Of the many mechanical upgrades that Jeepers are
dreaming of these days, sturdier axles are generally high on the
wish list. On Jeep CJ models, the factory Dana 30 front axle is
adequate with smaller tires, but as your tires grow larger , you
add a locker, a more powerful engine, and start using lower gears,
it begins to show its lack of brute strength.
Among the shortcomings of the stock Dana 30 are its relatively
small axle shafts and small outer axle u-joints that are prone to
failure, especially with a full front locker installed. For years I
have driven my CJ8 with the stock Dana 30 front axle, fortifying it
with ever lower gears and a Power Lock limited slip differential. I
never had a problem with it and I am sure that this was due at
least in part to the 'forgiving' nature of the clutch type Power
Lock limited slip differential, which when pushed, would slip, as
it was designed to do, instead locking up hard and breaking
something.
As my appetite for hard core
rock crawling grew, the limited slip started to show just how
"limited" it was. I needed the absolute traction offered by a true
locker. I had recently upgraded my transmission and transfer case
and now had ultra-low gears applying more torque to the stock front
axle than it was designed to handle. I was now in need of an
upgraded front axle, one that could take the stress that would
result from the compounded effects of a true locker and ultra low
gearing.CHOICES
There are several heavy duty front axle choices for the Jeep CJs. I
considered the Dana 60, but decided for my needs that it was
overkill for my 6 cylinder CJ; it was too heavy, had less
clearance, and that it would require too much alteration to make it
fit. Also considered was the Ford 9" front end, but again I
rejected it as the pinion exits too low, and it would also require
significant fabrication to make it work. The newer high pinion Ford
9" (which only has an 8.8" ring gear) looked good on paper, but was
very expensive. In the end, the tried and true Dana 44 was my axle
of choice. I found it to be the best compromise between brute
strength and weight, mass and clearance issues, and availability -
both of donor parts, and of gear and locker choices.
Once I had decided on the Dana 44, I did some research, talking to
people that had done this swap before. I found that no Jeep, or any
other vehicle for that matter, had ever been built with a D44 front
axle of the same width as the 1980's Jeep CJ models, the so-called
'wide track CJ', with a 55.8" front track width. To get a Dana 44
under my Jeep I would either have to buy a custom fabricated unit
or I would have to modify an axle originally used in some other
application.
With careful research I found that the best Dana 44 front axle
donors for my CJ, with it's passenger side differential
were:
'73-80 Scout
II
'70's full sized Jeep Wagoneer
Chevy Pickup or Suburban.
The Scout Dana 44s are plentiful, but they have
'0' degrees of caster built in. The axles from the Chevy could have
been utilized as a donor, but the axle is significantly wider than
either the Scout or the Wagoneer, and the steering is completely
different. So, in the end, I chose the Wagoneer Dana 44 as it was
closer to the width that I needed, had similar steering, and had 4
degrees of caster built in.
Outer U-joints: Left is a
Dana 30; Right is a Dana 44.
The 'outers' on my Dana 30 were the same as the
outers on a Dana 44. I had mostly new parts in my D30 outers,
including Superwinch's 6 bolt premium locking hubs and as a cost
saving measure, I decided to recycle the outers from my old Dana 30
and graft them onto the new Dana 44 housing. The 'outers' as an
assembly included the outer knuckles, disc brakes, steering
components, and hubs - basically everything from the knuckles
outward, except for the new and larger axle shafts and U-joints;
the real value in this upgrade.PREPARING THE
WAY
4" were removed from the
axle shaft.
A Dana 44 housing and inner axle shafts from a '77
Wagoneer donor were procured at a local wrecking yard. The next
step was having the Dana 44 housing to cut down to the correct CJ
width. I delivered the axle to Paul at Cook's Machine Works. He
removed the driver's side knuckle from the axle tube (the long
side) and cut it down exactly 4", and then refitted and welded the
knuckle back on. Added strength was gained by fillet welding the
tubes to the housing using 7018 welding rod, a good choice for
steel to cast parts.
With 4" removed, the stock CJ width is retained. Another option
would also be to cut it down only 3.25" and have a slightly wider
axle that would give the Jeep a slightly wider stance and thus gain
a bit more turning radius with big tires.
The long side axle shaft was also cut 4" and then re-splined.
The short side tube and axle shaft are not modified and remain
completely stock.
The existing spring perches and shock mounts on
the Dana 44 were cut off with a torch and the axle tubes were
cleaned up with a grinder. UPGRADED RING AND PINION
GEARS
I wanted to
use the best, so I called Randy's Ring and Pinion. Randy is truly a
giant in the business, someone who gives expert advice along with
his parts sales. I was changing the ring gear and pinion in both my
new front axle and the rear axle, so I ordered the 'kit' (which
includes all necessary parts for the installation) for each: the
4.09:1 gear kit for the new front Dana 44 and the 4.10:1 gear kit
for my beefed up AMC 20 rear.
Because of the gear design and the number of teeth on both the ring
gear and the pinion, it is common to have a slight numerical
difference in the gearing, this is OK as it will make virtually no
difference as long as they are within one or two percent of each
other.
Be prepared for a project like this to take some time if you are
farming out some of the process. Everyone has some excuse. However,
overnight, I received the new ring and pinion gear kits from
Randy's Ring and Pinion. This certainly turned out to be the
quickest and most painless part of the whole project. Armed with my
new pile of parts, I delivered both my old Dana 30 and the new Dana
44 housing to 4-Wheel Parts Wholesalers in Burbank, CA., where Rody
Jarve and Mike McAtee worked with me on the axle set up.
