[philip1000rr]

I recently paid off the car, so I'm moving forward with something I have wanted to do since I bought it. The car is a 2014 Accord EX-L V6 Sedan, and I am going to yank the automatic transmission out and replace it with the 6-speed manual. As far as I can tell this might be the first time this has been done on this car so I'm not finding a lot of exactly relevant information for this project. But I'm going to go ahead anyway and make it up as I go. I got other ways to get around town so it's not a big deal if the car is down for an extended period of time while I tear into it and fix the bugs that will inevitably pop up along the way.

I found a 6MT transmission from a 2012 accord V6 coupe at a local auto recycler. I'm gonna start with that. In addition to the used transmission, it looks like I'm going to need:

- new axles
- new front and rear engine mounts
- new transmission mounts
- new clutch pack
- used clutch pedal
- used clutch master cylinder
- used manual transmission brake pedal
- used shift linkage
- used flywheel
- used starter motor

I am worried about the wiring harness and ECU. My original plan was to take the 6MT engine wiring harness from a donor V6 coupe and ECU and move it into my car along with the transmission, but it looks like the V6 sedan and V6 coupes actually have different revisions of the J35 engine. The V6 sedan has the J35Y1 (VCM) and the V6 coupe has the J35Y2 (non-VCM). This makes me worry that the 6MT ECU for the coupe’s J35Y2 may not properly drive my sedan’s J35Y1.

So now my current plan is forming around leaving the sedan’s automatic transmission ECU and wiring harness in place and running it with the manual transmission. This poses its own problems, but I think I can solve most of them. The car won’t start unless it is in park, but I figure I can rig that sensor to my parking brake so the ECU thinks it is in park and will start with the brake engaged. The rev limiter is set to around ~5,000RPM in park, but that problem also goes away if the park gear sensor is rigged to the parking brake – let the parking brake down, ECU thinks it is out of park and in drive.

Question: If I leave the current ECU from the stock automatic transmission powered car in place with the manual transmission, what kind of check engine codes should I expect? Will this generate any check engine lights for missing sensors from the missing automatic transmission? Are there any easy ways to bypass these missing sensors?

Couple of pictures of the car before I tear into it:

 

[meowcat]

Save yourself a lot of money and a lot of headaches. Ditch the 6 speed manual transmission idea. What you'll need, and what will save you a ton of money (and I do mean a ton) you will need to find a doner car, a V6/6speed coupe and rob it of its entire drivetrain. You'll need everything from brake rotor to brake rotor, including the sub frame and clutch hydraulics. Oh, you'll need the complete engine and transmission wiring harnesses and ECU's, also, as well as a few interior pieces. This alone is a monumental task. Good luck with it. Trying to replace just the transmission? Yea, not going to happen unless you have $$$$$.

 

[200366HFP]

You forgot to add having a second car to drive for the months if not years you try to make the swap work.

Do a search of the one or two attempted AT to MT swaps over the past 10 years, and you will quickly change your mind.

 

[sub786]

0-60 from 6 sec to 5.6 sec I think thats what you are aiming for . Then it is not worth it. If you are too much into speed game then get sports car. Like your ride...

 

[RickBlaine]

Spend five minutes and research the monthly "Auto to Manual swap" threads. And you are doing it between two different generations of Accord?!?! Anyone with determination, disposable income, and ability can "make it fit"- but it will never run well.

For a 1978 Datsun 280z it would take you 3.5 hours in your driveway with basic hand tools. No computer, no wiring harness, just bolt off/bolt on.

Edit: You will need to fabricate new engine/transmission mounts too. Not just the mounts themselves, but how the mounts connect to the subframe.

 

[philip1000rr]

You'll need everything from brake rotor to brake rotor, including the sub frame and clutch hydraulics. Oh, you'll need the complete engine and transmission wiring harnesses and ECU's, also, as well as a few interior pieces. This alone is a monumental task. Good luck with it. Trying to replace just the transmission? Yea, not going to happen unless you have $$$$$.

The car is paid off now so I'm not worried about the cost. The budget right now looks to be around $4k, which is doable.

