7at 4.08 build
 

OK, so here we go. I am going to upgrade my 7AT gears from nothing to something. This is my second Z (1990 TT 300 PW), and my first with an automatic transmission. I love the car, but something is missing on the bottom end. I only shift with the paddles, so I still get to shift gears at my command, but I rarely get out of 5th gear. This is not a DD, so I'm not worried about gas mileage...

First, this is a pricey mod. So far, here is what I've bought.

-6speed open diff - $500
-Quaife Diff -$1,100
-4.08 gears and rebuild kit - $800
-Whiteline Bushings - $100
-Install - $900
-Uprev tune to turn off wheel speed sensor code- $950


I found a local shop that will rebuild the manual diff, then swap out my base open diff. I will post a log of how the build progresses.

The Quaife should arrive tomorrow and the gears later this week. I have the rebuild scheduled for 2/6. The hope is that I have everything done and back in the car by late February.

This is very helpful to me.. Subd

Also just bought the automatic companion flange, part number 38210-EC020. Dealer says the manual and automatic have the same companion flange, but I've read other folks on here saying they are different. I can always return it if I don't need it...

Cool man keep me posted

[attach]Attachment 99829[/attach]

Nice, was looking to do something similar. Hopefully it turns out great. Subd

Update: The shop had to order some extra shims to get the diff and gears into spec. Here is a before vid, not WOT, going through the gears. She is long legged and takes time to get through 4th. Although, she is getting to 60 in about 5 seconds...

https://www.youtube.com/watch?v=PrUlm6SANkY

[https://www.youtube.com/watch?v=PrUlm6SANkY][/YOUTUBE]

Fixed for you.

I'm getting 4.08 and Quaife fr my auto as well. How do you like it? A worthwhile mod? Did you do whiteline bushings as well? Notice any whine?

I bought a used open diff out of a manual car and have a shop doing the work. Right now, they are having a problem with the shims. It may be a couple of more weeks before I get the diffs swapped.

Regarding the Whiteline bushings. I am on the fence about them. I bought a set from Z1, but I am considering sticking with a new set of OEM bushings because of the whine other folks have talked about on here...

Got the diff and gears installed yesterday and it took the shop about 5 hours. The bushing on the top of the diff was a beast. That alone took an hour.

First impression is DAMN! She pulls in every gear. For the first time ever, I am now using 7th gear on the freeway. 80 mph is about 3,200 rpm.

One mod begats another mod. LOL!

The ECU doesn't like the gears, so the wheel sensors are throwing codes. I called Uprev and they indicated the codes can be removed in a tune. I scheduled an appointment with them in Austin on May 1 for a tune and dyno.

Regarding the Whiteline bushings and noise, it sounds sort of like tires on a 4 wheel drive. It doesn't bother me. But it is there and it's noticeable.

Love the car now, and she will grab a third gear scratch on demand. That is badass!

Did you lose cruise control?

Must pull like crazy,but Geeez I have a stock rear and a 7AT and first gear is already pretty low and have to shift to second before I even get across the intersection.You proably could start in Second!

I'm going to do the exact same thing. Looking for a MT open diff right now. Let me know if you run across one!

Yes, I lost cruise control. I did the gas pedal reset before moving the car after the install. What I didn't do was turn cruise on and then back off before moving. That may be the difference.

Believe it or not, first gear is still very manageable. First to second gear pops hard, and second to third will lay down rubber. The biggest difference is 5th, 6th and 7th. The car skips through these gears and begs for more. Highway downshifts are a beast!

Attachment 103183

Here is pic of my mpg in 7th gear headed to Austin for an uprev tune.

24 mpg is ok by me.

I've got a 7at open diff 370z, gonna get an LSD so I'm looking at these gearings at the same time.. The only thing is, I'm at 479hp to the wheels with a Stillen supercharger. Should I bother going down in gearing if I'm FI?

OH **** this thread was a year ago not today xD

People will tell you no. Typically the guys who go FI want the AT gearing because it means more top end speed and some other benefits im not aware of probably.

OH **** that post was may 2016 not today xD.

What did you do?!
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