WAIT FOR THE 3.90.unless you really want a grocery getter.
the 3.54 is stock on all280zs.and is no good for acceleration.

 

Well I am going to be running a 3.54 in my car, upgrading from a 3.36. I can't really answer your question yet, because my car doesn't have the swap yet. There is a 10% difference in ratios, so its my estimation that you will definately be able to feel the difference.

I am upgrading from an L24 to a warmed over L28turbo engine at the same time as the diff swap, so it will be hard to compare.

 

Hmmm... my normally aspirated 3:54 geared grocery getting does 13.9 in the 1/4 and tops out at 140.


John Coffey
johnc@betamotorsports.com

 

Definatly go for the 3.9. It is quick and has a good cruising rpm if you have a 5 speed

 

The transmission is an early Type B 4 speed. FYI... my car is built to the limits of SCCA Solo2 B Street Prepared rules. Its not really a street car anymore.


John Coffey
johnc@betamotorsports.com

 

And just for everyone out there in Zdriver-land that might not know-------John's 240Z is not only a beuatiful car, but one extremely fast Z..........I had the priveledge at last yrs MSA autocross to ride shotgun on one of John's passes through the course----------WOW is about all that I can say about his extremely fast and agile 240Z----------It was all that I could do to stay in my seat with the 5-point belts--------John's beast handled like it was on rails and excellerated better than any Z I have either ridden in or drove...........Nice car John

 

Thanks for the compliment. Unfortunately I won't be at this year's MSA event 'cuz I got a family thing going on in Texas that weekend. But, my car might be there with Erik Messley driving if I can talk him into it.

FYI... it will be faster too. New stuff!


John Coffey
johnc@betamotorsports.com

 

Rusty,

For the 4 speed tranny you are using, the 3.54 diff should work smoothly, if it is a stock engine. However, if you deside to step up to the 5 speed I recommand the 3.90. The concern is in the last gear, with the 4 speed and a 3.90 you may be a little high on the RPM's in 4 gear. So if you plan to travel distances, gas may start to be a issue. By switching out the tranny to a 5 speed you will have the overdrive to lower the RPM's. As well as the gearing. It makes sense to determine your use.

The engine is another whole issue. What engine, is it a Torque driven L28 w/ a e31 head?

 

Any rearend upgrade is worth it just remember you will need the mustache bar from the doner car. I just did 3.90 last weekend and it hauls some major glutious maximus. It does make an improvement even the 3.5 is better than what you have currently. It will take several hours with air toools.

Good luck