108 Axle Flip 2.0

I wasn't entirely happy with the original version af my axle flip setup, so I decided to re-do some stuff...... Problems were:
1)12 degrees of caster shims lowered the van an extra inch and still not enough caster
2) The van would easily scrape while driving down the road unless I kept 50+ pounds of air in
   the front shocks
3)I had to put down lumber to get into my driveway (or out)
4) Death wobble because of not enough caster......
5) Bump steer

My modifications were as follows:

1) New flip saddles/shoes with 14 degrees of caster built in to eliminate almost an inch of
  lowering
2)Tie-rod flipped to top side of steering arms
3) wedges welded to bottom to bump stop plates so u-bolts would have a 90 degree surface
   for their nuts to tighten against
4)One leaf added to each spring pack (now five leafs)
5) steering stabilizer shock installed

So, pictures!



picture of a spare axle settin at 14 degrees in the new saddles



Completed saddles with stabilizer bushing bracketd welded on and smoothed




Test fit onto springs with the u-bolts locked into the underplate that is centered on the leaf centering bolt....the axle tilts 14 degrees but the u-bolts are at about 6 degrees.....Nuts will not tighten flat like this...




Here we see the top bump-stop cap with 6 degree wedges welded to the bottom




Here we see the test fit on the left side



Right side painted and installed....Stabilizer shock hardware in the background



Left side painted and installed and another background shot of the steer shock...



Next up.......Driving impressions after completing the work.....Stay Tuned!..... Like and Subscribe and thanks for watching!

Wellll......

I'm now able to get a floor jack under the front leaf hangers and able to carefully back out of my driveway scrape-free.....The view out the front has more windshield at the top and I'm able to drive down pretty much any road now with no scrapes and that is without air in the shocks.....
I went to my (un) favorite highway bounce bridge and.......it's still got terrible side wobble as it bounces, both with air and without.....I'm certain that the springs gain and lose length ahead of the centering pins which tugs and pushes at the drag link which steers the left wheel left and right as it goes up and down.....
I'm having a hard time understanding why every one of these vans ever built wouldn't have the same issue.....
I believe I have the skills to design and build a cross-steer conversion, but I'd feel real stupid if all the effort involved didn't pay off...

Kind of weird posting all of the replies to my thread, but as i "learn stuff", some of my previous thoughts become less than accurate.....sohhhhhh.......
First, I learned that "death wobble" and "bump steer" are two different issues.... and that what I'm experiencing is "bump steer".....
I had learned pretty early in the axle flip process that if I jack the chassis up with the wheels on the ground that the steering wheel would re-clock 180 degrees by the time the wheels leave the ground.....
I had hoped moving the axle closer to the springs would yield improvement, but it appears that it's now slightly worse...
Looking more closely, it clocks left as it's lifted and if I bounce down (wheels on the ground) it clocks right....
I think this means that the drag link is pulling (needs more length) as it drops and wants to shorten as the suspension loads.....
In researching, I learned that the drag link attachment points need to be on the same "plane" as the relationship between the front leaf hanger pivot and the spindle center and also it needs to be the same length apart as those two suspension points.....
For illistrative purposes, consider that the bars on a four bar suspension on a 32 ford are the same length and parallel so that the front axle moves straight up and down rather than "rolls"...and that a drag link on such a car that is the same length and parallel at it's attachment points, will not bump-steer.....

The flipped axle now has a different relationship between the spindle and front leaf hanger bolt that most likely exaggerates front to rear movement as the suspension travels and the attachment points of the drag link are neither parallel to suspension travel, nor the same length and even if I could mathematically figure out attachment points for the drag link that would restore the geometry, I think those attachment points are physically impossible to accomplish.....
The leaf-sprung setup DOES NOT operate like a four-bar, but actually operates more like a ladder bar, in that the axle actually rolls forward as the suspension loads....
This actually suggests that the parallel drag link scenario is wrong......

One alternative I might have considered if earlier in the overall project would be to mount a rack and pinion right on the axle with a horizontal slip shaft between two universal joints hooking to it.....No possibility of bump steer in this scenario....

