I am going to start acquiring parts for my winter rebuild, which will include a new clutch and flywheel.

While I have it apart, I am debating whether I should get a used YS1 big spline tranny and if the benefits would be worth the cost. I currently have an A1 small spline that has not given me any problems yet.

Reading around, I have heard things like the differential is "stronger", the synchros are "better", etc. Basically a lot of platitudes but no solid info.

Can anyone articulate exactly what is different about the differential, synchros or any other parts that make the YS1 better and is it worth changing the transmission? It would be nice not having to worry about breaking things constantly.

 

The differential is the same in both, so the larger spline input shaft has nothing to do with this. Many parts inside the big spline cable transmission are also used in the newer hydraulic "B" series transmissions, so simply GETTING parts will be easier than those inside the A1 because it is long since discontinued and new OE parts are at best limited... likely unavailable. Aftermarket parts like bearings and synchros are plentiful, so as long as you only break those, you will be fine.

As for strength... all that reading you did was EXACTLY as you stated... just a bunch of opinion with no facts to back it up. Diff strength: same. Better synchros: nope. Maybe a stronger input shaft since it is slightly larger in diameter... but that would only be a discussion for a big HP car, so unless you are talking about making 600+ HP at the wheels, I would say it is also a non-issue.

By the way, if you really like the A1 transmission... I know a guy who most likely has the LAST brand new factory Acura A1 transmission in the Country... they have been discontinued for years... and it is for sale. PM me if you are interested and I can get you that information.

 

Thank you, that is what I suspected. Did not know that the differentials were exactly the same though.

I already have an A1 that I recently installed, it has 115k miles but works great. Since there are no real benefits to upgrading to a YS1, then I see no reason not to keep my A1 til it breaks then build a YS1 at that time.

The only reason I wondered is because I will be doing the clutch which is specific to the input shaft size, so it'd be an ideal time to do it.

Thanks again!

 

The diffs are not exactly the same. The diff pin is different, hence the YS1 being stronger. The synchros are a larger diameter in the YS1 so they are better (they function better and will last longer). You can easily change the gearing out in the YS1 as it is all readily available, not so much with the small splines.

 

Ah see, this is why it so hard to figure it out, conflicting information everywhere I go!

Stronger diff and synchros would make it worthwhile to me to pick up a YS1 while I've got it pulled.

 

The differentials are "interchangeable" for all practical purposes, however, I bow to Aquafina and his expertise for these "not seen by the naked eye" details. Aquafina, can you QUANTIFY how much stronger the YS1 diff and synchros are over the A1 for the purposes of educating the OP and future readers please.

 

Have you thought about going with the Hush Performance EF to Hydro Conversion and not even worry about the cable transmissions?

 

I can't quantify how much stronger the diff pin is. Honda used a different heat treatment on it and possibly a different grade of steel. It's still a weakpoint but not nrealy as much as the small spline.

The synchros aren't stronger, just a larger diameter so they function better as a result of more surface area.

If it is a pretty stock DD that isn't going to be driven hard and its in good condition a 92+ diff swap and rebuild is what I would do. If there are plans down the road to do something other than DD it I would go with the YS1. No need to go hydro as that is the only difference in the YS1 and the hydro transmissions. You can use any hydro internal you want in the YS1 case

 

Thanks so much for this information. The diff is what I broke in my last A1 tranny, it was in pieces.

A stronger diff would give me some peace of mind. Although this is just an occasional driver (not DD) but making 400whp and I'd like to be able to drive it hard sometimes without constantly breaking.

Is it silly to expect a stock tranny to handle 400whp?

 

Yes.

Use an MFactory helical LSD and Torco RTF.

 

Wait, you mean I have to spend money to make my car fast and reliable???



I'll get there, maybe the next time I break a tranny and get tired of replacing them.

 

please stop blowing up transmissions, there's none left anymore because people like you are too lazy to make it last for the next generation. Remember none of these cars will ever be produced again. We dont have new honda crate engines and trannys like mopar and chevy guys.