R180 LSD options for 200sx

VQ37VHR · 07:01:41 PM / 28-Dec-21

So to preface this post, I am well aware that welding my stock diff would be a whole lot cheaper than what I am planning to do. With that said, I want to drive this car frequently in non performance scenarios and would like to avoid excessive wear on my rear tires so an LSD is a must for me.

From my research I have found two practical ways to adapt an LSD to my R180, one of which seems to be a lot easier than the other:

1. Replace my stock open diff center with this unit from Quaife (https://whiteheadperformance.com/product/quaife-qdf5l-atb-helical-lsd-limited-slip-differential-nissan-r180-diff-115mm-datsun-240z-280z-280zx-510/) and reuse my stock ring gear and pinion. My only concern is axle fit, I am unsure if this diff center from Quaife has 25 spline or 27 spline holes for the axles. Any input would be appreciated on this matter.

2. Replace stock open diff with a Subaru WRX STI front diff center ($75 junkyard special

) and have a machine shop fab up some hybrid axles using my stock axles and the splines off of the STI CV axles. Not sure about gearing, the STI ratio is 3.9 so it would be robbing me of some torque down low. Might see if I can't re-use my stock ring gear/ pinion set here too. Other challenge is going to be finding a shop that can confidently make me the axles that I need, will still probably be cheaper than the Quaife helical diff but would need to call for an estimate to confirm.

Please let me know your thoughts on these two plans/ if you spot any blatant errors in what I have come up with, I have read most of the other posts regarding this topic and am yet to find anybody really talking about what I have thought up here. Thanks

iceageg · 04:22:03 AM / 29-Dec-21

You will find more details searching through the drivetrain stickies, but as memory serves a turbo Z31 LSD is also a good choice if you can find one.

VQ37VHR · 04:00:59 PM / 29-Dec-21

Well see I wouldn't be opposed to this option, the problem that arises is that the Z31 LSD is an R200 unit so it wouldn't be just a direct swap. I would need to find the Z31 rear driveshaft, Z31 4 lug axles, Z31 diff case and center and I would have to fab up a new diff mount if memory serves me right. This is why I was thinking to just use an R180 LSD center in my factory R180 diff casing, but if an R200 swap is more cost effective I might be willing to consider it.

sideways_s12 · 04:11:41 PM / 11-Jan-22

Why not find an R200 and Iirc the KAAZ LSD swaps in or the cheaper OBX LSD swaps in with slight modification..

VQ37VHR · 04:29:49 PM / 12-Jan-22

So will the R200 shortnose mate up with my existing rear driveshaft and axles or will I need those parts off of a turbo S12? It was to my understanding that you couldn't just drop in an R200 but if I am mistaken please correct me.

sideways_s12 · 11:56:39 PM / 17-Jan-22

IIRC we have the long nose r200 so the turbo and the VG powered s12's have the r200..and I think but I could be wrong the z31 is a long nose 200 as well...

VQ37VHR · 02:05:18 AM / 19-Jan-22

So I did some more digging around in this section and I think I have an answer. The R200 longnose came stock on the Turbo/SE S12s and used 29 spline shafts. Assuming that the mounting points are the same, what I will need to do is acquire an open R200 longnose off of an S12 or Z31 and run an S13 LSD designed for the open R200 shortnose. Will also need to hunt down a set of halfshafts from a turbo S12 which should bolt right up to my existing hubs correct? Please excuse me if I am discussing content already covered on this forum, I have been struggling to find a definitive guide on R180 to R200 conversions for the S12.

sideways_s12 · 04:04:30 PM / 19-Jan-22

Quote from: VQ37VHR on 02:05:18 AM / 19-Jan-22
So I did some more digging around in this section and I think I have an answer. The R200 longnose came stock on the Turbo/SE S12s and used 29 spline shafts. Assuming that the mounting points are the same, what I will need to do is acquire an open R200 longnose off of an S12 or Z31 and run an S13 LSD designed for the open R200 shortnose. Will also need to hunt down a set of halfshafts from a turbo S12 which should bolt right up to my existing hubs correct? Please excuse me if I am discussing content already covered on this forum, I have been struggling to find a definitive guide on R180 to R200 conversions for the S12.

You are correct. the r180 and r200 have the same mounting points on the subframe. and yes the shafts will work as well.

seishuku · 11:00:06 PM / 21-Jan-22

You'll need the rear diff mount for an R200 as well, those are different between the two, though one *can* be modified to work for the other.
It's a pretty minor difference.

VQ37VHR · 09:34:23 AM / 22-Jan-22

I'm going to need to pull the diff off of a tubro S12 anyway, might as well grab the diff mount while I'm in there. Anything else I'm going to need to do this job aside from the new mount?

seishuku · 06:46:46 PM / 22-Jan-22

I think you got it, as far as I know, all you need: long nose R200, half shafts, diff mount, and at least the rear section of the drive shaft (only the rear sections are different, at least on the S12).

sideways_s12 · 04:16:44 PM / 24-Jan-22

you shouldn't have to mod the diff mount I just swapped a whole rear subframe from an r180 car to an r200 car and it bolted right up with no issue. while I'm thinking about it you might be able to convince wondering raven to sell you the r200 diff that came off my car.