JDM Transmission ?'s

[lordnikon_04]

so i badly need a new tranny. i've heard quite a bit about the jdm switchable transfer case transmission and it caught my attention very quickly. does anyone have any opinions and/or experience with this tranny? and does ANYBODY know where i could possibly find one. i have been all over the net and can't find anything. any help and opinions will help me immensely. thanks.

 

[alex99gst]

I found a member by the name of "stompk" that claims to have one. There is a start.

 

[ian7321]

Just so you know the JDM galant switchable x-case is weaker than a standard one.

 

[staticbrainwash]

Why switchable? I never understood the draw to make an awd car a fwd.

 

[GVR4592]

Why switchable? I never understood the draw to make an awd car a fwd.

It wasn't meant to convert the car to fwd or rwd. It's just a differential lock, and people remove the driveshaft or axles to make it fwd or rwd.

Be careful with the jdm transmission's some of them have lower differential gears than the U.S. transmissions. They won't work properly in an awd car unless you switch out the rear diff as well.

Edit: I was wrong about removing the axles or driveshaft, the transfer case is switchable between fwd and awd.

 

[staticbrainwash]

Yeah, i know it is switchable. I just don't get what the draw is, at all. Mileage can't be that different btwn the two.

So why, you'll spend way less i'm sure on a new awd transfer case and tranny than a "jdm switchable".

 

[danielbui]

for DYNO TIME!! its easier to to swtich the JDM tanny over to FWD for dyno tuning or horsepower calculations. alot of guys are wanting this if there state doesn't have an AWD DYNO. like for instance my state doesn't have an AWD dyno, so one of the shop owners here bought one for that purpose. yeah it wouldn't be used alot but for him its nice to have. he makes 535hp to the Front wheels and it still holding strong.

So why a new tranny? is that cheaper than calling TRE and getting there budget tranny rebuilds?

 

[staticbrainwash]

The drivetrain loss you experience from FWD to AWD is a little bit of a difference. So that FWD dyno # isn't entirely accurate to judge an AWD's #'s. I understand it gives a little bit of a baseline, but i just don't see the point of spending so much for a JDM(which will probably need to be rebuilt anyway) when you could just rebuild your current trans/TC and call it a day.

 

[danielbui]

Understood about the drivetrain loss and others probably aswell. but like some areas of the US there is not a AWD dyno's available and some people are not willing nor do they have the time to leave state to get on a AWD dyno. and on the price, the DSM shop here does tranny rebuilds. so for him it was next to nothing. but yeah price for the normal DSM'ers it would be expensive for the price of the tranny and then sending it off for rebuild.

it also seems that people in general will buy used trannys and run them until they die without rebuilds. its getting even more commen then before.

 

[WatchItExplode]

D00d! With FWD you can go tray sliding!!! Can't do that with AWD!

 

[staticbrainwash]

You're kidding right? Do you care about your car at all?

I would never "tray slide". Learn how to drive the car and you can slide SAFELY without the help of plastic.

Maybe it's cost effective for you to get a JDM with your hook-up at a rebuild place. But yeah, It's just not cost effective for most people to go with a switchable. Honestly, i'd rather have an "UBER" AWD dsm that has no dyno #'s and is just a beast, than going with a switchable and not getting the specific dyno # for the AWD. Thats just MHO though.

If you bought an AWD car, i just don't see the point of making it FWD just to Dyno. You can tune it easily without a dyno, so thats no excuse.

 

[GVR4592]

You're kidding right? Do you care about your car at all?

I would never "tray slide". Learn how to drive the car and you can slide SAFELY without the help of plastic.

Maybe it's cost effective for you to get a JDM with your hook-up at a rebuild place. But yeah, It's just not cost effective for most people to go with a switchable. Honestly, i'd rather have an "UBER" AWD dsm that has no dyno #'s and is just a beast, than going with a switchable and not getting the specific dyno # for the AWD. Thats just MHO though.

If you bought an AWD car, i just don't see the point of making it FWD just to Dyno. You can tune it easily without a dyno, so thats no excuse.

A proper dyno tune with a load holding dyno is far superior to a street tune any day.

 

[staticbrainwash]

Maybe so, I would be stupid not to know that.

But to tune an awd car in a FWD or RWD stance is just dumb. The car will react differently in the different drivetrain variances. And also, you will have different losses for the rest of the AWD drivetrain that you can't directly account for when just tuning or testing on a front or rear dyno.

 

[GVR4592]

Maybe so, I would be stupid not to know that.

