s2000Junky

I'm sure someone has. They make a 3.90 final drive that some of the boost guys have used. I've heard as low as 3.60 but that would be rather compromising if you are making south of 350trq.

phiaceko

Would 3.90 final drive with an Ap2 transmission give you the same 1-5 gear ratio as an Ap1?

s2000Junky

No but not that far off. It would be equivalent to having a near exact 4:00 final drive. So an in between.

The primary gear reduction of the ap2 trans would be equivalent to running an ap1 trans with a 4:22 final drive.

twohoos

Just to be pedantic, AP1 secondary is 1.16, AP2 secondary is 1.208333, so an AP2 secondary in an AP1 trans would be like a 4.27 final drive.

Even better: A straight swap of an AP2 trans into an AP1 provides this "4.27" gearing advantage in 1st-4th (and reverse! lol), while 5th remains essentially the same, and 6th is slightly taller. So both acceleration and cruising comfort are improved.

For AP2 owners, swapping in an AP1 trans can be helpful for track driving. It gives a little more length to 1st-4th (equivalent to 3.94 final drive), potentially meaning less frequent shifting. On the other hand, 5th and 6th are significantly shorter, meaning upshifts land the engine closer to the F22's VTEC range. Combined with the gearing advantage, acceleration in 5th-6th is thus dramatically improved. The price is that with the F22, top speed in 6th is rpm/gear-limited to around 152mph; but that's enough for most tracks, and is about where the car tops out anyway. (If a little extra top speed is needed, taller rear tires could be fitted.)

s2000Junky

Unfortunately the gear calculator I/we used to make these calculations no longer exist so I will just have to trust you on the discrepancy in the primary drive equivalent to final drive ratio, but pretty certain it worked out to a 4.22. Unless the gear calculator trans ratio was incorrect from their source provided. Regardless I agree. I've always said in hindsight, Honda got the right trans on the wrong era/years of s2k. More trq and short rev band of the F22 should get the ap1 trans and alternatively the F20 could use the ap2 trans.

davidc1

I've seen lots of AP1 tranny's have the AP2 secondary gear installed to make all the gears shorter. 1-4 become like the AP2, but 5th and 6th become shorter also. Annoying on the freeway.

I like the longer gearing of the 1-4 on the AP1, for the track, and especially as my hp has gone up, the shorter ratios on my AP2 tranny are annoying.

What I really want to do is put the AP1 secondary gear in my AP2 tranny and therefore make all the gears longer. 1-4 will be back like my AP1, but the great advantage is 5-6 will be longer as well, for reduced RPM on the freeway.

twohoos

^Yep, AP1 secondary in the AP2 trans is basically a "3.94 final drive" option. At 75mph in 6th, you're at 3800 rpm instead of 4000, and top speed (assuming 8200rpm redline) is up to 161. Seems well suited to higher-hp tunes.