Contents:

• Introduction
• Ordering Information
• Installation Instructions

Introduction:

The Toyota 8" axle makes use of a dropout differential, or third member). Because of this, a drain plug is installing on the bottom of the axle housing to allow for draining the gear oil. Other types of axles feature a cover plate that serves this same purpose. One problem with the low hanging drain plug is that it is prone to getting hung up on rocks, and it can also become damaged to the point where removal is difficult, or worse yet can get knocked loose causing the loss of the gear oil in the axle. Several improvements on the drain plug have included low profile socket plugs, to welded in place plugs with alternate method of oil draining.

A second problem with the axle housing is that while the steel in the main part of the housing is approx. 3/16" thick, the steel in the face of the housing is perhaps 1/16" thick. It is susceptable to damage from contact with rocks and if pushed in far enough, it can contact the ring gear, either damaging the gear or letting the gear cut through the steel and create an oil leak. There are several forms of "diff armor" on the market to address this issue.

Over the years, I've tried a number of these techniques to beef up the axle to withstand trail abuse. Each problem could be addressed individually to some degree, but I wanted something cleaner and that would address all the issues at once. Below, is a rear Toyota axle housing showing the bottom section, containing the drain plug, cut out and replaced with a flat bottom plate that also wraps around the front (or rear) of the housing:

I developed an easy to install kit, pictured below, that incorporates a flat replacement for the bottom of the axle housing and a curved protector for the face of the housing, all out of 1/4" thick steel:

Ordering Information:

Kits available for the front or rear axle, for US$50.00 for either kit, plus shipping:

International orders: Add telephone number in "Note To Seller" field of the order form for the customs paperwork.

Add a weld-on spring perch spacer for the driver's side of the front axle kit for an additional US$7.50:

International orders: Add telephone number in "Note To Seller" field of the order form for the customs paperwork.

Already have a "diff protector"? No problem, a version of the plate that only covers the center section of the axle housing is also available for US$45.00:

International orders: Add telephone number in "Note To Seller" field of the order form for the customs paperwork.

Questions? Contact 4Crawler Offroad for more information.

Can't weld or want something ready to install?

No problem, 4Crawler Offroad can modify your old housing or may be able to supply Toyota 8" axle housings clearanced and ready to install, in exchange for your old housing (in good condition) in return. Contact 4Crawler Offroad for more information. Shipping empty axle housings is not all that prohibitive, they generally weigh around 50-75 lbs. and shipping each way is about $50. Send us your zip code and type of axle and we can get an exact estimate

Installation Process:

• Remove the axle from the vehicle (A)
• Remove the differential and clean the inside of the housing of gear oil
• Remove the lower four studs, the two lowest ones will become the oil drains (B)
• Mark the outline of the cutout area, using the included template (B)
• Make straight line cuts are made to remove the bottom of the housing:
  • Cutoff wheel, sawzall, oxy-acetylene cutting torch or plasma cutter will make the cut
• The opening is ground out to allow the plate to drop in (C)
  • You can cut/grind the back egde of the rear axle housing to let the plate sit in deeper if you have the rear pinion tipped up for a CV shaft
• Weld the plate in place, first tacking the corners then weld in short sections, allowing the housing to cool in between (D)
  • I find filling the bottom (actually the top) of the housing with water helps soak up the heat
• The tabs are bent over and the protector is welded in place
  • If needed, grind a deeper groove where the tab bends over the housing or heat to make it easier to bend
    • Fill in the groove after bending.
  • The two small 3/8" steel wedges can be used to fill the gaps on the ends where the tabs meet the housing
  • The inner seams can also be welded closed for a stonger and more leakproof installation
• Grind the outside welds smooth, clean, prime and paint as desired
  • I like to tip the housing back and fill it with water or paint thinner to check for leaks
    • If a leak is detected, re-weld the inside or outside as needed
  • Clean the inside of the housing and if desired, apply an oil proof primer/paint, such as POR-15
• To replace the oil drain plug the two existing lower studs that hold the 3rd member in place are converted to bolts by welding the nuts to the stud after its tight
  • These parts are not included in the kit, you re-use your old studs and nuts
  • Alternately, you can use some M8-1.25 bolts for the lower two studs in place of welding the nut to the stud
• You may find that it is easier to install the 3rd member if you drill out the mounting holes a little oversize
  • I used a bit about 1/64"to 1/32" larger than the existing hole to clean it up and make it easier to slip over the studs
• Re-install the axle on the vehicle

The end result of about 4-6 hours work is an axle that has 3/4" - 1" additional ground clearance (equivalent to a 2" tire size increase), a smooth base to easily slide over trail obstacles, an integral diff protector and no drain plug to get damaged or lost.

Here's a writeup from my first high clearance axle conversion:

http://4Crawler.com/4x4/CheapTricks/AxleTech/index.shtml#Clearanced

Here's Tim Stucky's excellent writeup on 4x4Wire:

http://www.4x4wire.com/toyota/reviews/shaved_diffs/