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Carbon LSD with NSX-R gear ratio

Joined
6 February 2003
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Location
Silicon Valley, CA
Does anyone have experience with the ATS LSD? I am looking at their LSD for the NSX. They make several other products for the NSX (clutches). I did a search but did not turn up anything worthy.

Here's their note on the NSX part:
"Type R countershaft (23220-PR8-J00 for C30A, 23220-PR8-T00 for C32B) and oil pump shaft 21173-PR8-J00 are included. ATS LSD for NSX comes with ATS 4.26 final gear -same gear ratio as the NSX Type R. For NSX, ATS recommends the carbon LSD except for the drifting competition or drag racing."
 
I have just installed the latest 1.5 way carbon LSD That comes with the nsx-r counter shaft and final drive. Ats USA is having a sale on these LSD. Great value for money. Cheaper than os giken and you can service and rebuild ats LSD if it wears out.
 
I have just installed the latest 1.5 way carbon LSD That comes with the nsx-r counter shaft and final drive. Ats USA is having a sale on these LSD. Great value for money. Cheaper than os giken and you can service and rebuild ats LSD if it wears out.
you can also disassemble, reconfigure, and rebuild an OS Giken as well. OSG claims they have never had a failure or have to rebuild their LSDs -ever. After putting 1,000hp through them road racing the FXMD NSX with no issues, I might have to agree..

I did a LSD writeup on MotoIQ.com under "Project NSX" -reconfiguring an OSG LSD and explaining how they work. Check it out, its a pretty good read.


Billy
 
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I also have the ATS CF 4:23 1.5 way It's very nice.

I know. I found out about ats from reading one of your threads. I went ahead to get ats LSD because of you. :smile:
 
has anyone installed it in a NA2 car- if so, did the EPS retain full functionality?
thx
 
has anyone installed it in a NA2 car- if so, did the EPS retain full functionality?
thx

Ats LSD retains eps function.
 
How would an LSD (of any brand) affect the EPS? Am I missing something?

There is a EPS sensor attached to the gearbox housing. The ATS LSD kit provides a washer for this sensor to maintain the right functioning gap so that the EPS still functions properly.
 
Very interested how the ATS compares to the OS Giken.

According to their site you can choose from either 4.235 or 4.429 Ratio's

They also do different types all availible for the NSX and cheaper than the OS Giken. Standard, Silent and Carbon.

So how does it compare to the OS Giken and which one is their better one for best comprismise. Road, drag and the odd track session?
 
I cannot compare because I have only had the ATS Carbon. I have never had a problem with any of the sensors. It is very smooth and quite.
Ken
 
Very interested how the ATS compares to the OS Giken.

According to their site you can choose from either 4.235 or 4.429 Ratio's

They also do different types all availible for the NSX and cheaper than the OS Giken. Standard, Silent and Carbon.

So how does it compare to the OS Giken and which one is their better one for best comprismise. Road, drag and the odd track session?
FWIW - the functionality/characteristics/adjustability of an LSD isn't very important for your intended uses. Anything will be better than stock so you can't really go wrong.

I've driven a few ATS carbon units in S2000s, NSXs, and a handful of other cars. However I have not adjusted or worked on them. While the OS Giken unit probably has more adjustability and since you do need to configure it to not be as agressive for street use, and since I think you're looking for a plug and play system that you don't have to touch, I think the ATS unit might be a better fit.

If you wanted to configure the LSD, were more into tracking your car and were more performance-oriented. I would suggest OS Giken.


0.02
 
argh.. just typed my reply and lost it :(

Anyway...

Thanks for the input, if there is enough interest perhaps there may be some group discount?

My other thoughts was, i have been reading up on diffs and apparently clutch type diffs require oil, and it requires to be changed every 2000 miles. Does this mean the gearbox oil changed every 2000 miles? or the actual diff? if it's the gearbox oil it's not really too much of a problem as it would be good practice to keep the gearbox oil fresh however if this means the actual diff can you imagine getting the gearbox removed and dissasembled every 2000 miles just so you can change the diff oil?? Servicing costs... Hello!!

My other thought is. What is the difference between stock and 4.23? Night and day difference?

And what is the difference between stock and 4.429? omg!!!???

And then the difference between 4.23 and 4.429?

Basically i'm trying to justify the cost of replacing the diff. If the difference is holy ***** then i can justify it, if it's only yeah bit better then hmmm... push it down the list couple places.

What i also need to keep in mind. the Nsx is a supercar, realisticly i will never get to do the top speed legally however that is beside the point, it is more of a talking point, my car can do xxx mph. I think as the Nsx is in the class it's in it needs to be able to hit at least a certain top speed even if you will never do it. This is making me wonder what my top speed will be with a 4.429 gearing, UK NA1 with the 5 speed tranny and the 16", 17" wheel setup?

I also need to keep in mind that some point i would like to change the wheels and go bigger which means i will loose acceleration and gain back top end. This means i wouldnt want to spalsh out for the 4.23 and then change my wheels and my acceleration is back to almost stock. So this would also drive more towards the 4.429.

