VHR + FD Gear Ratio upgrades - 3.9 and 4.08

shabarivas · 04-20-2009, 05:56 PM

Quote:

Originally Posted by RCZ

Roughly 80mph=3100rpm in 6th.

Thats w/ 4.08? I dont think so... should be close to 4k no?

wstar · 04-20-2009, 06:37 PM

Quote:

Originally Posted by shabarivas

Thats w/ 4.08? I dont think so... should be close to 4k no?

I think he meant stock rear end on 6MT (3.692)

ssqpolo · 04-20-2009, 11:09 PM

correct. i went driving today. i was around 3200 at 85 in my 6MT. so i guess with a 4.08 it would be like 3700-3800?

Minicobra1 · 04-21-2009, 12:45 AM

what's the average price of a rear diff swap out??

I think this would be a great mod, the 370z is a little sluggish exiting a sharp turn in second gear, this would help put it more into the powerband.

My only concern would be drivetrain wine/noise. I've done this swap before on my last few mustangs 4:10's and the drivetrain noise went up considerably. Maybe the gears weren't set right.

Skorch · 04-21-2009, 01:04 PM

Has it been confirmed that the final drive gears for the 350Z will fit the 370Z? If so, how difficult is it to install them?

LiquidZ · 04-21-2009, 01:35 PM

Quote:

Originally Posted by Minicobra1

what's the average price of a rear diff swap out??

I think this would be a great mod, the 370z is a little sluggish exiting a sharp turn in second gear, this would help put it more into the powerband.

My only concern would be drivetrain wine/noise. I've done this swap before on my last few mustangs 4:10's and the drivetrain noise went up considerably. Maybe the gears weren't set right.

I can probably answer this question for you. Were they Motive gears (or other), or Ford Racing Performance Parts gears?

KLRCADI · 04-21-2009, 11:48 PM

Price depends.

4.08's are a nissan part ( ring gear from a nissan frontier ) +/- $400
3.9's are aftermarket ( Central 20 ) +/- $600

Install requires a few OEM parts (Pinion bolt, crush sleeve, some seals,etc)

All in, installed probably about a grand. Considering it's less then some exhausts, it's a no brainer to me.

And yes, this is the same R200 diff in the 350z, G35, G37 ( and about a dozen other Nissan cars/Trucks)

Pete

ssqpolo · 04-22-2009, 12:37 AM

sweeeeet. this will be an awesome mod for us

Diversion · 04-28-2009, 07:02 PM

I'd definately consider this mod for people who aren't commuting in their Zs to work/school/wherever 5 days a week. Good for the weekend warrior type where gas mileage isn't so important. I'll consider this mod after I find a suitable daily driver!

ssqpolo · 04-28-2009, 07:07 PM

had a chance to ride in my buddies 350 with the 4.08 swap from Z1. all i can say is wow!! what a diffference. its like u shift down a gear...2nd pulls like first, as does 4th pulls like 3rd. it makes the car soooooo rev happy. it's a lot of fun. the only downside was that it made some noise. this seemed to be a problem with a couple other ppl. maybe becuase it had not been broken in, but i will ask him to update after 1k miles. he bought the stage 2 (or whatever) which came with all new bushings, etc. so it was basically a brandddd new rear end. cool mod. some1 should do it to the 370

wstar · 04-30-2009, 12:22 AM

Quote:

Originally Posted by ssqpolo

some1 should do it to the 370

You?

I'm starting to really think about just moving mine up to the 6MT's rear end (3.692 instead of 3.357 that came with my 7AT). I need to go run the numbers again and think about high-speed RPMs more though (that, and wait for a programmer like UpRev that can tell the ECU about it too).

Edit:

7th gear on a stock 7AT setup with stock Sport wheels/tires is approximately 32.78 revs/mph. Swapping in the 6MT's rear end would put it at about 36.04 revs/mph. This is what the revs would look like with the two options, cruising in 7th on a very long track:

mph | rpm | rpm
100 | 3278 | 3604
110 | 3606 | 3964
120 | 3934 | 4325
130 | 4261 | 4685
140 | 4589 | 5046
150 | 4917 | 5406

In the lower 100's it's not too bad a difference. Even at 150mph it's only 500rpm. Hmmmm....

ssqpolo · 04-30-2009, 02:34 AM

me. nah. i drive wayyyyyyyyyy too much on highways. im not really racing anyway. but u should look into it. that would be a nice swap (the AT to MT).

Unicorn_blood · 05-15-2009, 01:27 PM

Quote:

Originally Posted by KLRCADI

And yes, this is the same R200 diff in the 350z, G35, G37 ( and about a dozen other Nissan cars/Trucks)
Pete

Pete, I got a 350Z with 4.08s on it... so if I had a 370Z, I could take it to a shop and swap pumpkins?

This sounds like good news to me. My next question like the OP has asked...

How does changing to a lighter flywheel (like JWT) affect Synchro Rev Match shifting? Will it over compensate the rev? Or will it rev match instantly?

javol · 08-05-2009, 11:46 AM

Quote:

Originally Posted by wstar

You?

I'm starting to really think about just moving mine up to the 6MT's rear end (3.692 instead of 3.357 that came with my 7AT). I need to go run the numbers again and think about high-speed RPMs more though (that, and wait for a programmer like UpRev that can tell the ECU about it too)....

