08 Honda Fit ECO gearing swap

[iplaysdrums]

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.

[Ecky]

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

[iplaysdrums]

Originally Posted by Ecky

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.

[Ecky]

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.

[iplaysdrums]

Originally Posted by Ecky

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.

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.

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

[California98Civic]

Originally Posted by BongoBennie

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.

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.

[Ecky]

Originally Posted by iplaysdrums

[I]

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.

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.

[BongoBennie]

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.

[BongoBennie]

Originally Posted by California98Civic

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.

I didn't find it, link?

[California98Civic]

Originally Posted by BongoBennie

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

I went ahead and embedded your images for easier comparison





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