I was worried about the subframe and front end parts, but the part numbers are mostly the same.

The subframe and front knuckles are the same. The side rails are also the same, forgot to put the part numbers in there. The lower control arms are different, which is interesting. I'll be looking into the control arms closer soon. From what I can see from pictures of the two control arms, they look the same. The difference appears to be the coupe has an attachment point for something that mine doesn't have.

51350-T2F-A03 (coupe)

51350-T2A-A03 (sedan)

I think I can get away with re-using my control arms. I already know the subframe is the same, so I know both sets of control arms can bolt to my chassis. I'll know more when I slide the manual axles into them. There may be some subtle geometry differences that won't be obvious from pictures.

Already have the interior part numbers on order. Shift linkage, shift mechanism, shift boot, and 2016 sedan MT shift knob. Clutch pedal assembly has already arrived. That just about wraps up the interior parts.

You forgot to add having a second car to drive for the months if not years you try to make the swap work.

Yeah, I'm expecting this to take a few months. I got other ways to get around once I tear into it.

0-60 from 6 sec to 5.6 sec I think thats what you are aiming for . Then it is not worth it. If you are too much into speed game then get sports car. Like your ride...

Not interested in 0-60 time. I just want to shift my own gears again. Been planning this since I bought the car and have had nearly 4 years to sleep on it.

You are doing it between two different generations of Accord?

The only part I am sourcing from a 2012 accord is the transmission. The transmission did not change from gen 8 to gen 9, at least. It may even be the same transmission as the 7th gen accord, but I'm not sure about that. I stopped looking after I found a good condition 2012 transmission locally.

You will need to fabricate new engine/transmission mounts too. Not just the mounts themselves, but how the mounts connect to the subframe.

I don't think so. The subframe and frame rail part numbers are the same between my sedan and the V6MT coupe.

Pedals arrived over the weekend

Took out the seat to get a better reach under the dash - also a good time to vacuum under the seat

Old brake pedal needs to go

Mocking up the new pedals

New brake pedal mounted

Ran into the first obstacle of many to come. I had originally felt around the firewall and thought I had felt some punchouts to mount the clutch pedal. Unfortunately I felt wrong. When I got under the dash I was greeted by nothing but blank firewall, so I wasn't able to test fit the clutch pedal. No big deal, transmission isn't here yet, was just starting out with some test fitting. I am going to need to remove the dashboard to drill holes for the clutch pedal and clutch master cylinder. That job is going to wait for when I begin working on the swap proper.

I'm still in the parts accumulation stage of this project. I am picking up a used transmission from a 2012 accord V6 coupe tomorrow. A more solid plan is also beginning to solidify. I am building an excel spreadsheet of parts that I will need to order from honda new vs what I will be buying used from salvage yards.

At least it's not raining out anymore.

 

[cargopusher]

The car is paid off now so I'm not worried about the cost. The budget right now looks to be around $4k, which is doable.
Yeah, I'm expecting this to take a few months. I got other ways to get around once I tear into it.

Not interested in 0-60 time. I just want to shift my own gears again.

If you don't care about cost then I have to wonder why you drive a Honda Accord.

You aren't concerned about 0-60 performance and the only benefit from making this change is to row your own gearbox, so it would be more sensible to trade your car for a 6MT Accord Sport.

What you propose amounts to a major engineering effort for a team of people, let alone one person. Sure it can be done. But if you want it done correctly (and street legal) it will probably take years to get everything right, by which time you might lose interest after plowing lots of cash into a family cruiser.

Been planning this since I bought the car and have had nearly 4 years to sleep on it.

I think most people would be less surprised with your ambitions if your aim was to build a high performance car for the track, but it seems like a waste of money if all you want to do is swap the AT for MT.

 

[BLCKFLSH]

Been planning this since I bought the car and have had nearly 4 years to sleep on it.

You either need to sleep on it a few more years, or wake up, because you're dreaming.

You are going to sink $4000 more into this car, and drastically reduce it's value at the same time. Hope you don't total it soon after you get the swap done (IF the swap is ever completed).

Good luck anyway.

