08 Honda Fit ECO gearing swap
 

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


https://ecomodder.com/forum/attachme...3&d=1531173192

https://ecomodder.com/forum/attachme...4&d=1531173202

Subscribed.

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...

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.

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

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.

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.

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.

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.

I just bought a '15 Fit and am flabbergasted that top gear at 70 mph has me at 3500 RPM. I've never done any trans work at all, but if there's a gear available to swap for my current 6th, it would be a dream come true. I'll definitely be paying attention here.

6th gear, probably not. Final drive is likely your only option, and that will affect 1-6. There definitely are final drive options.

And this is why I'm here. I don't know what I don't know, though I know I don't know a lot. :D

Point of reference, all L series transmissions have the same first gear ratio. The lower the final drive, the longer it is. The Insight has a 1.0L motor and a 3.2 final drive. The Civic Hybrid (1st gen) has a 3.6 final drive and a 1.3L motor. The 2015 Honda Fit has a 1.5L motor and a 4.62 final drive ratio.

Or in other words, the Fit has a 1.5x multiplier on RPM in all gears when compared with an Insight and a 1.3x multiplier with compared with the Civic Hybrid, AND a bigger motor. Bot of these cars have motor assist systems so it's not a completely fair comparison.

Probably more fair:

2005 Civic HX - 1.7L motor, 3.84 final drive, AND a taller top gear on top of that. Plus this is a heavier car. So, I think you could very easily swap your final drive for the Civic Hybrid's 3.6 (assuming it fits) and it would be no more difficult to drive than a Civic HX.

A 3.6 FD would bring 3500rpm down to 2725rpm.

I'm personally putting a 2.0L or 2.4L motor in my Insight and going with an insanely tall 0.647 6th gear and 3.4 final drive, which will result in 2300rpm @ 70mph with the factory tire size, and 2200 if I go a bit larger in tires.

Quote:

Originally Posted by Ecky (Post 573762) Point of reference, all L series transmissions have the same first gear ratio. The lower the final drive, the longer it is. The Insight has a 1.0L motor and a 3.2 final drive. The Civic Hybrid (1st gen) has a 3.6 final drive and a 1.3L motor. The 2015 Honda Fit has a 1.5L motor and a 4.62 final drive ratio. Or in other words, the Fit has a 1.5x multiplier on RPM in all gears when compared with an Insight and a 1.3x multiplier with compared with the Civic Hybrid, AND a bigger motor. Bot of these cars have motor assist systems so it's not a completely fair comparison. Probably more fair: 2005 Civic HX - 1.7L motor, 3.84 final drive, AND a taller top gear on top of that. Plus this is a heavier car. So, I think you could very easily swap your final drive for the Civic Hybrid's 3.6 (assuming it fits) and it would be no more difficult to drive than a Civic HX.

Any suggestions on where to find out what fits? I have a lot of learning to do before I attempt anything like this, and now's as good a time as any to start researching.

:thumbup:

That sounds like quite the project, and quite exciting as well. Do you have a build thread for it yet?

You were asking about tools and other items I think. Have you seen Daox's thread on servicing his transmission? I think it was Daox. Lots of pictures and he used a magnet to collect small metal particulate before removing it, I think. It was surprising what collected on it. Good tip. Good pics.

A lot of this is new ground, but the final drive *should* be compatible between Civic Hybrid and Fit. Worst case, the JDM Fit had a 4.1 final drive which would still get you down closer to 3000.

Build thread is here.

When they pulled the 08 Fit trans the outer case was busted so they gave me a free 09 with 24K miles, Im hoping to just swap the Fit bell housing to the civic outer and call it a day. I can also use the 09 since I have to redo the trans mounts anyways. Keep in mind I also have an 02 Insight 5 speed with the 3.2 but its still in the car and its hot so it may take a while.

Looking at the clutch side, Left is 04 HCH, center is 09 fit, Right is 08 Fit.

I didn't find it, link?

I went ahead and embedded your images for easier comparison

https://ecomodder.com/forum/attachme...p;d=1531767088

https://ecomodder.com/forum/attachme...p;d=1531767122

EDIT: I HUNTED FOR THE LINK TOO, AND i COULD NOT FIND IT. WHEN I GET A CHANCE, I'LL HUNT SOME MORE.

cross-discussing this on the fitfreak website forums might be helpful.

I thought about posting this whole thread there but figured this would be more appreciated here. Think I should start a similar thread or maybe just a link to here? Looks like a 5th gear swap might work too and Im sure some of those guys would be interested.

Post the link to here :)

I decided to pay a buddy some chump change to do this for me as time is not my friend and low and behold its a direct swap as far as the case is concerned. I'm not 100% sure about swapping individual gears but it sure looks possible. It's still gonna be a minute before I drive my car but as far as the question if fitting an 03-05 Civic Hybrid gear set into an 07-08 gear box OR you can use the HCH trans and buy a Fit clutch side trans case, 100% yes.

While I never have personally taken apart a trans before I wouldn't hesitate to do it myself next time (I watched). It took him 2 hours and he said it was easier that K series for reference.

https://ecomodder.com/forum/attachme...2&d=1537753232

Great info. Thanks. I would imagine the Fit gets a nice bump in fuel economy with some taller gearing.

Yup, thanks for being a pioneer on this topic.

Thank you guys too, this forum has been a great read and balance from all the go fast stuff, even with goals of 50MPG in an insight (loser!), I still get great advice.

That is exceedingly cool to finally have confirmed. Thanks for coming back to post it. I understand about time... it's not my friend, either. How is it driving?

Honestly it will be about a year before the car runs but I knew this group would love to know about the trans in particular. I won't forget though..... maybe someone else will try it and post their results here too? Anyways, thanks again to this group as well.

Late to the game here, but last month I swapped out a LX gear set into my EX transmission. I ended up having to pull apart every bit of the gear trains in both transmissions to make it happen in order to get the final drive swap right. Having never disassembled the input and counter shafts had me worried I'd mess it up....and I did. But I caught my mistakes, took it apart again, and got it straight.

I now have a smooth running transmission with a 700-800 RPM drop at highway speeds. The best result is the lower RPM makes the engine drone non-existent. I must say the MPG gain is really negligible. Maybe .5-1 mpg boost but certainly not much more. I also swapped out the D17A2 with a JDM D17A that has turned out great. I think my car will easily get another 50-75,000 reliable miles.

The old engine had 250K, a head minor head gasket leak (used coolant), needed a timing belt change, and used 1 qt of oil every 1,000 miles. It needed to go. I spent $450 on the engine, $300 or so in timing belt, water pump, gasket kits, fluids & such. I sold the old engine for $100 so for $650 I get to keep driving my smooth, comfortable, 36 ish mpg car 04 Civic for another 3 to 4 years only paying for gas and minor maintenance.