JDM Trans Swap/Oil Cooler Questions

Accordx · Jun 20, 2019

Hey all, glad to finally be at the stage where I can get to work on swapping a JDM F23a transmission into my Accord. The BMW I've been driving in the meantime has had a ridiculous amount of issues for a car that just hit 100k miles. Anyways, I'm planning on buying the transmission from JDM Orlando (if anyone has purchased a motor or transmission from them I'd love to hear what you think about them). I'm also going to replace the leaky rear main seal while the transmission is off, as well as add a Mishimoto trans cooler (most likely a 10-row) behind the lower grill, which will be ran after the stock cooler and before the new transmission. This is more of a preventative upgrade if anything. I've already looked around on driveaccord and this forum and I've found some good threads related to the cooler and a little bit about the JDM trans but I've still got some questions I'd like to confirm the answers to before I get started.

I've heard the only difference between the USDM F23a1 trans and the JDM F23a trans (in terms of the install process) is the sensors, and as long as you use the USDM sensors/plug-ins it shouldn't throw any codes, can anyone confirm this?

Are there any other seals or gaskets I should look at replacing when I have the transmission off the car besides the rear main seal?

I'm going to be using a plate and fin universal oil cooler from Mishimoto rather than the tube and fin transmission cooler, will I run into any problems since it's not exactly a trans cooler? https://www.mishimoto.com/10-row-oil-cooler.html (link to cooler)

Will I need extra lines to run the trans cooler? Mishimoto offers a kit as well as just the cooler but the kit costs double the price.

Where's a good place to mount the trans cooler?

Is there anything else I should keep an eye out for with this swap/install?

Thanks! Any advice would be greatly appreciated as always. Glad to see this forum is still kickin

Eclipse99fwb · Jun 21, 2019

I will attempt to answer the questions i know for you:

1. The transmission should be the same, the sensors and plugs as well. If in doubt swap your current sensors as need be.

2. As for gaskets replace the rear main seal and both axle seals.

3. Not sure if that cooler will work as a trans cooler. Most common mount places would be in front of the a/c condensor possible use the impact bar. Now yes you would need additional hoses as the stock trans cooler lines wont reach and from the link attach different than the cooler your looking at.
I have seen people run a aftermarket cooler from the stock trans cooler, you would need to determine which hose is the inlet and which hose is the outlet from the stock cooler. Simple pull one hose off, have someone start the car and determine is flow coming from the hose or out of the radiator.
The biggest thing is if you use yhe aftermarket cooler make sure you attach your hoses secure, i see more trans. fluid leaks from either how the hoses are attached or from the coolers fittings.

Hope this helps you out.

Accordx · Jun 22, 2019

Eclipse99fwb said:
I will attempt to answer the questions i know for you:

1. The transmission should be the same, the sensors and plugs as well. If in doubt swap your current sensors as need be.

2. As for gaskets replace the rear main seal and both axle seals.

3. Not sure if that cooler will work as a trans cooler. Most common mount places would be in front of the a/c condensor possible use the impact bar. Now yes you would need additional hoses as the stock trans cooler lines wont reach and from the link attach different than the cooler your looking at.
I have seen people run a aftermarket cooler from the stock trans cooler, you would need to determine which hose is the inlet and which hose is the outlet from the stock cooler. Simple pull one hose off, have someone start the car and determine is flow coming from the hose or out of the radiator.
The biggest thing is if you use yhe aftermarket cooler make sure you attach your hoses secure, i see more trans. fluid leaks from either how the hoses are attached or from the coolers fittings.

Hope this helps you out.

Thanks! Appreciate any help I can get, this is very useful

Xwifesse · Jul 3, 2019

If u get a jdm transmission from Japan as I did u r going to need to use the sensors off the USDM transmission. The shop that did mine used the Japanese Honda sensors and the shifting was s little off my car would jump from a stop and lunge into second. I saved the old transmission and swapped the sensors. There are two if I remember right. When I put them on the car ran as it should.

Accordx · Jul 21, 2019

Xwifesse said:
If u get a jdm transmission from Japan as I did u r going to need to use the sensors off the USDM transmission. The shop that did mine used the Japanese Honda sensors and the shifting was s little off my car would jump from a stop and lunge into second. I saved the old transmission and swapped the sensors. There are two if I remember right. When I put them on the car ran as it should.

Sweet, I'll keep that in mind. Thanks