4.08 or 3.90 gear questions...

DeliriousClam · 11-22-2017, 04:44 AM

Quote:

Originally Posted by derraj06

Don't think you're going to get most of those posters to answer given how long ago this thread is from.

To answer your question, the SRM requires a re-calibration via ECUTEK or Uprev to consistently work with a 4.08 FD set.

Only issue I've had with SRM since going to 4.08 was it's off by like 200 rpm. Still works fine though

derraj06 · 11-27-2017, 11:46 AM

Quote:

Originally Posted by DeliriousClam

Only issue I've had with SRM since going to 4.08 was it's off by like 200 rpm. Still works fine though

Track guys have had it randomly turn off. Being off by 200 RPM also isn't ideal. Shouldn't hurt a street car however.

axmea? · 04-06-2018, 12:44 AM

Did 4.08s on mine and SRM was totally off, very noticeable. and quite annoying. Blips were off by a fraction of a second and simply turned it off until Ecutek tune. Tune took care of it and it is fantastic. 4.08 makes it funner

Maintaining the same driving style, my mileage dropped by 4/10s of a mile per gallon. Overall, a great mod for those staying N/A.

jmroy6 · 04-06-2018, 08:18 AM

So you can fix the SRM issue with Ecutek?

Quote:

Originally Posted by axmea?

Did 4.08s on mine and SRM was totally off, very noticeable. and quite annoying. Blips were off by a fraction of a second and simply turned it off until Ecutek tune. Tune took care of it and it is fantastic. 4.08 makes it funner

Maintaining the same driving style, my mileage dropped by 4/10s of a mile per gallon. Overall, a great mod for those staying N/A.

axmea? · 04-06-2018, 08:30 AM

Quote:

Originally Posted by jmroy6

So you can fix the SRM issue with Ecutek?

Yes.

binary0x01 · 04-06-2018, 11:09 AM

I don't have SRM, but after doing 4.08 install on my quaife I can honestly say, that's how these cars should come stock lol

SS_Firehawk · 04-06-2018, 11:18 AM

Big thing to keep in mind with gears, especially 4.08's is your gearing for and against you. At speeds over 90mph, you'd be in the same gears for a shorter amount of time. There would be 10, 14, and 18mph per gear that you are sacrificing to the next higher gear. For At those periods, the 3.69 will be more beneficial. The only way to get around this is compensate by rpm. So 4.08's really make sense if you can rev the engine to 8000-8250rpm. That implies that you have more aggressive cams, oil pump gears, ad damper at a minimum. It would also be recommended to replace your rod bolts and look into running a slightly stiffer valve spring on the VVEL side to prevent spring attenuation. That would make for a pretty Nasty NA Z, but costly. Anything over 8500 would need a new rotating assembly too.

On the track, 4.08's can be great for pulling out of a corner, but a PITA on the straights or high speed turn where you find yourself between the right gears.

axmea? · 04-06-2018, 01:34 PM

Coming from a 3.69 hands down I won't be coming back. I have a great street car and told Seb keep the old gear.

Bswanny · 12-07-2019, 02:13 PM

Any one know the top speed of each gear in the manual 3.69 final drive? Trying to see where gear shifts occur of going to a 4.10

Spooler · 12-07-2019, 02:50 PM

Quote:

Originally Posted by Bswanny

Any one know the top speed of each gear in the manual 3.69 final drive? Trying to see where gear shifts occur of going to a 4.10

Look in my thread. It was posted by Mr. Squeeze. He compared 3.69 to 3.3. It is around page 100.

Dentt42 · 03-03-2020, 10:32 AM

Now that the MT Nismos come with 3.9 from the factory, has anyone had more experience with them? I'm on the 3.62 ratio with factory VSLD, and having a tough time deciding if it would benefit me.

Street car, 1/4 mile for the fun, and HPDE type of events
NA for the foreseeable future, N20 (nitrous) if I start chasing ETs at the strip
Daily now, but hopefully retired to weekend car by end of year
Wavetrac diff for planned upgrade
My driving makes MPG a somewhat moot point

Thoughts, everyone?

Hotrodz · 03-03-2020, 01:05 PM

Quote:

Originally Posted by Dentt42

Now that the MT Nismos come with 3.9 from the factory, has anyone had more experience with them? I'm on the 3.62 ratio with factory VSLD, and having a tough time deciding if it would benefit me.

Street car, 1/4 mile for the fun, and HPDE type of events
NA for the foreseeable future, N20 (nitrous) if I start chasing ETs at the strip
Daily now, but hopefully retired to weekend car by end of year
Wavetrac diff for planned upgrade
My driving makes MPG a somewhat moot point

Thoughts, everyone?

There is not enough difference to make a change IMO. If you want gain more then run an 18" wheel and tire combo.

Sent from my SM-G965U using Tapatalk

Dentt42 · 03-03-2020, 06:15 PM

Quote:

Originally Posted by Hotrodz

There is not enough difference to make a change IMO. If you want gain more then run an 18" wheel and tire combo.

Sent from my SM-G965U using Tapatalk

Huh. Didn’t think of that. Muchas gracias.

BORNGEARHEAD · 12-12-2022, 08:37 PM

Are 4.08 gears avail through Nissan/Nismo or only avail aftermarket?

SS_Firehawk · 12-12-2022, 09:17 PM

There are Nissan oem ring gears in 4.08. I'm still running mine and depending on what you plan on doing with them, they're a great option. I find more benefit a lot of the corners I find myself in. At times, I find where I need to shift up so I don't run into the rev limiter mid corner. If you ever do Road America, I think a 4.08 would work perfectly if your redline is at 8000.

