limited976

Goodmorning,

I have a Honda S2000 from '00 so one of the first.
I sometimes have a grind (let says once in 20-30 drives) - the real issue is clutch (feels hard or soft sometimes) or the synchromesh from gear 1-2.
Oils, pivot shifter has been greased, ball has been changed, etc.. no real difference.

To be sure i'll be replacing the complete clutch + transmission and keep the spares.

I have the opportunity to buy a brand new transmission from Honda that they still has in stock, it's +/- 2-3 years old.
item code is : 20011 PCY 010 - check the inside at the shop and it seems to be the old belt housing inside.

I've been reading that the AP2 version has carbon synchros , the AP1 has brass syncros..
Are the "old" - new gearboxes from Honda for the AP1 also upgraded with carbon synchros?

Chuck S

Syncros may depend on the production year. Carbon synchros debuted in the 2004 "AP2" cars and gearboxes (different 5th and 6th gear ratios). Maybe our UK/EU friends know it the carbon synchros went in the "AP1" gearbox that same year. Makes sense from a manufacturing point to standardize as many parts as possible.

Regardless a NOS (new old stock) gearbox will have better synchros than one that's 20 years old.

-- Chuck

s2000Junky

Could just simply be a tired brake master and slave cylinder.

Billman250

Don’t underestimate OEM S2000 brass syncros.

They are going strong just like the carbon, I have noticed nothing different as far as wear or use in 15 years.

A brand new ap1 box will be fantastic. Just be sure the clutch is done correctly, and the clutch rod freeplay is zero (find diy video by Soviet) and it will be indestructible.

twohoos

^Agreed, but I have to say the positive outlook is really only possible due to the updated Honda MTF (circa 2007ish??). The original AP1/early-AP2 factory fill was frankly substandard in any kind of temperature extreme - notchy when cold, downright balky when very hot on track. There was a lovely, buttery window in between...but that almost made it worse by giving you a glimpse of how good it *should* be!

Anyway congrats OP on the rare find, I'm envious.

limited976

Hi, Thanks for the replies..
I'll be replacing the master en slave clutch cylinder as well..
To be sure everything is checked and to not have one more old part that can cause harm.

Guess nobody really knows if the internal parts have been upgraded for the 'new' old design transmissions.

Since the flange is different on the AP1/AP2 transmission it's pretty obvious that they keep selling these.
Honda wouldn't change the flange of en AP1 to an AP2 just to fit the transmission.. we will offcouse, Honda wouldn't.

I've been reading all new parts are carbon coated, also those for AP1 transmisison but I've found no real "Honda" answer.
So the question remains.. are the syncros still brass of also carbon?

s2000Junky

I've run both ap1 and ap2 trans and they all felt the same to me, which is different on any given day So for me personally the choice comes down to what gear ratio do you prefer. The lower range in the first 4 gears with a more over driven 6th gear of the ap2 trans, or the standard evenly spread ap1 ratio. To me with a relatively stock output s2000 I found more performance benefit going with the ap2 trans with an F20 and vice versa.

twohoos

It appears there was in fact a change in part numbers for Euro AP1s from 2003 to 2004, for first gear, second gear, and the synchro sleeve set.
2003:
https://www.lingshondaparts.com/part...ckref/M__0500/
2004:
https://www.lingshondaparts.com/part...ckref/M__0500/

Are the updated parts the same as US AP2s? For first gear, yes: the US AP2 first gear got an updated part number (even though it's the same ratio and same number of gear teeth as the AP1), and the updated Euro AP1 first gear got the same updated part number. Unfortunately in the US, the synchros and second gear are only sold as a set, so there are no corresponding US AP2 part numbers to compare with the revised Euro AP1. Still, the first gear change does seem to imply that the newer AP1s also got the carbon synchros.

Interestingly, the bell housing part number has never changed, in any market, even though it's known to have been redesigned with extra reinforcement forthe AP2. This appears to be an example of "transparent supercession", i.e. the new design simply replaces the old for all applications, including replacement of old components; but also, crucially, any "new old stock" parts with the original design are still considered to be valid for replacement.

For the OP's purposes, the fact that the bell housing of the new transmission seems to be the original design may or may not indicate that the synchros are brass; it's quite possible that if any older-style housings remained after the trans updates, they would have been retained and earmarked for replacement assemblies, whether or not those assemblies used carbon synchros.