My other Question is very important i think, what about the speedo? where is the speed sensor? does changing the final gear ratio make the speedo in accurate?
 
What is the difference between stock and 4.23? Night and day difference?
.... between stock and 4.429? omg!!!???
.... between 4.23 and 4.429?


see attached graphs and data on this from an acceleration model I developed in MATLAB some time back, for this purpose.

These compare three NSX with the JDM NA1 5 speed and
- stock diff (4.062)
- NSX-R diff 4.235
- 4.429 diff

At first the differences looks small, but the "car separations" chart is the most interesting to me. In a drag race, after 1 min 15 secs the 4.429 diff is 9 car lengths ahead of stock, and 3 car lengths ahead of the NSX-R

Basically as diff ratio increases the acceleration improves noticeably and top speeds drop a little, but only 3 - 4 kph. (see Data file)

I assume UK NSX have the JDM ratios, same as we have in Australian NSXs. But you'll need to convert to mph !
 

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  • Diffs car separations.pdf
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  • Diffs data.pdf
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argh.. just typed my reply and lost it :(

Anyway...

Thanks for the input, if there is enough interest perhaps there may be some group discount?

My other thoughts was, i have been reading up on diffs and apparently clutch type diffs require oil, and it requires to be changed every 2000 miles. Does this mean the gearbox oil changed every 2000 miles? or the actual diff? if it's the gearbox oil it's not really too much of a problem as it would be good practice to keep the gearbox oil fresh however if this means the actual diff can you imagine getting the gearbox removed and dissasembled every 2000 miles just so you can change the diff oil?? Servicing costs... Hello!!

My other thought is. What is the difference between stock and 4.23? Night and day difference?

And what is the difference between stock and 4.429? omg!!!???

And then the difference between 4.23 and 4.429?

Basically i'm trying to justify the cost of replacing the diff. If the difference is holy ***** then i can justify it, if it's only yeah bit better then hmmm... push it down the list couple places.

What i also need to keep in mind. the Nsx is a supercar, realisticly i will never get to do the top speed legally however that is beside the point, it is more of a talking point, my car can do xxx mph. I think as the Nsx is in the class it's in it needs to be able to hit at least a certain top speed even if you will never do it. This is making me wonder what my top speed will be with a 4.429 gearing, UK NA1 with the 5 speed tranny and the 16", 17" wheel setup?

I also need to keep in mind that some point i would like to change the wheels and go bigger which means i will loose acceleration and gain back top end. This means i wouldnt want to spalsh out for the 4.23 and then change my wheels and my acceleration is back to almost stock. So this would also drive more towards the 4.429.

My other Question is very important i think, what about the speedo? where is the speed sensor? does changing the final gear ratio make the speedo in accurate?
Where have you been reading up on diffs?

Here's a good read on LSDs, how they work, how to tune (OS Giken) - ON an NSX:

http://www.motoiq.com/magazine_arti...art-2-tuning-a-limited-slip-differential.aspx

The LSD uses the same oil as the trans. It might be a good idea to drain the fluid within 2,000 miles after you FIRST run it (break it in) then it should be good for routine intervals (say 20,000-50,000 miles depending on uses).

You'll be able to feel a difference from 4.06 to 4.23 as well as 4.23 to 4.4 The jump from 4.06 to 4.4 is pretty big (@3,200rpm the 4.06 will be 75mph while the 4.4 will be 69mph). This affects gas mileage and has the RPM higher for freeway cruising speeds, but the car WILL accelerate faster and be 'peppier'. Everything is a compromise.

As far as top speed goes. The NSX is limited by drag/power at ~165-170mph. The 4.06's geared top speed for a 5spd is 188mph. The 4.4's top speed is gear limited to 173mph. What top speed 'must' your supercar be able achieve?

Larger diameter and heavier wheels do affect acceleration but probably subjectively less than the change from 4.06 to 4.23.

The speed sensor isn't affected by the LSD on NA1s.
 
Thanks for all the info.

I have been doing some reading.

Those attached pdf's are very interesting.

Yes 170mph + is more than enough. That's great.

This info has really helped me thanks everyone.

I am now left with making the choice of 1.5 way or 2 way.

From what i have been reading the 1.5 way is the safest setup and shouldn't kick the rear end out on deceleration However the Carbon LSD from ATS apparently doesn't as much as a metal plates LSD. It's a hard call as a 2way you know where you stand you know what it's going to do and pradictable but the 1.5 way although their more garanteed not to kick the rear end out your not sure when it's going to lock. Hard choice :O

From my above statement it might appear i kinda know what i'm talking about, i really don't :p never driven a car with an aftermarket LSD. I did have a Quaife on my 300zx but never actually drove the car while that was fitted.

Thanks.
 
The 4.06's geared top speed for a 5spd is 188mph. The 4.4's top speed is gear limited to 173mph.

Keep in mind Billy is stating theoretical top speed if you could get to 8,000 rpm. In reality top speed occurs at highest rpm where the acceleration force (where the rear wheels meet the road) matches all the aero drag and friction forces. Based on my model the top speeds and rpms are:

4.062 173.6mph @ 7208rpm
4.235 173.4mph @ 7504rpm
4.429 171.3mph @ 7753rpm

Note the much higher rpm at top speed of the 4.429 !