04-06-2018, 12:44 AM	#48 (permalink)
axmea? A True Z Fanatic Join Date: Apr 2012 Location: SoCal Posts: 6,233 Drives: WELL ZED PW 6MT Rep Power: 53241	Did 4.08s on mine and SRM was totally off, very noticeable. and quite annoying. Blips were off by a fraction of a second and simply turned it off until Ecutek tune. Tune took care of it and it is fantastic. 4.08 makes it funner Maintaining the same driving style, my mileage dropped by 4/10s of a mile per gallon. Overall, a great mod for those staying N/A. __________________ >MyZ's Album< NISMO Convert/ECUTEK/Takeda CAI/F.I. HFC NR CB Carbon/F.I. 34 Row Oil Cooler/4.08 Final Drive /Powertrix+Swifts/Hotchkis/SPL/Whiteline/TWM/Zoom Engineering/EVO-R/AeroJacket Vented CF Fenders + CF Spoiler/Avant Garde-WORK/NST/Morimoto Halo/STi Clear Lenses/Carbon Signal Automotive/RJM Performance/ZSpeed Clutch Flywheel CSC delete

04-06-2018, 11:09 AM	#51 (permalink)
binary0x01 Track Member Join Date: Jun 2012 Location: Idaho Posts: 892 Drives: 2012 6-SPEED 3.7L Z Rep Power: 13	I don't have SRM, but after doing 4.08 install on my quaife I can honestly say, that's how these cars should come stock lol axmea? likes this. __________________ Tune (by Seb@SpecialtyZ) -- Upgraded Parts List : When in doubt, use brute force; if it doesn't work, you aren't using enough.

04-06-2018, 11:18 AM	#52 (permalink)
SS_Firehawk Premium Member Join Date: Oct 2011 Location: Tampa Posts: 4,142 Drives: 13' Magma Red Nismo Rep Power: 7334	Big thing to keep in mind with gears, especially 4.08's is your gearing for and against you. At speeds over 90mph, you'd be in the same gears for a shorter amount of time. There would be 10, 14, and 18mph per gear that you are sacrificing to the next higher gear. For At those periods, the 3.69 will be more beneficial. The only way to get around this is compensate by rpm. So 4.08's really make sense if you can rev the engine to 8000-8250rpm. That implies that you have more aggressive cams, oil pump gears, ad damper at a minimum. It would also be recommended to replace your rod bolts and look into running a slightly stiffer valve spring on the VVEL side to prevent spring attenuation. That would make for a pretty Nasty NA Z, but costly. Anything over 8500 would need a new rotating assembly too. On the track, 4.08's can be great for pulling out of a corner, but a PITA on the straights or high speed turn where you find yourself between the right gears. NismOrly22 likes this. __________________ Old Car:GTM TSC'd 550whp / 410lbft tq @ 11.88PSI New Car: Under Construction

04-06-2018, 01:34 PM	#53 (permalink)
axmea? A True Z Fanatic Join Date: Apr 2012 Location: SoCal Posts: 6,233 Drives: WELL ZED PW 6MT Rep Power: 53241	Coming from a 3.69 hands down I won't be coming back. I have a great street car and told Seb keep the old gear. __________________ >MyZ's Album< NISMO Convert/ECUTEK/Takeda CAI/F.I. HFC NR CB Carbon/F.I. 34 Row Oil Cooler/4.08 Final Drive /Powertrix+Swifts/Hotchkis/SPL/Whiteline/TWM/Zoom Engineering/EVO-R/AeroJacket Vented CF Fenders + CF Spoiler/Avant Garde-WORK/NST/Morimoto Halo/STi Clear Lenses/Carbon Signal Automotive/RJM Performance/ZSpeed Clutch Flywheel CSC delete

12-12-2022, 08:37 PM	#59 (permalink)
BORNGEARHEAD Base Member Join Date: May 2020 Location: WI Posts: 58 Drives: 2020 370z Passion Rep Power: 3359	Are 4.08 gears avail through Nissan/Nismo or only avail aftermarket? __________________ '20 370Z Sport - '15 Frontier - '04 350Z Roadster - '79 Datsun 620

12-07-2019, 02:13 PM	#54 (permalink)
Bswanny Base Member Join Date: Mar 2018 Location: New Mexico Posts: 135 Drives: 20 370Z Sport Rep Power: 7	Any one know the top speed of each gear in the manual 3.69 final drive? Trying to see where gear shifts occur of going to a 4.10

03-03-2020, 10:32 AM	#56 (permalink)
Dentt42 Base Member Join Date: Apr 2019 Location: Central Florida Posts: 80 Drives: 2012 G37 black 6spd Rep Power: 6	Now that the MT Nismos come with 3.9 from the factory, has anyone had more experience with them? I'm on the 3.62 ratio with factory VSLD, and having a tough time deciding if it would benefit me. Street car, 1/4 mile for the fun, and HPDE type of events NA for the foreseeable future, N20 (nitrous) if I start chasing ETs at the strip Daily now, but hopefully retired to weekend car by end of year Wavetrac diff for planned upgrade My driving makes MPG a somewhat moot point Thoughts, everyone?

12-12-2022, 09:17 PM	#60 (permalink)
SS_Firehawk Premium Member Join Date: Oct 2011 Location: Tampa Posts: 4,142 Drives: 13' Magma Red Nismo Rep Power: 7334	There are Nissan oem ring gears in 4.08. I'm still running mine and depending on what you plan on doing with them, they're a great option. I find more benefit a lot of the corners I find myself in. At times, I find where I need to shift up so I don't run into the rev limiter mid corner. If you ever do Road America, I think a 4.08 would work perfectly if your redline is at 8000. BORNGEARHEAD likes this. __________________ Old Car:GTM TSC'd 550whp / 410lbft tq @ 11.88PSI New Car: Under Construction

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