C notch dillema

[ic1480]

Here is my dilemma. Previous builder c notched the frame in the wrong place, 2.5" too far forward. He also built a ladder bar that is lethal by design.
and shortened the drive shaft.
I have a new cantilever, fourlink laying on the shop floor to install. KP setup.
I need some way to measure the rear axle to locate it properly so I can correct the c notch, and install the canti setup.
Measuring from the front hub is a little suspect as it is terribly aligned. TOE IN like 1-1.5"
Suggestions please.
IC

[Fitz]

Originally Posted by ic1480

Here is my dilemma. Previous builder c notched the frame in the wrong place, 2.5" too far forward. He also built a ladder bar that is lethal by design.
and shortened the drive shaft.
I have a new cantilever, fourlink laying on the shop floor to install. KP setup.
I need some way to measure the rear axle to locate it properly so I can correct the c notch, and install the canti setup.
Measuring from the front hub is a little suspect as it is terribly aligned. TOE IN like 1-1.5"
Suggestions please.
IC

There are dimensioned drawings of the frame in the factory assy manual. Since you didn't specify year or wheelbase here's all four. Measuring from the exact center of the upper A Arm mount (halfway between the bolts for the upper A arm mount) back 115 inches (shortbed) or 127 inches (longbed) will locate the center of the rear axle. Measure BOTH sides and mark each one. Measure across the diagonal between the front and rear points to be sure your frame is square. If it isn't you must fix that BEFORE moving the C notch. From the points you marked for the rear axle center, measuring to the center of your C notch will show you the direction it needs to move and how far to move it. If the PO screwed up this badly, don't count on the C notch being correct from side to side!

Nothing is foolproof because fools are so ingenious.

Good Luck!

[ic1480]

Ahh yes! Silly me! 1972 GMC LWB
Thank you for the reply. I will study the diagrams. IC

[Hdogkuvachio]

Where did you get those diagrams because it would be nice to have a set on hand for when I'm working on my frame.

[lolife99]

The ony REAL way to know is to install the rearend and center the wheel in the bedside.
Your KP 4-link should have the correct instructions to install the 4-link front bracket.
Get the wheel to LOOK correct in the wheel opening and then install your notch.
Some of these trucks have the wheels too far forward or rearward when dropped to an extreme amount with factory components.
You have the chance to correct that with your KP kit.
http://www.cachassisworks.com/Attach...27-4LBOC31.pdf

[lolife99]

http://www.cachassisworks.com/Attach...27-SNBOC31.pdf
Actual notch installation instructions,...

[ic1480]

Thank you Keith. Now for my next question.
When I ordered this assembly I specifically stated C notch, I revd. a step notch. I do not want to cut into the bed floor nor do I want to lower it that much. Did I screw up by ordering this kit? Do I have to use a step notch for the canti four link? Thank you again. IC

[lolife99]

The KP 6-link (4-link with a cantilever) is for an extreme notch.
The cantilever set up take a small bag and doubles the amount of lift you can acheive.
(as in from the ground up to ride height)
You can use the 4-link by itself with a small c-notch, but this isn't going to get you much lower than a factory trailing arm set up.
What are you trying to do with your truck?
Maybe you should explain from the begininning.

Leaf spring rear suspension or coils?
Just trying to get the BIG picture?

[lolife99]

Here's your set up with a fabricated step notch.

[lolife99]

And down,...

[ic1480]

Ahh the big picture. Sent the truck to a builder 3 1/2 years ago to be built for my sons graduation, 2 years ago. last month recovered the truck in an unfinished and seriously disappointing state.
We were hoping for a 4/6 drop. I had decided to bag the truck, hence the KP canti four link.
As stated earlier. the C notch is too far forward and the homemade ladder bars were lethal by design, so I am totally scrapping them and starting over with an engineered setup. We no longer have the trailing arms or any of the associated hardware.

[ic1480]

Lolife99. Thank you for the pic.s. We are not trying to lay that low at this time. This is North Dakota, our highways aren't that smooth. lol I have not yet figured out how to post a pic in a post but if you would, look in my photo album on this site and you will see the photo I just took of one side with the rubbing coilovers and C notch. thank you
IC

[lolife99]

I would install what you have and index everything off the KP front mount like the KP instructions say.
Then add a small c-notch.
You may have to fill in the old notch to regain frame strength, since I don't know what your current notch looks like.
You just wont be able to air the truck out as low with the c-notch, but your ride should be fine.
Here's your pic,...

[ic1480]

Lolife69 Thank you for all your input. Am I on a wild goose chase here or is the canti setup the way to go. I read a lot on it and was under the impression I would be able to get lower with that.
The reworking of the c notch is not a problem. I intend to plasma cut out the old notch and fabricate my own or maybe buy one and reinforce it with thicker inner box. I intend to weld the entire thing in. relocating the shocks may be a little tricky as the picture shows the tank on the left side of the pic. The exhaust will be another piece of the puzzle.
Thanks again
IC

[Vova]

Since you don't want to be too low get yourself stock trailing arms and just fix the c notch. You cab get a basic rear bag setup from porter built and call it good.
Sell the KP setup and recoup some of your $$.
Here is my truck with a c notch and basic air bag system. Axle sits inside the notch.

[lolife99]

Originally Posted by ic1480

Lolife69 Thank you for all your input. Am I on a wild goose chase here or is the canti setup the way to go. I read a lot on it and was under the impression I would be able to get lower with that.
The reworking of the c notch is not a problem. I intend to plasma cut out the old notch and fabricate my own or maybe buy one and reinforce it with thicker inner box. I intend to weld the entire thing in. relocating the shocks may be a little tricky as the picture shows the tank on the left side of the pic. The exhaust will be another piece of the puzzle.
Thanks again
IC

You are only going as low as your notch allows.
Any more than a c-notch will require you to cut the bed floor.
Even a c-notch will put the center section of the rearend right against the stock floor.
YOU are going to have to decided what you want.
Personally these trucks can achieve a 7" rear drop with the stock trailing arms and coils or a 2600 double convoluted air bag.
I would use Porterbuilt products.
They are the BEST in the business for C10 trucks.
Mild to extreme they have it all.
www.pbfab.com

The KP kit puts a lot of stress on the rear frame rails,... so your frame repair/notch is going to have to be stout.
I agree.
I would sell the KP kit and do some more research.
Also Porterbuilt has one of the strongest notches in the business. Check them out.