After one track event in 2012 the diff fluid was boiling and slinging out of the "rattle vent" so badly it coated the right rear tire and the back underside of the car. Problem really made itself apparent when I was running at Texas World Speedway going into
Turn 1 at 155 mph, where this oil soaked tire had literally ZERO grip.
Code Brown! I had to stop racing after three short sessions that day because it got so bad. I was cleaning up the mess between sessions but by my 2nd lap the underside right rear of the car was always oil soaked again.
the week after that TWS event, in summer 2012, our guys here at Vorshlag made this diff fluid catch can and external vent set-up for our 2011 GT. Differential fluid coming out of the axle vent was always a problem with this car, even when we just autocrossed it on street tires, but it was massively amplified once we started tracking this car on R-compounds and put 430 whp through a clutch-style diff. That diff fluid gets HOT, and we even melted both outer axle seals at one point.
This hose routing (inlet from the axle tube, which fluid can drain back down into the axle + the external vent line) is all going through a factory grommet in the trunk, so nothing had to be cut or drilled to route the lines. The can mounted with two small drilled holes in the rear deck, and two bolts.
Crappy pic but you can see the line routing from the axle. The factory vent is on an axle tube, but can be on either side of the pumpkin. The 2011 was on the right side, but my 2013 GT has it on the left. We added a service loop in the hose to allow for axle droop and bump travel.
Last but not least was the vent filter, which was routed UNDER the car. If you vent into the trunk it will make the whole car stink like hell, as others have noted. Not a big deal on a race car, but on a street or dual purpose car, it matters.
The lines are what make our kit different... the main line from the axle to the catch can is a proper crimped, braided line with real fittings - not hose barb and 99 cents of cheap fuel hose. I didn't want liquid differential fluid leaking in my trunk or onto the axle. The external vent line doesn't need to be as beefy and just goes to a small filter under the car. No fluid should be coming out of the top of the catch can, just vapors.
We are making a run of these diff fluid catch cans/line kits for production, with some updates and changes, and will have them for sale for the S197 soon.
Thanks,