A342 / 7MGTE discussions

[935motorsports]

I did not see this topic on SM, so I thought I would start it.

Using the A342 (1JZ Auto) on 7mgte has been done, but it seems there is little info on it.

I installed the 1J auto on the 7mgte tonight and wanted to provide some reference for future searches. I am by no means an expert on the conversion, and actually am not very familiar with AUTOs in general.

Most would not think of trying to do this, but I was inspired by a customer of mine who drags his auto constantly. He mentioned that the 1JZ Auto was holding up better then the 7M one, and swears by them.

If you think about it, most 7M autos are high mileage by now, causing the most problems. While 1JZ autos are typically low mileage and unabused. Also, 1JZ autos are near worthless, since next to nobody wants a 1JZ auto.

If I recall I paid roughly $50 for this 1JZ auto with Torque converter.

There was nothing wrong with my transmission, but I had a flex plate problem and while it was out I decided to change over. Here are the things that I noticed during the install into a 91 auto:

- The auto wiring harness plugs all bolt on, 1 plug will not hook up to anything
- For some reason the 7mgte torque converter would not install, I used the 1JZ torque converter
- I changed to the 7M bellhousing
- The 7MGTE flex plate bolted right up
- Shifter and driveshaft, fluid lines, all bolted up, kick down cable worked
- The transmission mount was unfriendly. I got it on, but it was shifted back but a couple of MM making it very difficult to get bolted up



All I did was get it installed. I have not been able to test drive yet, so I will give impressions in a couple of days after it is on the road. Overall, it installed well.

 

[koulee]

50 bux for a 1jz auto w/torque converter that has no problems? Damn skippy.

 

[encomiast]

AFAIK, the A342E from the MKIV Supra is a bit different from the MKIII's A340E, regarding shift solenoids and line pressure.
If this is also the case with the JZA70 AT, you might have a problem there.
From what I've read:
Line pressure: electronically regulated on the A342E (this might be the extra plug you mentioned), on the A340E the line pressure is regulated mechanically through the throttle cable.
Shift solenoids: on the A342E, they are getting a PWM (pulse width modulated) signal to vary shift firmness, the A340E solenoids are simply switched on or off once per gear change.

Soooo.... this _might_ mean you'll have problems with line pressure, and possibly even fry the shift solenoids or have a very rough ride
I don't know this for sure, it's just a heads up....

 

[935motorsports]

We'll find out.

It does have typical kick down cable, mechanical just like ours. Given that this is from a JZA70, that makes me confident that it will work. Also due to the fact that it was reported as working properly in another car gives me confidence.

 

[935motorsports]

Finally got a test drive in. It works really well so far. I don't have a good basis for comparison as I never had a bone stock setup. The previous 7mgte tranny was rebuilt and would shift really hard.

This OEM tranny shifts smooth and soft, as would be expected. It's silky smooth and relatively tame until about 3000 where the hammer drops and things get fun.

The unknown connector is still not connected. I will have to inspect the 1JZ auto harness to verify where it goes. I suspect its either related to manual button on the jza70 OR related to digi dash.

I ended up having to put in nearly 6 quarts of ATF to get the tranny near full. I also added a transmission cleanser to break up the JDM dirt and will do a complete flush this weekend. I'm willing to bet the filter is crap as well.

I stlll have to verify that the power/normal button is actually working or if it is stuck in a single mode.

It's a nice feeling knowing that the tranny in the car now only has 50k miles or less on it.

 

[encomiast]

It does have typical kick down cable, mechanical just like ours.

So does the A342E from the MKIV. On the MKIV, the cable to the tranny is only used for kickdown AFAIK. Hence the term "kick down cable"

Best of luck to you, and please keep us posted on how it behaves after a couple hundred miles
This might be a very worthwile upgrade.

 

[drunk_medic]

Actually, the MkIV tranny is the A340E - it's the same as the MkIII Auto transmissions, except with a different output shaft, one more clutch pack and more fluid capacity. The A342 is supposedly a one-off for the 1JZ.
Still, they must all be from the same family.

It's great to see innovation like this for our auto cars - keep it up!

The A342s ARE cheap, plentiful, generally unwanted, but hold more than regular autos, and I heard that they are geared shorter as well.

 

[Nick M]

The A342s ARE cheap, plentiful, generally unwanted, but hold more than regular autos, and I heard that they are geared shorter as well.

Makes sense with a smaller engine. The A341 for the LS had taller gearing.

 

[935motorsports]

A couple days in, I'm loving the transmission. It's tight and acts like a new transmission.

This weekend I will flush out all the nasty fluid and add fresh fluid with an external cooler.

For the price I paid, I am very happy. Dean reminded me that the JZ tranny had a different spline count, which is why the 7m TQ converter did not work. This is interesting, because it means that *maybe* I could use a 2JZ TT torque converter.

This is my GFs car, so I can't do wild upgrades. But if I can get a 2JZ TT stock TQ converter in, I would be happy. The engine has 205K on the original block, so it is due out at some point.

I did a few manual shifts today, and it did shift faster then I remember on the 7M tranny. After I get the new fluid in, I'm going to try some full WOT manual shifts to see how it acts. The previous transmission ( a rebuilt one ) would take a LONG time between manual shifts at high RPMS.

The final step will be the manual controller from Garrett (latent solutions), so I can shift electronically with a stick that goes up or down (like a video game).

 

[Kristian_Wraae]

Does the ABS work with the A342? I belive the are differences regarding the sensors for the rear wheels on the JZA70 vs the MA70?

 

[JCFsupraman]

I just found this in my search to find what to do with my 7mgte to get the hp up higher.
Any updates.

Also any MK3 turbo autos running the AEM EMS?
If so what else did you need to do and how is it performing?

 

[935motorsports]

I never did update.

It worked fine for over a year, until I finally pulled the engine out.

I found out that the "mystery" connector, was a torque converter speed sensor. This is not used in the 7mgte setup, so there were no issues not having it connected.

The 1JZ auto is a GREAT upgrade for any 7mgte setup. But, it must be a 90+ setup for all of the connectors to bolt on. An 87 type setup might require some changes.

 

[JCFsupraman]

I was told that the 7mgte body is too heavy for the JZA70 auto so I should just keep the built a340e that I have and get the Suprastick and install it stealth mode for just $350 or the PTCS with the paddles and monitor for $600. Did you find the car sluggish out of the hole or off the line?

 

[935motorsports]

Well, I had a 5 speed rear end. It worked great, but there was an odd spot on the freeway, where the Auto was hunting trying to find where to lock. Other than that, it seemed to work fine. From the hole it took off great, but I have never beat on it.

I think that the hunting was due to the lower ratio + the torque converter being different. I always wondered if the JZA70 had a higher stall.

The car should be back up soon, so I'll be looking to put a taller gear back in and see how it does.