Shaving a GM Corporate 14-Bolt Differential

Two things generate more excitement in off-roading enthusiasts than just about anything else – other than actually going off-road.

First, finding even the slightest bit more ground clearance so they can take their off-road vehicle where it hasn’t gone before.

Second, finding builder parts that can take the punishment when that extra bit of ground clearance isn’t quite enough for the course.

That second point is a real source of ‘friction’. Anyone who has suddenly heard and felt the unmistakable ‘clunk and grind’ of bottoming-out, especially on a particularly rocky trail, will tell you there is absolutely nothing pleasant about it. From the immediate concern of whether the vehicle is still mobile, to the realizations that more damage and costs have been incurred, it’s a situation off-roaders would rather avoid.

There are two main ways to that. First, you can add ground clearance, done mainly by using taller tires and/or making suspension modifications. Second, you can find very robust components for the undercarriage of the Jeep.

The GM Corporate 14-Bolt Differential

Few differentials have more going for them than GM’s ‘Corporate’ full-floating 14-Bolt diff; used on GMC and Chevrolet trucks and vans since 1973. That length of service means builders can find them fairly easily (and relatively inexpensively) in many junk yards.

Famous for the wide range of aftermarket parts available and the ability to manage up to 44-inch tires, the 14-bolt features one of the most straightforward differential configurations around; even beginners should find them fairly easy to take apart and work with. And you’re not going to get a tougher differential or one more able to take the punishment of not having enough clearance for the trail you’re tackling.

The One Problem With the 14b

With the need to protect a 10.5-inch ring gear, the 14b’s 13-inch diameter housing hangs further below the axle tube than most differentials. Can you guess what that does to your ground clearance? Yup, you’ll need even larger tires, and the budget for them, to compensate for the lost clearance versus other differentials.

So Shave It!

If you want the best of both worlds, the unbeatable robustness of the 14b, and maximum ground clearance, you can ‘shave’ it. Shaving the differential means removing metal off the bottom, doing the same to the diff cover and welding on a cap plate. You can shave a 14b enough to add as much clearance as 3-inch taller tires.

Just in case you’re not set-up to fabricate a custom diff cover and cap plate, TMR’s 15-Bolt conversion kit gives you all the precision-fabricated parts you need to armor-plate your differential after shaving.

Shaving GM’s 14b housing gives you ground-clearances in line with other popular differentials. Again, if you’re equipped to do the work yourself, there are four basic steps.

  1. Initial Cut – You can make the initial rough cut off the bottom of the housing and cover using and sawzall, porta-band or cut-off wheel.
  2. Grinding – Grind the initial cut to the angle needed to install the cap plate.
  3. Attach the Diff Cover
  4. Welding – Weld on the cap plate.

If you don’t have the right equipment, or simply prefer not to take the time to do the work yourself (you could spend a lot of time grinding the housing to the right angle), find a local machine shop or metal fabricator to do the cutting, grinding and welding for you.

That’s exactly what the good people at did when they put one of our 15-Bolt Conversion Kits to the test. They wrote about the whole process and their unbiased experiences with the kit – they even powder-coated the finished housing for their customer – in an online article titled Shaving a GM Corporate 14-Bolt Differential.

Check out the article to learn more about having the advantage of one of the toughest and easiest to find differentials around, while getting every inch of valuable ground clearance you can squeeze out of it.

And you can also check out the following two great videos for even more information on shaving a 14b:




If you want to learn about the kit from the people who design and build it, call or stop into TMR Customs. We’ll be happy to show you how it all comes together.