TH400 Swap for an SC400?

[jibbby]

Searching the forums I can't find anyone whom has successfully swapped in an Th400 transmission into a Lexus..This has been talked about before....Anyone know if this swap has been done yet?...I would love to see the results....Does it redline the engine practically while driving on the freeway, and what ECU was used in that swap?

I am getting frusterated with my stock Sc400 auto trans...I lose races because of the tranny...Example: I am cruising at 30mph or so and hit the juice the car rev's like crazy and goes nowhere, I release the gas and it kicks down then I floor it again and it moves...It's almost embarrassing as it is all noise and no go...From a dead start the auto tranny functions well in all gears but racing while moving there is way too much delay with this Lexus auto tranny..I am ready to ditch this tranny....Increased line pressure and shift kits are not the answer either...Building up the tranny for more Horsepower holding capacity is nice but does not help with timely shifting....Maybe a stand alone ECU will help some with shifting, not sure about that either....Any cost effective suggestions for my hinderance?

Don't want the R154 or V160 manual swap either in LA traffic...

I am thinking seroiusly about breaking out the welder and getting into a serious swap with a Corvette/Camaro LS1 engine, ECU, and auto tranny. Then deal with the instrumentation integration...What do you guys think of that swap in an SC400?

 

[WDoherty]

I am thinking seroiusly about breaking out the welder and getting into a serious swap with a Corvette/Camaro LS1 engine, ECU, and auto tranny. Then deal with the instrumentation integration...What do you guys think of that swap in an SC400?[/quote]

i think that would be alot easier and cheaper, there's tons of info on successful ls1 swaps into about everything. But jibby, i don't know how much the auto with ls1's can take, they also swap to th400 for drag, even though you are in l.a., i'd t-56, a 6 speed sc400 baby.

 

[Smitherz]

Yeah quit playing around with those automatics. :hitwithrock: If you want to win go with a manual. I know you want an auto for the traffic you have to put up with but you can't have it all! There is nothing better than popping the clutch and dropping the hammer at full throttle.

You seriously need like 350+ HP to get results with an auto. Now if you put a good ol American auto with a shift kit in it you might make some progress like my boy over at http://1uzfe.com/. He's got the right idea. I would personally go for a C6 as I've built a couple behind some monster engines and they tear it up without hesitation. Take a look at these options fo sho.

 

[jibbby]

WD - Yeah lots of many successful reported LS1 engine swaps going on..That is definetely one of if not the best engine to swap into any car for money......Didn't know the Vette auto trannies lack hp holding capacitiy....Good info?

Smithers - Pop the clutch and roast is not all that...I do that now from idle with the Dragon Torque Converter on my stock auto tranny and Sc400...I hear what you are saying though.....From a quiet idle to roasting tires suprises everyone, and that is kind of a gas......Especially under the NOS, smoke screen city..... Also those manual swaps are not exactly a piece of cake either, maybe the R154 swap is the most cost effective and easiest swap to perform....However the V160 would be my choice but not for 10 grand....I would rather just boy a Supra TT 6 speed used and sell my SC4 instead...Then build up the Supra Motor to my liking.........

I grew up with manual tranny's and I guess I could deal with one, but just not in bumper to bumper traffic...I get pissed, irritated, then if someone cuts me off I lose it, the finger automatiically goes up.......With the auto tranny I am always chill....Auto's aren't bad if you get them dialed in with an awesome torque converter and good differential gearing...

 

[WDoherty]

well jibby i know the a4's that come with camaro's should hold at least some decent power, stock is 280-290 rwhp you'll just have to find out what their limits are. Another good thing about the ls1 a4 is that the programs that tune the ls1 can also control shift points of the auto and compensate for a change in differential gearing which you would have. Another, is that i'm sure there is an aftermarket for these to be built. And you can't use a vette auto tranny because vette's have a torque tube that connects to the engine then goes back to a transaxle which houses the transmission and rear differential. Ever though about selling off the sc and going with a 97+ vette?

