R34 gtt

[Eager]

I have a 1999 gtt 4 door. Factory manual drivetrain as far as I’m aware. 

Any way of knowing if I have helecoil or a viscous setup ? And does that matter if I buy a 1.5 or 2 way or is it specific to the type of diff I currently have ?

It’s a road car and will likely upgrade at some point  

cheers

[GTSBoy]

Helical does not work like an LSD when wheels are off the ground.  So jack it up, put it neutral, turn one rear wheel.  If the opposite wheel goes in the same direction, it's viscous.  If it goes in the opposite direction (like an open diff would) then it's helical.  It almost certainly won't be helical because there's only a small fraction of R34s that have it.

If it's helical, unless you're going to track it, you'd be making a mistake in changing it to a plate type diff.  The helical is the nicest diff for street.  In Supra circles, the helicals for those cars change hands for big $$.

When you buy a diff centre you have to transfer the CW over from your old centre.  What matters after that is whether the new centre is supposed to work with your original stub axles or if it comes with new stubs.  The Nismo diffs come with stubs to suit (when buying for Nissan VLSDs) because the stubs on VLSDs are uneven length and don't suit real diffs.  Other brands of mech diff may or may not be made to work with the uneven length stub axles.  This is a problem when trying to ruin a helical diff, because helicals have even length stubs.  It throws all the variables up in the air and you have to pick through what's going to work and what's not going to work.

[niZmO_Man]

Perhaps look up your VIN on http://gtr-registry.com/

[Eager]

Cool lads. On the wheels turning when in the air, they turn the same way so suggests viscous, which is what I suspected as I had a s15 before with the standard helecoil diff and my car does behave differently I.e one wheel wonder at times

 

so a Nismo is deemed a good purchase ? I struggle to find a Nismo retailer in the uk, could you recommend anywhere and I could get it shipped? 

[GTSBoy]

Nengun, RHDjapan, etc.

[admS15]

Jesse Streeter.com is another good source for overnight parts direct from Japan manufacturers, lol.

[V28VX37]

^ What Bill said, Jesse supplied a Nismo GT 1.5-way (non Pro) for my 34 sedan.

If yours is mostly a street car, let alone a daily, please please go have a proper drive in a car with a mechanical diff before you get one of these, under different driving conditions.

In my experience a 1.5-way is awesome on the track and in spirited driving, and s__thouse for residential streets, tight T intersections, driveways, supermarket carparks etc. etc. You can live with it #becauseracecar but I wouldn't, not in a daily.

Just my $0.02