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Which final drive do you prefer or want?

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Discussion Starter #1 (Edited)
Hello all,

Its time to re-look at this and see if it really worth the trouble. The info that I have found is this to date is as follows;

The specs:
Stock/OEM Final drive is 4.76 (Stock SI and RSX Type-S)
King Motorsports Final Drive is 5.02 (Used in Grand-Am cars!!)
JDM ITR FD2 CTR Final Drive is 5.06 (The Type R)
J's Racing Final Drive is 5.10 (No idea)


What it means: The larger the number the faster your acceleration will be, at the expense of top speed.

The K20 likes to rev, and the K20 makes horsepower and torque at higher RPM = if you can keep the final drive gear at a higher RPM, you can reach higher speeds faster (final drive gear) and keep the RPMs up in the range that the K20 likes.

The 6th gear from the FD2-R tranny is the same one used on the USDM DC5 RSX-S (0.738). The one that is actually "shorter" is the one used on JDM EP3-R and DC5-R (0.78) and I believe should be harder to find. The combination of the FD2 Final drive with the 6th from the EP3/DC5 -R will hurt mpg in the highway. It will be pretty much useless, thats the reason honda give us a "longer" 6th gear (so in the highway it sits at lower rpms), for fuel economy at highway speeds. People with ITR trannys put TSX/FG2 6th gear so they can cruise at lower rpms on the highway. You are trying to do the opposite most people with ITR trannys want to to.

However, with higher RPMs comes lower gas mileage. So for the daily drivers among us, this makes a little less sense. That is unless you time attack your car. If you auto-X the car, you'll never see 6th gear anyway. So for time attack this makes most sense

Changing your final drive gearing changes your overall gearing in the entire system. This means that if nothing else changes then your theoretical top speed is reduced but can be reached more quickly. There is more to this than the theory. If your engine does not have the hp/tq needed to push the drive line that last bit then an even lower top speed comes into play. If you also get too aggressive with the final drive then you limit your top speed by changing gearing due to the change in size before it runs out of power to push your car to a higher speed. Redline will stay the same with a final drive. 8k so if you redline you see 198 hp at the flywheel with normal gears then you will see 198 hp at the flywheel with the upgraded final drive. So in other words you would not run out of motor.... you would run out of gear.

Let me see if I can simplify this. The term final drive means the last point in your drive line that gearing changes are made (the term was coined before hub gearing came into play on some vehicles so ignore that). Your final drive is located in your differential. Yes, there is gearing in there, it's how they take a single input and convert it to 2 outputs.

The short of it is, if you lower your final drive (lower=bigger number) then you sacrifice fuel economy and theoretical top speed for faster acceleration. Even a few hundred rpms makes a big change when you talk about highway driving and economy.

For those of you that want more detailed info check this out:
Click link-->How Differentials Work

I will continually update this thread as time progresses.
 

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Um, so is there a combination of higher final drive and a taller 6th gear? The way I see it the only bad thing about the Type-R final drive is that in 6th gear cruising you're going to be at higher RPM compared to stock.

For city driving I don't think having shorter gears is too much of a detriment since you'll just have better acceleration and be upshifting sooner. However, if you're just steady speed driving like in 6th gear, I'd rather keep a lower RPM to save gas.
 

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i like this info. i have thought bout swapping the final drive so i can have less rev in 6th on the highway
 

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I haven't redlined 5th yet(over 130) so i am perfectly content with the "tall" final drive. if anything a taller 4th would be nice so i can stay in 4th on the quarter.
 

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What I was thinking was, the percentage of people that aren't FI and keep their car as track sluts and of course don't daily drive would be the people that benefit the most from a final drive, or a gearing change in general. If you're FI (turbo OR Supercharger) you'll be spinning like there's no tomorrow if you make these gears any shorter, if you daily drive, you'll be at highway speeds in 6th gear at 5000 RPM, which is a complete waste of gas. So for most peoples needs, switching gearing, or the Final Drive is not really too beneficial, and not worth the hassle.
 