Any mathematical model can give slightly different absolute values depending on exactly what values are used for things like wheel diameter, Cd, air temp etc. For example Billy's top speed figures are probably based on slightly different wheel diameters to mine (and possibly US gear ratios too)

But the comparative differences between the results from the model can be taken as quite accurate. So I can say with confidence that the top speed of 4.429 diff is only 2 - 3 mph slower than the stock diff
 
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Keep in mind Billy is stating theoretical top speed if you could get to 8,000 rpm. In reality top speed occurs at highest rpm where the acceleration force (where the rear wheels meet the road) matches all the aero drag and friction forces. Based on my model the top speeds and rpms are:

4.062 173.6mph @ 7208rpm
4.235 173.4mph @ 7504rpm
4.429 171.3mph @ 7753rpm

Note the much higher rpm at top speed of the 4.429 !

Any mathematical model can give slightly different absolute values depending on exactly what values are used for things like wheel diameter, Cd, air temp etc. For example Billy's top speed figures are probably based on slightly different wheel diameters to mine (and possibly US gear ratios too)

But the comparative differences between the results from the model can be taken as quite accurate. So I can say with confidence that the top speed of 4.429 diff is only 2 - 3 mph slower than the stock diff
What power level are you working with in your model? HP should increase with RPM unless you factored in a big drop in torque above 7,200rpm.

What Total Cd did you use?

In the end, the 4.4 has better performance than the 4.23 or 4.06 with the only downside of lower gas mileage and higher cruising RPM.
 
Attach graphs show the power & torque curves I used, based on best data I could find published by honda, and yes there's a big drop in torque and thus power drops a lot after the peak of 272hp @ 7330rpm.

Cd = 0.32
Frontal area = 1.78 sq.m (19.16 sq. ft)
wheel dia. = 0.644m (25.35 inches)

To be honest the accuracy of reading honda's published engine graphs to the accuracies I'm aiming for is not that good, so If you can be point me to any better official data that would be great.

Personally I think this 4.429 is just about ideal for the NSX, the 4.55 that used to be available (from comptech I think) was a step too far, affecting top speed much more.
 

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How does HP play a role in this? All the speed calculators I have seen go by wheel size and gearing. I have 520RWHP with a 6 speed and 4.23 final gears so is my top speed still going to be the same as a stock NSX? My tires are 285 35 18 rear. I would have thought I would see speeds over 200MPH.
Thanks
 
The ATS differential (and Carbonetic, it's the same thing) is very similar to the factory design, which is really quite good. The only advantage I can see compared to the factory differential is the carbon-carbon material will be more consistent at higher temperatures for track use (and possibly lasta little longer). For a street car, I don't see much of a benefit. With the NSX-R plate, you can achieve the same break away torque as the ATS differential. The parts to do so are included in our NSX-R 4.23 final drive kit. Hard core track users will probably prefer the locking rate and capacity of the OS Giken unit.

-- Chris
 
How does HP play a role in this? All the speed calculators I have seen go by wheel size and gearing. I have 520RWHP with a 6 speed and 4.23 final gears so is my top speed still going to be the same as a stock NSX? My tires are 285 35 18 rear. I would have thought I would see speeds over 200MPH.
Thanks

ken, HP = Torque x RPM (x constant) which means you need both high torque and high revs to get high HP and high top speeds, since top speed is determined by the amount of HP you need to push through the air drag, and this goes up dramatically as top speed increases. When you get up around 200MPH air becomes more like treakle to push through. Witness the recent increase in power of the Bugatti Veyron needed to get from a top speed of 253 to 268mph, they had to increase the power from 1,000 to 1,200hp .... that's adding the power of a Golf GTi just to go 15mph faster!

Wheel sizes and gearing determine:

a) how much torque ends up at the rear wheels where they meet the tarmac. (this is the push you feel in your back)

b) the RPM of the wheels

note if you multiply a x b (x the constant) that is the rwhp

Even with 520rwhp you probably not going to get to 200mph, for a few reasons. Firstly with the 4.235 diff the 8000rpm redline limits your top speed to about 185mph at the redline. Secondly, if you modify the engine so it can get above 8000 you will need the engine torque to remain huge at these high revs.

If you're serious I can calculate what sort of power curve would be needed to do 200mph in your NSX :smile:
 
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Your chart has a bigger drop in HP and TQ than most dyno charts i've seen. Most of them the HP drops off around 10-20hp compared to the 40 in your formula.

thanks for the examples, when I get the chance I'll update the model and see what happens ...
 
How does HP play a role in this? All the speed calculators I have seen go by wheel size and gearing. I have 520RWHP with a 6 speed and 4.23 final gears so is my top speed still going to be the same as a stock NSX? My tires are 285 35 18 rear. I would have thought I would see speeds over 200MPH.
Thanks
That combination at 8,000rpm is geared to 203mph. Due to the 0.717 gear ratio of 6th gear, it will take a lot of power to overcome that overdriven 6th gear and power it all the way to 8,000rpm.
 
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