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1989 Honda Civic
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20 Posts
Discussion Starter #1
So I have a 1989 civic sedan with the D15b2 and 4 speed auto, simply put im wondering if it is possible to do a swap with a newer automatic D series transmission and what all that would require such as wiring, ecu, ect. I'm not looking to do a manual swap on this car just curious to see what an auto tranny swap would be like since I can't seem to find anything online about it.
 

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93 maybe 94 coupe
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289 Posts
If it's out swapping in a manual is easy, literally the hardest part is dealing with the brake pedal coming out as long as you don't mind being reminded how awesome you are for swapping it every time you turn on your car with an illuminated "PARK" indicator in your cluster.

Pedal swapping aside and back to topic, having had both a b7 and a y8 transmission side to side I see no reason it wouldn't physically swap in easily, but someone else will probably chime in that knows what's up w wiring differences between obd1 and 2

There are differences with the ecu chip so it's gonna be something you'll have to learn about on each vehicle involved in the swap, then make logical choices based on each's wiring but that's no big deal.

I've had problems googling too though, with hundreds of results being unrelated conditions with similar keywords in the discussions, or literally zero results and Google removing keywords for me thus displaying the same results AGAIN.

It helps to broaden your search to the system, and to learn about the how's and why's, THEN searching for individual specific stuff you have questions about. Broad questions give poor results. I'd start by Google image searching for the obd1 and 2 wiring diagrams.
 

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BATSLOMAN GIVES NO FUCKS.
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4,107 Posts
apparently youre not going the fun way. I retract my previous statement.
 

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\/Your Mom Was Here\/
Vibe GT
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4,833 Posts
The only one I could think of that you can run is the d15b7 auto trans. But you would need to MPFI swap and run the d15b7 auto ecu and figure out the wiring side on the trans.

Basically whatever trans you are going to run you need that computer for it, which means you need that engine pretty much, thats why I say d15b7 because with an MPFI swap on a d15b2 is nearly the same as a d15b7 engine.

But that would be a lot of work for no real gain.
 

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CRX ECODiesel Ram
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1,036 Posts
if you want a 91 or newer trans you need to rewire the car to run an obd1 computer. Best thing to do imo is take a look at a 1992-1995 civic engine harness from an automatic car to see the number of plugs that need to be connected and run back to the ecu. If you are up to all that re-wiring then good on you.

the real question on this is WHY would you be doing this?
 

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1989 Honda Civic
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20 Posts
Discussion Starter #8
Thanks for the help! Good idea to just cut down the specifics and go from there
 

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1989 Honda Civic
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20 Posts
Honestly more of a curious question than anything, the car all together only has 100,000 miles on it but the tranny shifts hard, it has no problems getting into gear but it gives you a heart attack every time it shifts. I'm under the impression this car did a lot of city driving if not maybe just a bad tranny from the start or maybe i'm used to newer autos. I had the fluid changed when I got it as well. Manual swap would be fun but for how much I drive in traffic I don't think I would want it currently.

Probably my best option until possibly doing a full swap and at that point i'd do the manual swap as well. Do you know if the 88-91 autos are just normally hard shifting, 80s early autos in general? If so im not that worried about it but if it's also working currently it might be a good idea to get it rebuilt till I can go full out who knows when. I just need reliable point A-B transportation.
 

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Brokedick Millionaire
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40,312 Posts
Your best option is to adjust the shift cable about a half turn. Then check the motor mounts for cracking issues, esp. the front and rear. If the rear mount is trash I have one, but it is NOT fun trying to get to it to swap.

When the trans won't start out in low gear, but does fine putting it in second, then you have problems. That generally happens at 250k miles when it is cold out.

Oh yeah, firms shifts are nice. My 91 EX with a Y8 swap would chirp the tires on 1-2 shift. The person who did the swap had the cable TOO loose an is would slip when hot in track.

PS: Getting to the adjust, there will be a blood sacrifice....
 

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92 cx
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934 Posts
Adjusting that shift cable just right takes a lot of trial and error if you haven't found a focal point, but once you get it just right the thing shifts smooth and grabs well when your in the higher rpms. And/Or change the trans fluid, cuz it's probably never been done before either.
 

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5,880 Posts
Make sure the kick down cable is not overly tight.

the 4th gen autos do NOT like crappy fluid. Since the OEM fluid is not available for you anymore, run something like the castrol ATF that specifies honda/acura. The valvoline multi-vehicle synthetic is giving me troubles in my 97 automatic. Switching to the castrol has proved to be a good choice so far.

engine and tranny mounts, like Transzex above stated, can really exaggerate shifting firmness. The rear mount is a spot of bother, you 9 times out of 10 will need to lower the rear crossmember to access, as very few people have the correctly curved/bent wrench to make it work, and most who DO have one, had to drop the crossmeber their first time.

On my old 1990, I bought 3M window weld from a partsstore and a calking gun, and filled my mounts. remove them, tape one half, fill like a pool, let em sit for 2-3 days to fully cure. Option of buying new mounts and filling only the rear, as the new mounts would help regardless (age is a bitch)

Finally, CV shafts getting loose in the joints will exaggerate shifts as well. My old Del Sol felt like it was shifting super hard, had no turning noise (clicking) to indicate worn CV joints, then left me on side of the road after accelerating from a turning intersection. Had been "shifting hard" for a few months at that point. new CV shafts removed the firmness feeling.

in short, do some diagnosis
 

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1989 Honda Civic
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20 Posts
Discussion Starter #13
Awesome, i'll have to look into the cable trick, I changed the front mount since that was bad. I got the fluid changed when I got it and that was what came up on inspection, ill check the real one as well. Thank you for the help, ill post an update when I can.
 

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1989 Honda Civic
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20 Posts
Discussion Starter #14
So finally took some time to adjust the cable and sure enough that fixed it, thank you all for the help! No idea how happy I am! Hopefully that cable being adjusted the way it was didn’t hurt the tranny much in the long run.
 
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