VHR + FD Gear Ratio upgrades - 3.9 and 4.08

ssqpolo · 04-28-2009, 06:07 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 · 04-29-2009, 11:22 PM

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....

javol · 08-05-2009, 10:46 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, 11:14 AM

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.

wstar · 08-05-2009, 11:22 AM

Oh and as far as upgrading the rear end ratio in the 7AT, aside from spacing out all the cash I'm throwing down, and having to consider whether I want to get rid of VLSD while I'm at it (perhaps the 1.5-way Carbonetic that Mike@DDM likes so much), the other thing holding me back is I'm not sure if it will make 1st gear too short. The 1st gear ratio on the 7AT is way out there compared to the 6MT. In stock form on the sports model, 1st gear ends at about 36mph @7500rpm.

My tire/wheel upgrades that are coming soon (moving to 295/30R18 in the rear) already drop that number a bit, and when I ran the numbers, the combined effect of the tire/wheel change and moving to 3.692 in the rear would put 1st gear topping out at more like 30mph @7500pm. 1st gear already ends so quickly that it makes timing the 1->2 upshift optimally challenging, so I'm worried this will make it insane. On the other hand a higher redline from the ECU stuff would offset this a little. We'll see what happens when I get to all this I guess.

ssqpolo · 04-30-2009, 01:34 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).

Z eliminator · 08-06-2009, 08:58 AM

I changed the diif on my 7 AT to a 4.08 gear set up. The rev matching in city driving takes some getting use to. It uses to turn 2100 at 100 km. Now it turns 2750 at 100.
Fuel consumption went from 7.8 up to 8.7 L / 100 km. I took it to the track and it ran a best of 13.201. Average pass was 13.32 to 13.43. The colder the moter the faster it goes.Going down the track i shifted at 7400 and the RPM only drops to 6300. I have to put in 5th. On the 13.201 pass i hit the limiter in 4th as i tried to make the pass in 3th
It ran at 102.8 mph in that pass. Mt best trap was a 107.9.
The only mod is a stillen G3 intake. Base line was 266 and 286 RWHP after the intake.
The next Z drag day is in Septmeber and it will have a stillen CBE. Berk cats, Stillen headers and the underdrive pully. It should run 12.8 on the 19 inch wheels. Its hard to hook the bridgestones. Best 60 ft 2.01 to 2.09.

wstar · 08-06-2009, 09:06 AM

Z Eliminator: How's the 1-2 shift with the 4.08? Given the slight input lag clicking the button, and how fast the car rips through first gear, I'm worried that a better gear ratio is going to make timing the 1-2 shift nearly impossible.

Minicobra1 · 08-06-2009, 10:27 AM

Quote:

Originally Posted by Z eliminator

I changed the diif on my 7 AT to a 4.08 gear set up. The rev matching in city driving takes some getting use to. It uses to turn 2100 at 100 km. Now it turns 2750 at 100.
Fuel consumption went from 7.8 up to 8.7 L / 100 km. I took it to the track and it ran a best of 13.201. Average pass was 13.32 to 13.43. The colder the moter the faster it goes.Going down the track i shifted at 7400 and the RPM only drops to 6300. I have to put in 5th. On the 13.201 pass i hit the limiter in 4th as i tried to make the pass in 3th
It ran at 102.8 mph in that pass. Mt best trap was a 107.9.
The only mod is a stillen G3 intake. Base line was 266 and 286 RWHP after the intake.
The next Z drag day is in Septmeber and it will have a stillen CBE. Berk cats, Stillen headers and the underdrive pully. It should run 12.8 on the 19 inch wheels. Its hard to hook the bridgestones. Best 60 ft 2.01 to 2.09.

Which model did you end up putting in, what was part#, cost, etc. Also, how is drivetrain noise now, is it much louder, or pretty much the same?

thanks!

javol · 08-21-2009, 12:50 PM

Quote:

Originally Posted by Z eliminator

I changed the diif on my 7 AT to a 4.08 gear set up.

