It is simply the design of the box. There is no reported reliable fix or substitute and most just change driving style to minimize the problem.

 

Easiest way to describe a dog box would be that, all of your forward gears are cut similar to the dog tooth reverse gear. This provides more surface area for gear to gear contact. It is just noisey by nature of the dog tooth gear geometry. It would basically sound like a WRC car since they all use dog boxes

 

[QUOTE=RGlbk,Apr 1 2007, 04:56 PM] Well I have had it with My05 and the crunching transmission with only 6700 miles on it!

Part of the problem is the synchros are not made to take the 8000 rpm shift from 1>2 without a pause and thats BS!

I drove a Boxster S and beat the hell out of it without ever having a problem.

I think part of the problems is the main input shaft weights in at about 20 lbs and so when you think about the shift from 1>2, the inertia of the input shaft including the clutch disc and gears needs to be slowed down from 8000 rpm to 50000 rpm, or about 3000 rpm to make the shift without a crunch.

 

a dog box utilizes dog engagement. a dog box can have spur (straight/'dog' cut gears), or helical gears.. of course the former is typically used because they are much stronger, which is basically a necessity due to the high forces put on the gears when using dog style engagement.

 

I have an '03, and the 1-2 grind problem was not uncommon on AP1s. My first transmission was rebuilt (under warranty), and then ultimately replaced (under warranty). My second transmission had no problems. I eventually switched to an AP2 transmission to augment my 4.57 gears. My AP2 transmission (in my AP1) has had no issue handling 9000 RPM 1-2 shifts. I use Amsoil MTF. Good shift technique is also key.
While the 1-2 shift issue is occasionally a problem with AP2s, the issue is about 90% driver error, according to Honda. There were a number of improvements in the AP2 transmission that eliminated the cause of the grinding problem that plagued AP1s. Shifting technique (attempted speed shifting) is the main cause of the problem in AP2s.
Cryo-treating will do little or nothing for the transmission. Grinding in the transmission is the synchros - not the gears grinding. Cryo-treating has no positive effect on carbon fiber - and AP2 transmissions use carbon synchros. Most of the synchros in the AP2 transmission are double synchros (except reverse). The AP1 transmission utilized double and triple brass synchros (cryo-treating does nothing for brass either).
As for "dog box" transmissions - good luck sourcing one for the S2000. They're designed for racecars - not for the street. Again, your missing the point: the strength of the gears in the S2000's transmission (AP1 or AP2) has never been an issue.

 

Maybe try changing out the tranny oil and taking out the CDV. This may help the "crunching" and redline shifts.

Christian

 

I think pulling the cdv would make matters worse, no?

 

If the "pause" at 8k shifts the OP is referring to is the car "pausing" and not the driver, then I think removing the CDV would help. I haven't removed mine, but from what I gather it makes the shifts at redline a considerable bit smoother. If you are really rowing through the gears and redline shifting all of them, the CDV will get you.

Christian

 

I think the CDV is the culprit, not the syncrhos.

 

So is thought that the CDV is delaying the rpm shift match?

In other words, the input shaft is still spinning away because the CDV has not allowed the pressure plate to lock back on the clutch disc fast enough?