fateo66
02-05-2014, 11:43 AM
I have came to the conclusion that the Subaru Knowledge base of differentials is a bit lacking and have decided to write a little something about them and include a Pictorial to help everyone out.
While I don't want to get into too many details on what makes each diff different, here is a nice link to what Dave Anton wrote on NASIOC:
http://forums.nasioc.com/forums/showthread.php?t=1126026
Also here is a nice video explaining what a differential is:
yYAw79386WI
I have compiled 13 different differentials for reference, which include all options for the US market and nearly all for the Japanese market as well. The only two factory options that I am missing are the 5mt front torsen that came in some late 90's RA V-limited STI's and the R180 AP Suretrac that came in the JDM Bugeye's.
http://i184.photobucket.com/albums/x310/fateo66/LSDs/All_zpsf4228ef8.jpg
To start out, here is a line up of the differentials available for a R160 rear.
http://i184.photobucket.com/albums/x310/fateo66/LSDs/R160_zps7404b2bb.jpg
http://i184.photobucket.com/albums/x310/fateo66/LSDs/R160opened_zpsbbcde148.jpg
And here is what a diff looks like when it breaks
http://i184.photobucket.com/albums/x310/fateo66/LSDs/3iUDTcW_zps1895b84e.jpg
Here is a version 1 viscous LSD. The unit in the center of the picture is not a mechanical unit; instead, it houses the viscous fluid and plates. This is the differential that requires two different style male axles. One side looks like a standard male rear axle and the other has two sets of splines as seen below. Please note the 4 spider gears.
http://i184.photobucket.com/albums/x310/fateo66/LSDs/Ver1vlsd_zps3c015875.jpg
http://i184.photobucket.com/albums/x310/fateo66/LSDs/Axles_zpsbffd62e1.jpg
Here you can see the inside of a version 2 viscous unit found in most wrx's. A version 2 VLSD is very similar in appearance to an open differential but if you look closely at the seat for the ring gear you will see that you can split the diff in half in order to have access to the viscous unit. Viscous LSD's typically are regarded as a bad unit. However, I do not feel this has to be the case. Yes a Viscous LSD is reactive in its approach to limit wheel spin because you have to have wheel spin in order to heat up the fluid inside the differential. At which time it will attempt slow down the faster moving wheel. Viscous LSDs make the car easier to drive on the street and or a situation where you have a long corner that you want to power through. The biggest down fall to the version 2 VLSD is the fact that it only has 2 spider gears and, as seen in the open diff, this becomes the first point of failure.
http://i184.photobucket.com/albums/x310/fateo66/LSDs/V2R160VLSD_zps16c72304.jpg
While I don't want to get into too many details on what makes each diff different, here is a nice link to what Dave Anton wrote on NASIOC:
http://forums.nasioc.com/forums/showthread.php?t=1126026
Also here is a nice video explaining what a differential is:
yYAw79386WI
I have compiled 13 different differentials for reference, which include all options for the US market and nearly all for the Japanese market as well. The only two factory options that I am missing are the 5mt front torsen that came in some late 90's RA V-limited STI's and the R180 AP Suretrac that came in the JDM Bugeye's.
http://i184.photobucket.com/albums/x310/fateo66/LSDs/All_zpsf4228ef8.jpg
To start out, here is a line up of the differentials available for a R160 rear.
http://i184.photobucket.com/albums/x310/fateo66/LSDs/R160_zps7404b2bb.jpg
http://i184.photobucket.com/albums/x310/fateo66/LSDs/R160opened_zpsbbcde148.jpg
And here is what a diff looks like when it breaks
http://i184.photobucket.com/albums/x310/fateo66/LSDs/3iUDTcW_zps1895b84e.jpg
Here is a version 1 viscous LSD. The unit in the center of the picture is not a mechanical unit; instead, it houses the viscous fluid and plates. This is the differential that requires two different style male axles. One side looks like a standard male rear axle and the other has two sets of splines as seen below. Please note the 4 spider gears.
http://i184.photobucket.com/albums/x310/fateo66/LSDs/Ver1vlsd_zps3c015875.jpg
http://i184.photobucket.com/albums/x310/fateo66/LSDs/Axles_zpsbffd62e1.jpg
Here you can see the inside of a version 2 viscous unit found in most wrx's. A version 2 VLSD is very similar in appearance to an open differential but if you look closely at the seat for the ring gear you will see that you can split the diff in half in order to have access to the viscous unit. Viscous LSD's typically are regarded as a bad unit. However, I do not feel this has to be the case. Yes a Viscous LSD is reactive in its approach to limit wheel spin because you have to have wheel spin in order to heat up the fluid inside the differential. At which time it will attempt slow down the faster moving wheel. Viscous LSDs make the car easier to drive on the street and or a situation where you have a long corner that you want to power through. The biggest down fall to the version 2 VLSD is the fact that it only has 2 spider gears and, as seen in the open diff, this becomes the first point of failure.
http://i184.photobucket.com/albums/x310/fateo66/LSDs/V2R160VLSD_zps16c72304.jpg