VHR + FD Gear Ratio upgrades - 3.9 and 4.08

wstar · 08-05-2009, 12:22 PM

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.

Z eliminator · 08-06-2009, 09:58 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, 10:06 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, 11:27 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!

Z eliminator · 08-06-2009, 12:21 PM

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, 01:25 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, 03:12 PM

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

javol · 08-13-2009, 04:23 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!

The Arp · 08-14-2009, 02:37 AM

So, does anyone know where the syncro rev match gets its speed signal to match the engine speed? If it is from the tranny itself then changing the rear end ratio won't affect it right? The reason I ask is, I think changing the ratio on my 6 speed to 4.08 is next on my list since I really only drive my car for fun and the occasional errand. I auto-crossed it last weekend and the car is just a little weak coming out of the slower corners in second and this would be a very stealthy way to fix that. Now I just need to find a shop in the SFV to do the swap and get approval from my "boss".

wstar · 08-14-2009, 02:49 AM

Quote:

Originally Posted by The Arp

So, does anyone know where the syncro rev match gets its speed signal to match the engine speed? If it is from the tranny itself then changing the rear end ratio won't affect it right?

SRM is based solely on the engine RPMs and the gear ratios in the 6MT. Your rear diff ratio can't affect it. Changing out gears in the 6MT would though.

Solus · 08-14-2009, 08:44 AM

Quote:

Originally Posted by Supergoji

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

Does the z32 have that same r200 diff as well?

javol · 08-15-2009, 10:55 AM

Quote:

Originally Posted by KLRCADI

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

At mynismo.com i found this item:

4.083 Ring And Pinion - Z33 (part nº 38100-0C760)

Asking them if it fits 370Z the answer that it's NOT.

According to them 350Z use a R205 DIFF...

Heeeelpppp!!!!!

javol · 08-21-2009, 01:50 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

kannibul · 08-21-2009, 05:47 PM

Quote:

Originally Posted by wstar

Yeah that's a concern for me too. In the 7AT our rear end is even worse ratio than you 6MT guys (7AT is 3.357, 6MT is 3.692). However, at the speeds I like to cruise at on the highway (when possible), I don't want the revs going any higher in 7th than they are now. 7AT really could use an 8th gear (or just taller transmission gearing in 6 and 7 both) for us high-speed cruisers

Did you type that backwards on the ratio = transmissions part?

A 3.357 would give a lower RPM...

That, and I thought the rear on the 7AT's had a higher ratio...

Z1Performance · 08-22-2009, 04:49 PM

Quote:

Originally Posted by Supergoji

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

Z32 rears will not fit into the 350Z, 370Z, they are totally different

FWIW, lots of cars (not just Nissan's) use the R200 - however, there are many flavors of R200, and not all swap with one another

08-05-2009, 12:22 PM	#31 (permalink)
wstar A True Z Fanatic Join Date: Mar 2009 Location: Houston, TX Posts: 4,024 Drives: too slow Rep Power: 3594	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, 10:06 AM	#33 (permalink)
wstar A True Z Fanatic Join Date: Mar 2009 Location: Houston, TX Posts: 4,024 Drives: too slow Rep Power: 3594	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

08-14-2009, 02:37 AM	#39 (permalink)
The Arp Base Member Join Date: Jul 2009 Location: Simi Valley Posts: 38 Drives: 2009 370z white m6 Rep Power: 16	So, does anyone know where the syncro rev match gets its speed signal to match the engine speed? If it is from the tranny itself then changing the rear end ratio won't affect it right? The reason I ask is, I think changing the ratio on my 6 speed to 4.08 is next on my list since I really only drive my car for fun and the occasional errand. I auto-crossed it last weekend and the car is just a little weak coming out of the slower corners in second and this would be a very stealthy way to fix that. Now I just need to find a shop in the SFV to do the swap and get approval from my "boss". Last edited by The Arp; 08-14-2009 at 10:52 AM.

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08-06-2009, 09:58 AM	#32 (permalink)
Z eliminator A True Z Fanatic Join Date: Jul 2009 Location: Ontario Canada Posts: 1,659 Drives: 370 Z 7AT Sports Rep Power: 19	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, 12:21 PM	#35 (permalink)
Z eliminator A True Z Fanatic Join Date: Jul 2009 Location: Ontario Canada Posts: 1,659 Drives: 370 Z 7AT Sports Rep Power: 19	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, 01:25 PM	#36 (permalink)
Solus Enthusiast Member Join Date: Apr 2009 Location: Jacksonville, NC Posts: 453 Drives: 2009 Nissan 370z Rep Power: 16	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, 03:12 PM	#37 (permalink)
Supergoji Enthusiast Member Join Date: Dec 2008 Location: Westchester NY Age: 36 Posts: 311 Drives: Z32tt / Supra tt Rep Power: 256	My Z32 comes with the 4.08 stock. people sell them very cheap on 300zxclub.com

08-13-2009, 04:23 PM	#38 (permalink)
javol Base Member Join Date: Apr 2009 Location: Chile Posts: 20 Drives: 370Z 7AT Touring Rep Power: 16	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!