Did you change the whole diff?

Putting on a 350Z (R200) diff with an upgraded 4.08 ring-pinion couple??

It seems this is the only way to move to 4.08 a 370 7AT.

At mynismo.com told me that 4.08 set (Ring & Pinion) for 350Z does not work in 370Z 7AT diff... (that is a R205).

Any other experiences or suggestions?

I'm a bit lost...

Thanks,

Gianni

javol · 09-21-2009, 08:28 PM

Quote:

Originally Posted by Z eliminator

I changed the diif on my 7 AT to a 4.08 gear set up.

What do you change exactly?

Do you install an aftermarket 350Z ring-pinion couple or what?

Thanks!

Z eliminator · 08-06-2009, 11:21 AM

The 1 to 2nd gear change is very quick. 2nd to 3rd is quick. It feels like your changing gears every 1 to 1.5 seconds.
It was built by a nissan mechanic. I bought it with 2000 km on it. I paid 1000.00 cdn for the whole diff. The only thing i did was i put royal purple gear lube in it. Im not sure what vlsd is in it.
There are no issues of hitting the rev limiter in first or second, lots of miliseconds to change gears. It very very fast. My 0 to 60 times based on the 8th mile time and traps is 4.4 seconds with a 2.01 60 ft time. It burns more gas. and it is in 7th gear at 58 to 60 km.

Solus · 08-13-2009, 12:25 PM

Does anyone know of any 4.08 or maybe higher gear sets or where one could order them? If we have the same diff as the 350's there has to be a few sets out there.

Supergoji · 08-13-2009, 02:12 PM

My Z32 comes with the 4.08 stock. people sell them very cheap on 300zxclub.com

javol · 08-13-2009, 03:23 PM

I live in Chile, no 370Z here yet, few 350Z, no Z-culture, help me US mates!!!

1) I'm going to change the final ratio of my imported (from USA) 7AT 370Z to 4.08, wich i read is "stock" on Nissan Frontier.

2) Change the whole diff is the only way to go with?

3) Is it not enough to buy an OEM Frontier pinion-ring couple?

4) If yes, anyone knows how many parts are necessary (any bolts?) and the serial # of each of them?

Thank you in advance!

08-05-2009, 11:22 AM	#5 (permalink)
wstar A True Z Fanatic Join Date: Mar 2009 Location: Houston, TX Posts: 4,024 Drives: too slow Rep Power: 3596	Oh and as far as upgrading the rear end ratio in the 7AT, aside from spacing out all the cash I'm throwing down, and having to consider whether I want to get rid of VLSD while I'm at it (perhaps the 1.5-way Carbonetic that Mike@DDM likes so much), the other thing holding me back is I'm not sure if it will make 1st gear too short. The 1st gear ratio on the 7AT is way out there compared to the 6MT. In stock form on the sports model, 1st gear ends at about 36mph @7500rpm. My tire/wheel upgrades that are coming soon (moving to 295/30R18 in the rear) already drop that number a bit, and when I ran the numbers, the combined effect of the tire/wheel change and moving to 3.692 in the rear would put 1st gear topping out at more like 30mph @7500pm. 1st gear already ends so quickly that it makes timing the 1->2 upshift optimally challenging, so I'm worried this will make it insane. On the other hand a higher redline from the ECU stuff would offset this a little. We'll see what happens when I get to all this I guess. __________________ 7AT Track Car! Journal thread / Car setup details

08-06-2009, 09:06 AM	#8 (permalink)
wstar A True Z Fanatic Join Date: Mar 2009 Location: Houston, TX Posts: 4,024 Drives: too slow Rep Power: 3596	Z Eliminator: How's the 1-2 shift with the 4.08? Given the slight input lag clicking the button, and how fast the car rips through first gear, I'm worried that a better gear ratio is going to make timing the 1-2 shift nearly impossible. __________________ 7AT Track Car! Journal thread / Car setup details

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04-28-2009, 06:07 PM	#1 (permalink)
ssqpolo Track Member Join Date: Jan 2009 Location: Florida Posts: 882 Drives: '12 Black Nismo Rep Power: 269	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, 01:34 AM	#6 (permalink)
ssqpolo Track Member Join Date: Jan 2009 Location: Florida Posts: 882 Drives: '12 Black Nismo Rep Power: 269	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).

