Great Miatas @ MRLS event! I'm working on gettings some pics/vid together from that. In the mean time, there were a couple things that sprang up at ACS that I needed to solve, and now after running MRLS I can confirm the fixes worked so I'll cover those..
First up, the differential fluid was exiting the vent cap on the top of the diff, leaving a very traceable mess on the underside of the rear subframe and down the side of the diff. A quick check with V8R confirmed they've seen this happen and fixed it by replacing the vent cap with a hose barb fitting and running a vent line up higher.
Vent cap (right) is just removed with pliers. It's being replaced with the 1/4" NPT to 3/8" barb fitting on the left:
Tapping the hole for the fitting is a treat when the diff is up in the car. I'd call changing the vent config on the getrag a must-do item so if you haven't installed your diff yet, just do this now before installing everything:
Fitting and hose installed with a loop in the hose:
If the vent tube mod works, we can just run the hose to the open air. But since we didn't know yet if it would work, I wanted to run the line to a reservoir to catch the fluid in the event that it was still losing any. I repurposed a Wilwood brake fluid remote reservoir for the task, with a barb fitting installed in the cap and a hole drilled in the top of the reservoir to vent pressure:
After 3 days at MRLS, the reservoir is still dry so that's confirmed that the vent hose is working perfectly.
The second fluid that was trying to exit the vehicle was the power steering fluid. This one was a bit trickier to diagnose but I came to the conclusion that because the reservoir cap was a vented/non-sealed design, in high-G right hand turns the fluid was being pushed against the side of the tank and effectively submerging the side of the cap, and thus exiting via the cap's vent.
The cap needed to be sealed. I didn't take a pic of this but sealing the cap involved drilling out the spot welds that held the three pieces of the cap together, removing the vent ring, welding the two remaining pieces of the cap back together and then ordering a second cap to scavenge a second O-ring from and doubling up the O-rings under the cap to take up the height of the missing vent ring and seal to the reservoir neck.
With the cap sealed, the tank still needs a way to vent pressure. Drilled/tapped a small 1/16 MPT hole in the upper left hand corner of the tank and ran a vent line off that, with a loop to stop fluid from passing down the line:
Same as the diff vent line, to confirm the modifications were working as intended, I repurposed another brake fluid remote reservoir to serve as a catch can:
Same story, 3 days at MRLS and the reservoir remained dry. Fix worked.