R34 Gtr Diff Into S15

[ben dinroad]

Just wondering if anyone has ever put an r34 gtr diff gear set into a s15 diff housing? Keeping the factory s15 drive shafts?

[GTSBoy]

That kind of depends on what you mean by "gearset". If you mean the CW&P, then there is a pretty bloody good chance that they will be mountable on both centres. I say this because the centres are the same - the same helical centre.

Same, but with one difference. That is that the splines for the axles are different. The GTR are of course the big strong 6 bolt ones, and the S15 are the smallest weakest 3x2 bolt ones.

So, for the sake of argument, there's no point in considering the other alternative diffs available in the 2 cars (the viscous centre in the S15 and the active diff in the R34) as they are both shit. Ignoring those 2 diffs, there's no point in swapping anything other than the CW&P. Given the slight change in gearing available from the GTR gears into the S15, I'm not sure I could be bothered with all the work to achieve it.

[Dose Pipe Sutututu]

Next question why?

Also the S15 runs a perfectly good helical / torsen centre.

Unless you're making stupid power or a really into circuit racing or drifting then swapping "may" be feasible however given the plethora of diff centres made specially for the R34 GTt and S15 you would be pretty mad to just use a R34 GTR centre provided it even fits.

[ben dinroad]

Thanks for the reply, its for a s15 subframe swapped datsun 240z with rb26 and rb25 tranny. Currently running the std s15 diff and was looking for something a little stronger

[GTSBoy]

Same same strength in diff. The stronger bits you want are actually the GTR shafts. Revise thinking accordingly.

[Dose Pipe Sutututu]

how much power you planning to make?

[ben dinroad]

400-450 whp - running efr7670 on the 26

[ben dinroad]

Pics for enjoyment

[Dose Pipe Sutututu]

Don't see an issue with the S15 diff with that power... but if you want to make it stronger, swap over to a R32 or R33 Skyline diff as it runs 5x1 bolts not 3x2 smaller bolts.

A car I recently worked on and re-tuned shits out 320kW at the rear and gets tracked every month or 2nd month and still is completely fine.

[ben dinroad]

What about changing diff ratio to 4.11 is there a crown and pinion that is interchangeable?

[GTSBoy]

What about changing diff ratio to 4.11 is there a crown and pinion that is interchangeable?

In general, all the Skyline and S chassis CW&P sets are interchangable. There are 2 sizes of bolts that can make life more interesting.

Question though.....your initial question was about putting an even taller diff into the S15 diff (from 3.7 or whatever they are down to 3.5 or whatever the R34 GTR diff is) and now you're asking about going shorter. I'm just checking to make sure you aren't confused about what you want to achieve.

[ichi-go]

Easiest way would be just to source whole diff centre from r33 gtst (4.11 for manual, 4.3 for auto) and swap the s15/r34 helical centre into it

[[200]]

Bit of a late reply but I swapped my s15 diff out for a r33 gts-t / gtr centre.

I bought a r33 gts-t diff and r33 gtr diff. Both were 4.11:1 ratio IIRC. I bought driveshafts from an r33 gtr too.

I dropped it off to a diff specialist and asked them to pull the centre out of the gtr and put it in the gts-t housing.

A few days later I picked it up. It all bolted straight back in the s15 subframe and the gtr driveshafts bolted up without any problems. Standard tailshaft went back in and I was on my way again. I was also able to retain ABS as the gts-t had the single wire speed sensor / abs sensor (whichever one it is).

[ichi-go]

If you pull the gtr centre and install to the gtst housing, that means you are using the gtst driveshaft?

As far as i know, the gtr driveshaft will not fit S-chassis as the spline counts are different on the hub, gtst driveshaft will fit s-chassis though

[GTSBoy]

If you pull the gtr centre and install to the gtst housing, that means you are using the gtst driveshaft?

No, if you use the GTR centre, you HAVE to use the GTR stub axles. The housing doesn't make any difference in the decision.

But the other aspects of your post are true. S and R chassis 5 and 3x2 bolt stubs are basically interchangeable (for the same types of diff.....let's not bring in the confusion of helicals and stuff).

[[200]]

I think I might have used gtr rear knuckles.

Pretty sure I did as I remember pulling the hand brake cable and drum assembly off.