K3-VET - what manual trans to use?

This is a little off topic but @601to602 how many hours do you spend cleaning your parts? they are always sooooo spotless and perfect. I spent like an hour on a gearbox, crack the shits and accept I will never get it clean and just have grubby parts. Everything I have ever got off you has been immaculate.
I respect your patience and meticulous attention to detail.

1 Like

Cheer’s mate , No real effort on my part here. The case i cleaned with an acid type cleaner Septones alli brite , although it will be soda blasted before reassembly , the bolts etc have all been replaced with new parts…easy. What i will do is buy some sodium dichromate from caswell as the bolts etc have a nickle coating dipping them in the dichromate solution will give them that iridescent gold color they would have had from new.


that is awesome information for cleaning. Thankyou. :slight_smile:

@601to602 the 1.3 sirion box also has the wider 1st and 2nd (without scissor gears) :slight_smile:

As a quick summary; as I am not 100% on all the codes used in this topic (I’ve read through it a few times over the past year) are the copen 660 and copen 1.3 gearboxes the same? And will they both bolt straight up to a k3ve2 sirion?
Reason being is that I’m looking to buy a cheap sirion which is for sale here, swap the exh cam, possibly look at the ports to see if there’s anything that can be gained from a quick porting, revise the air intake, reduce the weight & shorten the gear ratios. Then I’ll probably take a look at the ECU to see what I can gain with changing/modding that.

No they are not the same

They are not identical, but you could say they are the same model or series. The bell housings are different but the rear half of the housings is the same and the internals are interchangeable. Basically the same gearbox with different ratios and bellhousing.
If you go a bit further back in the thread you’ll find a list of the different ratios

Ah ok, so I’d need to take the final drive out of either the 660 or 1.3 copen box and stick it in the sirion box then?

what are you wanting from the car?
that’s a lot of work to get a very small gain from the engine
torque of the stock cam is very good
you’re not going to find much gain without ecu swap anyway
ratios are better with copen FD
but with 12psi boost on a nice tune none of that matters much!
such a great engine as they are just with a bit more punch!

…just dont wind the boost up toooo much - gearbox will go POP :man_facepalming:

1 Like

Yeah gearbox doesn’t handle torque, but they handle revs quite well. The rally cam (you didn’t get them your side of the planet) and a different air filter alongside an ECU reflash bumped the power up around 10% which is a considerable gain for N/A. If I wanted forced induction I’d get another Kei car, but I fancy a shouty little lightweight car on a budget. As all the parts I’d like are readily available and cheap then it’s a goer in my books. My bro is savy with building ECU’s anyway, and I’ve got a very competent rolling road tuner 5 minutes from me.

Hi peeps, I have 2 questions kinda related to this topic, so I figured this would be the right place to continue.

Question 1 (longshot): does anyone know if there’s a difference between the 3SZ gearbox and K3VE gearbox from a Sirion 2/Boon or Materia? The gear ratio’s are the same, and the difference in torque is only 12Nm, so I assume they use the same gearbox.
However, the 3SZ is fitted with a hydraulic clutch system, whereas the K3 is fitted with a mechanical (cable) system, so I’m not surprised by anything at this point

My second question is one I thought I’ve asked before, but I can’t find it on the forum anymore, so: Would an EJ-VE diff work in a K3/3SZ gearbox? The K3 diff has (as we all know by now) a ratio of 4.27, whereas the EJ-VE diff has a ratio of 3.94. Since the 3SZ has plenty of torque, I feel like the engine is doing more revs than actually necessary.

Both K3’s and prefacelift Cuore L7’s (EJ-DE) came with 4.27 diffs. I checked the part number for the ring gear that is used in the K3, and it appears to be the same one used in the EJ-DE Cuore. The same goes for the output shaft, which I would have to swap as well. You can check it here:

Now, with that in mind, I think I can assume that an EJ-DE diff can handle the K3’s torque, since they use the same ring gear. But, I’m not sure if I can assume that the EJ-VE diff will handle the K3’s torque as well. I’d like to hear your thoughts on this! Eventually I’d like to take a K3 gearbox, and fit the diff (or at least the ring gear) and output shaft from an EJ-VE, and perhaps 5th gear as well.

FYI, the L7’s EJ-VE and its gearbox are the same as those in an L251.

1 Like

replied on facebook :slight_smile:

1 Like

Now this topic couldn’t get any more nerdy could it!? :laughing:
Love all this information, really good to know and hats off to you guys supplying all the great info.

A little question for you all if anyone knows. Seeing as we are talking about different ratios to either gain more acceleration or for some too gain better drivability. How about a lightened flywheel for better acceleration? Has anyone had any experience in sourcing a lighter flywheel?

Also I do how the OP actually managed to decided what gearbox to use for his K3-VET!!:laughing:

There’s a company in the UK, called TTV racing, that does flywheels for both K3’s and CB80 engines. Haven’t seen an off the shelf product for E series engines though.

