Transmission options.
 

I have 94 civic DX hatchback with 1.5L sohc engine and manual transmission.
I am about to replace the clutch and since the transmission makes some bearing noise I am going to replace the transmission as well, what do you recommend for me to do as to increase MPG, do I need to swap the transmission from Civic VX? CRX HF? are they different than my stock transmission?

Look for alternative ring and pinion sets with taller final drive ratios, and a taller fifth gear.

It's easiest if you use a transmission that has the same type of clutch actuation as your current transmission. I think yours might be hydraulic? The HF trans definitely has a cable clutch. So the later transmissions (HX or whatever) may be an easier swap.

Swapping gears and R&P is possible, but I am not sure if it adds any extra complications. I know that in some older transmissions (e.g., the Porsche "901" gearbox) the gears and R&P have very finicky precise measurements and you wind up having to fuss with shims and such if you change any of the major parts like those. Honda transmissions could be simpler; I'm not sure.

User "Mista Bone" on d-series.org is the D-series transmission guru.

-soD

I have hydraulic clutch, I am looking for swaping the whole assembly, I thought that VX transmission will fit my engine and has different gear ratios than my stock transmission but I am not 100% sure.

Some other dave is right that the HF trans is not going to bolt up. But you are correct in thinking any 1992-2000 Civic manual transmission will bolt right up onto your 94 DX. The 1992-1995 VX and CX trim levels have the same gearing--the tallest in the 1992-2000 years with a 3.250 final drive. Your 94 DX has the 4.058 final drive gear that my 1998 DX also had. You can get somewhat taller gearing by swapping to the 1996-2000 DX (hatch), CX, or HX--all of which had a 3.722 final drive. Hope that helps. Here's the link (its really good, but not perfect): Honda Tranny Gear Ratios

Do you drive a lot of the highways, or is it mostly city traffic, stop and go?

I drive this car 90% of the time on the highway, I found a used transmission from 1999 civic, I may buy it if I can't find one from VX or CX.
Thanks a lot for the link.

Hydraulic clutches are not so great, more prone to fail than an a cable-activated one.

Maybe so, but they're all hydraulic in the 1992-2000 years, so unless he wants to fabricate a shifter mechanism...

Then I can see why taller gearing is a high priority. I do relatively little freeway driving, but I wanted to do more and I needed a replacement trnas, so I got this 1993 CX tranny.

It matters which 1999 Civic it is that you're looking at. The freeway cruising rpms will vary by something like 13%. If you're going to do the swap, might as well get the best bang possible. The EX had the shortest final drive gear and the HX, CX, and DX Hatch had the tallest final drive gears in those year (1996-2000). All the Civics had the same 4th and 5th gear in 1996-2000. So here is the test you can try to see if you have one of the taller geared or one of the shorter geared trannys: http://ecomodder.com/forum/showthrea...tml#post319503. Using that test, an EX (short gears) will make about 3.86 turns in 4th (pointing at about 10 o'clock) and a HX, CX, or DX hatch trans will make 3.38 turns (pointing at maybe 4 o'clock).

:thumbup:

james

I do NOT prefer the longer geared transmissions.

53 MPG in my 93 DX HB with aero/performance upgrades using a stock geared DX transmission.

VX stock gearing gives you 30 MPH per 1000 RPM. 3rd gear redlines at about 120 MPH.
Nice thing about tall gearing is it gives you have options you do not have otherwise. You can always downshift.

regards
Mech