What I have decided to pursue instead is to build a horizontal bellcrank behind the axle and tie-rod that operates a cross-steer link that hooks to the passenger-side steering arm....The cross-link would be parallel to the ground with the van loaded with two front passengers...
This puts the link at full extension in it's arc with very little inward movement during lift or drop because of the length of the link....the slight amount that would still exist is STILL bump-steer, but may be imperceptible....
I'm building a bell crank using a trailer wheel hub and spindle with tapered roller bearings so I can be assured of smooth, heavy-duty operation without wobble/looseness.....
I've already got the hub-spindle and started measuring and designing, but my sketches are pretty rough and hard to follow.....I'll have pictures as I progress, fully aware that I could be documenting my own suicide...

AzDon wrote:Kind of weird posting all of the replies to my thread, but as i "learn stuff", some of my previous thoughts become less than accurate.....sohhhhhh.......

Just to let you know you're not talking to an empty room, lol

I appreciate your posting this while I sit up here in the cheap seats. I have the bump steer also and likely won't get to any sort of repair like yours in the near future and really have no knowledgeable bits to offer so I'll sit and learn.
Thanks Don, If mods like this are not documented we're certainly going to lose the info to time...  
bruce

Don, Your creativity, ingenuity, and attention to detail are amazing! Those brackets are amazing! No worries about posting and commenting on your own post. Many of us, myself included do it as well as a means of documenting our own progress too. The memory is not what it used to be so it does also act as a backup as our project progress... Keep up the great work and look forward to seeing your progress.

~Dan  

Thanks Guys!
It did kind of feel like talking to an empty room, but I DO kind of have the feeling that either those that have the knowledge I seek are keeping it secret OR maybe I've tried stuff of my own design that has not been tried before so I have to be the person to see these issues through to completion because there is nobody else....(yes, that was a long sentence!)

I'm forging ahead because I still believe that I can solve this and I refuse to retreat while victory is still possible....

I'm happy being the kind of resource for others that i'm looking for when I need advice or opinions....This axle flip has been humbling, but I may never have tried to do it if I had waited for somebody else to publish a full recipe complete with pitfalls... Others can see that I jumped into it without full knowledge of those potential problems, but that I do my best to make safe and attractive parts that are overbuilt to a greater standard than original parts....

Anybody else considering getting four inches of lowering by flipping your front axle, my first advice is DON'T unless.... you have the knowledge and fab skills to make the parts you'll need, AND...
If you are starting from scratch, you should be willing to put a rack and pinion ON THE AXLE and drive it from one of those 90 degree 1to1 boxes in place of the original steering box BEFORE deciding on radiator mounting or underscoop design....

The cross-steer I'm creating would have ZERO CHANCE of operating in a van that doesn't have the engine pushed back 18 inches like mine....
Also, be aware that the leaf springs will be below rime height when finished, so having a front blowout will be about as safe as if you had one while riding a motorcycle...

If I were starting over from scratch, I'd be shortening a 91-96 GM wagon chassis and making it fit under my van and simply live with any "Ackerman" issues created by shortening the chassis, because everything else about the suspension and steering would be "as designed by GM...

More progress and more pictures...

Shown here is the spindle mounting plate which I spun 180 degrees and drilled a second time because the first hole (top one) was too close to the frame rail... second hole is moved 1 inch right (3" from rail)





In this picture, I'm determining travel lengths and ratios using CAD (cardboard aided design)
The two bolt holes nearest the camera are half inch and thread into the factory engine crossmember holes same as the two on the other side did before I spun the plate 180 for a second try...
The near edge of the plate is even with the frame rail edge, so we are looking at the arm that will be sticking out to the left just below the frame rail and have the lengthened drag link hooked to it....The left facing arm will have the cross-link hooked to it...



and in this picture as well...
The distances written on the arms are from spindle center to potential attachment points... There are marks along the left edge for 2.5 inches of travel and the unequal ratio of arm lengths was determined to be feasible...




Here, I've cut the holes through the 2x2 spindle brace that will weld to the top of the plate




Here is the hub test-mounted for the first of many times before I'm done....

A little more progress...

This picture showing the rough-cut bottom tie-rod arm on top and longer drag link arm on the bottom along with the cardboard patterns...and a second copy of the short arm on the bench behind it's pattern....each arm is a triple stack of quarter inch plates keyhole welded together... 3/4" so that they can be taper drilled to hold tie rod ends... The two arms can be bolted at various heights by adding shims above or below the hub...







This picture demonstrates the cardboard pattern laid on top of it's triple-stack drag link arm, which will be on top 1 inch below the frame... The short tie-rod arm will be mounted below the hub at whatever height puts the cross-link level with the ground...

Charting new territory is never easy... I haven't commented much but I am following along!