Why do you have to "wait for a programmer like UpRev that can tell the ECU about it too?"

Maybe i'm wrong but...

I do not see the reason to advise the ECU.

If you call a gear downshifting, ECU-tranny will give you it anyway, just checking the RPM, not speed...

Or I'm wrong?

Anyone has experience with changing ratio in AT (infiniti, 350Z etc)?

Bye!

wstar · 08-05-2009, 12:14 PM

Quote:

Originally Posted by javol

Why do you have to "wait for a programmer like UpRev that can tell the ECU about it too?"

Maybe i'm wrong but...

I do not see the reason to advise the ECU.

If you call a gear downshifting, ECU-tranny will give you it anyway, just checking the RPM, not speed...

Or I'm wrong?

Anyone has experience with changing ratio in AT (infiniti, 350Z etc)?

Bye!

I meant so the speedo will be correct.

04-21-2009, 12:45 AM	#19 (permalink)
Minicobra1 A True Z Fanatic Join Date: Nov 2008 Location: Orange County, CA. Posts: 1,205 Drives: 370Z Tour, Spt, 6mt Rep Power: 644	what's the average price of a rear diff swap out?? I think this would be a great mod, the 370z is a little sluggish exiting a sharp turn in second gear, this would help put it more into the powerband. My only concern would be drivetrain wine/noise. I've done this swap before on my last few mustangs 4:10's and the drivetrain noise went up considerably. Maybe the gears weren't set right. __________________ 370z Tour\| Spt Pack\|Navi\|BERK CBE\|Berk HFC's\| Eibach Springs\| Hotchkis Sway Bars\|SPC Camber Arms\|15mm Ichiba Wheel Spacers\| 19"Factory Nismo Wheels-Matt Black\|Stop Tech Rotors\|TWM Shifter\|3M Tint\|Black Fangs\|Black Rear Valance\|JDM Fog Light\| MY BAND-www.myspace.com/petroleum

04-21-2009, 01:04 PM	#20 (permalink)
Skorch Enthusiast Member Join Date: Feb 2009 Location: Phoenix, AZ Posts: 469 Drives: 2012 370Z Rep Power: 540	Has it been confirmed that the final drive gears for the 350Z will fit the 370Z? If so, how difficult is it to install them? __________________ '12 370Z + Sport \| Stillen Gen3 Intakes \| Stillen UD Pulley \| Motordyne M370 \| FI Exhaust \| FI HFCs \| 4.08 Gears \| Uprev tuned

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04-20-2009, 11:09 PM	#18 (permalink)
ssqpolo Track Member Join Date: Jan 2009 Location: Florida Posts: 882 Drives: '12 Black Nismo Rep Power: 267	correct. i went driving today. i was around 3200 at 85 in my 6MT. so i guess with a 4.08 it would be like 3700-3800?

04-21-2009, 11:48 PM	#22 (permalink)
KLRCADI Base Member Join Date: Apr 2009 Location: Toronto Posts: 11 Drives: 2005 CTS-V Rep Power: 16	Price depends. 4.08's are a nissan part ( ring gear from a nissan frontier ) +/- $400 3.9's are aftermarket ( Central 20 ) +/- $600 Install requires a few OEM parts (Pinion bolt, crush sleeve, some seals,etc) All in, installed probably about a grand. Considering it's less then some exhausts, it's a no brainer to me. And yes, this is the same R200 diff in the 350z, G35, G37 ( and about a dozen other Nissan cars/Trucks) Pete

04-22-2009, 12:37 AM	#23 (permalink)
ssqpolo Track Member Join Date: Jan 2009 Location: Florida Posts: 882 Drives: '12 Black Nismo Rep Power: 267	sweeeeet. this will be an awesome mod for us

04-28-2009, 07:02 PM	#24 (permalink)
Diversion Enthusiast Member Join Date: Apr 2009 Location: Jacksonville, Florida Posts: 393 Drives: 09 370Z Silver/Persi Rep Power: 284	I'd definately consider this mod for people who aren't commuting in their Zs to work/school/wherever 5 days a week. Good for the weekend warrior type where gas mileage isn't so important. I'll consider this mod after I find a suitable daily driver!

04-28-2009, 07:07 PM	#25 (permalink)
ssqpolo Track Member Join Date: Jan 2009 Location: Florida Posts: 882 Drives: '12 Black Nismo Rep Power: 267	had a chance to ride in my buddies 350 with the 4.08 swap from Z1. all i can say is wow!! what a diffference. its like u shift down a gear...2nd pulls like first, as does 4th pulls like 3rd. it makes the car soooooo rev happy. it's a lot of fun. the only downside was that it made some noise. this seemed to be a problem with a couple other ppl. maybe becuase it had not been broken in, but i will ask him to update after 1k miles. he bought the stage 2 (or whatever) which came with all new bushings, etc. so it was basically a brandddd new rear end. cool mod. some1 should do it to the 370

04-30-2009, 02:34 AM	#27 (permalink)
ssqpolo Track Member Join Date: Jan 2009 Location: Florida Posts: 882 Drives: '12 Black Nismo Rep Power: 267	me. nah. i drive wayyyyyyyyyy too much on highways. im not really racing anyway. but u should look into it. that would be a nice swap (the AT to MT).