JDM vs US tranny differences?

[EviLSpydeR]

Hi I’ve try to research the differences between JDM tranny not MR and US tranny but I haven’t had a good explanations. So my questions are what are the differences between the two besides gearings. I want to get a complete JDM engine and transmission to put in my VR4, would it be a straightforward swap or would I have to modify some parts? Also is it better to get a rebuilt tranny or buy used one? And is there anyone shop in PA that you guys would trust to work on our cars?

[Unlogic]

As far as I know the only difference between the US and the JDM/Euro version of the 6-speed W6MG1 gearbox is the gearing of the front differentials.

[CoreyB]

Yes, the 5 speeds are all the same gearing, but the 6 speeds are different from JDM to USDM. As far as I can remember from when I researched this.

Contact Ground Zero Performance | Doing What We Do Best Since 1998 ? Serve, Build & Race (http://www.groundzeroperformance.com/) They are a trust worthy shop.

[Tank]

If I am not mistaken you would need a JDM transfer case, and rear end as well.

Or, you would need to open the JDM Trans, and install the center diff from an american geared trans.

[Unlogic]

If I am not mistaken you would need a JDM transfer case, and rear end as well.

Or, you would need to open the JDM Trans, and install the center diff from an american geared trans.

Transfer case is the same. Either you change the front differential or the rear axle.

[CoreyB]

Transfer case is the same. Either you change the front differential or the rear axle.

And ONLY if a 6 Speed. Did the OP specify 6 speed and I just missed it?

[EviLSpydeR]

IC, thanks a lot guys. Now what do you guys think about the JDM engines and transmission combo they have on eBay? Sounds like a good deal, i've bought 1 for my rx7 awhile back and it ran fine, just wondering if anyone had actually bought 1 and wanted to know how the transmission is like, but they do warranty engine and transmission for 30 days tho.

[CoreyB]

Be careful who you buy from, I have heard both terrible and great experiences. I have a VR4 that has a 40k JDM engine, trans and TC in it. And its great, no problems, but I dont know the company that supplied it as it was done by the previous owner.

[EviLSpydeR]

So CoreyB, do you know if they swap the front differential or the rear axle on your car for the JDM tranny? By the way they'll warranty it for 30 days, so it's not that bad i guess.

[CoreyB]

Didnt need to change the differential or the rear end, its a 5 speed. Warranties are great, but if you do get an engine/trans and something is bad, you are stuck pulling it all back out and shipping it back. Then depending on the company, possibly fighting with them to get a refund or a replacement.

[RealMcCoy]

And ONLY if a 6 Speed. Did the OP specify 6 speed and I just missed it?

I'm still missing it.... What year car are we talking about?

[EviLSpydeR]

sorry it's a 6sp i'm asking about.

[GTOJOE]

As stated above transfer case is the same. Rear differential ratio is the same as the 5 speed so change tail shaft and diff is easier than opening the box to change front diff. That will also most likely void any warranty you have on it.

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[Hans@GZP]

We can help you out. Just give us a call at 610-438-0439

Thanks CoreyB

[Chris@Rvengeperformance]

As stated above transfer case is the same. Rear differential ratio is the same as the 5 speed so change tail shaft and diff is easier than opening the box to change front diff. That will also most likely void any warranty you have on it.

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you don't have to change the "driveshaft", just the rear end.

[EviLSpydeR]

ok thanks guys, lastly how would you know for sure that your transmission is bad, and how would you know if your transfer case is bad as well. My transmission grinds 2nd and 4th when shifting at about 3k rpm and above and when down shift into 2nd, so is it for sure that it is bad?

By the way, i haven't purchased anything yet. I'm asking this so i would know which route to take and which route would be more cost effective. Thanks again

[Unlogic]

Sounds like all you need is new syncros, get some quotes from reputable 3S shops that work on these gearboxes (Ninja, GZP, 3SX, Jacks, Kormex etc).

[GTOJOE]

you don't have to change the "driveshaft", just the rear end.

I was of the understanding that you need to change the last half of the tail shaft/drive shaft. Obviously he would need a jdm diff or a 5 speed one.

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[anyonebutme]

The difference in the driveshafts is only like 3/4". You can use either in either in a pinch and even on a 13t car launching hard no issues were had, other drivetrain parts break before you can strip out the yoke.


BTW, it's the front section that's different.

[Chris@Rvengeperformance]

I was of the understanding that you need to change the last half of the tail shaft/drive shaft. Obviously he would need a jdm diff or a 5 speed one.

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That is not true. The mounting flange and everything else about the rear 2 sections of the shaft is the same. I'm running a 6 speed rear section in my 5 speed car right now.

[Chris@Rvengeperformance]

The difference in the driveshafts is only like 3/4". You can use either in either in a pinch and even on a 13t car launching hard no issues were had, other drivetrain parts break before you can strip out the yoke.


BTW, it's the front section that's different.

Yep, I only changed my front section because there was little room for the yoke to slide into the t-case (it was a 6 speed shaft on a 5 speed setup). Solid or even good poly mounts would probably be fine.

[Chris@Rvengeperformance]

Sounds like all you need is new syncros, get some quotes from reputable 3S shops that work on these gearboxes (Ninja, GZP, 3SX, Jacks, Kormex etc).

If your transmission is grinding repeatably then you have a lot more damage than just syncros.

[Hans@GZP]

Yup. Once grinding starts, you are mashing up the expensive transmission parts. We do sell OEM synchronizers. The hard parts are obtainable, but they can take a couple of months to arrive.