Thinking about getting an AP2 transmission for my 2003. Would I also need to change the drive shaft and differential? Or would the AP1 drive shaft and diff work as well?

 

cheapest thing to do is take your AP1 tail flange off and bolt it up to the new trans.

I would suggest buying new seals and washers... But thats just me.

 

I've done the swap. Dif, tranny and propshaft.

Get the ap2 driveshaft with the dif. The ap2 driveshaft is a little different design and I believe it's worth it to switch.

The propshaft (driveshaft) change is part of their "weak dif" cure as is the difference in the case temper between an ap1 and an ap2 dif.

In addition, it's easier to change the connector on the back of the the tranny than at the dif. You'll like the change in gearing with the ap2 tranny. and you decide to stay with the ap1 dif and propshaft Change it at the tranny.

fltsfshr

 

I don't really see the appeal of this mod. You get *slightly* (4%) better gearing in 1-4, *barely* taller gearing in 6th (2%), and suffer *slightly* bigger gaps between 4-5 and 5-6 (16.5% rpm drop becomes a 19% drop), for quite a bit of effort.

It does seem that, for a street car, the AP2 trans would be a better compromise for the AP1, and vice versa, but personally I'd rather keep the AP1 tranny's closer 4-6 ratios, and change diff gearing if I really wanted to improve off-the-line acceleration.

 

The AP2 Tranny also has the carbon syncros and much smoother shifting, and I have never seen or heard of a AP2 trans with 1-2 grind. I went through 2 AP1 trannys and couldnt get the damn grind to go away... so I got a killer deal on an 07 ap2 trans with less than 3k miles. No more 2nd gear grind and its insanely smooth.

 

Hmmm, never any grindy problems with my '01 AP1's transmission, now with 85k miles and 16 track days on it. It's always been plenty smooove.

Did you try different fluids?

 

Back when I had the AP1 trans, I tried the original oem fluid, GM syncro mesh and even the new honda mtf. Nothing worked cept the new ap2 trans

 

If your AP1 synchros were wearing out, that might explain it.
Hope you kept the lighter-weight AP1 flywheel!

I'd still recommend against this mod unless there are problems with the existing AP1 trans and it needs to be rebuilt or replaced anyway. And personally, I'd still prefer to keep the AP1 ratios. But if slightly shorter 1-4 ratios and very slightly taller 6th ratio are desired, and the trans is coming out anyway, and a known-good AP2 trans is available for reasonable $$$, why not?

 

when I had mine done it was just the tranny. If you are doing it get a lighter flywheel - the combo makes the S blazingly fast in the pass zone.

 

Thanks for everyone's input.

Actually I don't think anything is wrong with my transmission. It does sometimes grind between 1st & 2nd, but I think it's just due to my inexperienced driving (i.e. not giving enough throttle on the shift).

My mechanic was the one who recommended the conversion, because he believes the difference between the two set-ups is significant. Plus he said with the AP2 setup I could use a 4.34 diff gearing, which is better than the 4.44, commonly used on the AP1. Honestly, I don't understand any of this.