PETERSON FABRICATION SHOWS US WHAT’S INVOLVED IN BUILDING A VARIETY OF COMPONENTS FOR ALL TYPES OF VEHICLES, FROM STREET TO STRIP! THIS MONTH, IT’S A DIFF BUILT TO HANDLE 1500HP
-
There are a few things that are important when building a nine-inch, especially behind a high-power engine. Firstly, the housing needs to be strong; for that reason this build uses Strange Engineering housings. With internal gussets and thick, quarter-inch wall axle tubes, they are far superior to factory Ford housings and, nowadays, much more readily available.
Secondly, the pinion angle needs to be correct. The number of cars we see arrive at the workshop with incorrect pinion angle never fails to amaze me. This can cause vibrations, premature universal joint wear, and inefficient power delivery. The pinion angle is always measured relevant to the crankshaft/transmission centreline. For leaf-sprung cars, I aim for four degrees pinion down; on a stock style four-link with rubber or urethane bushes, I aim for two to three degrees down; on a proper four-link car with rod ends, I aim for around 0.5 degrees down. There are always exceptions to the rule but those are a good starting point. The idea is that, under full power, the pinion should lift up to exactly the same plane as the crankshaft centreline.
Third, and very importantly, the housing needs to be straight. Any brackets you weld on have the chance of pulling the housing with the weld. Therefore, I always fit all the bracketry and weld it up before the final step of welding the bearing ends on with the line-up bar in place.
Here are the steps we took to build a nine-inch that is destined for a 1500-ish horsepower ’57 Chev on leaf springs. Time taken to date: approximately 8 hours.