|
Copyright © AATcorp |
||
|
Ultra low gears, big horsepower and larger, high traction tires multiply the external forces on stock rearends far beyond their intended capacity. Couple that with the high demands of severe driving conditions, and rear end housing failure is nearly unavoidable. One of the common problems involves the rear end bowing forwards as the tire tries to climb front ward faster than the center of the differential. Many times this is only a momentary, flex returning back to it's normal shape, but while under power the turning axles inside are trying to turn while slightly bent, thus resulting in premature axle failure. Another problem is the rear end bowing upwards under heavy suspension compression situations. Ford 9" housings are easy to back brace since the cover is not removable. A truss can be bolted or welded on but will hang down significantly reducing ground clearance. Here's a process that will reduce the effects from both forces. |
First the axle tube brackets are placed using 1/4" plate steel and reinforced to create a stable and rigid platform for the external brace to bridge across and tie one side of the tube to the other. 1/2" Weld nuts are welded inside the brackets where the bolts will fasten.
The braces need to be perfectly aligned in order to produce a very tight and precise fitting cover to tie into. Any clearance at all will allow the housing to flex before the brace is able to step in and resist the unwanted motion. This is the WHOLE POINT.
Welded and ready for powder coating shows the extended fill tube which accepts a polished alum. knurled cap for quick and easy fluid checks as well as ring gear inspections.
An allen set screw has a shaft welded to it with a washer on the end. This device pushes the brace off since the super tight fit will not allow removal without prying.
The device is threaded into a weldnut located on both ends of the brace. The washer prevents the assembly from backing out and becoming lost after installation of the cover.
The completed and power coated cover/brace unit ready for installation. The brace itself was also fabricated using 1/4" thick steel. While all this might appear heavy, the entire additional weight of the mounts on the housing and rear cover brace was only 18 pounds.
The center for ribs are bolted in first to draw the assembly up to the housing without deflecting the cover's gasket surface itself. Once the cover is flush, the cover bolts are inserted and snugged only to be torqued after the main rib bolts are fastened.
With the cover and brace assembly fitted to the housing, the main rib's twelve 1/2" Chromemoly bolts can be threaded into the bracket underneath to create an integrally stressed one piece unit that will resist rear housing deflection in all planes of force.
