Will s40 gears, synchros and sliders fit on an s20 mainshaft and countershaft?

 

Yes

 

With no clearance issues or anything?

 

You can use 1st, 3rd, 4th and 5th no problem. 2nd depends a lot on what S20 and what S40 you have. If it's an EX/Si model then flat out no. If it's a DX/LX then yes as long as they're both DX/LX trans. Really though 1st and 2nd countershaft gears should come from the same trans as the mainshaft.

S20 and S40 use a slightly different sleeve for 3rd/4th. One has a wider groove for the shift fork than the other. You can machine the narrow groove wider, but not the other way around. I can't remember which is which though. The synchros are the same between both trans. Also 1st/2nd synchros are the same as each other, same goes for 3rd/4th. Usually 1st and 4th synchros don't get much wear so you can take the best 2 out of 4.

 

The s20 is a dx a000 set. The s40 is a ex b000 set. So second gear wouldnt be interchangable correct? I really want the short 2nd,3rd and 4th. 5th gear and 1st gear are the same according to this chart im looking at currently.

 

4th is also the same. The only 2 gears different are 2nd and 3rd.

Why don't you want to use the complete EX trans? Without the EX final drive you wont see much improvement (only in 3rd, 2nd and 3rd if you use the mainshaft) and even then it's going to be minimal.

 

I meant cx a000 set not dx haha. The guy who messed with the trans before me destroyed the interlock and the isb was really bad so I bought the trans for $40 to use for the gears/ synchros because my old set was pretty ugly.

 

If it's a legit USDM S20 CX trans take the 3rd gear set out of it and use it as a short 4th in the S40 trans.

 

Im using the s20 trans with the s40 gears. The s40 case has a gouge in it from the failing isb and the interlock is broke.

 

opps nevermind. I just calculated my gears and it looks like I do in fact have the dx transmission.

 

Well I tried to use the 2nd gear from the y8 but it was to big and I couldnt evenly seat the mainshaft and countershaft and gear clearances were way off. Just wanted to see for myself why it wasnt usable I guess. I spent all last night getting the trans in the car and got to test drive it. There is this faint whinning/grinding noise on deaccel. I can feel it in the shifter even. The gearbox gets louder it sounds like. Im guessing towards a worn FD or maybe bearing?

 

Are all the gears matched pairs? If you used the countershaft first from one trans with the mainshaft from the other trans it will whine from having a wear pattern.

 

I used the s40 countershaft and s20 main. Would the first gears be whining with eachother?

 

Yes, as I said the gearset should be a matched set, from the same trans.

 

Yeah I remembered that when I tried matching all the gears dumbly forgetting 1st isn't removable and the s40 mainshaft is damaged. I had to get the car back together, mom and dad were getting pissed as its been there the past week lol. From my understanding as long as they are the same ratio they will be okay and just make the gear whine noise? The parents are happy its out but im willing to throw it back in the garage if I have to haha.

 

The will wear a lot quicker than they normally would.

 

Okay. I suppose I can live with that as ill be swapping out motors sometime within the next year. Thanks for all the help 94!

 

Just curious. How long do you think the gears would last before one wears down enough to break?

 

Honestly I don't know. It'll probably last for a while.

 

Okay. Thanks for all the help again. Learning about trannys is fascinating.

 

is it possible to swap an ex s20 gearset into a dx s40 without any problems? i mean both shafts and gears, i know the shifter arms are different but is there anyway to get the s20 gears to fit on the s40 forks?

 

Yes, but you will need to use an S40 3rd/4th sleeve. IIRC 1st/2nd and 5th gear sleeves are interchangeable.

 

so i can literally pull the complete s20 shafts with all gears it will drop right into the s40 case no problem? and at most, all i will have to swap over from the s40 are the sleeves? even if ones an ex and one is a dx? for for the reiteration i just want to be completey sure

 

p.s. what about the diff? basically what i want to know is if i can swap over all the ex s20 internals into the dx s40 without any problems

 

Yes, you'll need to shim the mainshaft though (this goes with any case swap, even from one S20 case to another S20 case)

Yes, and yes.

You can't swap the diff if unless both cases are from an EX/HX/Si or if both are from a CX/VX/DX/LX different bearing sizes. you'll need to swap the ring gears. The bolts are left hand thread and easy to strip, loosen all of them a little at a time before removing them altogether and it seems to help.