3:54 STI Diff experience

[Pjackb]

Picked up a 2010 STI Diff for cheap and wondering what are people's experience with the STI 3:54 ratio with a mild powered engine.
Other than being a nice higway cruiser I'm mostly curious about street behavior with the higher ratio and how well it matches with a ZX 5 speed tranny

Engine is a run of the mill stroker with Z22 block , a U67 ported head and cam
I plan to run ~23" tires in a 185/60/14 , 185/55/15 or 205/50/15 with the 14" being the most likely
Thanks

[datzenmike]

The zx transmission is a close ratio with an insane 25.5% OD. Of the three 71B gear sets sold in cars by Nissan this is a close ratio with the least first gear multiplication. This was used on a 2.4L six cylinder which has the power to use it. It will work on a 4 cylinder 510 because it's 500 pound lighter.

Your car should preform quite well as it is now with 3.70 or 3.889 and a 2.2 liter L series engine. Simply put if you lower the differential ratio you will be sacrificing get away torque in every gear. Each shift point will be take longer to get to. Try it but don't throw your H-160 away

At 50 MPH on 23" tires with 3.7 differential and 5th gear your engine is only turning 2,000 RPMs.
At 50 MPH on 23" tires with 3.54 differential and 5th gear your engine is only turning 1,900 RPMs.

[icehouse]

If you swap to a 6 speed it's the perfect ratio.

[Pjackb]

thanks

[DADZSUN]

3.54 STI is my favorite setup, and I've experimented with pretty much everything.

If you've got a grunty engine (ie: 2.2l+, KA), the STI 3.5 Torsen diff is so sweet. Very smooth action, quiet, virtually no maintenance, and less turn-in understeer.

Personally, I like not having to shift 1/2 way through an intersection and the taller gearing is nice for cruising.

[Pjackb]

The zx transmission is a close ratio with an insane 25.5% OD.

Actually mine is an early wide ratio with the 0.864 5th gear

[Pjackb]

3.54 STI is my favorite setup, and I've experimented with pretty much everything.

If you've got a grunty engine (ie: 2.2l+, KA), the STI 3.5 Torsen diff is so sweet. Very smooth action, quiet, virtually no maintenance, and less turn-in understeer.

Personally, I like not having to shift 1/2 way through an intersection and the taller gearing is nice for cruising.

Thanks ,
still figuring out the engine (bought it used ) but it looks like it was built for midrrange torque and might be a 2.3
Also picking up a set of Fritz's (Datsunrestomods) CV axles to go with the diff

[datzenmike]

Actually mine is an early wide ratio with the 0.864 5th gear

Yes, a first year '79 280zx. I have one and I call it a mid ratio as there are some truck 5 speeds that are even wider.

Close ... 3.062 first gear. Only used in the '80 -83 280zx.
Mid ..... 3.321 first. Also used in the 620 and 720 truck, 810 and S110 200sx.
Wide.... 3.592 '79 620 and 720 trucks