Best way to locate a C-Notch

[502ss]

I am about to install my bolt in C-Notches and was wondering the best way to locate them on the frame? I am thinking about unbolting the rear shackle and lowering the frame down so the axle touches the frame. Then mark where it touches and figure that as the center of my notch?

Any other suggestion?


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[SCOTI]

That's the way.

[502ss]

Originally Posted by SCOTI

That's the way.

That worked perfectly!

So I traced the pattern. I am not too concerned but the odd shape of the frame makes the pattern skewed on the frame. I am going to cut tomorrow.


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[SCOTI]

Originally Posted by 502ss

That worked perfectly!

So I traced the pattern. I am not too concerned but the odd shape of the frame makes the pattern skewed on the frame. I am going to cut tomorrow.

That's because you have a 'generic' c-notch for a straight frame (top & bottom fame lip are parallel to each other).

The 73-91 C30 specific c-notch is shaped differently (it is like the frame) & has more material most likely making it safer than that one ('safer' being debatable).....

[502ss]

Originally Posted by SCOTI

That's because you have a 'generic' c-notch for a straight frame (top & bottom fame lip are parallel to each other).

The 73-91 C30 specific c-notch is shaped differently (it is like the frame) & has more material most likely making it safer than that one ('safer' being debatable).....

I did know it was a generic but I plan to box the frame in that area anyway so I am sure it will be fine!!
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[SCOTI]

Originally Posted by 502ss

I did know it was a generic but I plan to box the frame in that area anyway so I am sure it will be fine!!
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Boxing doesn't help like you think it would. The strength is in the height; boxing helps w/torsional rigidity. Of course it 'can' work.

Even though many have similar set-ups, it still remains weaker vs stock. I usually drop my stuff immediately but I've been driving the dually since October @ stock height for this simple fact: Cutting enough out of the frame & bolting one of these c-notches in results in a weaker frame.

[502ss]

I hate to say it but I agree with you. The deal is if I don't notch I will only have 3-4" of clearance until the axle hits the frame. Now I am going to do a airlift 5000 kit to assist but I am not sure if 3-4" is enough. I am even ok if every once and a while the axle hits the frame on a really big bump but it would drive me crazy if it did it all the time!
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[N2TRUX]

I have found that the "Best way to locate a C-Notch" is to lay it on the floor, and walk around barefooted. This method seems to work on just about any heavy object.

Seriously, if your concerned about it bottoming on occasion install a small 'button style bump stop in the center of the notch. If it does bottom out, it won't knock your fillings loose.

[502ss]

Originally Posted by N2TRUX

I have found that the "Best way to locate a C-Notch" is to lay it on the floor, and walk around barefooted. This method seems to work on just about any heavy object.

Seriously, if your concerned about it bottoming on occasion install a small 'button style bump stop in the center of the notch. If it does bottom out, it won't knock your fillings loose.

The bottoming out is a concern only if I choose not to c-notch. I really don't like the thought of effecting the integrity of the frame, especially when I know I will be using the truck mostly to tow my 10,000lb. boat!
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[SCOTI]

Originally Posted by 502ss

The bottoming out is a concern only if I choose not to c-notch. I really don't like the thought of effecting the integrity of the frame, especially when I know I will be using the truck mostly to tow my 10,000lb. boat!
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I came up w/a 'partial' solution to keep things under the floor but it is involved & would require welding/fabrication (different design bolt-in c-notch). I say partial because although I have data to back up my proposed design, it's still unproven in the real world. I do feel it would be 100% better than what is available.

Because of the complexity of this & trying to keep the bed floor intact, I am considering cutting out my floor & going w/a step-notch to maintain the height of the frame rail that's needed.

[502ss]

Originally Posted by SCOTI

I came up w/a 'partial' solution to keep things under the floor but it is involved & would require welding/fabrication (different design bolt-in c-notch). I say partial because although I have data to back up my proposed design, it's still unproven in the real world. I do feel it would be 100% better than what is available.

Because of the complexity of this & trying to keep the bed floor intact, I am considering cutting out my floor & going w/a step-notch to maintain the height of the frame rail that's needed.

I went the easy route, I talked my self out of the c-notch all together(you helped with the decision). I measured today and I have around 5 inches of travel. I know I will probably lose another inch once I put the bed back on and she is full of fuel. Now when I put the boat on I will probably lose another 1.5 inches but that will all be compensated by the air ride helper system. If I go the summer and find out she bottoms out then next fall the bed comes off and I will address it then! I am not going to cut the frame unless I absolutely have too. I will post some pictures later!
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[lakeroadster]

FYI: The following thread discusses C-Notches vs. Stock Frame strengths: http://67-72chevytrucks.com/vboard/s...24#post4373024

[502ss]

Originally Posted by 502ss

I went the easy route, I talked my self out of the c-notch all together(you helped with the decision). I measured today and I have around 5 inches of travel. I know I will probably lose another inch once I put the bed back on and she is full of fuel. Now when I put the boat on I will probably lose another 1.5 inches but that will all be compensated by the air ride helper system. If I go the summer and find out she bottoms out then next fall the bed comes off and I will address it then! I am not going to cut the frame unless I absolutely have too. I will post some pictures later!
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Picture as promised...


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[SCOTI]

Originally Posted by 502ss

Picture as promised...

Wow... That's bettter than what I was working with.

I got the flip kit. As is, it's about 7-8"..... I was going to eliminate some leafs which would reduce the drop, but the amount of clearance needed was still 3" into the frame (I feel you need 3" min travel). My rear axle tube to the frame is 7".

[502ss]

Originally Posted by SCOTI

Wow... That's bettter than what I was working with.

I got the flip kit. As is, it's about 7-8"..... I was going to eliminate some leafs which would reduce the drop, but the amount of clearance needed was still 3" into the frame (I feel you need 3" min travel). My rear axle tube to the frame is 7".

This is why I think I will be fine without a notch. The airlift 5000 system will help to keep the axle clearance around 4" regardless of what I am carrying or towing!

Thanks for helping to talk me out of the c-notch!
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