I just bought a '95 Civic DX hatchback w/ 68,000 original miles (replacing my '95 VX I sold 2 weeks ago). Drove the DX back from NC to RI Friday afternoon/night and got 38.3 mpg. Drove 70-75 MPH 75% of the way, drafted buses and trucks about 25% of the way, minimal coasting, tires only inflated to 36 psi (dealer's air compressor gauge was apparently off by 8 psi...I put 44 psi in, but found it to be 36 psi when I checked it after the trip). I know the fast driving and cold air hurts FE, but I still thought I would get 40 mpg.
My intention, even before buying the car, was to swap the transmission for a VX or CRX HF transmission to lower my RPMs (man, the DX tranny is quite the high speed blender vs. the VX tranny), but an entire tranny swap seems like overkill. Since the DX and VX tranny ratios are exactly the same for 1st, 2nd and 5th gears (and 1.172 DX vs. 1.066 VX for 3rd gear, .909 DX vs. .853 VX for 4th gear), wouldn't it make more sense to simply change the final drive gear in the DX tranny from its current 4.058 to the VX's 3.25 or the HF's non-CA 2.95? A final drive is much cheaper at around $150 than a used tranny is at $300+ (plus shipping). And changing the final drive gear means I keep my 68,000 mile transmission rather than a more worn, higher mileage tranny.
With the power curve of the DX engine, should I be concerned about lowering the final drive ratio from 4.058 to 3.25 or 2.95? Is a final drive gear more labor intensive than a tranny swap? Any other parts need to be replaced in order to replace the final drive gear?
swapping out a final drive is twice the work of a tranny swap. and i do not know anybody that is not a junkyard that would sell a vx or cx transmission for more than $150. i would just hold off on the tranny swap for a while and enjoy the acceleration you have now, while doing other mods for fuel economy
don't waste your time or time will waste you
Shucks, I thought I could get lucky w/ a final drive swap. I'm not into the acceleration....would rather have the great FE...and the high RPMs drives me nuts. I'll try hunting down a CX or VX tranny. Tks for the info.
I would set aside atleast $600 if you want to replace just your final drive, because you are going to want to replace the gaskets that get destroyed (at least $50), the counter shaft because I think that is the one that has the gear that drives the that final drive gear ($240), then you have the gear that is on the differntial ($135), then while you have it all appart you might as well replace seals, and check bearings, and of course because you are swaping parts around, there are those shim washers... good luck finding a book that will tell you what clearences are needed when putting everything back together, as my factory shop manual tells the dealer to outsource this work to a shop that specelizes in it.
When I called around to ask about getting my VX tranny rebuilt, I was quoted $1,200+ and they would not do it unless they also removed and installed it, if I wanted a compleatly new tranny it would be around $1,500, of course that would not include installing it.