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).

[Tillis3]

On 7/4/2024 at 11:50 PM, Butters said:

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.

I've heard so many mixed things on the Nismo. I think there is more to these situations than brand- maybe diff tuning and fluid play larger roles here. Some people claim they are silent and perfect and others say its just like the one I have... 

 

 

On 7/4/2024 at 9:58 PM, TurboTapin said:

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. 

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... 

Good call out on the different ratio's. After some more research, I think your assessment is spot on. I am going to aim for a 3.7 when I make the switch.

 

 

On 7/4/2024 at 11:50 PM, Butters said:

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.

Are you suggesting a 32 GTR center in the rear differential? I haven't come across this topic yet.

[Dose Pipe Sutututu]

On 05/07/2024 at 10:23 AM, Murray_Calavera said:

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. 

I second this, try use a thicker oil.

 

I have an obnoxiously annoying KAAZ 2 way in my shit box, however I'm running a 85W140 LSD oil and it seems to make it a bit more enjoyable 

https://www.supercheapauto.com.au/p/penrite-penrite-gear-oil---85w-140-2.5-litre/342307.html#q=Penrite%2Blsd%2B140&lang=en_AU&start=1

 

[Murray_Calavera]

@Tillis3

Any luck with the thicker oil?

[Butters]

this seems aligned to our experiences 

 

 

[Tillis3]

On 8/2/2024 at 7:10 PM, Murray_Calavera said:

@Tillis3

Any luck with the thicker oil?

It’s sitting in my garage waiting for me to swap fluids!

 

I found some interesting information regarding ATB diffs offered by Quaife and spoke to a guy who went from a Tomei Trax 1.5 way to a quaife ATB 2 way… says he heard everything in the Tomei on the street and hears almost nothing on the ATB.

 

Since that’s the first direct experience I’ve come across, I’ll go that route if the thicker fluid doesn’t alleviate things. 

[GTSBoy]

7 hours ago, Tillis3 said:

a quaife ATB 2 way

That's not a thing.

7 hours ago, Tillis3 said:

says he heard everything in the Tomei on the street and hears almost nothing on the ATB.

Makes perfect sense. The Quaife is a helical diff. A totally different operating principle, in no way similar to a clutch diff. Helicals are the most polite street LSD possible.

[Tillis3]

Well, it appears you're right. Suppose I should have done more of my own research instead of trusting and parroting. One of those scenarios where you get excited because its what you want to hear and choose to believe it.

Do you have any experience with a Helical diff on track? More specifically, the Quaife ATB?

Edited August 7 by Tillis3

[GTSBoy]

A helical is not the best choice for a track diff, particularly if there is going to be inside wheel lift (simply from high G cornering and high roll stiffness, or from hitting kerbs). This is because a helical acts like an open diff when when one wheel is unloaded.