PS: I used a trans off of a standard YRV as that’s what was available, but 4th gear is awfully long and i could use a longer 5th or final drive, much like was commented a couple posts above.

1 Like

Time for some more headaches!
I’m not really a fan of the way K3 gearboxes are ratio’d. It seems to work better in the Sirion than my 3SZ swapped L7 (because the L7 wasn’t really made for a K3/SZ swap, but oh well), but I still don’t agree with the ratio’s. The biggest issue being that from 3rd to 4th is too big of a gap, and 4th to 5th is too small. The last one being the culprit for doing a lot of revs on the highway. So, I decided to look at some gears 'n ratio’s from EU Dai’s, and created a theoretical ideal (for me) gearbox.

Standard K3 box on the left, ideal box on the right

You can clearly see that 4th is now closer to 3rd, and 5th gives a nice overdrive, without really altering the first gears.

Some graphs

1st: Cuore L7/L251 (EJVE)
2nd: Cuore L7/L251 (EJVE)
3rd: stock (since basically every gearbox has the same 3rd gear)
4th: Copen L880k (JB/K3) / Sirion M100 / MoveL9 (EJ) / Charade G1 (HC)
----- Applause A1 / Charade G2 / Gran Move/Pyzar (HD)
5th: Cuore L7/L251 (EJVE) / Charade G2 (HC/HE) / Gran Move/Pyzar (HE)

Final: Cuore L7/L251 (EJVE)

Because 1st and 2nd gear are shorter, the total reduction is roughly the same as for a K3 box, which is nice for driving off. However, 1st and 2nd are strengthened in K3 boxes, I’m not sure how EJ gears would hold up. Those two gears are part of the input shaft, so they can only be swapped together or not at all. I have a spare K3 box, and an EJVE box as well soon, so I’ll compare the two and see if there’s any visual difference. I read in @Mick 's topic that 1st and 2nd have wider/thicker gears, so that should be easy to compare. Using the K3 gears wouldn’t be the worst thing, just not ideal. Better safe than sorry.

4th gear shouldn’t be a problem. The torque from HD’s is similar to that from a 3SZ, and according to Partsfan, all cars with this 0.92 ratio use the same gears. So whether the gears come from a Move or Gran Move shouldn’t matter, in essence.
(part nr: 3333497203 & 33338-87703)

5th gears is a bit of an issue. You can only search for JDM cars, if you’re after Dai parts, and that is a problem. Why? Well because they didn’t make an EJ L7 for Japan, and used different ratio’s. Whereas we got the 0.707, they used a 0.75 for the JDM L7’s. Because of this, I can’t cross reference them and see if they are the same as the gears used in HE-powered Dai’s. Those gears should be strong enough, so if they are the same as from an EJ, I can use those from my spare box. I found this links where someone swapped his 0.75 for 0.707, so at least they should fit:

Swapping the ring gear on the diff requires swapping the output shaft as well. As for the first two gears, I guess it’s a matter of checking for any major visual differences. I think it should hold up, as they’re usually made quite bulletproof, but it’ll still be somewhat of a gamble.

Btw, here’s a screen of an Excel file (I can’t upload the file itself in here) with a bunch of different ratio’s I gathered, for those of you who are interested:


I’d like to hear your opinions on all of this!


That’s allot of info, great job. To bad I don’t really know anything about gearboxes. Aren’t there any Toyota or other gearboxes which use the same type of gears? I really don’t know how to see if a gear will fit a box so I might (probably) am saying something really dumb.

Unfortunately i didn’t get any cross references (well except for a Toyota Duet, which doesn’t count because it’s a Sirion). Everything can be made to fit, but then you’ll have to do the whole shebang. So in case of a different gearbox: adapterplate, flywheel, clutch, axles, a nightmare.

Agree, like I said I don’t know much about gearboxes but thought that the gears might just be interchangeable (of example the Yaris engine and gearbox are Daihatsu related). Don’t really know how to check it and what’s makes a gear fit or not.

1 Like

That’s what I meant with “cross reference”. You can go to partsfan, look up a number, and see all the cars that use that part. It’s also useful to see get an overall idea of the sizes and shapes

1 Like

IMO the main concern is the power capability of these gears
I’ve blown L7 gears and diff with a factory EJ engine-let alone running behind a k3 with almost 45% more torque …let alone a VET which this thread started asking about which is basically 100% more torque [88nm up to 177nm] in factory and weve seen with a bit of boost and flow increase it was above that [ 320nm] you’re going to see hot knife through butter effect

…although I’ll admit to looking in to heat treating a brand new set of L7 1st and second …it still is only slightly more pricey getting a new forged replacement - and easier since our machinist does a new input shaft to suit

The other issue is the machining required to fit these

For me, it quickly justified aftermarket set

Although I can vouch changing to copen 4th and final drive is an easy swap! For sure worth the effort - although k3 diffs dont seem to like much abuse either - again ive had them fail just with road use in standard cars. The DRS LSD is an awesome kit, although not super cheap …but nothing in gearboxes actually is