interest in 4.44 final drive

[ScienceofSpeed]

We're posting to gauge interest in a 4.44 final drive gear set for 1991-2005 NSX. The stock final drive is 4.06:1. We currently have the 4.23:1 final drive by means of the NSX-R as well as the 4.44 final drive from OS Giken that requires the OS Giken LSD. A 4.55 gear set was once offered by Comptech which had some strength and noise issues.

The 4.23 is limiting to 1995-2005 owners as this requires purchasing the early 5-spd LSD as found in the NSX-R. In addition, the electronic power steering computers are also not compatible with the speed pulse created from the 4.23 which disables EPS.

We propose to create a 4.44 final drive gear set that is compatible with both LSDs (two separate ring gears will be required) as well as compatible in either 5-spd or 6-spd (two separate pinion shafts will be required). The kit would also include a new oil pump gear compatible with the new gear ratio. This ratio is compatible with the factory EPS system and does not trigger an error fault code.

The final drive set would be hot forged, hardened, and shot peaned for maximum strength. In addition, the gear tooth design would feature a broad tooth with a high contact patch - similar to the existing 4.44 final drive gear set used by OS Giken currently. This design creates a very strong gear at the expense of minimal gear mesh noise barely audible in the cabin.

The projected price is $1400.00 and would require a purchase of 40-50 pieces. We'd be looking for a 10 pc commitment before producing these gears. This pricing would put the gear set higher than the factory final drive but much lower than Comptech's discontinued 4.55 set.

Please post if you have interest.

Cheers,
-- Chris

 

[whrdnsx]

Yes, I'm interested in a set for the 6 speed differential.

As long as it's reliable enough for FI applications as well.

 

[nsx1]

Definitely interested for my 2002. In fact, I was planning to upgrade to the OS 4.44 in the not too distant future. The only hesitation I had with the OS LSD was that I would have lost my stock torque-reactive LSD.

Just for clarification... this is a ring & pinion set that will bolt onto our existing LSD, right?

 

[ScienceofSpeed]

Just for clarification... this is a ring & pinion set that will bolt onto our existing LSD, right?

That's correct.

Cheers,
-- Chris

 

[len3.8]

I'd be interested if it is strong enough to handle over 550ftlbs. of torque...
How long of a wait would there be if you had 10 orders tomorrow?

 

[Veleno]

Is the 4.44 better than the 4.55? Why not just build a better 4.55 gear than what CT had to offer? Is noise the only issue with running gears?

 

[John McCain Racing]

I thought it was a 4.40???

 

[AutoVation]

Is the 4.44 better than the 4.55? Why not just build a better 4.55 gear than what CT had to offer? Is noise the only issue with running gears?

If the 4.55 is better, than shouldn't the OS 4.642 be even better? I'm interested in the 4.40 gear (i think you are right John) also since it can swap directly into my setup.

 

[mackash]

Put me down for a set.

 

[ScienceofSpeed]

The 4.55 ratio is too short for most customers, especially with most customers considering power adders. Going any higher would be too short for even factory power cars in my experience. The 4.44 ratio is in the "sweet" spot of acceleration vs. shifting requirements & high way speed for 90% of our customers.

The tooth design of the 4.44 is pretty rugged and is designed to have a high contact patch for strength. I don't think 550 lb/ft will be a problem as long as the torque comes in smoothly. No final drive factory or aftermarket that will fit into the NSX transmission case will last clutch drops on a heavy high horsepower grippy tire equipped car.

Please keep notes on your interest coming. With enough interest we'll continue with development.

Cheers,
-- Chris

 

[stacy'snsx]

What kind of time frame would you be talking about before these would be ready to go if you had 10 sales right now?

 

[ScienceofSpeed]

Approx 60-90 days.

I'd say we're at about 5 definites.

take care,
-- Chris

 

[len3.8]

The 4.44 ratio is in the "sweet" spot of acceleration vs. shifting requirements & high way speed for 90% of our customers.

The tooth design of the 4.44 is pretty rugged and is designed to have a high contact patch for strength. I don't think 550 lb/ft will be a problem as long as the torque comes in smoothly. No final drive factory or aftermarket that will fit into the NSX transmission case will last clutch drops on a heavy high horsepower grippy tire equipped car.

Please keep notes on your interest coming. With enough interest we'll continue with development.

Cheers,
-- Chris

Thanks Chris.. My driving style (No drag racing) fits within the described parameters...

However, there are 2 aftermarket final drives that will handle that kind of power.. The costs are the limiting factor... They would be very expensive to produce, the mock up that was made, held the power, the halfshafts on the other hand did not, which I would rather have happen anyway, the solution on the halfshaft was to use a stronger metal, which again would be very expensive..

So I would agree that in the aftermarket section, this final drivr would be, within reason, a much more viable solution to all...

