Tips on Fitting the Girling Stainless Floating Brake Disc Rotor

We have recently taken delivery and sold through our initial shipment of Girling’s new 37-4275G Stainless Floating Brake Disc Rotor. The reception in the marketplace has been favorable and the increased performance characteristics of the nearly 2 lbs. of rotational weight savings have been reported on various social media sites and forums.

Specs

The beefy 6mm thick stainless steel floating brake disc rotor allows the drilling pattern and cooling slots to contribute to increased braking power and a reduction brake fade caused by heat. These rotors are suitable for fitment to both front and rear Triumph disc brake hubs. It has also been suggested they are ideal for dual-disc front brake conversions, which would at least involve the substitution of the longer 21-7085 through-bolts for the 21-2207 single disc bolts.

Fitment Challenges

“When a standard 3/8-drive 9/16 socket is applied to the nut, there is often not enough clearance to gain acceptable purchase on the nut, as the distance between the flange and the corners of the flats on the nut is narrower than the wall thickness of the socket. There are a couple of solutions to this problem.”

One topic that has been discussed in the online forums is the challenge to install the floating brake disc rotor to the hub due to the tight clearance for the 3/8” locking nuts at the spot face, between the angled aluminum inner flange of the rotor and the body of the hub. The hard-anodized inner flange is manufactured to a “maximum metal” condition, where the least amount of material possible is machined away from the flange to preserve strength and rigidity under hard braking conditions.

When a standard 3/8-drive 9/16 socket is applied to the nut, there is often not enough clearance to gain acceptable purchase on the nut, as the distance between the flange and the corners of the flats on the nut is narrower than the wall thickness of the socket.

Solutions

There are a couple of solutions to this problem. One is to use a high quality deep 3/8-drive 9/16 socket, such as a Snap-On, Blue Point, Matco, Mac, or even a Craftsman. The more expensive sockets are made from superior materials and can be manufactured to a thinner wall thickness, allowing more clearance in tight spots.

Another possible solution is to acquire a cheap 9/16 socket from the flea market for $3.00 and grind it down to fit down over the nut. This may or may not work, since the considerable 20 ft lb. torque specification may cause the modified socket to crack under load, but with varying qualities of tools, you may be able to successfully torque down all (4) nuts before the socket gives up.

One other solution that has been proposed for this floating brake disc rotor, is to substitute (4) of the 21-0692 12-point cylinder base nuts, for the original 3/8-24 UNF Nyloc nuts. The base nuts also are 3/8”-24 UNF nuts but are tightened with a ½” 12-point socket, which ostensibly has a smaller outside diameter than the 9/16” version, allowing full purchase on the nut. In this instance, an application of thread locking compound, such as blue Loctite would be recommended, since the cylinder base nuts are not of the locking type. As you can see, there is more than one way to skin a cat.