Things You Shouldn’t Do With A New Differential

Take it from me, you want to pay special attention to this video if you ever plan on installing a rear differential in your ride. I sought out the best rear gear installer in my local area, dropped off my 1999 WS6 Trans Am with a set of gears and a small pile of cash and waited for his call. A few hours later, I was rolling out of his driveway with a brand new set of 3.70 rear gears where the factory 3.42 gears and then a set of too—high-for-my-tastes 4.10’s had been. I’d been instructed not to “shock” the rear end: no hard launches, no hard shifts, no hard acceleration. Basically no fun for the first few hundred miles.

I was on board until I lined up beside a Mustang at a red light the very next day. I was 18 and stupid and could not let the opportunity pass. I won the race but regretted it before I was even over, as I heard the obnoxious whining start before I shifted into third. The whine persists to this day and it’s every bit as obnoxious now as it was then. So when Jason from Engineering Explained tells you to take it easy for that first 500 miles, he means it.

This video is a great look at the role the gear lube plays in keeping a rear differential working properly, thanks of course to Pennzoil and their excellent products and Jason and his never-ending quest to understand and educate every part of the automobile. The rear diff is often overlooked, as it’s generally pretty low maintenance and durable as long as you’re not putting down a ton of power on sticky tires – or dealing with wheel hop, am I right 4th Gen F-Body brethren? – but all it takes is for things to be ever so slightly off for the diff to become incredibly annoying. So make sure when you are breaking in your new gears, you drive carefully and then change the fluid out to get rid of any metal shavings that may have been created during the break-in process. After that, you just want to periodically check things out, flush the fluid every so often to make sure things are nice and clean inside, and enjoy your new gears!