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you think your gearing is going to change that much? to go from around 2500-3000 to 5000 rpms at cruise? i would expect to switch gears faster, but i don't think it's going to be that drastic a change unless you switch out every gear. as far as top speed is concerned, you're only going to lose a couple miles off the top, it's not like 10 or 20. I'm not sure how much a final drive cost, but im sure it's a pretty penny, especially if you're going to get a shop to install it. I think if you're looking for faster gearing, but not change your final drive, and have the money for it, then this might be more suited for your needs.
CorSport Online Store: Honda - 06+ Civic Si - MF-TRS-01KP
 

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Hello all,

Its time to re-look at this and see if it really worth the trouble. The info that I have found is this to date is as follows;

The specs:
Stock/OEM Final drive is 4.76 (Stock SI)
King Motorsports Final Drive is 5.02 (Used in Grand-Am cars!!)
JDM DC5 ITR FD2 CTR Final Drive is 5.06 (The Type R)
J's Racing Final Drive is 5.10 (No idea)


What it means: The larger the number the faster your acceleration will be, at the expense of top speed.

The K20 likes to rev, and the K20 makes horsepower and torque at higher RPM = if you can keep the final drive gear at a higher RPM, you can reach higher speeds faster (final drive gear) and keep the RPMs up in the range that the K20 likes.

The 6th gear from the FD2-R tranny is the same one used on the USDM DC5 RSX-S (0.738). The one that is actually "shorter" is the one used on JDM EP3-R and DC5-R (0.78) and I believe should be harder to find. The combination of the FD2 Final drive with the 6th from the EP3/DC5 -R will hurt mpg in the highway. It will be pretty much useless, thats the reason honda give us a "longer" 6th gear (so in the highway it sits at lower rpms), for fuel economy at highway speeds. People with ITR trannys put TSX/FG2 6th gear so they can cruise at lower rpms on the highway. You are trying to do the opposite most people with ITR trannys want to to.

However, with higher RPMs comes lower gas mileage. So for the daily drivers among us, this makes a little less sense. That is unless you time attack your car. If you auto-X the car, you'll never see 6th gear anyway. So for time attack this makes most sense

Changing your final drive gearing changes your overall gearing in the entire system. This means that if nothing else changes then your theoretical top speed is reduced but can be reached more quickly. There is more to this than the theory. If your engine does not have the hp/tq needed to push the drive line that last bit then an even lower top speed comes into play. If you also get too aggressive with the final drive then you limit your top speed via gearing causing the engine to red line before it runs out of power to push your car to a higher speed.

Let me see if I can simplify this. The term final drive means the last point in your drive line that gearing changes are made (the term was coined before hub gearing came into play on some vehicles so ignore that). Your final drive is located in your differential. Yes, there is gearing in there, it's how they take a single input and convert it to 2 outputs.

The short of it is, if you lower your final drive (lower=bigger number) then you sacrifice fuel economy and theoretical top speed for faster acceleration. Even a few hundred rpms makes a big change when you talk about highway driving and economy.

For those of you that want more detailed info check this out:
Click link-->How Differentials Work

I will continually update this thread as time progresses.
just to clarify some wrong information, the DC5/ honda integra type R does not come with the FD2 CTR 5.062 final drive. it comes with the 4.77 like the US 05 06 RSX type S and US FG2, FA5 civic Si
 

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i went through this dilemma last year when i still had my ep3. i had an all motor setup but the 4.3 final drive from the k20a2 was hurting it imo. especially after i switched over to 17 inch rims with a 205/45 tire.

i decided to make the switch to the 4.7 final drive and i loved it. the acceleration was so much better. from an all motor perspective where you're pretty much looking at any little thing to help out the powerband i think it's a great mod.

from what i've seen, the final drive that honda has chosen to use over the years with the 6 speed tranny's has depended on the rim/tire size. the 02-04 rsx-s came with the 4.3 and had 16's. the 05-06 rsx-s, the dc5 itr, the ep3 ctr, the accord euro-r, the tsx, and the 06+ civic si all came with 17's and thus used a 4.7 final drive. the fd2 ctr is using 18's and thus is using a 5.0 final drive to make up for the increase in rim/tire size.

for those with forced induction setups, even the stock 4.7 final drive may be too short.
 

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Wow, that's more aggressive than I had expected, with stock being around 80MPH @ 3500RPM
Also, the FD2 FD reduced my top speed in 5th gear from 142MPH down to 127MPH. my rev limit is 8700RPM.

:yeahthat:


Same observation from my FG2 with the FD2 FD. I'm getting about 25 - 30 mpg with a lot of highway miles every day cruising between 60 - 70mph.

Never really had a chance to meassure mpg's before the FD, I bought the car with the FD already installed.
 
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