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http://sphotos-e.ak.fbcdn.net/hphoto...67895724_n.jpg

Google translate didn't do a very good job. Looks like something that replaces a part in the dif that can get deformed under heavy stress and cause wear/damage. They posted this on their Facebook page today so I don't think its a repost.

Toyota 86 / Subaru BRZ
Differential drive pinion
Distance color

Rear differentiated Publisher
And pinion gear in Le
The clearer of the ring gear
Nsu (backlash)
"Type crush" to adjust the
I have adopted the color
Hatiroc / BRZ. This
The suspension and drive system in a manner
Tune, powered up
An increase in load due to flop
Color collapses further,
Pull the big trouble
May cause. Network
Scores of "Difaren

Shall drive pinion distance color "is," Sim-like
's Part to change the polynomial ". Strong material that is difficult to deform
Color quality, me firmly support the run hard.
When you put your hand in the final def change LSD and installed, the same time
I want to strongly suggest that the mounting.

Improve the reliability of the drive system, to great effect to prevent trouble
Required item "run" of 86 & BRZ!

And through the propeller shaft from the engine-transmission
Power is transmitted to the drive pinion of the differential case in formic
I turn the shop. Ring gear that is orthogonal to it (final formic
By turning the drive shaft meshes with the dealer), engine
The rotational force of the pin is transmitted to the tire. Therefore Doraibupi
Engagement condition of the ring gear and anion of (backlash)
Adjustment will be very important.

Crush type of color Hatiroc / BRZ nor shim adjustable color,
I can as well initial adjustment during assembly. (Ime
J: left illustration)
But to be deformed high load is applied such as sport driving,
Position of the drive pinion is a deviation, You become a source of trouble
To. On the other hand shim adjustable color of Cusco is difficult to deform a strong
District, I will prevent the trouble. (Image: right illustration)

Lol in for more

It's a solid spacer that replaces the crushable stock sleeve on the pinion gear. They use them a lot in drag cars and also when you set up different gears in the same housing. It doesn't deform under the the stress of a hard launch(in a drag car) that will sometimes "crush" the stock sleeve a little when the pinion gear pushes against ring gear so hard it pushes the entire pinion gear forward instead of turning the ring gear. Instead of deforming to get the proper preload you use shims behind it to set it up. I can't see a need for it in that sense with these cars, but it also allows you to set up the pinion gear depth and preload easier than crushing the sleeve with a long bar and then checking the drag repeatedly. I run these spacers in the 9 inch differentials I have for my Mustang.