This will be a little lengthy, but I thought I'd share what technical information I've learned doing five dropped axle installations along with the reversed arch spring thing on my own cars (1936 thru 1948).
SPRING:
1)If you try to lower the front end a significant amount by just
reversing the arch of the front spring and removing leaves, you
can have a problem with the stock radius rods hitting the frame
rails, especially on the stock steering box mounting bracket (it
can be heated and bent for more clearance with no saftey issues).
With this solution you've lowered the front end but have sacrificed
suspension travel. You can alter the length of the axle rubber
bump stops to limit suspension travel to prevent the radius rods
from hitting the frame but it will "bottom out when hitting
a significant bump.
2)An advantage of a thinner spring "package" is you
can shim between the frame and spring to get "your"
desired ride height or "look".
3)Another problem with this method a reduction in shock absorber
travel. Lever action shocks will have the arms pointed "uphill"
unless you shorten the shock links. Make sure tube shocks aren't
bottoming out in their travel. I've had to go with shorter shocks
to correct this problem.
DROPPED AXLES:
1)I've used Bell, Chassis Engineering, Magnum and Mor-Drop I-beam
axles. All are OK depending upon what you're doing. Most importantly
with a dropped axle you retain most of your suspension travel.
Depending upon the amount of "drop" you want, you may
not have to reverse the arch of the front main leaf. Removal of
a few spring leaves might be all that's needed, primarily to improve
ride comfort. Remember to install shim(s) of equal thickness to
what's taken out so your stock U-bolts will clamp the spring tight
in the crossmember.
2)The Magnum and Mor-Drop(a stock axle with ends heated and reformed)
have stock perch pin (or radius rod mount) spacing. If you're
using the stock transmission or just want to retain the stock
radius rod mount on the frame, this is the way to go. Why? Because
the stock radius rods can stay the same length. Looking at the
radius rods as a triangle, none of the dimensions have to be changed.
The axle is "almost" a bolt in replacement. I even use
the stock lever action shocks and sway bar under my '40 Coupe.
2)Bell and Chassis Engineering(CE) have a reduced perch pin spacing.
This changes the dimensions of the radius rod triangle and moves
the pivot ball location to the rear of the car. If you're doing
an engine and later model transmission swap, plan on using a radius
rod split kit with these axles. They work great! Also, plan on
a shorter spring main leaf because the distance has been reduced
between the shackle pivots.
STEERING ARMS:
1)I have heated and bent steering arms, but don't like to because
it can mess up the Ackerman, other geometry and cause safety issues.
2)I like to use the dropped steering arms made by each individual
axle manufacturer. You have to cut the stock steering arms off
the spindles to do this. But spindles are plentiful because all
the hi-tech street rodders are installing Mustang II "stuff"
under their cars and selling off the "good old stuff".
So, if you want to back to original some day, pick up some spares
at the swap meet.
TIE ROD and DRAG LINK:
1)I think the Magnum axle is about 1" shorter from king pin
to king pin. I think the CE and Bell are even narrower. This tucks
the rims and tires inside a little to gain needed tire to fender
clearance when turning.
2)Because I'm pretty frugal, I use the stock tie rod and drag
link with the Magnum axle swap. Because the kingpin spacing is
reduced you have to shorten the tie rod an equal amount. I cut
off the right hand threaded end of the tie rod and rethread with
a right hand thread tap I bought from Travers Supply. I reslit
the tie rod with a thick hacksaw blade or zizz wheel and reinstall
the clamping collar and tie rod end. The tap is special, you won't
get it at Lowes or Home Depot! Cost about $10.
3)Because you only have to shorten the drag link about 1/2",
you can usually get that much distance out of the adjusting sleeve.
This is using a stock steering box.
SHOCK ABSORBERS:
As I mentioned before, make sure the shocks have enough travel
so they don't "bottom out". I've used both lever action
and tube shocks. It's amazing how good the old lever action shocks
work!
TIRES:
The best "hot rod look" I've obtained is with a 165/80R15
(26.5" diameter) on a 5" wide rim on the front and a
P235/75R15 (29" diameter) on a 6" or 7" rim on
the rear. If you're using a stock spring in the rear you'll probably
only be able to use a 6" rim with close to original back
spacing. Otherwise, the rim will contact the spring shackle mount.
Also, you'll have to heat and bend the stock shock arms toward
the frame, otherwise they'll hit the tire inner sidewall.
ALIGNMENT:
Assuming we all know what the terms mean. I run 1/16" to
1/8" toe in with radial tires. Camber on these replacement
axles has been consistently correct, about 1 - 1.5 degrees positive.
After dropping the front end down, usually I have to adjust the
caster back to 5 - 7 degrees positive. This "stuff"
is not rocket science and can be done in your "well"
equipped home garage. I'll save the procedure for another day
if someone wants to know.
OVERALL:
For me, the dropped axle front end is the best way to go. My cars
with this set-up handle great, track down the road straight and
have plenty of ride comfort. My '40 pick-up with only the spring
thing done works OK, but lacks the ride comfort of the dropped
axle cars. It's slated for an axle change in the future!
I've owned old Fords with Mustang II independent front ends and
didn't like 'em for a variety of reasons. Sometime in the future
I envision hot rod parts suppliers selling kits to convert Mustang
II front end old Fords back to straight front axles!!!!
by Modifieddriver