7AT 4.08 gear swap review
 

I just had the 4.08 gears installed in my 7AT 2011 Z a few days ago. Seb at Specialty Z did the install and did a great job. I had a diff sent directly to their shop so it was all ready and they just had to do a pumpkin swap when I brought my car in. That is definitely the way to do it.

So with the new gears, the engine revs much quicker and smoother. There used to be a lag and sort bogged down revving int he low RPMs until you hit the range where there's actually power. Now the car is always in or very close to that rm range so it's always ready to go. Freeway driving is much nicer now, when I want to accelerate or pass, it just happens, no more laggy revving to the 3k range. Another bonus is that the engine sounds smoother when cruising since I am in the upper 2k to 3k rpm range. I have FI resonated HFCs and CBE and there was a lot more noise when cruising before in the low RPMs. I used to put it in M to raise the RPMs sometimes for the quieter ride. Of all my mods, this is the one I feel the most after install. I had HFCs and CBE installed with a tune all at the same time and the difference in driving feel and fun was less than this.

No review would be complete without stating the negatives as well. Like everyone else has noted, cruise control no longer works (see update below, it is now working) but i rarely ever use that anyway. I'm also losing maybe 2-3 mpg in freeway driving.

A note to those with 2011 and newer models. Mine was the first one newer than 2010 that Seb installed the gears in and I had the Service Engine Soon light come on. The code was p0500 which is Speen Sensor A. Seb chekced I tout and the problem si that there is some kind of miscommunication between the sensor and the ECU. Since theya r enot getting the same reading, it si throwing the light. HOWEVER, this isn't really a problem because it doesn't affect or damage anything. Also, my speedo still works fine and gives me about the same reading as my nav for my speed. Seb can program the ecu to get rid of the light so it's no biggie since it doesn't really affect anything. If I get more info on it form him, I will update this post.

UPDATE:
My cruise control is now working. I guess whatever it was Seb did to fix my Service Engine Soon light also gave me back my cruise control. I tested it to confirm it didn't work right after I had the gears installed. I tried it again tonight for the hell of it and was surprised to find the cruise control was now working. I even turned it off and set it a second time to make sure it wasn't a fluke.

Another UPDATE
I drove from Los Angeles to San Francisco and back this past weekend. I was mostly cruising around 80 and got about 23 or 23.5 mpg for the trip.

nice :tup: I am looking to do the same in the future.

Do you need a 6MT pumpkin to do the swap? Did you find the pumpkin yourself?

Yeah, you need a MT pumpkin with vlsd if you have a sport. Yeah, Seb can get the gears but not the pumpkin. I found mine on ebay from a '08 350z.

First to second must be so fast for you when you launch! It's really fast for me lol.

The 3.692 swap into the 7AT is geared higher than the 4.08 in a manual, minus 5th gear, and you're 10% above that. It'd be cool to compare the two. Do you have any videos? I love the 3.692 in the 7AT. Much better gearing!

No videos, just had the install done Friday.

How much did he charge to do that if I may ask. PM me if you don't want to say it private. Thanks!

Subd.....

is the CEL still on , or can it be recailbrated not to come on. Inspection issues ? No?

Seb turned the light off after confirming it wasn't a real problem and programmed the ECU to not have the light come back on for that reason.

updated my review regarding cruise control for anyone sub'd and interested

just talked to Seb, going to go there tomrw and see if he can fix my cruise control problem too. Will update you all on what happens.

Cool, hope it works out for you too.

[QUOTE/]The 3.692 swap into the 7AT is geared higher than the 4.08 in a manual, minus 5th gear, and you're 10% above that. It'd be cool to compare the two. Do you have any videos? I love the 3.692 in the 7AT. Much better gearing![/QUOTE]

Do you need to find a used 3.692 gear or can you buy new? I also have the 7AT. I am more interested in the 3.692 than the 4.08 swap. Does it need the same pumpkin from a MT?

Does the 3.692 also cause cruise control to not work?

Thanks.

If you want the 3.692 gears from a manual, then you will need a manual pumpkin 350z ones work just the same as 370s). I am not sure if you can find them new. You'd have to ask Nissan. Everyone gets them used. If you're not swapping out gears then it'll probably be a straight pumpkin swap. As for cruise control, we got mine to work even with the 4.08 gears so I can't imagine it would be a problem having it work with 3.692.

