08 Honda Fit ECO gearing swap

[BongoBennie]

My goal is to explore the gearing possibilities of the 07-08 Honda Fit Manual gear box using the gears from the 03-05 Civic Hybrid manual. From some online research and help from some internet friends Ive decided to buy both trans missions and document the process and see if everyones questions can be answered. I have a lifetime of experience building cars to different degrees but this will be the first time Ive ever cracked open a Honda Transmission. This not a ‘how to’ post rather a ‘me figuring it out’ post so please chime in with any help.

So far it appears the difference in the case is just the bell housing and the gear sets appear to be the same with the exception of some syncro differences


My goals are mixed with ECO and high powered performance and will be looking for 200HP at the wheels but would also like to get some damn good freeway MPG’s as well. This thread however is not about my car or my goal but about the transmission itself so I will try and keep on the subject of it and cars in general, link to my car is here (it needs updating to reflect this project as it was an A/T before)

https://honda-tech.com/forums/honda-...muter-3290050/

Honda Fit
1st. 3.462
2nd 1.870
3rd 1.321
4th .970
5th .757
FD 4.294

HCH
1st 3.462
2nd 1.870
3rd 1.241
4th .912
5th .711
FD 3.6

My first question I need to answer is what special tools will I need, I do have the factory Fit manual but won’t buy Honda specific tools if I don’t need to.

The following graphs show all info @ 3000RPM or @70 MPH

[Ecky]

Subscribed.

[samwichse]

Did they change any of this significantly for the 2009-2014 series? There are a buttload more of those on the road and it still uses the L15A...

[BongoBennie]

There are similarities between them all according to the detailed pics in the parts catalogues but I haven't figured any other years out yet. Of all the trannys though its the HCH that has the low FD. I would guess there are several possibilities throughout the L series.

[samwichse]

Even a Civic LX would be an improvement, although not as extreme:

LX 5M Gear Ratio

First 3.462
Second 1.870
Third 1.241
Fourth 0.970
Fifth 0.711
Reverse 3.231
Final Drive Axle Ratio 4.111

[Ecky]

Originally Posted by BongoBennie

There are similarities between them all according to the detailed pics in the parts catalogues but I haven't figured any other years out yet. Of all the trannys though its the HCH that has the low FD. I would guess there are several possibilities throughout the L series.

The Insight's 3.208 FD is probably also compatible. The 3 cylinder ECA engine in the Insight is an L series in sheep's clothing.

[California98Civic]

Subscribing.

Really basic question I am betting you already have the answer to: Honda reversed the engine/transmission placement beginning 2005 or 2006, right? Are the FIT and Gen1 Civic Hybrid compatible in that regard? Can you turn the engine around in the engine bay if necessary?

And hoping that this inspires me to break open my 6th Gen DX transmission to inspect it. I might rebuild it or play with swapping a VX FD and countershaft that I have had on hand a long time. I know the results are possibly known. My project is just for experience and skill building and reviving my old trans.

Tthe G1 Insight FD and your project... hmmm ... the benefit might be kinda small for your project. And given that you also want a quick car, not just a fuel economy champ... well 3.2 is way wicked tall, hey. I have 3.25 and 15" rims. Way tall!

I love these hybrid power/FE projects. Like PGFPRO's great work.

[BongoBennie]

Yes, 03-05 HCH is an L variant and spins clockwise, the D series FD would fit but the gears are cut backward. 01-05 Civic D17 and 08 Fit used the same diff.

I just purchased the two gear boxes and will be here any day, I also have an insight 5 speed. it too is a very similar trans but the pinion shaft looks longer, Id really love the 3.2..... it is longer though so maybe it can be machined? I need to pull it out of the car still but I will and pull it apart just for reference (and practice)

One thing about my car is I want a small tire, smaller than the fit..... when it comes to eco this isn't a good example of what it could be, for me its comfort based since even a stock manual Fit has horrible highway gearing even for the eco-unconscious.

One other option is importing a EDM or JDM trans with 4.1 FD for the same price I paid for the two with shipping.

[Ecky]

Lots of pictures please.

[BongoBennie]

Originally Posted by Ecky

Lots of pictures please.

They are coming, Im actually setting up lights for this, It will be a slow methodical process since it my first time doing anything like this. I also want to answer questions. The main Honda trans thread on this forum has been invaluable, thats why Im posting this here.