I'm looking to change out my final gear. I herd I can expect to pay anywhere from 300-600$ on installation Plus the gear (~1300$) and any other small parts that may be needed. Not to mention I'll probably be without my G for 2 days (thats if necessary parts are redily available).

See here.
http://www.grubbsperformance.com/Mer...oupePowertrain
And here.
http://www.350z-tech.com/zwiki/Final_Drive_%28FAQ%29

Has anyone gone this route on your G? I saw a thread on a Z forum about it but I haven't seen much here (doesn't seem to be too popular over there either).

What are some opinions you guys/gals have? What about the Speedometer and odometer, can they be adjusted for the ~10% change in gearing?

Also how about the finned Differential cover, is that recommended?

 

I’m in the same boat trying to decide on this mod, I know it will make a big difference in performance however there is not a ton information about it.

Recently I came real close to having a local shop perform the install for $300, but they backed out because they were unsure they would have all the necessary parts for the install (even though I was supplying the gear and the install kit). Basically they called their Infiniti parts guy and were told that there are several different setups so until you get the car apart you will not know which setup you have and which specific parts you will need. The shop owner explained that it would put us both in a bad position if my car was on the rack for several days trying to get the rights parts, because it is my only car.

Also I talked to one of the head techs at the Nissan dealership, who by the way has been modifying cars for over 20 years, and he recommended not changing out the gears. He did not really specify why, just said that I would run into a lot of problems. He also recommended that if I’m looking to get better acceleration to just get a lighten flywheel, he has a 13lb flywheel in his Z and says it will make a big difference.

So at this point I’m trying to decide between the ACT prolite clutch/flywheel combo, or trying to find a way to get the 3.91 gear installed.

Sorry for the rambling but that’s the situation I’m in.

 

Everyone skip's over the 3.7 gear set... IMHO its my favorite...

You get the shorter gears, better acceleration, still have some traction accelerating and doesnt lower your top speed as much....

 

Here's a writeup I did before when I did my swap.

 

helldorado - great write up!

 

Hellorado. Very, very, VERY nice write up. Thanks so much for detailing everything out.

If you ever find out that the TCM is indeed programmable, that would be great for us AT guys. Maybe the shift logic can be altered alot with an up in line pressure?

 

So You enjoyed your experiment with your AT?
Any regrets doing it? I didn't read the thread to the end.

 

That's what I have been considering... pricing please...

 

Just be careful on the loooooong trips.

 

No support for the TCM programming yet. I heard rumors that UpRev was looking into it, but that's it. Nothing concrete and no way to adjust it right now.

No regrets at all.

 

So that just leaves out the Speedometer and odometer adjustment. Is it possible to adjust those two items to match the new gear ratios?

 

the quest for this has been going on for quite some time... seems as though no one is able to accommodate.

 

Update….

Well I went by the Nissan dealership today and this time spoke with their head tech. After talking to him for a while I found out that this guy used to own a performance shop and has built all types of Nissan engines. He told me that he has installed several gears on Z’s and said that it is hands down the best bang for buck. He mentioned that the acceleration gains are similar to adding a supercharger, but not that great of course.

Anyway I plan on having my 3.91 final drive installed sometime in early April so I can report back once installed.

After hearing this guy talk about the gear swap I really feel like this is the best mod our cars if you are going to stay NA.

 

There is no reason to adjust. They're unaffacted by the swap.

 

For an NA 5AT there won't be much difference in terms of 1/4 mile acceleration. The stock gearing is already pretty optimal unless you plan on doing some wild NA mods like cams. The 3.54 swap is a waste and actually hurts 1/4 mile performance. I've tested it and I was actually slower with a 3.55 gear. Just because the gears are deeper doesn't necessarily mean you'll be quicker. It will no doubt feel a lot quicker, but the numbers most likely will not reflect it. 350Z owners are in agreement that deeper gears don't do much for 1/4 mile acceleration. On a road course, they can help depending on the type of course.