200SX Differential Cover

I acquired an aftermarket diff cover with the extra oil capacity thinking it would be a good safety measure. These things are not a very well thought out design and suffer from one huge issue. The baffles on the inside are all in the wrong place. The vertical plates are too far in from the edge of the diff center and the upper most horizontal plate is too close to the breather pipe. This results in a lot of oil being flicked up into the top most recess where the breather is located. It only takes a few mm of oil to get flicked up into that tiny recess and it starts blowing oil out the breather. It would loose about half a litre of oil over a week end event and make a huge mess under the car.




Nissan S15_-_6_bolt_axlesI'm still running the standard 6 bolt rear axles - A lot of people say the 5 bolt axles are stronger but at this stage I haven't broken any (fingers crossed). The original axles had a bit of slop in the CV's so I sourced a good second hand set and gave them a clean out and packed them with fresh grease and new boots.

I also picked up another good set of 6 bolt axles that belong to another Nissan, possibly a Skyline or Z car. These were a bit longer than the S15 axles but the inner splines are the same as the S15 axles so I was able to transplant the good CV's onto the shorter S15 Axles along with fresh grease to make up a spare set of axles just in case.




gearbox swapOriginally this 200sx was fitted with an Automatic Transmission. I purchased a standard 6 speed box that had no shifter or associated clutch components, finding just a gearstick was an impossible task so i ended up buying a second gearbox.

One of the local Brisbane wreckers had a one piece Apexi flywheel that they were happy to part company with, A new Apexi clutch and throw out bearing were purchased to go with the flywheel.

I was lucky enough to find a manual pedal set, master cylinder and slave cylinder on Ebay.  A new clutch line was manufactured rather than use the original item with built in damper. 

The guys at Road and Track performed the conversion.


Transmission SR20DET SR20DE
6-speed manual 5-speed manual
1st gear ratio 3.626 3.321
2nd gear ratio 2.200 1.902
3rd gear ratio 1.541 1.308
4th gear ratio 1.213 1.000
5th gear ratio 1.000 0.838
6th gear ratio 0.767 -
final drive (diff) 3.692 4.083


diffThe standard Nissan 200sx S15 viscous diff was never going to last and its weakness showed after about 10 laps of testing at Queensland Raceway . The viscous diff would get hot and loose its ability to Limit the slip.

Whilst the differentials from S13's, S14's and various Skylines will fit there are subtle differences that require other changes to make them fit the 200sx chassis. The other problem is that most of the second hand diffs available are 4.11 rather than 3.7

The Nissan 200sx S15 diff housing has rubber front mounts where as the S13 and S14 are solid mounted. Most S15's have 6 bolt axle flanges where as the S13, S14 and most Skylines have 5 bolt flanges. The 200sx S15 also has a speed sensor on the input shaft.

I believe the axles can be swapped between various models but I could not find any definitive information about swapping the half shafts. The simplest and best option was to find a diff with the right configuration that would bolt straight in.


Feb-2013 :  It's taken nearly 18 months to finally track down a "real" LSD Diff with a ratio suited to circuit racing rather than drifting that would bolt straight in. Today we fitted a 200sx S15 Nismo 2 way diff with 6 bolt flanges and a final drive ratio of 3.7:1. It appears the diff can be changed from a 2 way to a 1.5, but i have left it set as a 2 way to see how it goes. 

The picture above shows the new diff fitted showing the larger front mounts, 6 bolt flanges and the speed sensor just hidden behind the drivers side front mount.


Feb-2014 :  After looking at the IQ3 Dash data it seems the choice of a 3.7:1 diff was not a good idea. :( - I'm now on the hunt for a 4.11 or similar ratio.


r200-diff- coverr200-diff-cover-2Aug-2014 :  That side mounted filler on the rear differential casing was stating to annoy me, its near impossible to get out and there is hardly any room for the oil filler hose to go in. So necessity being the mother of invention I added a secondary filler hole into a spare rear housing which i'll fit next time I have access to a hoist.


Jan-2018 : Yet another diff change, 4.3 with a Kaas 2way LSD, This should improve acceleration considerably and allow me to use more gears.