I want to C notch the frame. I'm going to put the rear end on top of the leaf springs and I wanted to know how high is the cut for for the c notch. I want to trim down the arches I have to fit. It looks like it's 2 inches or so. Has anyone done this with some measurements.

 

The picture of the red frame is a random picture off of the Internet with the mid fifty notch.

 

Here is my frame with the Midfifty flip kit installed. The chassis is out in my storage barn so I can't measure it but maybe you can get a feel for the depth from the picture. Be aware, if you use this notch and make it so your rearend will travel up that far, your differential WILL hit the floor of the bed. I raised my bed floor 2 inches to compensate.

 

Are you using an explorer rear end?

 

No, that's a 9 inch with the Ford Racing disc brakes (like used on the Explorer)
I find it interesting the red frame in the first photo has the same shock mount crossmember setup as mine.

 

The disc brake setup looks good on that 9 inch. I have the TCI rear leaf spring kit that lowers it 4 inches in the rear. I'm going to use a 8.8 from a 98 explorer 3.73's gear ratio disc brakes. I will have to look into the clearance issues once I get the c-notch done. It had a 9 inch but it needs a rebuild. It still had some clearance. I'm thinking of fabricating some lowering blocks cause I have a rake stance right now. The front end has a mustang II suspension with the 2 inch drop spindles up front. thinking about making a 1 or 2 inch lowering block. I still need to put the springs on the mustang 2 suspension and drop the engine on the frame to see where the frame sits to see how much to lower the back end.

 

That sounds like a nice suspension set up.

You could do it like this too... Level your frame to the rake you intend to use using an angle finder. Preferably on level ground if you can. 1.5-2° rake would be typical. Then set your lower control arms to the level position with jack stands or bailing wire. That's how they should be when you put the springs in and weight on. Now measure from the center of your front hub to the ground. Lets say you have your frame up on tall jack stands and that measurement is 24 inches.

Put your rear end on a jack and raise it up into the frame until you get the 24" measurement to the center of your axle to the ground. Keep in mind that's if your front and rear tires are the same height. If your rears are taller take the difference between the front and rear tires, divide in half and subtract that from the 24". That will show you where your axle will be in relation to the frame at normal ride height.

 

Nick I have seen your build it looks nice its coming along good. What size of wheels and tires are you running and the offset.

 

I'm using 18×9 - 255/45/18 and 18×10 - 295/45/18. 4.5" BS all around. I'll have to add small tubs in the bed. One thing I noticed when setting up my rake and ride height is that if I went much lower in the front (drop spindles) I think it would be real hard to get the rear low enough without c notching the frame deeper than I think one should. It all depends on what you like for rake. I like a more level look, so I would have had to go real deep with the notches using drop spindles.

I think with the drop spindles you will have your choice of an aggressive raked stance, or raise the bed and beef up the frame rails above deep notches. But that's just a guess. You should be able to tell for sure if you set up the frame like I mentioned.



Good luck with it!

 

Interesting reading on C notches

Frame Notch Based On Strength - The 1947 - Present Chevrolet & GMC Truck Message Board Network

With leaf springs I would the make the frame as strong as possible. Coil overs or coil springs that do not put the load on the rear section of the frame would not need as much strength.


Also front lower control arms will not always be level at ride height, depends on the suspension system. Jag IFS has the lower control arms angled downward at ride height on my XJ6s, so I set them up the same way on my project cars.

 

It's interesting that you mention that you are going with an 8.8...I have changed course a bit after that pic was taken. I came across a new TCI full show 4 link w/air bag option and a 8.8 3.73 Trakloc rearend so I am replacing the 9 inch and the leafs...the clearance issues however do remain. Here is a pic of how I opted to fix the floor clearance...the tubs in this pic are OEM Ford tubs from an F250 bed, the framework is constructed from 1x2 and 2x2 tubing.

 

^^That's an interesting link. I certainly don't doubt it. But wished he mentioned how he took the measurements. Maybe be did and I missed it. I'm guessing it is a computer simulation? That would be cool if it was something you could do on a PC at home when building frame bracing and stuff.



I was just referring to the Mustang 2 suspension he mentioned he had. As far as I know all M2's should have the lower control arms parallel to the crossmember.

 

If I can't get it leveled enough I might buy a set of the standard spindles and sell these 2 inch drop spindles.

 

Based on the color diagrams I would say that the ME used a computer based FEA system. When I was in engineering school we used some computer simulation and it is a very powerful tool...assuming you have accurate data to input. For instance, the dimensional data (H,W,D, thickness) and the physical properties of the metal under test. The other critical data points are the forces applied to the structural member under test...both the point at which the force is applied and the amount of force at each point. He did make note of the fact that the load in the bed would have some bearing on the test/results. For the frame to bend at the notch, both sides of the frame member on either side of the notch must move up at the point at which the leaf spring is attached. The bed and the load in the bed both push down at these points which help to counteract the upward forces. There is the possibility that the rear spring perch could move back and cause the notch to break but that would assume a lot of load on the bed or a mechanical failure in the perch. I am very confident in the notch in my frame and would only give it a second thought if some ME actually did a destructive test on the system...that is, load the frame until it broke and then analyze the forces that it took to break it. I was an electrical engineer and if you designed every circuit to meet the requirements of the system you would soon find that your circuit did little more than produce great quantities of smoke. Theoretical values are great for simulations but holding those tolerances in the real world are tough.

 

What kind of measurements did you get? Rake vs axle to frame distance?