Differential Options:

[veilside180sx]

If you aren't making a bunch of power, there is nothing wrong with the VLSD. The clutch diffs are nice, as are the helical. If you do cave on the clutch diff...make sure you don't get a 2 way.

[spool_sample]

S15 Helical. To me, helicals feel like a 1.5-way but without the harshness or constant maintenance.

[veilside180sx]

S15 Helical. To me, helicals feel like a 1.5-way but without the harshness or constant maintenance. i concur, but a clutch if setup right...isn't too bad. Most have them set up to aggressive for road course duty imo.

[AceInHole]

If you can set your car up well enough, the helical does a great job. On the other hand, if you're band-aiding the issue of an unloaded inside rear with a clutch diff, I can't imagine the diff lasting very long. I've known of a couple guys who've blown up clutch diffs in high traction/ high power applications.

[ramm]

I've been doing alot of research on this also, it is obvious that the Helical is the suggested LSD for my needs. Now i have to find one! Thanks guys, i think this board is really progressing...

[McCoy]

I remember doing a fair bit of research before making my purchase. I picked up an S15 HLSD and the output shafts while I was in Japan earlier this year. No reviews yet since it's still sitting on the shelf in my garage. All that I do know is that with a T28 at 10psi and an open diff makes for a fun day at the track : -)

[AceInHole]

I'm running an OBX HLSD. Seems to be holding up fine. I rebuilt mine with McMaster belleville springs when swapping it to the new car, though.

[ramm]

Another question, actually 2? Is it worth it to buy the OBX HLSD and save money over the HLSD? Or Just buy a VLSD? Also can you run R-Comps effectively with these differentials?

[AceInHole]

The VLSD was woefully inadequate for R-comps at/ near the limit. The HLSD and some suspension tweaks to get more rear bias helped enormously. I've been happy with the OBX LSD. It seems as effective, if not better, than the S15 diff. I'd recommend re-packing it with better bellevilles before installing it, though.

[ecugrad]

The VLSD was woefully inadequate for R-comps at/ near the limit. The HLSD and some suspension tweaks to get more rear bias helped enormously. I've been happy with the OBX LSD. It seems as effective, if not better, than the S15 diff. I'd recommend re-packing it with better bellevilles before installing it, though. What diff housing did you put the OBX in?

[ramm]

AceInHole Where did you source your OBX HLSD from, how much? And how much for the McMaster bellevilles? this is probably going to be my next mod and i would like to do as much research as possible. Also this will be going into an S14 open diff...

[AceInHole]

I got my diff through my friend's shop straight from OBX, I think. They're on EBay all the time, though. The McMaster part number I used was: 9712K83 Type Belleville Disc Springs Material Steel Steel Type Grade 1074 High-Carbon Steel Minimum Inside Diameter .630" Maximum Outside Diameter 1.250" Thickness .062" Overall Height .092" Load 480 lbs. Deflection at Load .015" Flat Load 870 lbs. Specifications Met Not Rated I preloaded it REALLY tight, although the most important part is the case can still fully close (took a lot of trial and error).

[turtl631]

Oh cool, so using those springs allowed you to get some preload a la that Quaiffe that's not available for the 240SX that comes with some preload? Does this avoid total loss of torque transfer if you lift a tire?

[mmdb]

Another question, actually 2? Is it worth it to buy the OBX HLSD and save money over the HLSD? Or Just buy a VLSD? Also can you run R-Comps effectively with these differentials? I'd have to say no. S15 HLSD was a direct drop in. I then had it checked at the local differential shop and it all came back within spec. I'd say it's definitely worth it knowing you have an oem piece in your car. Prices on s15s have rather dropped. You can find one on ebay for ~500 dollars with axles. It's not so much more than other brands such as OBX, but like I said it's proven. There's no reason why you can't run with a VLSD, but will it hold up? That'll always be a question in the back of your mind. I'd say do it once and get it over with - go HLSD.

[SOneThreeCoupe]

VLSD just plain sucks for autocross or track. It spends way too much time heating up and being unpredictable.

[steve shadows]

S15 Helical. To me, helicals feel like a 1.5-way but without the harshness or constant maintenance. I was also interested in the s15 helical, however I am at about 330 wheel torque on a dynodynamics dyno (like 375+ on a typical dynojet!) Some have mentioned (maybe mis-information) this will torch the s15 diff? I currently have a JDM VLSD with the 4.3 rear gearing and I can still pretty high speeds in Overdrive, more than I need for any local courses. Consistancy with the vlsd leaves a lot to be wanted. I used to run a 3.90 J30 rear diff for drag, tne purchased this current car with the 4.3 installed already about 2 years ago, finally got the car ready for the track last summer and finally tracked it this past sunday. The rear tail likes to get sloppy under hard braking, not a lot but enough in really hard shutdowns to note. Otherwise even with all that power and a little high ride hieght in the rear I had no complains about exit acceleration, maybe a tiny bit of oversteer on some turns. Eitherway I have to feather the 2nd gear exits at 400+hp.

[ramm]

So i've been doing research on the S15 HLSD, and am probably going to scoop one up very soon. I just have a few questions... Has anyone else done this swap before? this is going into my 95 Se (open diff) I would also need the S15 output shafts, correct? Anything else I should konw about or purchase to make this diff swap as painless as possible? Thanks once again

[turtl631]

Steve: How often do you go into 2nd? I've gone into 2nd gear in only one spot on a few tracks I've run, and never at some of the others. I'd think with that 4.3 FD you'd be able to keep it in 3rd all the time. 2nd gear with big power is just tough on these cars, its a short gear and you blow the tires out. I mean, I really have to feather it with a stock KA, I can't imagine what it does with a 30R. RAMM: Yes, you need the HLSD unit, and the output shafts. Other than that, it bolts into your open diff case. I forget what the final drive is on the S15 diff, I swapped my stock 4.08 over which is probably what took the longest.

[steve shadows]

Yeah If I want I can stay in 3rd for most of the turns at my local big tracks. It's great. and the car still has close to 170mph potential. Yeah 2nd gear is a joke on azenis haha. I have to put down about 30% throttle through 2nd, and still the car is moving like a frieght train.

[turtl631]

When I had my ~350 whp KA-T setup it would break my 245/40 Kumho MXs loose in 2nd gear just rolling into the throttle in a perfectly straight line. WOT would not have been an option on the track ever below 3rd gear. That's why I think shorter final drives are great if you have any tight corners like that to contend with; being able to stay out of 2nd gear helps out a lot, and you still have more than enough top speed gearing for anything sane/reasonable. If you like to do 160+mph runs, well, then you have issues :)

[a_ahmed]

What about 180mph runs :D lol jk :(