Just found this on everythingg35.com. Im not even sure if its for our year cars, but im guessing it is because it says g35s and 350z. Im not really to famiiar with gear ratios and what not, but i do know that changing them can help out big time.

Anybody whos more educated on this subject, can you please answer me one question. Im quoting this from the item description.
"These gears really begin to shine with the larger staggered tire setups prevelant in the Z/G world"

why would that be?

so what do yous think..good or no?

http://www.g35parts.com/9083/osc/pro...roducts_id=601

BTW what kind of gears do we have in the car now?

 

I don't know if the FD is still applicable. I know the FD swaps are still available for the 07 z's, but they retain the same gear ratios as the previous years.

The gen2 sedans use 3.69 gears, for both the automatic and 6mt's. The difference between the 3.69 and 3.92 gears is less than 6%. The shorter FD will help acceleration in any given gear, but the difference is so minor I doubt it would even be measurable by the clock. Not to mention that it would adversely affect gas mileage.

Another thing to consider is that in the first gens, many people(but not all) that performed FD swaps lost functioning cruise control.

 

thanks trey...i figured that you would be the person to give me the rite answer on this subject.

 

There have been swaps done into the new 07 pumpkins with aftermarket LSD's. Everything fits no worries.

I am not sure where you are getting your info on the rear diff ratios. It is pretty common knowledge that the automatics in the Z's and G's run a 3.23 rear ratio while the 6mt's run a 3.5 ratio. A lot of the FI guys swap the taller 3.2 ratio into their cars for better top end speed. The 3.9 swap is stictly for better bottom end performance and does take away from the top end of the cars speed.

 

I have not been aware of any FD swaps with the 07 sedans. I know that there have been a few 07 z's that have swapped diffs, but that's not a big deal because the ring/pinion and FD remained unchanged when the 07 z received the HR motor. What remains unclear as yet is if the ring/pinion in the 07 sedan can be swapped without issue. I imagine that it's not a problem, because some have changed from the 3.53's in the 6MT's to the 3.69's of the Frontiers in previous years, and I believe it's this same 3.69 Frontier FD that is now in the gen2 G35 and G37.

Read my post again. For the first gen g35's, you are correct. For the 2nd gen sedans and the new G37 coupe, the 5AT's and 6MT's share the same 3.69 FD.

BTW - the auto in the first gens come with a 3.35FD, not a 3.2.

Another note - the taller FD(the 3.3's) does not increase top-end acceleration. Taller gears will always negatively impact acceleration. If the gear ratios are the same, the car with a shorter final drive will always out-accelerate the one with the taller final drive given the same gear and starting rpm. That even applies up top, say at 6k rpms.

The forced induction guys go with the taller FD's for two reasons: traction and gear length. Because one cannot change the individual gear ratios, one can extend a gear by changing the FD or the tire size. With all that power down low, the forced induction guys have a problem with traction in the lower gears. And by lengthening the FD, that means they can stay in a given gear for longer. That is especially useful in the 1/4 mile. If a guy traps 115mph, then he's more than likely going to have to shift into 5th before the end of the run. With a 3.3FD, 4th will top out at a higher speed. And although the taller FD hurts acceleration, the difference in gearing is only about 5%, versus the 27% gearing difference between 4th and 5th.

 

going with a 3.3 from a 3.5 will theoretically increase top speed, but decrease acceleration, which is where I think g35_6gear is getting confused. A good way to test this is using a simulator such as gran turismo with a custom tranny. You can change individual gears and final drives and test the acceleration and top speed changes due to this. Its a very good way of really understanding the topic in depth

 

A taller gear will not be decrease to speed..it will do the opposite. Why do you think the salt flat racers use a lower # (taller) gear for higher top speed. They get more tire revolution for a given rpm with a taller gear and more top speed. This is why they need a push start because the gears are so tall.

 

Exactly my point. With the FI guys all the power is in the top end. By going to the taller gear you don't have to shift into 5th.....giving a higher mph.

With regard to the top end my point is that the taller gears can yield a higher top speed for a given rpm, I am not talking about acceleration up to that point.

Diffrentials are the same in the 07 z's as the older cars. I have done Z rear end swaps before when I had my 04 6mt sedan so I see no reason why the LSD or FD parts for the Z would not work in the sedan. It did before.

 

Agreed.

Sorry, I misunderstood your post.

I know that the diffs are internally the same, and the diff covers are different, but that's for the z. I have not seen any concrete information on the Diff/FD for the new sedans, so I honestly don't know. I assume that the swaps can still be performed, but it would suck for some one to spend 2k+ on a swap, based on my baseless affirmation, then have to give up.

 

You could always get a 07 350Z rear end from a wrecker, do the swap into that diff and then do an entire diff swap. That's what I did with a KAAZ in my old car when they came with an open differential. I kept it for awhile and then sold the whole thing on the forum and swapped in a complete coupe viscous LSD rear diff. It's all in the experimenting.

 

i think sharif on the z boards said that everything is the same.... might wana double check just to be sure, but he is a very reliable source.

 

That's where I saw the info too.

 

Yeah, I noticed that. That's where I saw that the diff cover had been changed.

 

All this concern over top speed!!! Unless you live in Montana, Bonneville, or are just plain stupid, where are you going to exploit the top end capabilities of a higher gear? I live in Houston, population 2 million, 4 million if you count the out lying areas. My top speed is 65mph. Give me 3.90's any day, F.I. or not....

DOMO <<< doin' the 3.90 gear dance on yo' face!!!

 

If you read the thread, you would understand that it gives you a higher top speed in EACH gear. This is benefitial to high HP cars usually with turbos since traction is a major concern, and the power band is usually shifted to the higher end. Put 3.9's on a high HP TT setup, and you'll be slower than with 3.3 gears because you won't be able to go WOT through 1st and 2nd gears. 3.3's would also give better gas mileage cruising on the fwy compared to the 3.9 setup for those concerned with $. Final drive gears are not for final top speed only, they have other advantages/disadvantages as well.