I started off with a very dirty transmission, similar to the engine. The unit I purchased was a TY754VBAAA. This has a taller 5th gear with an overdrive ratio of 0.738. In the process of fitting the Subaru-Gears reverse ring and pinion, I also ordered a complete seal kit from Rallispec (RST-1118B), along with new speedometer sensor, clutch slave, case bolts, an assortment of pinion shaft shims, and some other misc items.
My initial group buy purchase from Subarugears including the 4.1:1 reverse ring and pinion:
Some of the initial dis assembly of the case halves. Breaking them loose took some work and a very fine blade to break the sealant.
Cutting down the center differential housing:
Slightly more progress, still need to clean it up and seal it with the plug and some devcon:
Moving on to the case clearancing, I used a porting tool for cutting down the webbing. This worked quite well and gave a lot of control over not "missing". It just took a fair amount of time and patience.
Got it down pretty clean, close enough:
Fitting the new SubaruGears ring gear to the Quaife LSD:
Final test fit. I initially started off using the stock differential as a mock up and some clay to find where I need to clear more material. You can still see a piece in the picture.
Stock pinion shaft:
Now with the washer removed, I improvised a bit on pulling this off by using an L bracket and even force on opposite sides:
The gear set with the pinion shaft removed, including the stock shims:
Pressing on the pinion washer onto the new pinion shaft using a piece of PVC as mentioned by another forum member:
Mocked up in the case with the Suba-Spool installed. In order to measure the backlash accurately, I later removed the Suba-Spool for the dial gauge to be able to line up with the splines and measure just the pinion backlash and not the whole gear set.
Once mocked up with no shims installed, used the pinion depth tool to figure out how much to add in:
At this point, I ended up returning the 4.1 ratio for the newly released 4.86 ratio to better match my overdrive gear, high rpm, and taller tire goals for the car. This translates to approximately 3400 rpm at 70 mph and 163 mph at 8000 rpm which gears it better for track events.
Measuring backlash, the photos show about .007 difference from the angle but was closer to .006" or .15mm. The previous video posted earlier shows the actual difference better:
With the 4.86 ratio Todd mentioned the pinion depth tool won't fit properly due to the non-standard Subaru ratio and oversized pinion head. So I went with the physical mesh test to determine the shims needed after properly setting the backlash. I went at this many many times to get a baseline first, what I found is that the pattern didn't change too drastically and shim thickness had little to no affect on the backlash measurement. The pattern I got wasn't perfect and showed the mesh close to the toe (inside), however once loaded this will move closer to the center.
Also, just to be sure clearances were good between the Quaife LSD and the pinion head, I took a picture and found enough clearance between the two.
Almost finished with this after way too long, I think I started it last August. Just waiting for more case bolts and other pieces and to seal up the center diff housing. I also figured I would attach the Suba-Flanges in order to attach a cross bar to torque down the pinion shaft nut.
More pics once I get that finished...