jdm svx trans, will it work?

herffstyle · #1 05-12-2009, 08:21 PM

I have a '92 SVX, the tranny died and i found a JDM svx trans and got it. what will i need to change to make it work. its all bolted in and ready to go but i haven't started the engine yet. i just read that the jdm wont work because of the tcm. what is different? can it be modified?

thanks
Steve

redlightningsvx · #2 05-12-2009, 08:46 PM

I think the gear ratios are differant also but don't quote me on that.

TomsSVX · #3 05-12-2009, 09:30 PM

depends, does the back end of the transmission look any different than the old one?

Tom

oregondave · #4 05-12-2009, 10:50 PM

it needs the jdm tcu as well as it being designed for AWS

oab_au · #5 05-13-2009, 02:07 AM

Yes you will need a 3.7:1 rear diff, and swap the C solenoid for the US one. Then use the US TCU.

Harvey.

herffstyle · #6 05-13-2009, 04:54 PM

Here are some pics of the trannys, the one on the jack is the JDM, the plywood is the US one.

IMG_1300.JPG

IMG_1302.JPG

IMG_1299.JPG

oregondave · #7 05-15-2009, 12:15 AM

Quote:

Originally Posted by oab_au

Yes you will need a 3.7:1 rear diff, and swap the C solenoid for the US one. Then use the US TCU.

Harvey.

Should have kept my mouth shut

herffstyle · #8 05-15-2009, 03:46 AM

where can i find the 3.7:1 gears?

1986nate · #9 05-15-2009, 03:51 AM

Quote:

Originally Posted by herffstyle

where can i find the 3.7:1 gears?

JDM SVX only...

Trevor · #10 05-15-2009, 09:12 PM

Quote:

Originally Posted by oab_au

Yes you will need a 3.7:1 rear diff, and swap the C solenoid for the US one. Then use the US TCU.

Harvey.

Steve, please note.

You must retain the JDM normally open solenoid as well as the JDM TCU. The US TCU might operate after a fashion, but the programming is unlikely to suite the centre diff. set up.

Fitting a US normally closed solenoid will reverse operation in respect of front rear bias. The use of different solenoids, enables the same on/off sequence for the pulse width modulation signal, to be used for both types of transmission. There is no doubt that this is sensible economical design, resulting to several areas of reduced cost, as well as a logical common set up.

herffstyle · #11 07-16-2009, 07:09 PM

I have an update,
everything is installed, tranny, rear gears with SVX LSD.
I drove the car down the road and all was well at low speed, when i needed to turn it felt strange, kinda like a 4x4 truck in 4wd on pavement. So i belive the center diff is locked or something.
I dont really know how the center diff is set up in the JDM.
I am using a US Spec TCU.

other than that it accelerates quickly and shifts nicely.

Anyone have input?
Think the JDM TCU will fix it?

Thanks
Steve

TomsSVX · #12 07-16-2009, 07:13 PM

yes

The JDM trans' center diff works on an opposite method so when the TCU commands FWD the trans will apply AWD. You will need the JDM TCU. Whether it will plug right in is the only thing I am not sure of

Tom

svxistentialist · #13 07-17-2009, 05:48 AM

Quote:

Originally Posted by herffstyle

I have an update,
everything is installed, tranny, rear gears with SVX LSD.
I drove the car down the road and all was well at low speed, when i needed to turn it felt strange, kinda like a 4x4 truck in 4wd on pavement. So i belive the center diff is locked or something.
I dont really know how the center diff is set up in the JDM.
I am using a US Spec TCU.

other than that it accelerates quickly and shifts nicely.

Anyone have input?
Think the JDM TCU will fix it?

Thanks
Steve

Steve

Aside from the debate about whether you should be using a US spec Sol C or a JDM spec Solenoid C, I'm of the opinion you should be using a JDM type TCU to control that gearbox.

The TCU has different maps for each gear

It uses a large range of data inputs to ensure traction works, and that it works in tandem with your ABS. Essentially you are now using [US] maps that vary traction from 10% rear standard mode to 50% rear under hard acceleration which is the US gearbox specs.

These US traction maps are incompatible with the gearbox you now have fitted, which has normal standard distribution to the rear of 64%, varying upwards to 50% under hard acceleration [VTD maps, JDM traction control]

Were you to completely disconnect the signal to Solenoid C, I would suspect in default mode your gearbox should operate permanently at 36% front and 64% rear and be entertaining to drive. I'm wondering if perhaps with the signal your American TCU is getting from the Solenoid C that the incompatibility issue may be causing it to lose its marbles and go to 50/50 lock up?

Also, the symptoms you describe sound like 50/50 centre diff lock-up. Please check if the fuse is inserted under the hood. In the US cars, inserting the fuse causes 100% front wheel drive, and does no harm. With the JDM gearbox, inserting the same fuse locks the centre diff 50/50, and will do harm if you keep driving in that mode.

My best advice is you need a JDM style TCU. Even the UK/OZ type will be less than ideal. It will have the correct traction maps but uses different speed input data.
BUT CHECK THAT FUSE IS NOT INSERTED!

Joe

oab_au · #14 07-16-2009, 08:05 PM

Quote:

Originally Posted by oab_au

Yes you will need a 3.7:1 rear diff, and swap the C solenoid for the US one. Then use the US TCU.

Harvey.

A bit late to do this now, so it is either swap the TCU with its "speed limiter" or do the C swap.

Harvey.

Hondasucks · #15 07-16-2009, 08:26 PM

All you need is a circuit that will invert the signal going to the solenoid. Since on the JDM trans full power = AWD, not FWD as in the US model. Wouldn't be all that difficult, and probably lots easier than getting a JDM TCU. I'm sure I could come up with a circuit that would work, I'd just need some time!