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D Series EF Civic and CRX Hydraulic Transmission Swap - Wrenchin

Swap A Hydro Tranny Into Your D-Series EF And Leave Busted Shift Forks Behind

Tim Kelly
Mar 1, 2008
Photographer: Hasport Performance
Htup_0803_01_z+ef_civic_and_crx_hydraulic_transmission_swap+under_car_view Photo 2/17   |   D Series EF Civic and CRX Hydraulic Transmission Swap - Wrenchin

As a parent, in order to make things fair you have to treat each child the same as you do your firstborn. With engines, the B-series always seems to get the most attention so it's time for a good tech story with the D-series engines that are becoming more and more popular.

One of the biggest problems with the second CRX and fourth-generation Civic chassis, or the EF as it's also known, is its weak aluminum shift forks. Quick shifts, like you'd do at the dragstrip, place added pressure on the forks, which make them respond by snapping faster than Britney Spears. Losing a shifter fork won't just stop you from shifting, it can also send pieces flying around your gears, making the repair even more difficult.

2018 Honda Civic
$18,940 Base Model (MSRP) 28/40 MPG Fuel Economy

The newer hydraulic transmissions, which made its debut on the '92 Civics, had a complete internal redo with much stronger stamped steel shift forks. These transmissions are quite strong and, aside from synchro problems, are very reliable. But getting one in your older EF cable-operated transmission-bodied chassis is a big project.

The first challenge is that the EF chassis lacks firewall provisions for the hydraulic piston needed to operate the hydro transmission's slave cylinder. Those with talent and time have mounted one on the inside of the firewall and made a custom clutch pedal mechanism to drive it, but that's beyond what Honda Tuning preaches.

The next challenge is the mount. The newer tranny has a slightly different setup so a bit of welding and fabrication would be needed to make it bolt in. Finally, the speedo sensor can be a problem, but of them all, this is the easiest to conquer.

With so many of these stronger hydro transmissions laying around the junkyards, it was only a matter of time before someone created a complete kit to help EF guys make the swap. When it comes to Hondas and complete kits that someone is nearly always Hasport. The big name in swaps now has a complete bolt-in kit for any of the fanatic D-series guys who feel the need to swap that hydraulic tranny into their EF.

The swap you see here is the most unique and includes a few extra parts, but we'll be sure to make note of what you need if you simply want to put a newer Civic Si hydro tranny in your older EF Civic Si and call it a day. This car is a dedicated drag car and has a ZC twin-cam engine but retains the car's original transmission. The extra is a JDM-only LSD that's found in ZC-engined CRXs and Civics. That tranny also uses a half shaft and equal length driveshafts to fight torque steer, unlike the D-series axles we have here that comprise both a long and a short axle setup. This LSD and half shaft can mate easily with any D-series tranny, which is exactly what Hasport has done here.

Htup_0803_01_z+ef_civic_and_crx_hydraulic_transmission_swap+under_car_view Photo 2/17   |   No foreplay here, let's get right to it. The front crossmember should come out because you'll need the clearance to remove the tranny. Disconnect the suspension links and lower arms from the strut forks and then remove the stock axles.

Now onto the swap. First, find your hydraulic tranny. The second and third synchros can be worn on higher mileage boxes so try to get a guarantee. You won't need the slave cylinder or the speed sensor, so don't panic if they aren't there. After that, it's time to remove your cable tranny. All of this requires a bit of work and you'll find that a lift really pays dividends, but then again we've done these on our backs more times than we can count. Remove the front lower crossmember that attaches to the lower suspension links. Then remove the axles from the front hubs by taking off the lower fasteners so the shock fork is free from the lower arm and the axle nuts.

With the axles out, support the underside of the engine around the oil pan area for when the right side mount suddenly goes missing. Remove each of the bolts around the tranny's bell housing first, including the starter bolts. Be sure to disconnect the battery. When that is done, get to work on the right side or transmission mount and bracket. The bracket is a little tricky because there is a bolt under it that will only come out underneath the car.

Once you're sure the engine is properly supported, wiggle the transmission off. If you're using a lift, a tranny support will save the day, but if you don't have one, it's really a two-man job. The transmission is heavier than you think.

For this car, a '96 EX tranny was taken apart and the ZC LSD was installed. This required a ZC half shaft and axles (or '90-'93 Integra), three pieces total instead of the usual two. Next is the speed sensor. The older cars use a cable to drive the speedo, but the newer hydro trannies have an electronic speed sensor. But, luckily for us, Honda in all its infinite wisdom doesn't see the need to reinvent the wheel. The cable VSS assembly will drop right into the hole left by the electronic VSS.

You will need to remove one of the mount studs from the new transmission. The Hasport kit uses a bolt so if you miss this step you'll be dropping the tranny again to fix it. Next, mount the Hasport-supplied cable fixture. This is the new arm for the cable that operates the clutch. Move to the cool Hasport billet bracket. Bolt it to the transmission and it will mate to the stock (or new Hasport) mount in just a few minutes. The front of the tranny is where another piece of billet bolts up for the Hasport clutch operation assembly.

If there is any money left in the budget, now is the time for a new clutch because the tranny is ready to go back on the engine. In this case, the car is also getting a complete set of Hasport mounts and the rear mount gets you a new bracket. If you don't get the complete mount kit, the only mount that is included is the tranny mount. Since your car is likely almost 20 years old, don't you think all-new mounts would be a good idea?

Once the rear mount is swapped, the transmission goes on the engine. The installation isn't a whole lot different from its removal. This tranny is a '96 EX with the ZC LSD and matching axles but a straight EX (or any similar tranny) will bolt right in with the axles you already have. Connect the reverse sensor wires, the speedo cable and the clutch cable.

What makes all this work so nicely is the Hasport billet linkage that makes use of simple physics to operate what would otherwise be a big, hairy man clutch pedal action. With no more effort than a hydraulic tranny, the clutch pedal easily pushes to the floor. For that, we give Hasport an A in physics.

The entire point of this swap was to take a tired and perhaps broken tranny and replace it with a more modern and plentiful unit. The new, stronger mounts, and maybe even an LSD, can be part of the game and for hardly any more time you can also have a new clutch. This ought to make the D-series guys happy again.

By Tim Kelly
23 Articles

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