S15 Diff Into R32

[Ryno]

Hey guys,

I was just asked a question by a forum member on how to swap the S15 Helical diff into the R32, so I thought I'd post it on here to help anyone else out.

A quick "Google" search will find plenty of articles explaining the benefits of the Helical diff centre. For me it seemed like the best choice, as the diff is awesome for street driving and does not wear out like viscous and clutch type LSD's tend to. The only down side to the diff is that it's not the best for drifting, and it can tend to open wheel if one wheel as zero traction (as the centre cannot detect any torque, so it doesn't know to transfer it to the other side)... Though I'm told that if you lightly apply the hand brake (when getting out of slippery spots) it should solve this problem and drive both wheels.

I'd purchased a whole S15 diff, with the half shafts, so I was hoping I'd be able to swap the whole diff over and not have to pull them apart. Unfortunately it wasn't that straight forward.

The S15 diff has the mounting holes is a slightly different position (due to the speed sensor at the front of the diff). In the attached photo's below the S15 diff is on the right.

So I had to remove my diff and pull it apart to swap centres.

My initial plan was to go with the 3.7:1 ratio from the S15, but after reading a few posts on here, I decided it would probably be too tall for what I was after. My diff was already 4.08:1, so it's taller than most.

After the diff was removed, oil drained and pulled apart. I unbolted the crown wheel from the viscous centre and then bolted it onto the helical centre out of the S15. I then reassembled the diff.

There are 3 shims that position the diff centre correctly (2 thin and one thick). As the crown wheel on the S15 diff is thicker than the R32 crown wheel, the thick shim had to be installed on the opposite side from when it was removed. It does seem quite tight to remove and reinstall them, but I had the correct amount of backlash when it was all done.

You then tap in the S15 stub axles, and bolt back on the rear cover. You cannot use the 5 bolt stub axles (from the viscous diff) on the helical diff centre, as they are different lengths.

I then reinstalled the diff onto the car, and bolted it up to the "6 Bolt" S15 half shafts.

I did this all by myself (with a little help from the wife) last weekend. The hardest thing is getting the bolts undone that hold the crown wheel onto the diff centre. A good vice and a breaker bar did the trick (my rattle gun didn't have the power).

There's a good tutorial on "R33 LSD shimming" in the DIY section, which explains how to remove the diff and crown wheel etc, and the rest you should be able to work out. (but if you have any dramas, just get in touch with me)

In all, I'm very happy with the upgrade, so if you can find an S15 diff and half shafts for the right price, go for it.

Ryno

Edited January 26, 2010 by Ryno

[wlspn]

I assume you are referring to a torsen (torque-sensing) centre.

Helical is a style of gear cutting...

e.g straight-cut or helical (angle-cut)

Suppose if you came across a s15 setup cheap enough could be a good mod but still no match for a mechanical LSD in a race situation.

[Ryno]

You are correct in saying it is a Torsen centre, however it is the "Helical" type. The other two main types of Torsen centres are referred to as "Parallel Gear" and "Planetary".

I'm not sure why everyone refers to the S15 Helical centre as helical and not Torsen, but that seems to be the case.

The setup cost me $250, so I can't complain about the cost.

As for performance, I couldn't be happier with it. My Skyline is my daily drive, so going with a mechanical centre or spool type (which may be better for the track) doesn't really suit the driving I do.

All I can say is, it's a massive improvement over my old viscous LSD centre. It gives off no diff noise, and behaves just as awesome going in and out of the driveway every morning, as it does when giving it the berries in a fast sweeper.

[Dose Pipe Sutututu]

awesome write up!

I was going to put a S15 Helical into my R33, but thought the shafts wouldn't fit due to the output shaft differences, so I ended up getting a Nismo 1.5 way and now too lazy to put it in.

[benl1981]

Old thread..

So same applies with the R33?

The S15 mechanical centre can be swapped in easily enough? Would this be a reasonable upgrade to allow some limited drifting. The current VLSD seems to single spin all the time

I called a diff shop today re. other options: They told me I needed to source a plate type mechanical cenre for my diff so they could put in a Nismo centre. They said my model or some of the nissan's came standard with the plate type mechnical.

I take it the helical centre of the S15 is not a plate type LSD.. so I'm not sure what they are talking about.

I assume that since the VLSD can not be pulled apart they need a housing to place the nismo centre??

Any ideas?

Might be worth trying the S15 centre first with the R33 gear sets and see how that feels.

I'm thinking this may be better than shimming of the R33 vlsd.

[simpletool]

I'm not sure what a plate type centre is? The LSD centre bolts into the crown wheel (the S15 helical and clutch type both fit). The important differences between the centres is the required shaft diameter and number of splines that exits both sides of the centre. AFAIK the S15 centres requires the S15 output shafts which are a 6 bolt type - so they won't bolt to the Skyline 5-bolt axles. So you need the complete half shafts with the centre.

[DJRIFT]

Not sure if this will help.

im not totaly sure what you diff shop means but at a guess i think thay are taking about GTR diffs as they are mechanical from the factory and can be rebuilt using nismo parts.

otherwise if you get a nismo diff to suit a r33 gtst it comes as a complete centre. you just need to change over the crown wheel to the new center and pop it in. simple as that.

i belive a properly rebuilt Vlsd would work ok for a while. most people just shim them to be locked.

dont get a cheap mechanical diff if its a street car as they tend to be very noisy.

[Lonewolf1983]

or get a quaife to go straight into the factory box, depends how cheap you can get an S15 diff + shafts for