(First post ever)

I guess my question is... can I swap the 3.722 FD from my HX transmission into this EX transmission I'm looking at? Is it even possible?

Here is my story:

I'm in the military, so when I got back from basic training I was on the hunt for an inexpensive fuel efficient little car and what better maker to turn to then Honda. I do a lot of highway driving, and where I live is an extremely rural area. I try to never exceed 70mph and my constant speed is somewhere around 60mph.

I ended up finding an 1998 Civic HX w/ 141k on it. 5 speed manual, 100% stock. I bought the car knowing it has a bad input shaft bearing, but I put it off for the past 8k miles since I bought it last fall. Now, I plan on taking the car on a trip out west to Illinois (I live in PA) and that bad input shaft bearing scares me a little knowing that I'll be driving 600 miles one way.

Ive sourced a 91k mile EX box that I've been contemplating on purchasing for $200. The only thing is, I don't want to loose the 47 some odd miles to the gallon I've been getting with my current factory setup. (.702 5th gear and 3.722 FD @23.3 inch tire diameter.) that puts me at 2.5k rpm @ 65 rpm. I'd like to be able to utilize the shorter 2nd and 3rd gear from the EX box but still maintain that cruising RPM.

 

2nd and 3rd aren't going to be very noticeable with the long FD. They've also been discontinued so if they need to be replaced you're out of luck. Changing out the ISB is much simpler than changing the FD.

To answer your question, yes you can use the HX FD in the EX.

 

To make sure it's the input shaft bearing that's the issue - I push the clutch in, no noise. I let the clutch out (at the "bite point"), there is a noise. Like a hissing noise.
I was quoted for a rebuild which is the reason I want to do a swap. But finding a decently low mileage (<120k) HX transmission is frankly impossible for me in my area. I called in a 50 mile radius to me and I ended up finding a DX trans with 100k. Does $150 sound like a good price to you?

 

Price is irrelevant without knowing the condition its in.

A Y7 hatchback (CX or DX doesn't matter, just that it is from a hatchback) is identically geared to the HX trans. The only difference is the bearing sizes in the case which won't have any affect for your usage. They're much easier to find than the HX trans. Check the VIN number from the VIN plate on the trans to see if its a hatchback trans.

 

It's coming from a DX coupe. It will have the 4.06 FD? The car looks like a piece but there is no telling. Thanks for the input, I really appreciate it. Will shift linkages fit right up between the hatch and the coupe? I know switching them is a pain with that one pin underneath the boot on the tranny. Nevertheless, I can always use my own shift linkage.

Thanks again!

 

Using a rpm calculator, I really don't think the DX coupe final drive will hurt my mileage much. I live in pretty hilly terrain so it might help not having to downshift to 4th as often.

 

Non-HB is 4.058. Everything bolts up the same. I would keep the 3.722 FD since the HX uses a lean burn engine. The ECU is designed for low RPM fuel efficiency. Any other engine, higher RPM will usually net better fuel economy.

 

Awesome, the new hunt is on!!

 

this might interest you

Short Gear Ratio / LSD 5 speed - Insight Central: Honda Insight Forum