

I am installing a 72 body on a 2001 Silverado frame. The frame drops the cab pretty low, which is nice, but the rear of the frame kicks up a lot.

In my hot rod truck situation, I am needing to lower the bed down over the wheels. Not really any different than raising the wheels up into the bed wheel well, just looking at it from a different perspective. I can channel the 2.5 inch bed cross mounts that are underneath the bed floor. I will remake them with 1.25 inch tall channel iron (2 inch wide). I can install as many of these as needed. (How many would I need?).
I still need 1 inch more, Can I section the height of the 5.25 inch tall frame by 1 inch? Making the bed area of the frame 4.25 inches tall, would I get back to original strength by boxing the inside of the frame rails?

MANY thanks in advance!

Looks like an intersting build. That frame looks sweet! The way it is boxed under the cab and the tubular cross members are slick.

Since you are making home made cross sills anyway why not make them out of 2 x 2 square tube and weld them to the frame? Then bolt the bed to the cross sills in the factory stock locations around the perimeter? I'd avoid reducing the height of the frame... especially with all those cross members. And I would recomend against notching the frame web for the 2 x 2 tube, notch the 2 x 2 tubes themselves. Notching the frame flange should be fine as long as you are welding the tubes to the frame.

I made a quick model of what I am trying to descibe.....Makes sense?

Wouldn't that work for ya?

John

[drewskiren]

Originally Posted by lakeroadster

Looks like an intersting build. That frame looks sweet! The way it is boxed under the cab and the tubular cross members are slick.

Since you are making home made cross sills anyway why not make them out of 2 x 2 square tube and weld them to the frame? Then bolt the bed to the cross sills in the factory stock locations around the perimeter? I'd avoid reducing the height of the frame... especially with all those cross members. And I would recomend against notching the frame web for the 2 x 2 tube, notch the 2 x 2 tubes themselves. Notching the frame flange should be fine as long as you are welding the tubes to the frame.

I made a quick model of what I am trying to descibe.....Makes sense?

Wouldn't that work for ya?

John

BRILLIANT !!!!!

How much do I owe you?????

Seriously, this is a perfect solution and I am pretty sure it will be all I need to get low enough. I think I might want the outriggers to extend out to the inner bed sides to support them fully. Maybe cut the tips at 45 degree angles and weld an end cap on for looks? I also could have a box tubing section right on top of the tubular x members for great strength.

[lakeroadster]

Originally Posted by drewskiren

BRILLIANT !!!!!

How much do I owe you?????

Seriously, this is a perfect solution and I am pretty sure it will be all I need to get low enough. I think I might want the outriggers to extend out to the inner bed sides to support them fully. Maybe cut the tips at 45 degree angles and weld an end cap on for looks? I also could have a box tubing section right on top of the tubular x members for great strength.

Just glad I could help, I get a real kick out of this stuff. Your bill is paid in full.

The 2" square tube (I'd use 10 ga. or 3/16" thick tubing) should be more than adequate, compared to the stock 2-1/4" high sheet metal stock cross sills.

The only disadvantage to this concept is you will have to assemble the bed wood (assuming your not going with steel) with the bed on the truck. This is doable, but not as convenient as doing it off the truck.

Good luck and be sure to post up photos as you go !

[68 TT]

Originally Posted by lakeroadster

Sweet truck!

I feel compelled to state, purely from an engineering strength of materials perspective, that the notch that was installed drastically reduces the frame strength behind the axle. I arrived at this conclusion by running a hypothetical Finite Element Analysis on a stock frame section and then the same section with a deep notch, see printouts below. These show a frame reduction of strength of 76%! See post #24 of this thread for more information on how these c-notches reduce frame height and how that radically effects frame strength.

In order to retain frame strength on such a deep notch, reinforcement needs to be added above the frame. I am sure you have seen step notches and frames with truss structures directly over the notch.

Just want you to be aware of these limitations, better to be aware than to not know.

I'de suggest you inspect the notch, adjacent to the welds, for possible future fatique cracks and do so on a very frequent basis. Since the shocks on the 60-62 model frames are mounted behind the axle they may flex the frame enough to create these cracks (On 63-66 the shocks mount ahead of the axle on a cross member).

Just trying to help.........

The information I am posting here is for reference only and results will vary based on actual dimensions, materials used and the quality of the implementation and fabrication.

