While many car enthusiasts know how a differential works, very few actually know what it looks like inside your differential cover as you're driving down the road. Gale Banks, founder of diesel performance parts company , put together a great video series demonstrating exactly what's going on inside your differential. And it's all part of Banks' investigation into making the perfect aftermarket diff cover.
This post was originally published Sept. 24, 2018. It has been updated with the release of new differential videos from Banks Power.
Mr. Banks is on a quest to determine if the current crop of aftermarket pickup truck differential covers actually do anything beneficial. Most diff cover designs claim to reduce wear by increasing oil capacity and dissipating the heat generated by the ring and pinion gear. A variety of diff cover shapes and sizes are available, including large-volume flat-back covers with cooling fins.
In order to investigate what's going on under these aftermarket diff covers, Mr. Banks has created a bunch of clear plastic replicas of the various cover designs. When installed, these see-through diff covers let Mr. Banks see how the gear oil flows through the differential at low and high speeds. Ever the scientist, Mr. Banks is also performing a series of tests to see whether these aftermarket covers actually reduce gear oil temperatures when driving, as they claim.
The first video in the series explains why Mr. Banks is doing all this testing, the scientific methods he's using, and what he hopes to find. If you just want to see some inside-the-diff action, you can skip this one, but it's great to find out what he's doing and why.
The second video gets even more into the science behind Mr. Banks' testing, and why he's investigating this in the first place. If you want to skip to the clear diff cover videos, you can pass this one up too.
Part three is where it gets good. Here, Mr. Banks has installed a clear plastic version of a stock Ford pickup truck differential cover, so he can see (and show us) exactly what's going on behind the factory differential cover. You can see how the shape of the diff cover influences the flow of the lubricant.
Part four is where Mr. Banks starts testing the flat-back differential covers sold by his competitors in the tuner truck market. In theory, these aftermarket pieces should help reduce differential operating temperatures, by increasing the oil volume in the diff and running it past some cooling fins. But as Mr. Banks points out with his clear plastic differential, the shape of the flat-back diff cover actually increases aeration of the lubricant, and its shape leads to a lot of errant flow that increases heat without adding lubrication to the moving parts.
We will continue updating this post as Mr. Banks goes further with this investigation. As he points out, nobody in the truck tuning business has done tests like this before, and none of the aftermarket diff cover companies offer any concrete data on what their designs are supposed to improve. Engineer Gale Banks won't stand for this inaccuracy. He's setting out to get some hard data points, and we'll be watching along as he forges ahead.