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Old 05-30-2006, 06:51 AM   #1
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DIY Honda Civic 5-Speed Conversion

Well, I figured I'd start a new thread for this, since I'll be getting started on it this weekend. This thread will document the process of my DIY 5-speed covnersion from an automatic transaxle in my 1990 Honda Civic DX. First I'd like to say that this project becomes much more difficult (that I am aware of) if you leave the 1988-1991 Civic realm. I know for a fact that if you do this on a 1992-1995 Honda Civic, you have to drill spot welds and move a welded drivetrain mounting bracket on the car's frame.

As a history, you can click HERE to see my DIY on a manual pedal cluster install, and HERE to see my DIY on a CRX HF transmission overhaul. I'm getting my background for this DIY from many posts across many message boards, and THIS site as well.

05/29/06 - The car is down at my dad's house in the shop, awaiting saturday, when I'll start the process.
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Old 05-30-2006, 07:30 AM   #2
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this really makes me appreciate owning an eg...
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Old 05-30-2006, 07:45 AM   #3
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Another tranny swap thread. I like it. Good luck, DaX.

Care to give us some background on the different gears/final drive numbers involved?
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Old 05-30-2006, 09:30 AM   #4
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Quote:
Originally Posted by thisisntjared
this really makes me appreciate owning an eg...
Why? Because it's more difficult to do a 5-speed conversion on them?

Quote:
Originally Posted by MetroMPG
Care to give us some background on the different gears/final drive numbers involved?
Sure. The reason I'm doing this conversion is - (a) I love driving a 5 speed and (b) I'm hoping the longer gear ratios from the HF transmission will allow me to get more gas mileage by maintaining lower engine RPM's at constant speeds. This will help me (in theory) as > 80% of my driving is highway @ sustained speeds.

The gear ratios in my HF transmission are as follows:

1 3.250
2 1.650
3 1.033
4 0.823
5 0.694
R 3.153
FD 2.95 (non-California model)

I have verified this by counting teeth on the gear sets while I was rebuilding the transmission, but I seem to have misplaced the sheet where I wrote the actual gear teeth numbers down at.

I do not know what the gear ratios are for a 1990 Civic DX with an automatic transmission, but perhaps someone else can give insight into that (SVO?).

This will be my first time attempting the conversion, but I don't think it will be that hard after reviewing the limited information available. I still haven't decided whether or not I'm going to pull the entire engine/tranny or just the tranny. Pulling the entire setup isn't necessary (it is more work), but it will yield more room. I'll probably end up yanking the whole thing.

Basically, the parts I have collected for this conversion are: CRX HF transmission, D-series flywheel, stock Exedy replacement clutch kit, Clutch cable, engine mounts from a civic with a manual transmission, an ECU from a manual equipped civic (DPFI), and a shift linkage from a 1988 Civic with shift boot & shift knob.

I have already rebuilt the transmission with new bearings and seals. I opted not to replace the synchros for money reasons (it would have been an additional $250 for parts) and because people rarely abuse HF transmissions - I'll admit I'm taking a chance on this, but it's a calculated risk. If necessary I'll pull it back out and throw in new synchros at a later date. I have also already installed my manual pedal cluster over a year ago. It's been weird riding around with a dead pedal, especially when going from my manual 1988 Civic to this auto 1990 Civic.

It's a pretty direct swap, all in all. There is some wiring necessary for the reverse lights (on an auto, the reverse light switch is located at the shifter console, and on a manual, it is locate on the transmission) and for the park lockout. The latter is a mechanism on automatic cars that prevents the key from being removed from the ignition unless the car is in park. Wiring is simply needed to fool the car into thinking it's always in park. I will need to cut a hole in the center tunnel for the shift linkage to poke through. Eventually, I would like to acquire the proper piece of sheet metal from a manual equipped Civic and weld this in place - this will cut down drastically on road noise and wind entering the cabin, as the sheet metal has a lip that allows a rubber boot to seal the cabin.

Anyhow, sorry to be so wordy. This weekend will mainly focus on getting the tranny (or engine/tranny) out, moving the mounts around, and getting the manual transmission bolted to the engine.
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Old 05-30-2006, 09:35 AM   #5
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Quote:
Originally Posted by DaX
Anyhow, sorry to be so wordy.
No, don't apologize! That's good info. Thanks for the backgrounder.

So it's the same transmission that Ben just installed?
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Old 05-30-2006, 09:36 AM   #6
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Quote:
Originally Posted by DaX
Anyhow, sorry to be so wordy.
No, don't apologize! That's good info. Thanks for the backgrounder.

So it looks like the same transmission that Ben just installed. Is that the tallest tranny option that fits your engine?
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Old 05-30-2006, 09:44 AM   #7
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Quote:
Originally Posted by MetroMPG
No, don't apologize! That's good info. Thanks for the backgrounder.

So it looks like the same transmission that Ben just installed. Is that the tallest tranny option that fits your engine?
I believe so. Here's a comparison of the HF tranny to the VX tranny, which are the two tallest transmission options available for D-series engines (I think):

-----VX------HF--
1---3.250---3.250
2---1.761---1.650
3---1.066---1.033
4---0.853---0.823
5---0.702---0.694
FD--3.250---2.950

I also forgot to mention that I plan on attempting to fix the air conditioning while I have the car in the shop.
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Old 05-30-2006, 09:51 AM   #8
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Quote:
Originally Posted by DaX
Why? Because it's more difficult to do a 5-speed conversion on them?
err. i meant 'im glad i have a 5spd eg' i think they both have their ups and downs and it is more expensive to do a manual conversion on an eg, but there is a lot more room to move about.

to some extent i agree with taking the whole swap about of the engine bay. especially since you have a hoist.

i would rather do a swap than a auto-manual conversion. it seems like swaps take less time.
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Old 05-30-2006, 10:00 AM   #9
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Quote:
Originally Posted by thisisntjared
err. i meant 'im glad i have a 5spd eg' i think they both have their ups and downs and it is more expensive to do a manual conversion on an eg, but there is a lot more room to move about.

to some extent i agree with taking the whole swap about of the engine bay. especially since you have a hoist.

i would rather do a swap than a auto-manual conversion. it seems like swaps take less time.
I totally understand what you mean about the EH2. I really miss my EH2's sometimes, but as time progresses, I grow more and more attached to the ED6 bodystyle.

I agree with you on swaps taking less time - with all the right parts available, I can do a swap ALONE in one day. The more I think about it the more I'm leaning toward pulling the whole engine. It will also lead to better (less cluttered) pictures for the DIY.
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Old 05-30-2006, 10:22 AM   #10
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Awesome project. I was going to start my engine today, but we have family visiting this weekend and I need a four door car, so the engine swap is put off another week.

Is anyone driving through Utah next week for a few days next week and wants to get their hands dirty?

Anyone?
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