REWORKING MY FORD 8.8 REAR AXLE
I had three goals when starting this project:
more clearance, wider stance and beefier tubes. Here is how it
First, I measured the stock clearance, 5-7/8"
from the fixture to the bottom of the F8.8. After marking the
portion that I could trim, a reciprocating saw removed it with
a bit of elbow grease.
I built a new 5/8" steel bottom plate
to fill the hole after shaving the bottom. The little bump in
the bottom is for ring gear clearance. Since I did not need the
anti-lock brake sensor tone ring, or its pickup, I removed it
and the bulky hardware in the top of the housing, and welded the
As you can see, the amount of clearance gained
at the lowest part is now 6-7/8". At the flat part of the
plate it is 7-3/8". That is a gain of 1-1/2" over 90%
of the bottom of the housing! The 3/4" thick reinforcing
ring was cut out with a hi-pressure water-jet. I then transferred
the holes from the F8.8 diff to the ring, drilled and chamfered
After bolting the ring to the housing with
tapered socket head, stainless steel bolts, the next steep was
to build a new cover.
The flat cover plate was fabricated from 5/16"
thick cold-rolled flat stock. I shaped the gear cover portion
from 1/4" flat pieces, then tack welded everything in place,
frequently checking for gear clearance.
The 1/2" bolts on each side will press
against the carrier bearing caps to reinforce them.
After fully welding the cover, I drilled and
tapped another set of holes in the the reinforcing ring, then
bolted the cover in place.
For extra strength the four bolt heads you
see on each side of the ring attach it to the "webs"
cast into the F8.8 housing.
Since the plan was to change the rear suspension
from leaf springs to coils, I needed a flat area to weld the upper
link brackets to.
I fabricated this unit that bolts to the reinforcing
ring, and the nice flat area that Ford installed near the pinion
I punched holes and "dimpled" them
to add rigidity to the structure. Plus, it looks trick too!
Next, I cut the stock tubes off of the housing,
leaving three inches sticking out. The stock tubes had been fully
welded to the center section previously, making removal very difficult.
If I had this project to do again, I would have removed them.
The stock tubes on the right are 3-1/4"
O.D. x .188 wall, seamed tubing -- choice for replacement was
3" OD x .500 DOM. I had the diff end turned down to press
into the stubs sticking out of the F8.8 shown above. The outer
end received a custom flange to accept my Warn spindles.
The new tubes were built to add 3" to
the overall width. After removing the seam in the stock tubes,
I pressed the new tubes into the center section.
Above and below is the jig/fixture I built
out of a chunk of "I"-beam. With center pucks and lineup
bar installed. When I was sure everything was aligned, I welded
the new tubes to the F8.8 tubes, inside and out. The housing was
straightened with a 12 ton bottle jack when all welding was completed.
I decided to truss the top using adjustable
rods, for future "tweaking" and to be able to preload
the housing. Plus, the rod ends Im using are the same size
as my steering linkage, so it's a handy place to carry spare rod
Here is the completed F8.8 under the
CODE 4x4 Jeep. It received 4.56 Yukon brand gears, a Detroit Locker,
Warn full float spindles and 31 spline alloy axle shafts. I ditched
the stock Ford parking brakes but retained the Explorer disc brakes
and calipers. The new width is 65" WMS to WMS.