Dealing With The Centerlocks

I'll be the first to admit that when I found out the new centerlock wheels were to be standard equipment on the '10 Porsche 911 GT3, I was kind of pissed off. As the car's delivery time drew nearer, and the more I read about them and how they worked, I slid further down the slippery slope of perpetual grumpiness. In the flesh, the wheels are indeed stunning if maybe a little too flash for my more conservative tastes, but I decided that I just better get bloody well used to them and learn how to deal with the locking nuts properly. Note that Porsche only supplies the special centerlock nut socket (3/4-inch drive) with your new car and no other tools to help you get the wheels off. With a set of wheels on the way from Forgeline, I figured I had better add to my toolbox arsenal, so I ordered a long 3/4-inch-drive breaker bar (rated to 1,000 ft-lb) for loosening, and a jumbo 3/4-inch-drive torque wrench (rated to 700 ft-lb) to tighten the centerlocks accurately to the specified 370 ft-lb (or 500 Nm).

However, when these industrial (MAN!) sized pieces of equipment showed up at my doorstep, I knew more tools would be necessary, because these would be near impossible to carry conveniently on a road trip or vacation in the GT3. So I then purchased a small 1/2- to 3/4-inch-drive torque multiplier (with a 3.3 to 1 multiplier ratio) and a 1/2- to 3/4-inch drive converter, to allow for a more compact (albeit not nearly as precise) method to deal the centerlocks in the middle of nowhere.

Now I have three methods to deal with the Porsche centerlock nuts (listed in order of ease and torque precision; also note that the Porsche-supplied socket is also required for each method).

Proper Method: 3/4-inch-drive breaker bar for loosening and 3/4-inch-drive torque wrench for torquing-the simplest and most straightforward method.

Emergency Method: Torque multiplier, 1/2- to 3/4-inch-drive converter, 1/2-inch-drive breaker bar, and 1/2-inch-drive torque wrench-use the torque multiplier and 1/2-inch-drive breaker bar for loosening, and then following the emergency Porsche torquing instructions. Use the drive converter and 1/2-drive torque wrench to torque the centerlock nut to 74 ft-lb (100 Nm); mark the 100 Nm point on the wheel with a pencil and tighten the nut to the "STOP" point marker (turning ~50°) with the torque multiplier and 1/2-inch-drive breaker bar. Note that you could also use the 3/4 breaker bar for loosening and tightening in this procedure-but she's a big mother to carry around.

Bare Bones Method: Torque multiplier, 1/2-inch-drive breaker bar, and 1/2-inch-drive torque wrench-use the torque multiplier and 1/2-inch-drive breaker bar for loosening, and use the torque multiplier and 1/2-inch torque wrench for torquing. Note that the torque input for the 3.3:1 multiplier is only 112 ft-lb for 370 ft-lb output; however, the error I measured was greater than +/- 10% using this method and my cheap torque multiplier.

One additional "spanner in the gears" is the centerlock nut cap/dust cover. You must very carefully pry off this cap with a small flathead screwdriver at the machined slot, and note that it is very easy to accidently bend the tight-fitting caps when they're new. They do loosen up a bit over time, so hopefully they won't start flying off by themselves. I am also very careful aligning them when putting them back on-no mini Frisbees yet. Good luck! -DN

By Doug Neilson
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