I need help on deciding what tranny to put in my GS400

[TTGS4]

This is my first post here, so dont rip me too bad for my lack of education on this topic! I have searched both here and numerous other sites and Im getting mixed information that doesnt match up. The info I have read on this site seems to be the most detailed and informative, but I am having troubles following what cars are what with the different names overseas.

I have a 2000 GS400 that I am doing a Twin Turbo set up on at the moment. We are looking to get in the mid 600's with a fully built motor, etc, etc. We are trying to address the tranny issue at the moment, and we had the suggestion of going with the Supra TT automatic tranny...which has been built successfully to handle tons of power. I guess the question is what tranny is the one to go with, the A340E is what I have told locally.

I have a few options lined up for a tranny, one that came out of a 1JZ ( im assuming this is the equivalent of a Supra??)....I was told that it is a A340E.

Then one out of a 95 SC400, that the seller thought was a A341E.

My concerns are both with wether iM getting the right tranny to build, and if IM going to run into other issues such as the ECU not working right, the spline being different (both in number of grooves and lenght, driveshaft, TQ converter, etc, etc..

Any light that can be shed on this would be greatly appreciated.

I have searched this out, I have seen that the Supra TT has an A341E on some sites, then an A340E on others. I have also seen this for the SC400.

Thanks in advance.

 

[Lextreme II]

The 2000 GS400 doesnt havent 340 or 341E. After 1998 Lexus car got 5 speed automatic tranny. The code number is 350E. Please check here http://www.lextreme.com/transmission.htm. The best person to talk to is Chris Anderson or Carlos Romaris. They are from www.anderson-audio.com They have resource to build you a unbreakable tranny. The have done one in a Twin Turbo SC430 which is the same tranny http://www.lextreme.com/forums/showthread.php?t=1052.

Good luck and welcome to your forum. Where you will find lots of great info and people about the Lexus-Toyota V8 Engines. Please keep us updated with your project.

 

[TTGS4]

Thanks for the info Lextreme. I know the tranny in the GS4 is a 5 speed, what I was going to do was switch it to the 4 speed A340E, since there are a ton of people out there that build them to be damn near bullet proof. It is my understanding that the 5 speed that is in my car does not have all of the aftermarket parts available to fully build it (clutch packs). I will touch base with the guys that you mentioned and see what they recommend.

Thanks

 

[TTGS4]

After reading through the link that you posted for the gear ratios, etc. (which is exactly what I needed by the way, thanks), I am still confused on two things.

One, what exactly is the difference between the A340E, and the A341E?

Also, the Supra TT is listed as running the A340E on the top where the gear ratios are listed, then its listed as an A341E on the bottom chart that has them tranny per vehicle laid ouot. THis is exactly what I ahve been running into at other sites as well. Which one does it run, and does it really matter...are they pretty much the same tranny?

What does a 91 1JZ GTE run, I have someone that wants to sell one to me that says its a A340E....and what would the gear ratio be?

 

[Lextreme II]

The 340 and 341 is pretty much the same except the have different gear ratio. The 340 E which is used in SC400 have more aggressive gearing the then LS400 which has 341E.

I wonder why would you want to run 340 or 341 in your 350 equipment car? You might have to modify the drive shaft or bell housing and so on. Beside the physical changes, possible sensors and plugs need to modify too.

 

[TTGS4]

the only reason that I am contimplating the change is the fact that the 340e can be fully built, where as the 5 spd tranny cannot be "fully" built. It can be built, and I know a guy that has 500rwhp on a built one that has held up fine....im hoping to be int he mid 600's though, so who knows if it will withstand the punishment without being "fully" built. I am starting to wonder if its worth all of the trouble though, I know there will be other issues involved in the swap that I dont know about right now.


By the way, that SCTT is absolutely sick! I printed those pics out to take to my guy tomorrow. I might have to copy there design on the fabrication and placement of the turbos.

 

[Lextreme II]

Ask for Chris and tell him you are referred by Me.... David from this site. The SCTT has the same tranny as yours. I have seen this SCTT in person in Altanta. Its lots of work. Have you thought about Single Turbo? Much easier.

 

[cseufert]

the only reason that I am contimplating the change is the fact that the 340e can be fully built, where as the 5 spd tranny cannot be "fully" built. It can be built, and I know a guy that has 500rwhp on a built one that has held up fine....im hoping to be int he mid 600's though, so who knows if it will withstand the punishment without being "fully" built...

Umm, have you had a look at the differences between an A34xE & the A350E. From what i understand its the same, Toyota has made a 5th ratio (new 2nd gear), by engaging the Overdrive unit with 1nd gear, to get a lower ratio 1st to use as 2nd gear, and then 3rd, is what 2nd would be in a A34xE type gearbox.

Im not sure about the parts that are different, i know the A350E has electronic pressure regulation, where as the A340E used a cable that ran on the back of the throttle butterfly, it also has a 2nd speed sensor between the O/D unit and the rest of the gearbox, plus the A350E has 6 Solonoids, which will make the A34xE gearbox electrically incompatible with the factory ECU. (A340E uses either 3 or 4 Solonoids).

oh, have a look here, esp the pdf links
http://www.mx83.com/a350e automatic.htm

 

[TTGS4]

Thanks for the info. I have seen the side by side comparison as to what aftermarket clutch packs, etc. that are available for either tranny. I have not gotten into the depth of the differences betweent he two as far as the elecrtrical aspects of it all. It seems like the best bet is to build the A350E as much as possible and hope it holds.


Thanks again.