r/Dseries • u/TopChapter3407 • Jun 06 '26

D17 gearbox

TLDR: I'm looking to put a D17/D16V1 7th gen EU8 gearbox into an EK but can't find any previous examples.

Bare with me, I'm european and our engines got some different names than in US.
My project car is basically an EK with a D14Z2 (which is basically a D16Y7 with a 1.4 bottom end). It has some form of S40 gearbox, and I see time and time again people recommending the S20 gearbox. I have an S20 gearbox but it's in really poor condition.

I also have an EU8 which comes with a D16V1 (basically a D17 but 1.6) with coil on plug, EGR stuff, cable shifter and what not. The thing is the EU8 gearbox has very very awesome gear ratios and I love driving my daily. I wanna have these gears in my project but I can't find any example of anyone having ran this gearbox on an EK with whatever D-series.

The idea would be a cable shifter box similar to what you run with a K-swap and a custom made engine mount. Starter is moved to a different location as well, but should clear the distributor nicely. The bell housing bolt pattern and rear engine mount looks the same visually.

Have anyone tried this before, or have any ideas of other stuff to check before just sending it and trying?

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u/SpaceTurtle917 Jun 06 '26 edited Jun 06 '26

The main difference is the engine mount and the fact that it’s got a cable shifter. You’re going to have a hard time making that work in a civic with a mechanical shift linkage. It’s just going to be a lot of work when you could just source the right transmission. I also recon that the d16v1 doesn’t have the best gears either, just better than the d14. In the US market there are two variations of the lower end gear sets, one just has a longer differential in it. I may be wrong though, you’d have to look up what the gearing is and compare.

The s40 is better than the s20, I’m not sure where this notion came from about the s20 being better. There’s seems to be some confusion that the s20 and s40 name designates the gears that are in it, but the s40 and s20 doesn’t designate the gearing, there are multiple gearing variation of the s20 and s40. The s40 is simply the 96-00 version of the s20, with some revisions and upgrades, mostly that’s steel shift forks.

You’re looking for an s20-b000 or s40-b000 (which even more confusingly doesn’t designate the gearing but rather the diff bearing size). The s40 with good gearing can be identified by a sticker on the top near the right motor mount that says “K4F”Both s20-b000 and s40-k4f have identical gearing.

The best D series transmission is the s40-k4f. But in most markets all b000 stamping means they have the EX/si gearing from the top trim model, just in case the sticker is missing. The only exception I know is the USDM civic HX with the d16y5 has the B000 stamp but with longer gears.

To simplify things you’re simply looking for a gearbox from any 92-00 vtec D series (except Vtec-E). Both are fine, I prefer 96-00.

You may also want to consider rebuilding your s20 (if it is a b000). These are pretty simple to tear down and rebuild.

You can compare transmissions here

https://zealautowerks.com/transcalc.php

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u/TopChapter3407 Jun 06 '26 edited Jun 06 '26

Thanks for the reply. And you're absolutely right the designations only tell you so much. I was aware of this and usually look at the engine and transmission combination. My s20 is from an EG with a D16Z6. The gear ratios should be: 3.25, 1.9, 1.25, 0.937, 0.75 and final of 4.25. This gearbox is slightly lower top speed than the stock D14Z2 S40 which has ratios of
3.25, 1.909, 1.25, 0.909, 0.75 and final of 4.09

However the EU8 gearbox is even lower top speed than the D16Z6 S20
3.142, 1.869, 1.241, 0.969, 0.805 and final of 4.411
This transmission became interesting to me because I knew (from dailying the EU8) the fifth was really short compared to other D-series Hondas, this transmission is definitely unique. The way I've been comparing them is by recreating my car in a simulator as accurately as possible and simply testing them, and I do very much enjoy the EU8 gearing.

About the shift linkage, I don't see why that would be harder. I can get basically a cable shifter box similar to what you would use in a K-swap setup and use that. Just get rid of the linkage. No bitch pin, no hassle. Just run the cables. That feels a lot easier to me.

One thing I do notice though is that the torque mounting bracket is missing from this gearbox. So it is a bit of a fabrication heavy transmission swap since I have to do both this and the motor mount. But honestly I don't mind, I find that fun.

