Well, I swapped my 5AT pumpkin out today for one from a 6MT with the stock VLSD. Of course the 5AT already had the VLSD, but what I was really after was the different final drive. The Auto comes stock with a 3.3xx FD ratio vs the 6MTs 3.5xx FD ratio. As my sig states, I already have a lot of NA mods and I have been wanting to do this swap for quite some time.

Install:
I did the swap in my garage with jack stands and a floor jack. It was a little tricky by myself as the complete pumpkin is pretty damn heavy ~70lbs. There are quite a few nuts and bolts to break loose, a couple speed sensors to unhook, and a hose that must be unhooked. Once everything is out you better be ready!! The pumpkin has to move forward then down and back to be pulled out. Just the opposite for reinstall. It went fairly smooth and took me about two hours total, no air tools or impact wrenches, just plain old hand tools.

Driving Impressions:
There is a noticable increase in acceleration through 3rd gear and it did exactly what I was looking for. When shifting from 1st to 2nd or 2nd to 3rd, the rpms always seemed to drop just a little too far. Well not anymore!! The car accelerates smoother, faster and the shifts feel the same way. I wanted to do this mod before a TC or VB upgrade just to see what would happen. I still think a mild VB upgrade would be a nice compliment but I do not feel as great a need now. With the 275 19" wheels, I had lost some acceleration and off the line punch. That is all back and just a little more. From a stop, putting the pedal to the floor roasts the tires, before I had some wheel spin, but it was not easily maintained as the tires would catch grip. When I get some 17" DRs it will be interesting to see how much better I run through the 1/4 mile. Unfortunately the local track is closed for the winter here in Iowa. I am pretty sure high 12s are where I will be. At higher speeds it is of course harder to tell a difference. There is not much of a difference in cruising RPMs and I expect to loose 1-2mpg on average once I stop hammering the pedal

In closing:
I would recommend this to any 5AT owner, even those with a SC. I initially wasn't sure if this would be a good thing with a SC but I now feel that it would be a great match as it gets the car into the sweet rpm range faster and keeps it there between shifts. Many have wondered about the 3.9 FD from 350EVO and to tell you the truth, I think it would work quite nicely if you want your Z to be more of a muscle car that rules the streets, strip and the track. The only issue I can see is that gas mileage would be much worse than stock making it a little overboard for a daily driver.

 

Now all I need is for Doug at Crawford to post some results of his latest adventure so I can start planning my next trip to Nashville.

 

glad to hear you like it. Before the fd, i didn't really get any wheelspin while flooring it from a standstill (without power braking), but after i had the FD installed, the tires would break loose. This was on 17's. After i had my 19's put on, the car still felt faster than when i was on 17's without the FD.

 

how much did this cost you?

 

The 3.5 lsd is one of the things being done to my car this week and next . Glad to hear it helps .

 

It's not a good thing to run the oem viscous limited slip with a SC because more power and the stickier tires they are bound to have will power right past the viscous fluids ability to do it's job. The only thing standing in the way of being a open diff is that viscous snots ability to withstand torque, add more power and stickier tires and those two things will shear the fluid and win, meaning no slip limiting. Got FI, get clutch type LSD.

 

can you get a clutch type LSD for a AT?

How much are we talking?

 

Once you use the 6MT Ring & Pinion you can use any LSD on your Automatic...

Here is a link to the parts you will need for the 5MT FD to 6MT FD swap...

6MT Final Drive Gear Package

Once you have this you can instal a factory VLSD, or even a NISMO LSD.

One can install the 350EVO FD Gear which we do have instock as well, but with an AT you would most likely NEED the Stillen Valve Body upgrage...

We do offer that as well...

 

this is a must on my list of things to do.

 

OK I am still learning here but what the diffrence between the NISMO Limited Slip Differential and the 6MT Final Drive Gear
?

 

your car has something called vLSD, which is Nissan's OEM limited slip differential... basically, it transfers torque between your two rear wheels to help minimize or eliminate wheel slip under acceleration... the Nismo LSD is just a beefier version (better at reducing wheel slip than the stock unit)

The 6MT final drive is a different set of gears... i.e. gears of different ratio which translate engine RPM into actual wheel movement... i can't remember the exact ratios off the top of my head, but the 6MT final drive is composed of shorter gears than the 5MT set. So for a given engine RPM in a given gear, the 6MT will be going slower... but that also allows you to accelerate faster, as shorter gears take less work to spool them up. It's also why you see a number of people swapping the 6MT gear set with the 350Evo set which is much shorter. Increasing your ability to accelerate isn't just about horsepower and torque, it's about how you use it and how you translate it to the ground.

 

so would swaping a 5AT with the 350Evo be better than swapping the 5AT with the 6MT drive? or could you even do that.

Hey thanks for the good answer

 

ok did a search and look like the big question is 3.5 or 3.9

 

i don't see why it would be a problem, but there are quite a few more knowledgable people on the board than I

it depends on how much you like your top speed and if you do a lot of highway driving what RPMs you like to cruise at.

I was originally considering the Evo set pretty hard, but I do a LOT of highway driving (put about 7000 miles on the Z in the last 4 months)... and I cruise at about 85-90 which puts me around 3200rpm in 6th... i don't know how much i'd like to bump that up to 4000 or so with the evo set, but if I can stop doing all the highway traffic, I'm definitely going in for the swap... just watch zillinois' vid of his acceleration with the tilton & 3.9fd and you'll be in lust (well, at least I was!)

 

3.5 the stock 6MT final drive gear will be more then enough for the 5AT car...

If you put it in your 5AT your car wont go much faster then a 120... would be good for a 1/4 MIle car.. thats it

 

And the link you posted is the 3.5

 

yep, looks like it

 

The nice thing about having the 6MT pumpkin is that I could now get the Nismo LSD and have it dropped in as Jason mentioned. Because of some issues there was talk about a 5AT specific version if I remember right, but I haven't looked lately to know if it is available yet.

I had to go out of town today for an unexpected trip and so I monitored my gas mileage very closely. I did not loose anything on the highway!! In fact I think I may have some slight gains. I am not totally suprised at this as I knew it could happen, but I was prepared for a loss. Since I have cams and also 19" wheels, I believe engine load and efficiency are making this happen. At cruising speed I am just into the cams and since this FD relieves some stress on the drivetrain I can actually tell a difference in the sound of the exhaust note from having the TB closed more. Another reason to love this mod. I also had more time today in 4th and 5th gear which I was very impressed with. Driving in 4th gear is much better now and I think I will end up using it more in town than I used to which may reduce in town gas mileage as well. Fifth gear is also better and at cruising speeds I am just into the cams so passing acceleration is there and I would only need to downshift if in a real hurry.

 

You mean with 350EVO's FD the car won't go much faster than 120 right?

 

OK so the NISMO Limited Slip Differential and 6MT final drive gear would be a good set up for the 5AT? anything else needed when placing a order for this?