Mike installed and set the new 4.09 ring gear and pinion and new
ARB Air Locker, along with new bearings and seals. He also removed
the outers from my Dana 30 and installed them on the Dana
44.
SETTING THE SPRING
PADS
Since I
was retaining spring-over-axle configuration I already had, I would
need new spring saddle pads welded on top of the axle. I also
started collecting the weld-on mounts for reattaching the shocks to
the axle.
Since I had my old Dana 30 as a
template, I decided to do most of the welding on the bench. Once I
got the newly fabricated D44 axle housing to my garage, I set it
securely on two jack stands.
Using a degree gauge, or magnetic protractor to measure the
necessary angles, I set the knuckles (king pins) on the axle tubes
for 4 degrees of positive caster, which in this case happens to be
correct when the steering arm is parallel to the ground.
I then clamped the housing to the stands, supporting the rear
pinion with a block. This was my base measurement when it came time
to attach the spring perches. Since my old and new housings were
exactly the same width, I took measurements off the old Dana 30
housing to determine the placement of the spring pads on the new
Dana 44, and then trial fitted the spring pads in their new
locations.
Passenger side spring
perch.
Since the axle housing was originally made for a
spring-under configuration, a flat spot had to be machined on top
of the edge of the differential housing for the spring perches.
After marking the housing, I used a 4" hand grinder, a
reciprocating saw, and a file to machine away the necessary
material from the differential housing to fit the passenger side
spring perches. I also machined the perch a bit to fit very close
to the housing, leaving just enough space so the spring centering
bolt would not bottom out when everything was in
position.
On the flat bottom side of
the differential housing where the original spring location had
been, I had to make cut semi-circular grooves into the housing to
fit the U-bolts that would now be facing up. Optionally I could
also have used square ended U-bolts and skipped this step, but this
would require using non-standard parts that would be tough to find
in a pinch or on the trail.
I also had to decide exactly which spring perches to use. I
eventually was planning on moving to 2.5" wide Wrangler (YJ) front
springs, as they are a bit flatter and flex better than the 2"
wide, 7 leaf CJ spring pack I had built up. So I decided to use a
2.5" wide spring perch, even though I was not changing from the 2"
wide CJ spring just yet.
Spring perch with spacer
& shock mount.
I used a low profile 2.5" wide perch made by
Con-Ferr (#G-8036) on the passenger side, and the same perch with a
1/2" plate welded onto the pad for the drivers side (on the tube).
Since one perch had to be mounted on the differential housing and
one on the bare tube, the spacer was necessary to keep the perches
matched vertically.
Using Con-Ferr and Pin
& Plate weld-on shock brackets (#G-8400), I welded on new shock
absorber mounting brackets vertically aligned with the center of
the axle and to the rear, with the outboard edge of the plate
exactly 1" in from the knuckles on either side.
Each of the centering holes in the spring pads were centered 5
15/16" from the edge of the knuckles, with the distance between
them being 27 3/8". This ensures that the springs drop vertically
straight down from the frame, at least on my Jeep. My front axle
was always off-center from the factory, and now it is perfectly
centered.
With everything positioned perfectly I securely clamped and welded
all of the parts, re-measuring often along the way, using 7018 rod
(with a higher nickel content for welding cast parts) and utilizing
the on-board welder in my Jeep (which was up on jack stands with no
front axle). Once I was satisfied with the welds, I re-mounted the
wheels on the axle, and rolled the subassembly under the Jeep;
lowered it onto the springs, settling into the centering holes, and
then installing and reattaching the U-bolts, spring plates, drag
link, brake hoses and shocks. The shocks now pivot on the same
plane, unlike the stock positioning.
Upon completing the re-assembly of front axle, I drove the Jeep
back to the folks at 4Wheel Parts Wholesalers (with a 4.09 front
ratio, and a 3.54 rear ratio) to have the rear axle gears changed
to 4.10, and the rear ARB Air Locker installed.ODDS AND
ENDS
U-bolts & spring
plates
The 2-3/4" diameter tubes on the Dana 44 are much
thicker (1/2" thick) and stronger than the 2-1/2" diameter tubes on
the Dana 30, so new U-bolts had to be procured. I had 4 custom made
U-bolts drawn, 4"diameter by 7-1/2" long. I cut some 5/16" plate
and drilled 4 holes to use as spring plates on top. If I can find
some original Wagoneer plates, I'll switch over to them.
Tie rod interference with
D44 differential cover.
I used the thick, flat front end Dana 44
differential cover and the tie rod still touched it just a bit at
full steering lock, so I bent a slight curve into the tie rod to
accommodate this, welding a 1"x1" angle iron gusset to the tie
rod.
The Dana 44 Pinion is 1 inch longer to
the back of the pinion face, than the Dana 30, so the front
driveshaft needed to be shortened by 1 inch.
As a result of changes, the front of the Jeep is now about 1"
higher than before, but a switch to YJ front springs should bring
it down to the desired altitude again.
The finished
project.
Following years of fooling with the front
anti-sway bar at the trailhead, I decided to just leave it off, for
good, so I didn't weld on the anti-sway bar brackets this time. I
felt that it was always in the way and cut down my turning radius
with big tires. I run the shocks at a stiffer setting on the
highway now, but don't have to disconnect anything at the
trailhead. After a couple hard core trips under my belt, including
a week at Moab, I am delighted by the performance of the axle
upgrade. This project has given me significant peace of mind, and I
am now comfortable that my axles are up to the the kind of hard
core jeeping that I love.
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Posted Oct 19 2008 04:52PM