08-06-2009, 08:58 AM	#7 (permalink)
Z eliminator A True Z Fanatic Join Date: Jul 2009 Location: Ontario Canada Posts: 1,660 Drives: 370 Z 7AT Sports Rep Power: 20	I changed the diif on my 7 AT to a 4.08 gear set up. The rev matching in city driving takes some getting use to. It uses to turn 2100 at 100 km. Now it turns 2750 at 100. Fuel consumption went from 7.8 up to 8.7 L / 100 km. I took it to the track and it ran a best of 13.201. Average pass was 13.32 to 13.43. The colder the moter the faster it goes.Going down the track i shifted at 7400 and the RPM only drops to 6300. I have to put in 5th. On the 13.201 pass i hit the limiter in 4th as i tried to make the pass in 3th It ran at 102.8 mph in that pass. Mt best trap was a 107.9. The only mod is a stillen G3 intake. Base line was 266 and 286 RWHP after the intake. The next Z drag day is in Septmeber and it will have a stillen CBE. Berk cats, Stillen headers and the underdrive pully. It should run 12.8 on the 19 inch wheels. Its hard to hook the bridgestones. Best 60 ft 2.01 to 2.09.

08-06-2009, 11:21 AM	#12 (permalink)
Z eliminator A True Z Fanatic Join Date: Jul 2009 Location: Ontario Canada Posts: 1,660 Drives: 370 Z 7AT Sports Rep Power: 20	The 1 to 2nd gear change is very quick. 2nd to 3rd is quick. It feels like your changing gears every 1 to 1.5 seconds. It was built by a nissan mechanic. I bought it with 2000 km on it. I paid 1000.00 cdn for the whole diff. The only thing i did was i put royal purple gear lube in it. Im not sure what vlsd is in it. There are no issues of hitting the rev limiter in first or second, lots of miliseconds to change gears. It very very fast. My 0 to 60 times based on the 8th mile time and traps is 4.4 seconds with a 2.01 60 ft time. It burns more gas. and it is in 7th gear at 58 to 60 km.

08-13-2009, 12:25 PM	#13 (permalink)
Solus Enthusiast Member Join Date: Apr 2009 Location: Jacksonville, NC Posts: 453 Drives: 2009 Nissan 370z Rep Power: 18	Does anyone know of any 4.08 or maybe higher gear sets or where one could order them? If we have the same diff as the 350's there has to be a few sets out there.

08-13-2009, 02:12 PM	#14 (permalink)
Supergoji Enthusiast Member Join Date: Dec 2008 Location: Westchester NY Age: 37 Posts: 311 Drives: Z32tt / Supra tt Rep Power: 258	My Z32 comes with the 4.08 stock. people sell them very cheap on 300zxclub.com

08-13-2009, 03:23 PM	#15 (permalink)
javol Base Member Join Date: Apr 2009 Location: Chile Posts: 20 Drives: 370Z 7AT Touring Rep Power: 18	I live in Chile, no 370Z here yet, few 350Z, no Z-culture, help me US mates!!! 1) I'm going to change the final ratio of my imported (from USA) 7AT 370Z to 4.08, wich i read is "stock" on Nissan Frontier. 2) Change the whole diff is the only way to go with? 3) Is it not enough to buy an OEM Frontier pinion-ring couple? 4) If yes, anyone knows how many parts are necessary (any bolts?) and the serial # of each of them? Thank you in advance!