Since you already built the FEA model for the pipe notch can you add a length of 1/4"x2" flat bar along the top flange of the modified stock frame?

It should help increase the section modulus a bit and it would be an easy way to add some strength to the frame of people running this kind of notch.

I'm curious how much of an improvement it will make.

Also please take a look at how far away from the pipe notch the added material needs to continue to gain the most benefit from the change.

Out of curiosity how thick would you have to make the pipe notch material to give it the strength of the stock unmodified frame?

[Hottrucks]

Ok Lake I have been tagging along on this thread and heres what I have been thinking...

since my front is lower than the back ( surprise there) I was planning on lifting the floor of the bed 3" ( the amount of space from the top of my wheel tub to the bottom of the inside rail and I could use the space for tires too) in order to keep the floor strong and FLAT ( since I work the hell out of it) I was going to get 2 pieces of 2" X 3" X 8' box tubbing and place them from the back of the head board to the end of the frame then remove the C notch I have to gain the extra 1 1/2" +/-

This is where you come in
what is the best way to attach the box to my frame

( I was thinking 3 plates ( say 3" wide) on each side in front of the axle and 2 behind it...... plates on both sides )

how strong will it be??

I need to be able to pull my 4000 lbs boat ( 250 lbs tongue wgt,) from the bumper

Thanx

[REDNOSE65]

Originally Posted by lakeroadster

There was previous discussion here about commercially available c-notches.

From what I have seen Beltech has a very good notch kit, but they don't offer them for our 60-66 trucks.

Take a look at the pictures below and the followig link: http://www.belltech.com/trucks.php


Basically they have a heavy formed c-channel with a welded notch. Then this bolts through the frame and there is a heavy backing plate.

This essentially triples the wall thickness of the frame. Interesting. If any body has one of these I would be interested in knowing how thick these components are.

They don't offer them for 60-66? WTF??? That's Racist!!! LOL

[superwade57]

Originally Posted by lakeroadster

I had a little time to run some FEA today and decided to run a step notch and a half circle notch. These are available from multiple places, I got the dimensional data from this website: http://www.*****************/node/415.

As expected the half circle is the winner as far as strength. It just makes sense, less stress risers as a result of less notches and joints.

I also spent some time designing my own "Ultimate Notch" design.... (Stronger than stock)

The information I am posting here is for reference only and results will vary based on actual dimensions, materials used and the quality of the implementation and fabrication.

Step Notch FEA


Half Circle Notch FEA

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Stock Frame FEA

im a cross-over from the 73-87 boards lol, i started a thread there about capability of towing an 18 ft steel deck car trailer with notched frame and bags and either trailing arms like the older models or a 4 link set up. and was refered to this thread, and not to take away from any one else who posted here, but recomended to read specifically all posts by lakeroadster- "the man" as he was refered. any way this is an in credible thread and cudos and thanks for all the info. my question is for lakeroadster- considering i am lookig to tow a trailer how well suited is the mentioned step notch for my application? i dont need to lay frame or anything. i will be running 18 in rim tire combo and want a low aggressive stance and plenty of room for a heavier duty bag over axle. thank you so much for all your help knowledge and expertise.

[superwade57]

thank you again for all your knowledge and time invested. we all appreciate it. and im sure will all be sending people to this thread for years to come

[lakeroadster]

I reviewed this thread and was concerned that some of the information that was posted would be taken out of context and misused. To prevent this from happening I deleted my posts and reworked the data into the following:

Frame Notch Based On Strength

[Hottrucks]

thanx and I think I'm going to build your tub notch for my floor lift

[neto]

Very nice write up. Thank you for your expertise.

[kieth]

Hey Lake Roadster, read this thread and your analysis with great interest, the information is invaluable and I would just like to ask a question about the beam analysis. You state that most of the strength is being added by adding material above the frame, I would say it is also being added by the double wall material in the tubing ?

1. If one built a 2.5" notch kit that had upper and lower frame flanges inside and outside of the frame lets say 5/16 110,000 psi yield strength material bolted in with grade 8 bolts couldn,t we pick up enough strength to equal the old frame. (I do not ask this to be critical just a different way of looking at the problem)

2. What is the section modulus of the stock 60-66 frame and the yield strength of the material.

thanks in advance. Kieth