Ok so I was doing so research that the Rx8 transmission and S2000 transmission are basicallly the same, and internals too, also heard only difference was gear ratio.

The AP1 S2000 had brass Synchros which go bad like our cars.

The AP2 S2000 came with Carbon Synchros which is strong as ****, since that's what everybody said on the honda forum. Honda now doesn't carry brass synchros but Carbon Synchros replacment for the AP1. The factory TSB said to replace the 5th gear synchro and should solve the grinding issue.

My question is since I cant find aftermarket carbon syncho, should I just buy a S2000 AP2 transmission for $750 and swap synchro's to the rx8 transmission?

good idea? let me know whoo beefier transmission

 

i want to do something similar down the road, my 5th gear is ****. funny that it is the only gear to go out. i bought mine at 47k and it already had the issue. no matter how fast i'm going and with or without rev matching if i go into 4th before 5th, it will go in smooth, so thats just what i've been doing.

 

Damn :/ my 5th and 6th seems fine, just 4th gear is going out soon, 1st 2nd and 3rd feel notchy, especially 1st and 2nd. mine as well replace all synchos and inspect each gear also throw in new bearings and RR syncho saver would be awesome. :o

 

Anyone know if the carbon synchros are a valid swap

 

Synchrotech Carbon Synchros

dunno if the Rx-8 works, as they don't mention the S2000. we have been running a synchrotech trans in the race car (99 integra) for a couple years and its fine

 

The problem isn't exactly synchro related. They're involved but they aren't the real culprit.
Just buy an s2 transmission and rear diff.

 

Does anyone know what kind of synchros the s2 trans has? Maybe it'd be more cost efficient to just switch to a s2 trans, it already is considered beefier than the s1 and it's a direct swap.

 

That's what I'd say. Why buy a tranny for $750, then spend $1k or more to have someone rebuild the aisin box. Even if you did it yourself, unless you're a professional transmission re-builder I don't think it would be worth it.

You can get a s2 tranny used with low miles between $1200-$1600, and then get a s2 differential to make it worth it.

 

Some of them are carbon coated for sure.
Keep in mind that it's just a coating like most synchros anyway

 

I there any advantage to the S2 rear diff other than the shorter gear ratio?

 

Other than the 4.77 gear, I really don't know. Maybe someone else could chime in? bse?

 

I have a set of 17" wheels and because I autocross at fast tracks I don't really want to shorten the gear. I currently get 70mph in 2nd gear (@10,000rpm) shortening the great will make a 3rd gear shift more likely and actually make my times slower, on the faster courses.

 

You can always get a s2 trans and leave it mated with the s1 diff. It's what I'm currently running.

 

That is my plan I might have to wait for my tax return to buy the S2, I really don't want to pay out $1400 for a new transmission at the moment, but ultimately If I need a new one I will try to get the S2.

 

My transmission has a lot of miles on it, and it makes a grinding noise in 2,4,6 gears. 1,3,5 are all fine. I am assuming that it is a synchro issue, and was looking for better aftermarket syncros. I have heard good things about getting rid of power loss through the transmission by getting better syncros, but can't seem to find any online. If they don't make them, I guess I'll just get an s2 transmission.

 

grinding when you shift? or just when you're driving down the street?

i ask because the rubber shift boot tears, and in 2,4,6 the hole opens, and lets the transmission noise in, and in 1,3,5 the hole closes and keeps the noise out

 

go ahead and waste the $750 if you feel like experimenting. if the gear ratios are different then you can bet the syncros won't be a direct swap.

 

Dude this thread is like almost a year old, a little late here

 

It's a continuous noise when I'm in gear. It goes into and out of every gear fine, and it feels like the synchros work so I'm not super concerned. The noise is just annoying.
I think I'm going to get an r3 trans this summer when I have money for one. Does anyone know off the top of their head what the 4.77 Diff does to your gas mileage? It seems like freeway driving above 70mph would be much worse...

 

don't talk to me as if i'm the one who bumped it...

i'll be sure to remind you to read post dates every time you post as well.

 

The basic premise of this thread is a fail. The idea that all Aisin AZ6 models are interchangeable in whole or parts is just the usual 1+1=3 internet hocus pocus by people who take a sliver of information and the try to write a made up thesis around it. The closest derivative to the RX8 S1 trans is tge 1999 - 2005 6 spd Miata trans. They share the same main housing with some similar internals, but everything interchangeable on the RX8 version is an upgrade do we can't gain from them.

Does the noise decrease or stop when you push the clutch in while the car is stationary?


.

 

My noise is there whenever the car is in gear and moving, regardless of the clutch position. It seems worse sometimes, but that could be just changes in levels of ambient noise that cover it up. I can't hear it when the windows are down, only when the car is closed and the radio is off.