I'm replacing the tranny in my '90 Si. I've found one local, but it turns out it's a DX tranny instead of an Si tranny (I checked the gear ratio in reverse as indicated by "jlicrx").


First, will the tranny bolt up with my existing engine and axles?


Second, what is different? Is the Si stonger? Are each of the gears (1st, 2nd, and R) going to all have different ratios?

Thanks for any advise you can give.

Paul C.
Huntsville, AL

 

They are the same in strength and are interchangable, however the Si has closer gearing making it much more desireable.

 

Be sure the three screw threads on top of the tranny are'nt srtipped before you get it. I had mine in the car before i realized the dang things were stripped. I've still got it in, with one of the three bolts holding it with that mount. It has'nt fallen out yet, but it just bothers me to know.

 

transmission will bolt right up and use your existing axles
the only difference in the DX and Si transmissions is the differential Final Drive - DX is 3.888:1 - Si is 4.25:1 - gears 1 thru 5 are the same - what this means is that the Si is geared lower in every gear because you multiply the individual gear ratio by the final drive ratio

 

You can fix stripped out threaded holes with Helicoil inserts. Basically, the kit is a special tap, the Helicoil inserts, and a tool to thread the Helicoil inserts into the hole.

I guess with a lower Final Drive ratio, you'll get better gas mileage but not have quite as zippy accelleration. Should you have the speedometer calibrated after the swap?

 

no need to - the speedometer gear in the transmission will take care of that - different gear in each to match the final drive - the only thing that causes the speedometer to be off is different size tires

 

Thanks for all the help! It's worth a million - and the check is in the mail! These being the only differences, and me being more interested in economy than racing in this car, I'm torn between my two options.

Do I take the tranny back to the &#*@ that sold it to me? I'm compelled to do this to spite him - and carve a big 'DX' in the case so that he can't screw someone else.

Boy am I getting more cynical... what's up with people and their careless greed?? Why didn't he level with me and tell me he didn't know what tranny it was. GRRR!!! This is why I believe in Karma - I really want to know that he's gonna get his - somehow, some way... and on this Earth.

Or do I just put up with his attempt to stick it to me and take the fuel economy?

I think I'll stick it to him.

 

generally speaking, Si transmissions will usually cost you about twice that of a DX - maybe he should refund half your money?

 

Well dang dern. Maybe the used one i got for my si is a dx tranny. How can you tell the differnece by looking at them?

 

Tankard- Look for the thread called "tranny ID." That'll tell you how to determine DX or Si (thanks to jlicrx).

JLICRX- Well, I've also heard from a local tranny shop guy that the old man that runs that place deals in junk cars a lot - not just wrecks. That makes me suspect of this guy and his used tranny. I don't wanna have to do this twice. That would be a real GRRR.

He must have known, or assumed, it was a DX tranny since he only charged me $150 for it. I found another tranny about 50 miles away for $350. I'd rather have the right tranny for the car and not have to worry about it being junk.

Again, thanks a mill!! Gotta love this internet thingy, eh??

Paul