 

[14v6]

Great determination on your part but remember that there is no VCM on the coupe manual V6 and IIRC, the engines are different and have different part numbers for other reasons in addition to the VCM. Even something as simple as putting paddle shifters on the EXL-V6 sedan from the coupe was never pulled off AFAIK. I think you will have a lot of engineering headaches ahead, and who knows how it will even run. Meowcat makes a lot of sense in suggesting to get a donor drivetrain and ditching your current engine and transmission.

 

[drowned12]

Great determination on your part but remember that there is no VCM on the coupe manual V6 and IIRC, the engines are different and have different part numbers for other reasons in addition to the VCM. Even something as simple as putting paddle shifters on the EXL-V6 sedan from the coupe was never pulled off AFAIK. I think you will have a lot of engineering headaches ahead, and who knows how it will even run. Meowcat makes a lot of sense in suggesting to get a donor drivetrain and ditching your current engine and transmission.

I'm fairly sure someone did manage to get paddles into a sedan but I don't remember if it fully worked or had quirks. I thought it wouldn't work at all so I was surprised.

Agree with assessment that if you want to do a swap you need to rewire and re-powertrain your car to be a coupe in a sedan body. The days of swapping this and that into a computer-on-wheels are over. I'd love to spend $10k and drop a 2.0T crate engine into my car...but it would probably break everything else in the car from wiring and ECU being completely different. Honda loves to do little changes (like VCM vs. no VCM) that would insta-break a direct swap.

 

[BLCKFLSH]

What about the MICU and the gauge cluster? They communicate with the automatic shifter, so what happens when it's not there?

 

[ethan2014]

Although your shopping list looks good, I also agree with meowcat on a donor drive train. The biggest obstacle is the ECUs between the manual and automatic. If those don't work out, the CEL will become the biggest problem. Smog check stations will give a visual fail before they do any emissions testing.

I suggest you seek guidance from different mechanics before your project becomes a track car only. Your car looks great and if successful it will make it "an incredible machine." We're all hoping it works out for you. Everybody knows Cali has the best modded cars on the planet.

 

[philip1000rr]

I think you will have a lot of engineering headaches ahead, and who knows how it will even run. Meowcat makes a lot of sense in suggesting to get a donor drivetrain and ditching your current engine and transmission.

Finding solutions for all the random problems is going to be half the fun of this project. Good thing I know how to pretend to be an engineer.

Ditching the J35Y1 for a J35Y2 is an option but I'm going to keep it in my back pocket for now. Gonna try stock J35Y1 + 6MT first and see how far I can get with that before I resort to a full engine swap.

It looks like I might be able to flash a manual transmission base map with something like KTuner and disable the automatic transmission sensors along with VCM. Here's a forum thread where somebody in a 06 TSX had used an automatic ECU and the thing immediately flooded full of check engine codes from missing transmission sensors. They were able to flash to a manual base map and they all disappeared. I know it's a different car with different features, but I think that's exactly what I'm going to need to get this swap to work. I've emailed the KTuner guys to see if I can expect the same thing in my application. Would be really nice if this problem went away with a quick ECU tune.

View topic - 2006 - CELs using 2007 AT ECU

Also found some more answers to questions I had previously. When I was comparing the parts numbers for engine and transmission mounts, I had noticed that the 6MT J35Y2 coupe had different front and rear engine mounts than my J35Y1 automatic engine uses. Turns out my J35Y1 has active engine mounts because of the VCM cylinder disable feature, and the J35Y2 has solid mounts because it doesn't have VCM. So that explains that.. I'm going to try re-using my active mounts and see what happens.

Although your shopping list looks good, I also agree with meowcat on a donor drive train. The biggest obstacle is the ECUs between the manual and automatic. If those don't work out, the CEL will become the biggest problem. Smog check stations will give a visual fail before they do any emissions testing.

I suggest you seek guidance from different mechanics before your project becomes a track car only. Your car looks great and if successful it will make it "an incredible machine." We're all hoping it works out for you. Everybody knows Cali has the best modded cars on the planet.

