"Which Subarus do I look at to find an LSD?
Clutch-Pack LSD:
1985-1986 (production up to 3/86) XT 4WD is listed with a 3.70 LSD option (Subaru part # 7220 11000).
1986-1987 (production from 4/86-10/86) GL 4WD is listed with a 3.70 LSD option (Subaru part # 7220 11001).
1986-1991+ (production from 11/86) Loyale/GL 4WD is listed with a 3.70 LSD option (Subaru part # 7220 11002).
1988-1991 GL and XT-6 4WDs with single range transmissions are listed with a 3.90 LSD option (Subaru part # 22011 GA022).
July 1986 onwards LSD assembly (just the carrier) is also available new from your Subaru dealer if you wish (Subaru part # 22049 GA010).
Viscous LSD:
1991-92 Legacy 4WD turbo 4dr sports sedan is listed with a 3.90 viscous LSD option (Subaru part # 27011 AA131 or maybe 27011 AA070 -- the manual is unclear about the AA070 unit).
Any Subaru's since 2000 that came with an LSD came with a viscous unit.
Here is a table of various newer AWD Subarus with their respective drive ratios and VLSD Availabilities:
(from Wayne Chin http://wac.addr.com/auto/obs/lsd/lsd.html )
Model Year Model Trim Transmission Front Ratio Center Ratio Rear Ratio Rear VLSD
1991-1992 Legacy Turbo AWD 5MT 3.900 1.000 3.900 Yes
1992-1997 SVX AWD (R-180 VLSD?) 4EAT 3.545 N/A 3.545 Yes
1993-2001 Impreza 1.8L, 2.2L AWD 4EAT 4.111 N/A 4.111 No
1993-2001 Impreza 1.8L, 2.2L AWD 5MT 3.900 1.000 3.900 No
1998-1999 Impreza 2.5RS 4EAT 4.444 N/A 4.444 No
1998-1999 Impreza 2.5RS 5MT 4.111 1.000 4.111 No
2000-2001 Impreza 2.5RS 4EAT 4.444 N/A 4.444 Yes
2000-2001 Impreza 2.5RS 5MT 4.111 1.000 4.111 Yes
2002-2003 Impreza 2.5RS 4EAT 4.444 N/A 4.444 No
2002-2003 Impreza 2.5RS 5MT 4.111 1.000 4.111 No
2002-2003 Impreza TS, Outback Sport 4EAT 4.111 N/A 4.111 No
2002-2003 Impreza TS, Outback Sport 5MT 3.900 1.000 3.900 No
2002-2003 WRX 4EAT 4.111 N/A 4.111 Yes
2002-2003 WRX 5MT 3.900 1.100 3.545 Yes Other North American Subaru models with VLSDs, either as standard equipment or available as an option:
2000-2002 Forester S (All Weather Package)
2003 Forester XS
2000 Legacy GT, Outback
2001-2003 Legacy (all)
2003 Baja
NON-LSD
Most R-160s you see under Subarus will NOT be an LSD. There were no LSDs of any kind in 1995-1999 Subarus.
Look for the following Subaru part numbers (look at the foil sticker for part number and ratio):
7220 11010: 3.70 ratio
7220 11011: 3.70 ratio
7220 11012: 3.70 ratio
6220 06020: 3.90 ratio
6220 06021: 3.90 ratio
6220 06022: 3.90 ratio
27011 AA151: 3.90 ratio
27011 AA040: 4.11 ratio
27011 AA110: 4.11 ratio
27011 AA111: 4.11 ratio
What do the various differentials weigh?
R-160 Subaru LSD (w/o mustache bar or stub axles) = 50lbs
R-180 open diff from '83 Maxima (w/o mustache bar or stub axles) = 60lbs
R-200 open diff from '87 200sx V6 (w/o diff mount attached without stub axles) = 75lbs
He also weighed an open R-160 from a 510 and an R-200 LSD. They are both within 1-2 lbs of the weights listed above.
What's the deal with Phantom Grip LSD units?
Phantom Grip units are advertised as a way to convert an open differential into an LSD unit. They run $250-$300, and have applications for R-160 and R-180 differentials. From the looks of it, all this unit does is spring-load the side gears against their washers, turning them into half-assed clutches, while adding a wedge ramp to increase the pressure as the side gears try to turn relative to the cross shaft. There are several problems with this approach. First, those side gear washers have no clutch material on them, and the Phantom Grip unit doesn't appear to come with any that do. (Not that it would do much good, there being no provision in the differential case for a proper stack of frictions and steels.) As this unit operates, you're gonna be wearing away the side gears and differential case. With the spring pressure against them, but without the waffle surface of a clutch disc, there's not much opportunity for lubricant to get into the side gear washers. Since the "clutches" are just metal-on-metal, and running virtually without lubricant, the breakaway characteristics are not going to be very progressive, or predictable, as things heat up. The wedge ramp also induces stresses on the differential case that it was never designed to handle. When (not if) this unit chatters, the wedge ramps are gonna be trying to split the differential case in two. Incredible testimonials aside, this seems to be a very poor substitute for a proper LSD, and way overpriced for what is essentially a couple machined plates and a few springs. I would certainly not consider the Phantom Grip in the same league as PowerTrax or Air Locker."
What about other aftermarket Clutch-Pack LSDs?
With the popularity of higher-powered Subarus, as well as increased use of the 240sx in drifting, there are many quality Japanese aftermarket Clutch-Pack LSD units. Choices include Cusco, ATS, KAAZ, and Tomei Trax, with prices from $900 to $1500. Not all brands are available in R-160, R-180, and R-200 sizes, so check for actual applications to be sure. OEM LSD units usually have two pinion gears. Most of the aftermarket units have four pinion gears, theoretically making them stronger. The aftermarket units vary in construction and clutch plate material (steel alloys, carbon fiber) as well as mode of action. They usually have between 12 and 24 clutch plates, which depending on how they are assembled, can vastly vary the locking action of the unit, allowing the owner the ability to "tune" the LSD to their car and driving preferences. Furthermore, many of these differentials can be purchased in 1-way, 1.5-way, or 2-way configurations. 1-way units act as an LSD upon acceleration only. 1.5-way units act as an LSD on acceleration, as well as to a lesser extent on deceleration, but with less understeer than the 2-way units. 2-way units have full LSD action on both acceleration and deceleration. Some of the units can be easily changed from 1-way to 2-way, etc. Because of the tremendous hype surrounding the various brands, it is hard to know which unit to use, so do your research before your buy. "K.M. Hafer
There is an age old debate about an LSD against a welded diff.They will both argue that this one is better than that one.I have used both and honestly think that it is a moot point.I break ************ no matter what. I prefer the welded diff, but i do not offroad rocks very often , well, not like they have on the west side of the state......
I have had and built several r160 diffs.i have LSD'd 5 different diffs. i have welded 3 diffs. i dunno, a lincoln locker is cheap , LSD's are some coin....
MOnstaru......
some threads.....
http://www.ultimatesubaru.org/forum/showthread.php?t=105317&highlight=welded
http://www.ultimatesubaru.org/forum/showthread.php?t=101721&highlight=welded