If you are really interested how the TH400 with the gearvender overdrive unit works on the GS talk with TTurbopimp. He has had it installed for over a year. I haven't heard of any complaints from him about the setup.

 

I will reach out to him but if the GV unit is 4K we are back to 6 speed price tags.

 

You are left no choice but to be a pioneer for the 6-speed stick shift my friend.

 

Yea Hameed I think the truth is starting to set in.

Just out of curiosity I stopped by my local toyota dealer to price a 6 speed. The tranny itself is 6K brand new. So I guess 2500 to 3000 isnt that bad (relatively speaking) for a used one.

I guess my problem is that I have already spent a ton of money on this car and I am at the point where I just want to drive it for a year or two without having to spend any more fixing stuff.

Timing is also bad, because I dont have the kind of cash on hand that this project would require. One of my concerns is that the ECU is going to throw fits when it realzies that the auto tranny is gone. I know we hear that you can fool it but you really dont know untill either someone esle does it, or you spend 90% of the cash get it installed start it up and then find you have problems. Then you start spending again and hope that you can fix it.

I may just throw a stock tranny in for the time being and then see about doing the 6 speed in 6 months or a year, hopefully finances will be better or someone else will have worked out the bugs and answered the questions

 

Morris,

Sucks that you are back to being the Guinea Pig. I have read great reviews about the TH400, but with the amount of power it steals, I sometimes have to question if it is worth it or not.

So how much hp are you putting down right now to need a tranny that can hold 800hp?? Spill it Morris!!

Jonny

 

Well I have been running just under 500 since Nopi last year when I took 3rd place in the 8cylinder and above FI dyno contest. A viper and a blown TA beat me for first and second.

This year I wanted to be able to take first place and I was thinking that 800 should do it. my nerves can barely handle 500hp so 800 would be a one time thing not daily hp.

So my plan was to replace my rods with some forged rods maybe oring the cylinders and dial up the power. But now I begin to question what the point is, if I cannot get a tranny to handle the HP whats the point of spending the money on the forged rods.

Any how I am currently running or will be running off the 6psi spring if I have to go with a stock tranny till I figure something out.

I have pretty much ruled out the TH400, rpms are to high and if you add the overdrive unit the cost is such that I may as well do the 6 speed.

 

After reading the dilemna you are going through Morris, it only makes perfect sense to do the 6-speed stick tranny mod.

It makes sense from a financial standpoint and "winning-the-dyno-ratings-show" standpoint.

Show those Vipers some *** baby!!!!


<chanting>get that six-speed tranny, get that six-speed tranny, get that six-speed tranny, get that six-speed tranny</chanting>

 

Alright, let me chime in with some "real world" answers for you. I have researched my options extensively on this subject, and I settled in with the TH400 and GV unit.

First and foremost.....stop fuggin with the stock tranny, it will never be built enough to handle this kind of power...period!!

In my mind, the best option for me would be the 6spd conversion, but it will not be cheap. Dont get caught up in the price of the adapter plates and cluth, your price will surely rise significantly by the time it is installed. You will pay around 3 grand for a used tranny that you have no idea what kind of shape it is in. Contrary to what others have said, these tranny's break too. So lets say 3 grand, then another $2300 for the adapters and clutch, then another, I dont know, $400 for the pedals, masters, etc, that you need.....you are up to around 6 grand before labor. The labor will be the kicker, your talking about an install in a car that never had the punch outs for the pedals, and that has rarely been done. I have talked to a Very Reputable shop that I have used for my Supras of the past, and we were guessing that at the end of the day we would be looking at between 8 and 10 grand for the entire project....with a used tranny...thats a big *** nut!! Dont get me wrong, I would love to have it, and as much as I have spent trying to get the right combo, I could have had it if the option was that easy back then.

Now to the TH400 set up. Keep in mind that the TH400 is a solid piece, no unboltable bell housing.

