Thursday, August 31, 2006

Diffs. - for What is a diff, please go to

Front LSD:

Q: I want a front lsd -

why? unless you are on the gravel (i.e. you own a rally car, not a fanboy car), you need not apply. There are circumstances (SCCA prosolo contenders, 500 awhp), that justify a front LSD, but for the most part its an extra expense that you would be better allocating to your food budget, girlfriend budget, etc.

Q: how much does a front LSD cost:

- $800 or so depending on the diff, then the labor to a transmission shop to pull the gearbox, break it open, and install it. I would budget $1500 or so.

Q: which JDM gearboxes had front LSD / How much will it cost me for one:

version 5/6 sti-RA only, version 7/8 RA, usdm sti as well. budget $3000 for starters for the 5mt JDM gearboxes. quite rare and tought to come by.

Centre LSD -

Q: I want a DCCD, Do i need a dccd?:

no. DCCD only comes in STi-RA models from version 2+. if you are going for the DCCD Look, you can buy the dccd button alone for $45 new. that completes the look. DCCD is not really that useful, many people are slower with DCCD than without it.

If you are looking to make your AWD driveline more rear torque biased, then we can talk. STi 15kg and 20KG centre diff does just that, so do the Cusco and KAAZ centre diff products. I have a dccd in my car, i leave it default rear biased 65/35. its really the same as if i had an aftermarket, but am hampered with an annoying little turny wheel that riceboys like to drool over :P

the car is easier to drive with the stock 50:50 centre diff. if you are overpowering the centre diff, or desire a more rear biased driveline for competition purposes, then the aftermarket parts are good to consider.

rear LSD -

How to fit a rear LSD on my car:

Rear LSD is the one of the 3 diffs that is arguably useful. on a Low power NA car - ej25/22/18, you may have more fun with an open rear diff, unless you are planning on loosing time in corners by sliding the car too much. Sliding is fun.

you can AWD lift-off drift a Ej18 with open diffs at 80mph. Just turn in hot and lift off to unweigh the rear end, then WOT to exit.

rear LSD will make your car want to go straight. On snow or dirt its quite useful, same for rain. Dry traction with good tires, you quite possibly might not notice it at all.

Q: Viscous LSD: worth the trouble?

If i was in a snowstorm, I'd rather have a VLSD than no lsd. If given the choice however, VLSD is almost a waste of time to instal. unless bought for very very cheap, I'd pass and wait it out for a JDM Mechanical R160 unit.

Q: Mechanical R160- which cars had it?

JDM sti's tend to come with Mechanical R160's. Subaru and part spec is quite a random game though, so JDM WRX's have been known to come with them somtimes as well.

Q: What parts do I need to fit a rear Mechanical LSD?

- R160 LSD unit - ideally complete pumpkin with proper Final drive ring and pinion to fit your gearbox.
- R160 LSD axels for mechanical LSD - differnt from open and viscous
- all AWD R160 rear hubs are compatable with R160 axels. you will NOT have an r180 in your car unless you have a 2004+ GDB sti, or a JDM GC8-STi RA v3+ complete car.

* some of the early impreza L models came with tiny diffs smaller than R160, and a dogbone style mounting X member like the legacy and GDA wrx. Just swap the studs over from the diff cover and it goes right in.

R160, R180, R200-

what do these things mean?

r160- all subaru diffs are R160 - for the most part, all usdm subaru's came with R160 diffs. Dating back to the datsun 510, its about the oldest thing on the block. Very simple dissasembly, a beginner can swap ring and pinion gears in about an hour or so.

R180 - the same diff as some of the datsun Z cars and the S12 200sx, the R180 rear diff in subarus has a 180mm (or so) diameter ring gear. Very creative name, the R180 is a direct fit onto any AWD subaru X member, just need to have the proper axels and driveshaft (or custom drill small pattern R160 driveshaft bolt pattern into the R180 flange- easy to do).

R200 - rear diff from a nissan Silvia, Skyline, 300ZX. its big, dosnt fit in your subaru without a guy+welder+metal fab shop. Useful for drifting, and people who like to destroy things, we do not put R200's in subarus.

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