So if I get a 370z MT pumpkin, it already has the 3.692 gear, I can just swamp pumpkins?

Wait, if you already have 3.692 gears, what are you swapping to? I thought you said you didn't want to do 4.08. I took it as you had an auto with 3.6 and wanted to swap to the 3.6 of a manual.

I need to check my notes. I thought the 7 AT had 3.3 rear end gear.

I have the 7 AT. According to my notes the rear end gear 3.357

I want to swap to 3.692 vs. 4.08.

Yes, I believe so. Do you have the VLSD? If you swap in the MT VLSD pumpkin, that's all you need to do. Not sure if VLSD or open diff. is a factor though. The pumpkin I have is a VLSD MT one that had a quaife diff. in it. No need to go to 4.08 FD gear.

sorry, read it wrong. Thought you said you already had a mt. Yes, the pumpkins will just swap.

If your car has vlsd then you need a manual with vlsd. If not, then no.

No VSLD in the base coupe. I have been looking at the caronetics VSLD. I should do it all at once if I pull the trigger on the 3.692 gear.

Well, if you're just swapping pumpkins, you can id without an LSD. They're not opening it up. If you're changing gears though, then you can save a lot of labor costs y installing an after market diff at the same time if you plan to go that route. I don't plan to so I didn't. However, if I do decide to, I will regret not doing it at the same time I had the 408 done.

it doesn't matter if you install the vlsd or open carrier if doing a pumpkin swap, the 370z stubs all have the same flange for the side axles so if you swap the whole pumpkin and stubs together it will fit. only diff you can't put in is the g35/g37 sedan as the driveshaft only has 3 bolts. also remember if you get a 350z or g35 differential you should change out for 370z stubs because the abs rings have different numbers of teeth between the two generations.

hod did it go? Did you get it worked out?

this guy knows his stuff lol

It was actually really strange. It worked the first time I tried it when I left his shop, then after I turned it off and back on to try it again, no luck. So it didn't fix the cruise on my car.

sorry to hear that. I tried mine twice and it was fine, but I will try it again the next time I am cruising on the highway to see if it is still working.

Guys, I drive a 7AT (2010 Roadster) and I want to swap to 4:08. Is this the pumpkin I require? New 03 04 05 06 07 Nissan 350Z 09 10 370Z Differential Case 38410 2C500 | eBay

Please advise and thanks in advance!

That's the carrier, not the pumpkin, which in most axle assembles is all you need to change, but I guess Nissan decided to use different housings (pumpkins) for some reason http://www.gixxer.com/forums/images/.../confused1.gif Still stying to get a handle on the Z platform myself

Ooh! I just saw the word "case"....darn. Anyone know where I can find one please?

You need something like this, but with the vLSD if your car has that or you can swap out for a quaife. But this is an example of the whole 'pumpkin'. Just check ebay for one that fits what you need.

03 08 350Z 350 Z Coupe Open 3 5 Differential Diff Z33 | eBay

I don't think mine came with VSLD. Anyways to verify this (I bought mine used)? Will any Quaife fit (presuming made for 370z)? Any particular requirements?

well if you want to go 4.08 don't use the automatic diff and the 350 and 370 diffs are the same p/n's. I would say figure out whether you have a vlsd or not and buy the manual diff for the stubs that you have, because if you do use a 350z case you will need to reuse your stubs because the abs tooth wheels are different.

so here is a scenario for you:

If you're buying a 350z manual pumpkin, and your 370 pumpkin doesn't have the vlsd-->buy a manual base quafie unit, 4.08 gears and install parts, and reuse your 370z side flanges

If your buying a 350z manual pumpkin, and your 370 pumpkin does have the vlsd--> buy a manual quaife unit for the vlsd(or the base quaife and the extra base side flange), 4.08 gears and install parts, and reuse your 370z side flanges(or replace the long one with the spare short one if buying the base model quaife)

If your buying a 370z manual pumpkin, figure out what factory diff it has and buy the appropriate quaife for that diff, 4.08 gears and install parts, and bolt it on.

If you buy a diff from a g35 or g37 sedan (possibly x coupe also) you will need to swap the front driveshaft flanges on the diffs when you install the gears because those cars have a 3 bolt flange instead of the 4 bolt.