You can do it a few different ways. The way that AAP, and most of the other Supra shops do it is this. They take a TH400 tranny and machine the bell housing off. They then make an adapter plate that excepts the Lexus bell housing, and it uses a hybrid torque converter that is made for this set up.

The other way is to use the entire TH400 tranny without having it machined, and use an adpater plate that mates the tranny directly to the engine. This set up uses a straight TH400 converter. I know this is the way that MSP (Paul Efantis) does his TH400's in the Supras he builds.

I have had 2 TH400 set ups, and changing to the second one was a waste of cash. The first one I went with the second option, I used the TH400 tranny complete, and the adapter set up. I changed it after about 30 miles to the AAP set up thinking I was getting something better......basically because my boy Mitch was getting it. To be honest with you, I should have stayed with what I had. Not that the AAP one isnt good, because it is, I just dont think I gained anything by changing. The AAP and others like it will set you back between 4 and 5 grand. I bought my first tranny from a well known domestic tranny builder in my area. The tranny set me back under a grand, fully built with a reverse valve body. You can get the converter from Pro Torque for something like a grand.

GV unit.......its expensive but you will need it for highway driving. I have had no issues or complaints, it does what its supposed to do.

If you get a local guy to build you a tranny for around a grand, then get the converter, the adapters, and the GV unit, you are still waaaay less than the other options and it works great. If you are into racing, you cant beat the TH400. It is seemless in shifting and you lose no boost or momentum while doing so. I raced my boy in his 6spd Viper GTS, everytime he shifted I gaind about a half car length on him. It is a great racing tranny that will handle anything you throw at it, and it is in expensive to get one built if you look for a domestic shop. I can turn you on to the guy here in Maryland that built my first one.

If you want to go this route, I have some stuff that will get you half way there. I have the adapter kit for using the complete TH400. It comes with the adapter plate, a spacer plate for the converter, a drive shaft adapter plate, and the adapter for the nose of the converter. I also have a brand new B&M Hammer shifter that was with my original set up. All you need is the tranny and the converter and you are good to go. Oh, you will have to get a custom driver shaft made, but they are cheap. If youre interested, or have other questions feel free to PM me for my phone number.

Good luck with it......

Jeff

 

Jeff, you are the man!

I just got in and am tired as all out doors but I will hook up with you in the AM.

Thanks Morris.

 

so why not use the 4l80e then??? that would give you the best of both worlds, power handling and driveability. and also, does the GV really cost that much??? i thought i heard it was under a grand for it???

 

The GV are around 2K-2500 from the pricing I have seen.

But now I have a bigger problem, I have been running off the SAFC for engine management. If I do a tranny swap I have to go to a stand alone I'm guessing because the stock computer will have a fit without the Lexus tranny being attached. This once again pushes the cost out of reach for me.

Unless of course someone finds out how to fool the ECU into operating without a Lexus tranny in the car

I guess the only reason I hadnt considered the 4l80e was because I havent even heard rumors of someone doing it with a 1uz. At least I know a few people that have actually done a TH400 in a GS.

But you have a point if I am going to be guinea pigging again (big if) it may not really matter.

 

the 4l80e is basically just an electronically controlled th400. i havent put them side by side yet, but i would have to imagine that they both have the same bolt patterns on them, so anything that would work with the th400, should work with the 4l80e. not only that, in stock form they can handle a TON of power. friend of mine was putting down over a 1000whp through his, with only a shift kit, and converter, and thats in a 5000+ pound truck.

 

I can second that truck, it's impressive to see a truck run in the 10's with stock tires in 4wd Hot Rod did an article outlining some of the benefits of the 4L80 and they specifically said that it's big, can can handle about anything you could realistically throw at it. BTW, the bellhousing pattern is the same. I am really interested into looking into this option as well, just don't have the time to properly research it right now. Good luck!

 

i think that is really the only drawback with the 4l80e, is its size. i saw one side by side with a th400 at SEMA and it was bigger, but not a ton. i have heard with the supras though that you need to "enlarge" the tranny tunnel a bit to fit it, so i'm sure the 4l80e would take a bit more work to get in.