 

[clarknm]

I'd be all over it if I had the money . What does this end up doing to the max speeds in each gear? I didn't see 4.44 in the FAQ either just the 4.55 and 4.23 specs.

 

[nsx1]

I'd be all over it if I had the money . What does this end up doing to the max speeds in each gear? I didn't see 4.44 in the FAQ either just the 4.55 and 4.23 specs.

Nathan,

Here's a Ring & Pinion RPM & Speed calculation spreadsheet I put together a couple years ago. It compares the stock, NSX-R and Comptech 4.55 R & P sets. Just replace the 4.55 with 4.44 in the appropriate cell. (I should probably fix that because 4.55 is not available.)

http://www.nsx1.com/rp.xls

Thanks, Steve

 

[goldNSX]

The 4.23 is limiting to 1995-2005 owners as this requires purchasing the early 5-spd LSD as found in the NSX-R. In addition, the electronic power steering computers are also not compatible with the speed pulse created from the 4.23 which disables EPS.

Are you sure? If there's no EPS there's nothing else needed for a 4.23. So I don't see a limit of the 4.23 to 1995 to 2005 cars.

 

[MvM]

hi Chris,

The 4.44 final drive sounds great to me.
However, personally speaking, I would be much more interested in a Group Buy for the Short Gears...

 

[ScienceofSpeed]

Are you sure? If there's no EPS there's nothing else needed for a 4.23. So I don't see a limit of the 4.23 to 1995 to 2005 cars.

Yes, the limiting factor is:
the factory 1995+ LSD is not compatible with the 4.23
The EPS computer (which is placed in all 1995+ US NSX) is not compatible with this ratio and will cause a fault code.

I'm not sure if I'm understanding you right on why you think this is not true?

Regards,
-- Chris

 

[goldNSX]

Yes, the limiting factor is:
the factory 1995+ LSD is not compatible with the 4.23
The EPS computer (which is placed in all 1995+ US NSX) is not compatible with this ratio and will cause a fault code.

I'm not sure if I'm understanding you right on why you think this is not true?

Regards,
-- Chris

Misunderstood you here (my english, sorry for that). I got the idea that the 4.23 is only for 95+ cars. That's wrong know by now. But good to know it anyway.

 

[collegeboy]

Sweet! I just bought a 4.11 gear set for my 300ZXTT (stock is 3.69). I'd love to jump on a 4.44 gear set for a newer NSX 6speed! Keep the project going!

 

[John McCain Racing]

We're posting to gauge interest in a 4.44 final drive gear set for 1991-2005 NSX. The stock final drive is 4.06:1. We currently have the 4.23:1 final drive by means of the NSX-R as well as the 4.44 final drive from OS Giken that requires the OS Giken LSD. A 4.55 gear set was once offered by Comptech which had some strength and noise issues.

The 4.23 is limiting to 1995-2005 owners as this requires purchasing the early 5-spd LSD as found in the NSX-R. In addition, the electronic power steering computers are also not compatible with the speed pulse created from the 4.23 which disables EPS.

We propose to create a 4.44 final drive gear set that is compatible with both LSDs (two separate ring gears will be required) as well as compatible in either 5-spd or 6-spd (two separate pinion shafts will be required). The kit would also include a new oil pump gear compatible with the new gear ratio. This ratio is compatible with the factory EPS system and does not trigger an error fault code.

The final drive set would be hot forged, hardened, and shot peaned for maximum strength. In addition, the gear tooth design would feature a broad tooth with a high contact patch - similar to the existing 4.44 final drive gear set used by OS Giken currently. This design creates a very strong gear at the expense of minimal gear mesh noise barely audible in the cabin.

The projected price is $1400.00 and would require a purchase of 40-50 pieces. We'd be looking for a 10 pc commitment before producing these gears. This pricing would put the gear set higher than the factory final drive but much lower than Comptech's discontinued 4.55 set.

Please post if you have interest.

Cheers,
-- Chris

Is it a 4.40 or a 4.44? I did a search on the OS Giken Japan site and it shows a 4.4? I remember the #'s on mine before it was installed being a 4.40. I could be wrong though being that it was a few years ago. How easy is it to adjust the LSD once it's installed? I'm guessing it would have to be removed to do this.

 

[ScienceofSpeed]

The number is a ratio of the number of drive and driven gear teeth which normally goes into the 3rd or 4th decimal place. The number 4.4 is probably just a rounded number of the actual ratio.

cheers,
-- Chris

 

[nsx1]

Any news.

 

[ScienceofSpeed]

I'm sorry, we did not receive enough interest to look into producing this at this time. However, I am interested in hearing any interest. You can shoot an e-mail to [email protected]

cheers,
-- Chris

 

[Da Hapa]

Chris -

FWIW, I would be interested in the 4.44 final drive. My only caveat is that there are several other projects that I plan to do on my NSX first (suspension, for one) but my experience with the final drive changes in the S2K tells me that this would be a great mod, even on a 6 speed NSX.