But to tune an awd car in a FWD or RWD stance is just dumb. The car will react differently in the different drivetrain variances. And also, you will have different losses for the rest of the AWD drivetrain that you can't directly account for when just tuning or testing on a front or rear dyno.

I agree with that, tuning an awd as a fwd or rwd is a waste of time.

 

[silver eclipse]

You tune the engine with a dyno, not the drivetrain. the tune should be no different wether its awd or fwd. if you do some thing to make more power on a fwd it will make more switched to awd.

The only reason i personelly would have a switchable is to get good hole shot launches at a drag track with awd or rally, then disengage it for high speed or rolling start type races because fwd is better at those types of racing.
-Chad

 

[staticbrainwash]

How do you make more power AWD than FWD? You don't understand how things are set-up my friend.

You have A LOT more drivetrain loss being AWD than FWD. It's proven. Look it up.

I understand the draw to dyno tune. It heeds more power than street tuning, BUT it isn't the same. Hence the issue with drivetrain loss. Not to mention the switchable tranny's and TC's are inherently weaker than a stock AWD tranny and TC.

 

[silver eclipse]

Just to clear things up, i know that AWD doesnt make as much power to the wheel, but its not gonna change a tune of the engine, the engine doesnt react differently to an injectore cycle, or cam degree just because it has a transfer case. What im talking about is like hooking an engine to a engine dyno, you tune it perfect, then you put it in an AWD or FWD its gonna put more to to the wheels in a FWD but not as much as to the crank. Its not gonna change the tune of the engine just because you chose a FWD or AWD. This is to the people that said its pointless to tune an engine set with FWD then turn AWD back on because the tune will be different.
-Chad

 

[staticbrainwash]

OH MY GOD DUDE! I KNOW. The tune will be the same, but the power is different. Thats why i think it's pointless. Sure you make better power dyno tuning, but you have to use an inferior tranny. Or you street tune the shit out of the car, which can't be THAT much different if you're using a good tuner and you use a solid tranny.

I just think it's not very cost effective.

 

[Waredtalontsi]

. Not to mention the switchable tranny's and TC's are inherently weaker than a stock AWD tranny and TC.[/QUOTE]



Do you have proof of this statement or is this your personal opinion? I have been beating on a switchable tranny and t-case on my car since 2003 and its still holding fine. (FYI) This tranny is one of the smoothest shifting DSM trannys that I’ve encountered.

 

[staticbrainwash]

No personal experience, just what i read from other tuners about it. You are the first i've heard that's had an alright time with one.

Like i've been saying this whole time. If you want to be my guest. I just don't think it's cost effective nor worth it. But it's just my opinion, as i would never put one in my car, (if i had a manual trans that is).

 

[GRNDSM]

Well, in that case, let me interject with some personal experience:

1. I have used a switchable transfer case for over 5 years (putting well over 200 passes in the 10.1-11.4 sec range) and never had a problem with it...

2. I analyzed a broken switchable transfer case and compared it to a broken US spec transfer case. The part that usually fails is the same diameter and hardness on both units (thus suggesting that there no material advantage in one vs. the other). However, US shaft is around 2-3 times longer than the JDM shaft and it fails in a different manner: it experiences torsional deformation due to its length, to a point of failure. JDM shaft can not flex, because it is so short, so it fails in a pure shear stress manner.

Without doing some actual experiments, I would guess that the rigid quality of JDM shaft makes it more vulnerable to shock (read: wheel hop), but it is stronger and will be less likely to fail under a uniform load.

As for the tranny itself, it is just OK... It is of similar construction to the 90-91 DSM tranny, so it is not the best shifting tranny (no where near as good as 93-99 trannies), but it is stronger. Also, because JDM trannys usually have low mileage, they tend to shift well, despite the poor design.

And would you guys drop the RWD from this thread! It does not offer a RWD mode!

You have: AWD, 4x4 (locked center diff) or FWD. And none of those modes effect have any effect on your tuning...

 

[DevilSperm]

I have a switchable tranny and t-case as well. For the most part it stays in awd mode. The one time it came in very handy was when I drove my car to the track and broke a rear axle. I put it in FWD and limped my way home. Another time was bolting the driveshaft back up to the rear end and using it in FWD for free spin.

 

[azkikr10]

wouldn't it come in handy if you ever needed to tow your car too? No more waiting for flatbed.

 

[GRNDSM]

wouldn't it come in handy if you ever needed to tow your car too? No more waiting for flatbed.

Or, for that matter, using a 2 wheel dolly on an AWD car!

 

[SleeperG]

It would be nice to be able to set it to fwd only, for a long road trip.
I'm sure the fuel savings would be worth it, with the engine not having to turn the rear wheels and differential.