How wide do I make my 'C' notch?

Quick question. I'm about to 'C' notch my frame for rear axle clearance. What's the minimum width I should make the notch to clear the axle?

Maverick rear axle housing that's 3" wide. 2"x3" mild steel frame. Car in my avatar.

 

I woulds mock everythingnup and measure it out. I assume your talking height? As width woulds stay the same

 

No, actually the axle will be level with the frame rails. When I hit a bump it will bounce up. I don't want it banging against the sides of the notch. The axle housing is 3" wide. I was thinking of making the notch 4"-5" wide.

 

i was going to say 6'' front to back.

 

I wouldn't go any less than 4 inches, centered on the axle where it touches the underside of the frame when the suspension is collapsed.

 

If your axle is 3 inches, use a 4 inch piece of tube and center it on the frame rail, mark it, cut it and use the 4 inch piece split in half to weld in the openings on each rail. That will give you 1/2 inch of clearence front and rear of the axle, which is plenty. If you use a 5 or 6 inch radius the notch will look to big. If your frame was 5 or 6 inches wide it would be different, but with a 2 x 3 frame you need to keep the notch smaller. Just make sure you center the notch before you cut it !!!

 

In my opinion you should not be "C" notching a frame rail that only has a 3" side height in the first place. That is, unless you add another 2 x 3 section, or similar reinforcement, above the location where you want the notch.

A "C" notch such as you are proposing substantially weakens the rail. Remember the old adage "A chain is only as strong as it's weakest link" ? Your "C" notch is that weakest link, unless the strength lost by the notch is restored. There are several ways to do that.

Ray

 

^^^^^^^^^^What he said, I agree. You don't have a whole lot of frame to work with.

 

I agree that you should not cut much more than 50% of the frame height for the notch. Make your notch about 3 inches wide, so it sticks out 1/2 inch per side and lay in a nice fillet welds all around the 4 inch half tube. If you can put a piece on top of the frame over the notch, it can go deeper.

With your frame sitting close to the rearend now, you really need to build a frame with a taller notch. Look at Gambino's super notch kit for the 49-54 Chevy's to see. You need a tower, not a c-notch! Best is to Z your rear frame.

 

I used 4''tube cut down to 1.75'' Height for my buicks 3'' axle. It also never hurts to plate/reinforce the frame at the notch.

 

Check this out.
I'm sure it's been posted before
http://67-72chevytrucks.com/vboard/showthread.php?t=457037