Customs 57 F100 Rear Axle Bottoming

My 57 F100 has been lowered by flipping the axle. I have a c-notch in the frame and a hole in the bed for differential clearance. Occasionally the axle will bottom out in the C-notch. One particular time, it flattened the brake line. I know the simple answer is to weld an arch in the frame, but I was hoping to not have to cut up the bed floor any more. So my question is, do I need stiffer rear leafs? And I don't even know the spring rate because I got them from the previous owner. So all that being said, hit me fellas. What's the best plan?

 

Brake pipes shouldn't be anywhere close to anything that might crush them under any circumstances.

Bump stops present? I suspect not! I'm guessing, but if they were you wouldn't be asking the question as the occasional bump, but cushioned, wouldn't be of concern.

Having said that, studying the pic, it looks like there's 6 inches or so of clearance over the axle, or is there? If the c notch is in the wrong place, or of insufficient width (tube diameter) it might as well not be there as it'll be doing nothing. What's hitting and where? Kiddies Playdough or Bluetak can come in useful if the contact points aren't already obvious,.

Chris

 

Add some arch into the helper springs in the photo so they are in contact with the main leaves.

If you want to experiment before dismantling the springs, Jam some wooden wedges between them and try it out.
If there is an improvement , then Re-arch them properly

 

Fit a progressive rate bump stop between the axle and the frame. 4x4 suppliers have them. Also check the shocks by bouncing the rear. The high angle of the shock means you are losing damping efficiency

 

Recently, on my 55 Plymouth that I lowered.It was perfect ride height but the springs were so worn out that it bottomed out a lot. I've removed a lot of Springs from a lot of cars at work. So I have some pieces to choose from. I ended up putting
In one Leave spring on each side From some unknown vehicle that had the right Width To fit my Spring pack. It raised the car 2 inches, but made it the right stiffness that I need. So
I took the Springs out that I just put in and dearched them in the press and made them basically flat. It lowered the car an inch and I'm okay with how it looks now and it rides good. I'd recommend taking those 2 bottom leafs out and arching them till they fit the pack a little better and it will stiffen it up.

 

I've done this, 4X4 bump stops and standing the shocks more upright. I had to get shorter shocks, but it controls bottoming a lot better. I had already added leaves to the springs.

Gary

 

Thanks everybody for the responses. All good advice. Exactly what I was looking for. Now I know where to start.

There's no bumpstops, that's on the list of things to address. It rarely bottoms out, and it's not too much of a slam, but it was just enough to flatten a section of the brake line. The brake lines were run just slightly back from the top of the axle. I'm swapping the drums out for discs and moving the new brake lines lower on the back of the axle out of the way. The c-notch was done well and it's well aligned. The axle tucks right up in when bottomed out. I just need to stiffen it up a tiny bit to keep it from bottoming. Probably need to get brackets to move the upper shock mounts outboard a bit too.

 

I like this idea. As soon as I get my new brakes on, I'll give this a try. Thanks.

 

I'm not seeing any notch but better shocks would help a bunch over those "cheapest ones they had" ones. Good shocks for a stock rig and I sold hundreds of them back in the day but there are better shocks that would help a bunch. When you get the weight on it the angle of the shocks isn't helping much at all either.

 

The notch is there. It just doesn't show well in the pic. You can see it just to the left of the upper shock mount. And yeah, the cheap shocks are on the chopping block.

 

It really is ridiculous the change some good shocks can make. Seems like they’ve got you pointed the right direction

 

Is the axle tube centered in the notch when the suspension is compressed? There is a short arc of axle travel when cycling through the range, so it could look centered at ride height, but due to the arc of travel it could contact the frame instead of the notch. You can check by disconnecting the shocks, and pulling out all the leaf springs except the main leaf, then have someone jump up and down in the bed to cycle the suspension.

Also, I second the idea of re-arching the overload springs. It's simple to do in a shop press or even a cheap pipe bender. Just make a few lines with a marker every inch or so outward from the centering hole, and barely put some pressure centered on each line with the press/bender until you achieve the desired arch.

Another idea is to ditch the overload springs, and find some other leaf springs that are the same width as your current leaf springs. Cut a few down and put those in place where the current overloads are to create a progressive spring pack. Depending on the thickness, length, and arch of the "new" leaf springs into your existing leaf pack, this could stiffen or soften your ride without affecting ride height.

The current shock angle is on the edge of efficiency. Maybe relocate the upper mount outward and try a slightly shorter shock to get the angle more vertical to get more effectiveness. You can keep the current upper and lower shock mounts and buy a pair of adjustable shocks where you can dial in the compression and rebound settings to keep it from compressing so much under a hard bump or heavy load.

Bump stops are also recommended. Look into off-road bump stops as they have many more options and sizes over what you'll find in a hot rod parts catalog.

 

I don’t see it either.
Maybe someone can edit the pic and point it out?

 

I’ll take your word for it, or run out for 1.5 mag glasses

 

Okay. Catching on

 

Thanks for assist. I'm out of town right now and can't post up a better pic.

Yeah it's centered. You can actually tell from the way it scratched the axle housing. As soon as I get back in town, I'm gonna swap out the upper mounting points for the shocks and put some better shocks in the back (I'm also putting coil overs up front with my Mustang II front end), and adding some bump stops. That's probably gonna be in August. Thanks everybody, all good stuff.

 

You can see the notch better in this video:

 

Say it ain't so!

 

Would it be possible to take a photo of the axle in its bottomed out position
when all the way up?