Thanks man. We got some great roads to go with our great cars, but it's offset by CARB in a big way. That's the end goal here - not just a manual transmission in this sedan, but a manual transmission that behaves like it's supposed to be there and can pass smog. So the end goal is for the car to drive fine without any CEL.

 

[ethan2014]

Like shot caller @RickBlaine said the bolt-on bolt-off was doable in the old days. It's just cars today are run by computers. Sometimes I hate new technology. I miss the 1990s when it was more simple to do these projects. Good luck little brother!

 

[200366HFP]

Well, at least you've started with the easy stuff, like mounting pedals. Oh wait, you found that's not going to be so easy either.

Good luck, you're going to need it.....

 

[Elias]

Subscribed!

Good luck! Take lots of pictures. If successful please do an in-depth write up!

I want to do this for my AT coupe in a few years when there are more donor cars available (and when they are cheaper)

Also, everyone should try being a little more encouraging. Obviously he knows it will be hard and expensive! Let him go for it! There's too much negativity on the forums...

 

[17wop6mtcr2]

OP, props to you for undertaking this build. As you can already see, you will receive a lot of hate and doubt but it can be done with patience and money (it will take more than 4 grand btw - even if you perform most of the labor yourself). Your car is paid off....do whatever you want to it. It seems like you’ve done quite a bit of research as well so that’s a plus.

I was going to finally start a turbo build for my i4 Accord but ultimately gave up on the project. I did, however, end up finding a shop that has worked on Honda K/F series turbo builds who said it can definitely be done (via kit + fuel upgrades + a custom 3” exhaust) and really was willing to work with me. I was torn between giving them the ok on the build or paying the car off this summer but I found out I’m continuing school in the fall so I had to be an adult about it and do the right thing. Good luck with your build! Looking forward to seeing the progress. Also, pedal mounting/placement was probably the last thing to focus on haha

Edit: what are your wheel/tire specs?

 

[RickBlaine]

Drama

Negativity? Hate? Are you kidding me?

No one hates the OP- they are just pointing out that all these stories of an Automatic transmission to Manual transmission swap- in late model cars, is doable but extremely inefficient, costly, and never seem to run well. Spend one year on this forum- do you think that "HOPE" is a plan?

They all start with enthusiasm but end as yours did, @17wop6mtcr2

You mentioned you found a shop that will "work with you"....many shops will work with you if by "work with you" you mean "take your money" and never complete the project.

Once again- is it possible? Yes.
Has anyone here done it on a late model computer, -er, I mean car? Yes, the physical swap was completed, but the car never ran well. Sensors get deleted, some things are not compatible, computers freak out- even wiper motors won't operate. Weird stuff happens.

This isn't hate....it's caring.

 

[drowned12]

This isn't hate....it's caring.

Well...I hope people are successful in their attempts, but I've seen dozens of threads of "going to swap this into that" and the floppyflop dude is the only one to actually just go and do it (although I have a separate beef with that guy for marketing turbo kits as a doable thing and then leaving out the death-by-a-thousand-details that'll bloat the time and cost way beyond the sticker price).

Pretty much you're either young, stupid, and too poor to do it -or- you're old, less stupid, and realize it's a waste of money to do.

 

[x2aws]

I'm fairly sure someone did manage to get paddles into a sedan but I don't remember if it fully worked or had quirks. I thought it wouldn't work at all so I was surprised.

Agree with assessment that if you want to do a swap you need to rewire and re-powertrain your car to be a coupe in a sedan body. The days of swapping this and that into a computer-on-wheels are over. I'd love to spend $10k and drop a 2.0T crate engine into my car...but it would probably break everything else in the car from wiring and ECU being completely different. Honda loves to do little changes (like VCM vs. no VCM) that would insta-break a direct swap.

That was me, and yes, worked with zero problems. If you are going to go as far as swapping, don’t try to butcher anything, get the correct harness, parts, etc....

Its those people that try to reinvent the wheel that run into issues. If you can buy the part, buy it. If it wont fit or you cannot buy then build it. Its those people that skimp out on buying the part that try to reverse engineer everything that throw money down the money pit.