Stock Diffs And Diff Ratios,

[raZ1911]

Right now i have a RB20DET in my 180sx running a RB20DET box with a SR20DET auto diff thats running 3.9 gears. It has basic mods like Miens ECU, front mount with 25 turbo, exhaust etc, nothing big.

I have a couple of questions about diffs and diff ratios and what difference would each make etc.

1. What stock diffs can be change over to my car?

2. what kind of a change would i see going from a 3.9 to a 4.1 diff ratio or even a 4.3? Where would i see the differences? As in quicker acceleration, bad on gearbox etc.

3. or should i just leave my 3.9 diff ratio?

Andrew.

[blind_elk]

1. If you are running a R200 type diff, then any R200 diff (GT-R / GTSt / Stagea) should fit.

2. If you fit a 4.1 or 4.3 ratio, you will get better acceleration. In general, you would lose top speed, but it is possible you may get better top speed because the engine can more easily turn the rear axles through the lower ratio. But you will be revving the engine higher, regardless.

3. I would think that a 3.9 should be more than adequate for a RB20 in a car designed for a CA18 / SR20

If you are happy with the performance now, I'd say leave it be.

[bubba]

Just keep in mind that if you are changing ratios you need to get the whole housing as the pinion gears are matched to the crown wheels.

I went the opposite way, 4.3 to 3.9.

[raZ1911]

Is it true that the car would be quicker if i were to put in the 4:3 just say?

[bubba]

It should accelerate faster which means you should notice it spool up quicker..