Differential Recommendations for HPDE Built R32 GTST

[Tillis3]

Hey everyone. I'm looking to change the rear differential in my 91 GTST Type-M. The car is RB25neo swapped with a CD009 6 speed transmission from a 370z.

 

The car currently has a very aggressive 2 way differential- It was the only modification on the car from Japan when I got it 8 years ago so I am not sure on the brand. It feels incredible on track but it makes horrendous noise and chatter on the street. Trying to find a happy medium.

 

I am looking for a longer gear ratio, currently a 4.36, maybe something around 3.7-4.0. I am looking for recommendations on brands and options from users with real experience. The car is built around weekend/mountain driving with 3-5 track days a year.

 

I've done some significant research on various forums, more specifically, on the Nismo GT Pro, OS Giken, and Quaife. They all sound great on paper but haven't been able to talk to someone with real life experience using them.

 

Thanks in advance!

[Murray_Calavera]

What diff oil are you currently using?

I'm using a Nismo GT Pro diff, let me know if you have any specific questions. I've had it in the car for something like 10 years now, it's been perfect the entire time. 

[Tillis3]

1 minute ago, Murray_Calavera said:

What diff oil are you currently using?

I'm using a Nismo GT Pro diff, let me know if you have any specific questions. I've had it in the car for something like 10 years now, it's been perfect the entire time. 

Awesome to hear! How does it feel and sound on street? How does it operate on the track?

 

For diff oil, I went with the recommendation of a local shop about 5 years or so ago. I'm fairly certain it was a GL-5 75-90 Redline fluid. To my knowledge, there is no LSD additive which I have heard can potentially quiet it down a bit.

[Murray_Calavera]

26 minutes ago, Tillis3 said:

How does it feel and sound on street? How does it operate on the track?

The diff is adjustable, how mine is setup, on the track? I think it's perfect. It locks up super quick, is consistent and reliable. On the street? I also think it's perfect lol. So, on the street doing low speed turns, think parking lot, you get cute little diff clunks and tyre chirp occasionally. I really like the character, I'm guessing these clunks and chirps are a lot more tame then what your currently experiencing. 

As for the diff oil, in my swift I ran a Cusco RS 1.5 way diff, it took me a while to find a gearbox/diff oil that made the diff happy. The wrong oil made it feel like the diff was trying to violently eject itself out of the gearbox pretty much at all times. It was a nightmare. Good news, Motul gear FF-LSD oil tamed the diff down 100%, the bad news is the cost of the oil

I'd say try using something like this first and see how you go - 

https://www.supercheapauto.com.au/p/nulon-nulon-ezy-squeeze-heavy-duty-limited-slip-differential-oil---80w-140-1-litre/577669.html#q=NULON%2BEZY-SQUEEZE%2BDifferential%2BOil&lang=en_AU&start=4

I use this diff oil, feels the same as running the Nismo oil without the Nismo price tag. 

As for additives, when I was on my swift diff adventure, no additive I tried made any real difference. I don't know if you'd have the same experience (having the diff separate from the gearbox makes life infinitely easier, so maybe there is something out there that might help but I'd for sure try the above diff fluid before worrying about additives). 

[Tillis3]

8 minutes ago, Murray_Calavera said:

The diff is adjustable, how mine is setup, on the track? I think it's perfect. It locks up super quick, is consistent and reliable. On the street? I also think it's perfect lol. So, on the street doing low speed turns, think parking lot, you get cute little diff clunks and tyre chirp occasionally. I really like the character, I'm guessing these clunks and chirps are a lot more tame then what your currently experiencing. 

As for the diff oil, in my swift I ran a Cusco RS 1.5 way diff, it took me a while to find a gearbox/diff oil that made the diff happy. The wrong oil made it feel like the diff was trying to violently eject itself out of the gearbox pretty much at all times. It was a nightmare. Good news, Motul gear FF-LSD oil tamed the diff down 100%, the bad news is the cost of the oil

I'd say try using something like this first and see how you go - 

https://www.supercheapauto.com.au/p/nulon-nulon-ezy-squeeze-heavy-duty-limited-slip-differential-oil---80w-140-1-litre/577669.html#q=NULON%2BEZY-SQUEEZE%2BDifferential%2BOil&lang=en_AU&start=4

I use this diff oil, feels the same as running the Nismo oil without the Nismo price tag. 

As for additives, when I was on my swift diff adventure, no additive I tried made any real difference. I don't know if you'd have the same experience (having the diff separate from the gearbox makes life infinitely easier, so maybe there is something out there that might help but I'd for sure try the above diff fluid before worrying about additives). 

Great advice, Murray- Thank you. I will give this fluid a shot before making a big pricey move to a new differential.

 

I would give a lot to get some noises I'd consider "cute" ha. The noise is more like you described in the latter- Violent! Passenger's think my car is broken haha.

[Kinkstaah]

I had this issue with the (presumably older) Nismo "2" way, or rather the "1.5" way. They advertise a "1" way (the 1 way is the one you want. Check Nismo's documentation!!).

Anyway. You want something with less locking on deceleration. I can confirm that with a stiffly bushed car, it feels like full on violent axle tramp at 1-10kmh 100% of the time, not fun chirps which I have experienced in other cars.

[TurboTapin]

I also run a CD009. I'm currently on a 4.08 and it's not great. I originally intended to run a 3.3 but had issues, more on that later. I'd stick to anywhere between a 3.3-3.7 as found in the 350z. 

As for brands of ring and pinions, absolutely stay away from Speedtek. They are absolute garbage. See my build thread for more information on that. I went through two of there 3.3's and both had bad runout. They were paperweights and they have still yet to refund me. 

I ended up putting in a Nissan 4.08, which was better then the original 4.36 but is far from ideal. I'm going to pop a 3.5 in this winter. I'd stick Nissan. I've also heard of a company "Neat Gearboxes" that makes them. Haven't tried them, but they can't be worst then Speedtek... 

[Butters]

I've had a range of rear diff centres - open, viscous, helical, mechanical, welded, etc.

 

I can't go past a refreshed factory 32 gtr centre for consistent lock and street driving.

The next step up for me would be the nismo 1.5 way , which likely suits you better as track sounds like the focus. Will chatter in carparks but its not the worst.

 

I have never tried a quaife rear diff, an option I've looked at before and might be one for you .....

 

Currently playing with an S15 centre at the moment and I hate it.  The transition from single wheel spin either side is just weird.

[GTSBoy]

58 minutes ago, Butters said:

Currently playing with an S15 centre at the moment and I hate it.  The transition from single wheel spin either side is just weird.

I have S15 helical too. It is a bit worn. I think the drive behaviour you describe is related to this wear. Wear of helicals is something that no-one seems to have paid a lot of attention to, but now that they (as in original Nissan ones) are all a bit old - we're starting to  see the consequences.

The ends of the helical spurs wear into the casing. That's where they perform the braking that diverts torque. Some of the more modern helical designs have proper wear surfaces introduced there, but the Nissan ones are just steel on steel (or iron).