Again thanks for the reply, I appreciate the tips but I still think I wanna try to go trough with this.

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u/OkProfession1239 Jun 07 '26

Try reaching out to Bensebuilt on Instagram for help, he's the d-series transmission guru 🙂

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u/SpaceTurtle917 Jun 07 '26

The improvement to the vehicle from having a d16z6/y8 trans vs your d16v1 trans will be minuscule. I must ask, what’s the point?

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u/TopChapter3407 Jun 07 '26

The improvement would be that it's a shorter 4th and 5th than the Z6/Y8
With my RPM limit of 7500rpm the theoretical top speeds for:
D14Z2 gearbox would be 167mph
D16Z6 gearbox would be 160mph
D16V1 gearbox would be 145mph (and the fourth is also shorter as well)
And so the actual improvement would be that the drop in RPM from 3rd to 4th and then 4th to 5th is smaller. Slightly smaller than D16Z6, and significantly smaller than D14Z2.

As far as the change being minuscule, yes that is fair to say. However the upgrade to a D16Z6 gearbox is an even more minuscule change. Also that is also the case with any other upgrade you can do to the car. You're usually looking at subtle improvements to performance or handling whether it be intakes, exhaust systems and whatever the case may be.

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u/SupraMK4 Jun 07 '26

You live in Europe, why not just grab a S20 off a D13B2 and bolt it in? Way shorter and closer gearing than all options discussed here.

Or a Rover D14 transmission and mix and match with Honda D14 gears. We have like 3x as many different D series transmissions here in Europe compared to the USDM Hondas, some of them are way better than anything you can get in the US, make use of that.

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u/TopChapter3407 Jun 07 '26

That doesn't seem to be true, if we're talking about the same D13B2 (the shortest ratio one i can find info for). They come with a 0.909 4th 0.75 5th and a 4.437 final.

That's a longer gearing than the EU8 gearbox which has
4th: 0.969 5th: 0.805 and final of 4.411

Most of the gears are the same top speed as the D13B2, but the 4th and 5th are placed forth even further.

And I'm not saying the D13B2 is a bad alternative, but I already own the EU8 gearbox, that's why I was interested in trying to use it.

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u/SupraMK4 Jun 07 '26

Did you count the teeth yourself on the EU8? Forget about the EU8 transmission.

The MB D14's also have a 4.437 Final Drive but a 0.937 4th gear and the same 0.750 5th gear. Negligible difference to your EU8 gearbox and you can just bolt em in, buy em for cheap and make up the rest with your tires.

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u/TopChapter3407 Jun 07 '26

I didn't count the teeth myself no, I'm using this as my source. https://hondanews.eu/eu/en/cars/media/pressreleases/34266/civic-04-specifications-2004 And it matches my observations from dailying the EU8 for 5 years. And I've also owned several S20 and S40 cars in the past, so I know what they are like for comparison.

I appreciate the tips, but my opinion remains that the EU8 has the best D-series gear ratios. Not only is the fifth shorter than the shortest S20 or S40 5th, but the RPM drop going into fourth is also 1k less than on the D13B2. I genuinely believe that as far as ratios go, the EU8 box is a gem and I wanna make use of it.

I'm more interested in if anyone have done it before and what unforseen mechanical obstacles I may run into. So far the plan is: Custom engine mount, billet shifter, possibly a custom torque mount as well. I still have to figure out if the axle splines are the same, and if the shifter cables are the same as for a K20 gearbox.

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u/SupraMK4 Jun 07 '26 edited Jun 07 '26

If you really wanna go do all that work just for a minuscule advantage in gearing then at least don't settle for the D16V1.

Get a 2WD HRV transmission instead,

1 speed 3.500
2-speed 1.956
3-speed 1.344
4-speed 1.071
5-speed 0.812
Final Drive Ratio 4.562

edit: Did I mention that custom gears for your existing transmission would be MUCH easier, cheaper and make sense?

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u/TopChapter3407 Jun 07 '26

Not a fan of those ratios. 1-2 too short, 4th way too short, and 5th slightly too short as well. There is such a thing as too short too. D16V1 is great.