SET YOUR CAR
Cusco RS Rear LSD 1.5 Way (R160)
MODEL # CUS LSD 183 L15
One of my favorite upgrades
MikeG 6 months ago
Most recent WRXs (GR onwards) have come with open rear diffs, which even at stock power levels allow the inside rear tire to spin when applying a lot of power in tight turns. You have the option of leaving traction control on and having it cut engine power or trying to drive around the tire spin. I figured when I bought this that the worst case scenario (provided I did the install right) would be that I wouldn't notice any difference with this part installed. That worry immediately vanished on my first drive with the diff. The diff (depending on the settings you use, to some degree) locks up tight when power is applied. I don't even bother turning traction control off most of the time anymore because it rarely detects slip now, even when driving the car hard. It helps the car rocket out of corners, and makes driving in snow a lot more fun as the car has a more tail-happy character. Snow donuts and oversteer were always disappointingly lacking in my WRX until I installed this diff - but not anymore. I actually bought an extra stock diff housing and diff from eBay to install this into to reduce the risk of being left with an undriveable car and to give me plenty of time to do the install right. Install went something like (omitting the obvious diff housing removal/install from the rear of the car): 1. Remove diff housing rear cover 2. Remove diff housing side plates (keep track of the shims and sideplates and don't get them mixed up) 3. Pull the original open diff 4. Stick the original diff in a vise and remove the ring gear 5. Press new bearings onto the Cusco diff 6. Press new axle seals onto the sideplates (not required, but you don't want to have to fix a leak once this is installed back in the car) 7. Setup the Cusco diff with your desired settings then bolt it together 8. Install the ring gear on the Cusco diff 9. Grind down the two small nubs inside the housing that prevent the Cusco diff from sliding into the housing then clean out the housing. 10. Install the Cusco diff into the housing with the sideplates and shims 11. Get out the dial indicator and prussian blue to measure backlash, preload, and pinion to ring gear engagement. Install & remove shims on the sideplates as needed. (lather, rinse, repeat until the measurements are within spec). This is the only part that requires much skill - just take your time. 12. Bolt up the housing rear cover and new gasket. Started the diff on Redline 75w-90 GL5 with friction modifier. Added even more Redline friction modifier to ease the break-in process. The diff was extremely stiff during break-in, nearly how I would imagine a welded diff to feel. After this it settled to a very nice state where it's only noticeable when you want the diff to be working. When I initially set up the Cusco diff, I installed all the coil springs for 100% preload. I didn't really understand this setting until driving it the first time. The preload is how much the diff locks without any accel or decel being applied. What I noticed with full preload was that the car was noticeably resistant to initial turn-in (I had always liked how eager the car was to turn-in). After the 1000 miles break-in, when it was time for the first fluid change I pulled the diff entirely and changed the preload to 1/3. This is actually less than Cusco recommends (minimum 1/2), but this is the least you can reasonably get away with with the design of the diff. I reinstalled the diff and the turn-in was back without any noticeable sacrifice to lock-up under power! My settings: 1.5way 80% lockup (4/5 clutches engaged) 1/3 preload (4/12 coil springs installed) These work pretty well for a daily driven / auto-x car.
hagen152754595 2 years ago
I bought this part after my stock differential decided that the spider gears were going to grind down to almost nothing. I ordered this part and had it next shipped to the transmission shop that my car was at. I have a 2009 Subaru WRX, which requires the shop to make two small alterations to the housing in order for the differential to fit in. It was nothing extensive. It took about two minutes for them to grind down the two dimples that where stopping it from going in. It did not compromise the integrity of the housing at all by doing this. After that it went right in and the shop finished putting everything back together. Rallysportdirects customer service was amazing when I ran into this issue and even contacted Cusco directly. I will continue to purchase parts from here. Always great products and a reasonable cost.
MrBadguySan 2 years ago
Had it professionally installed by a transmission shop for about, so I can't attest to the ease of installation, but there were no reported issues. Just finished the break-in and performed the first differential oil change, using Cusco LSD Oil (80W-140) both times. Noise is minimal after break-in, and only occurs when performing low speed turns (think parking lot speed). I don't daily my 03 WRX, but I certainly don't mind it, though I guess it could briefly startle a passenger or pedestrian. Overall, I'd say the harshness of this unit is over-stated, and probably mitigated by the use of Cusco LSD Oil. While I haven't flogged it too hard, just a little city driving and a short canyon romp, I can definitely tell there's a lot more grip coming from the rear. Throttle input will have much more effect on how the car turns after you install this unit, and it'll take a lot more throttle input to fully break traction; more torque than a Cobb Stage 2 kit like mine could provide. Haven't tested the locking torque under deceleration yet, but I'll give it a nice pull of the handbrake soon. Price is much cheaper than the Torsen Diffs on the market, which seems to be the only other game in town when it comes to Bugeye Rear LSDs. Though I haven't tested it out much, and I can't attest to how long it'll last, I'm pretty happy with my purchase.
Wow what a difference in the way the car drives
woodytoyota81683 4 years ago
I bought this to replace my broken stock diff. I initially broke it in with some Lucas Gear oil and friction modifier. The diff was loud and popped a bunch. I searched around and found others talking about how loud it is. After 500 miles I drained the fluid and replaced it with the Cusco LSD oil. Noise and popping is gone and the wife is a happy camper now. The car powers through corners much better now. If your going to buy this I defiantly recommend the Cusco LSD oil. 2003 WRX wagon 4EAT Stage 2
More grip=more speed.
soykraut15032 5 years ago
This diff has definitely helped me with getting the power to the ground. My car has a tendency to lift the inside wheel during sharp corners. Rather than tune my suspension to compensate for this, I decided to add this diff to the rear of my 2002 WRX. The difference was absolutely astonishing. I was able to keep the balance of the car while completely eliminating any power loss due to having a wheel off the ground. I went with an 80% locking setup with 8 initial pressure springs and it seems perfect. Not too noisy after break in, and definitely not too aggressive for daily driving. The car hooks up much better coming out of corners and the rear end stays planted during high speed sweepers. I can apply power earlier, and no longer have to worry about pushing wide from getting on the throttle to soon. I broke the diff in using non synthetic 75/90, figure 8's in a parking lot at 5mph for 30 minutes. After I got sick from going in circles, I drove with the diff at a local autocross, drained the fluid and switched to a non synthetic 85/140. The diff is now quiet and seamless in its operation. Lifting mid corner, then reapplying the throttle gives the car the ability to rotate easily. Then getting back on the power firmly allows the car to remain at the desired angle through the rest of the turn. I would highly recommend this diff to anyone who wants to be able to make use of their AWD system to the fullest extent! However, one thing that should be noted is that many WRX differentials will need to have 2 small tabs ground or filed off inside the differential housing before the Cusco diff will drop in. Not a big deal, but just be prepared to have to do a bit of housing removal. Overall, 5 stars. I just wish that I had installed this diff sooner!