R34 Gtt Diff Issue

[david.r34.gtt]

I bought a 1998 R34 GTT Series 1 a few months ago, as a daily'ish driver and for occasional track outings for my son and I.

As far as we know this car has the original viscous LSD. It is producing 165kW ATW.

The car had it's first track day over the weekend and we found that it just wanted to spin one of the back wheels everytime we tried to accelerate. The tyres on the car are nothing special, but this was ridiculous.

A quick "test" on a gravel area (away from the track!) showed that it only ever spun one rear wheel.

I suspect our limited-slip diff is no longer limited much! :-)

From reading this forum, and elsewhere, it looks like the we should replace the diff with something better, but which is still streetable.

My understanding is that the suitable options are:

1. A complete mechanical (torsen?) rear diff from an R34 Series 2 GTT manual, which would be a drop in replacement.

This sounds like the best option, with least mucking about, and best suited to our street/track mix

2. A complete rear diff from an R34 GTR.

Not sure if this is a drop-in replacement?

I believe they have a 2-way LSD, so it will be less streetable than the R34 GTT torsen.

3. An after-market 1.5 way (eg Kaaz) diff centre, either new or used, which could be installed in our existing housing with the current gearset by a diff expert.

More work (and cost?) with the result being better for the track that option 1, but less civilised on the street.

4. A clutch/torsen type mechanical diff from earlier model Skylines (R32/33), although that may require replacing other parts, eg driveshafts. If we can't keep the ABS that is a showstopper for this option.

Any other options, or comments on those I have listed please?

Edited May 18, 2015 by david.r34.gtt

[GTSBoy]

Option 1. S2 R34 GTT helical diffs are like rockinghorse shit. Don't hold your breath expecting to find one. R34 GTR helical centres are not drop in by any means.

Option 2. Complete diff from GTR is not really a drop in proposition either.

Option 3. Aftermarket mech centre is an easy option. Nismo, Kaaz, Cusco, etc, all suitable options in 1, 1.5 or 2 way depending on how aggressive you want it to be. For a track toy a 2-way is a solid choice.

Option 4. No earlier R32/3 2WD cars had anything other than a viscous diff. GTRs are a mech 2-way but not an easy drop in.

GTRs have 6 bolt driveshafts and thicker splines on the stub axles. The input end also has a CV style connection to the tailshaft rather than a uni joint like the 2WD cars. Those are just a few of the reasons that they're not a simple drop in.

[GeeDog]

Following on from David's questions, we are in a similar position but with an R33 GTST.

Looking at option 3 (which I think is the best option), any opinions on which is the better choice between Nismo, Kaaz & Custco (and why - what are the differentiators), and where is a good place to buy from? How much is involved in changing the centre and setting it up - we've done everything else ourselves but never touched diffs.

[david.r34.gtt]

Thanks GTSBoy.

I will check around just in case a torsen is available, otherwise like GeeDog, go for an after market diff centre.