 

[jibbby]

WD - We've talked about these LS1 swaps before, it sounds to me like you are jazzed up about these LS1 swaps and maybe heading down that road one of these days...I had my eyes on the LT1 for years and now the LS1, and dream of the LS7... I have measured the swap fits for an SC400, the engine height is no porblem, fabbing motor mounts no problem, width wise it will not fit with the stock LS1 headers..The steering colume is trouble as well with any new header design...In order for that engine swap to happen in any SC some very creative custom flat headers would need to be fabbed...It is doable just need to work out the exhaust design...Custom mounts, alot of welding, custom driveshaft and I think it could be done fairly easy, well let's just say easy for a swap in general..All swaps are challenging......I am speaking about the LS1 and tranny swap together...Then later take the time and work out the instrument integration..Obviously use the LS1 ECU.....I would only seriously consider this swap if I could work out a solid tranny that could hold big HP..Like 600whp or so... Supercharging the LS1's is common...Turbo's not so common.. If the stock tranny holds 300whp your probably safe to ad another 100-200whp, we need to look into this.. The Z06, LS7 tranny would do the trick but that is too expensive.....

I still would not shy away from a Single Garrett exhaust turbo on the 1UZ-FE like LEX has..That is an easy 400wp right their....I have looked over Lex's LS400 setup first hand and it looks very simple and easy to design and install..Not a big deal......Again the transmission issue is what is holding me back from climbing the horsepower latter on this SC400 of mine...

 

[stevechumo]

John,
I haven't driven James's swapped Supra engine & auto tranny yet, but I think the Supra TT auto tranny is quicker and can hold more power than our Lexus SC tranny. If you decide to go for the auto Supra TT, maybe James can help you with an experience. I've driven a '91 single turbo auto Supra before and it's pretty fast. Its auto tranny had no shifting problem whatsoever. Therefore, the later year Supras should be even better. I hope David can have some other shift kits for you that are not as jerking as you've experienced. To me, the jerking from the tranny isn't a problem. The manual trannies of many other cars are even worse. As you know, they jerk at every shifting, but people still love them.

 

[Smitherz]

Jib - You can't give up on the SC4 just yet. I would definitely go the route of the Supra Auto trans. They are desinged with performance in mind. Plus they have been on the market for a long time so the chances of scoring one in a yard are much higher than average. I agree that autos make you a cooler driver. Driving any manual car/truck puts me in Mr. Wheeler mode just like the Goofy cartoon.

 

[jibbby]

Supra TT Auto 93-98 - 500whp holding capacity is what I have read...That does make good sense... I wonder if the TT auto tranny can be worked in with the SC400 ECU transmission codes?....Thanks fellas I will look into this....Fitment might be very similar, the subframes are identical between the two cars, and I am currently running a Supra LSD off a 95 Supra TT auto that bolted up perfect......

 

[jibbby]

Ok good news which I didn't know -

The A341E 1993-1998 Supra TT Auto tranny has the same ECU codes as the SC400 and LS400's... This swap seems too easy to be true....Could it be? I can pick one up today from a 95 Auto TT Supra....I found this info just now......

A341E - 93-98 Supra Turbo transmission ECU codes -

93-97 SC400
92-98 LS400
93-07 Volvo 2.6L (AW30-40LE)

Holding power on these auto Supra trannies are reported to be around 500whp.. Can any one shed a little more light on this swap for me...It would be most appreciated...

 

[WDoherty]

I'm not sure about the tt auto, i bet it is pretty similiar in holding capacity maybe a little bit more. I thought most said it would hold around 400rwhp so that may be a little more or the same as the sc400 tranny. I'm not a big proponet of ls1 swaps in general, it just sounded the only answer for you based on how you always talk about low-end torque and instant throttle response and not liking turbo chargers. Anyway, if you now think turbo is the way to go, which it is the only way to go with the 1uz in an sc400, you should go with it. If you turbo a stock engine, i believe a built engine is going to run you close to 4K, you can leave stock compression and keep all the low-end you already have and boost 7-8psi like lextreme's old set-up and make around ~320rwhp and also with simple air/fuel management. Your stock tranny should hold this and you could add an external tranny cooler to help out. Then in the case it did blow, you could swap in a tt auto and see how it does for you (should be cheap to do). Might be a little stronger, but i think you still wouldn't be able to control when it shifts so that annoying 1-2 shift might still be there, maybe not. What do you think?

 

[Lextreme II]

Perhaps this article will help. I want to put this in my SC470TT. TH400 Transmission

 

[jibbby]

WD - The Supra TT tranny has a longer first gear, more clutch plates and a some other beefed up stuff in comparison to the SC400 stock trannies...I called the dealer and talked with the head mechanic, and he told me the differences...It is probably 100whp stronger then the Sc400 tranny compared stock to stock.....The shifting is much better and more timely too..

Bellhousing and torque converter concerns is my two remaining questions in regards to doing this swap.. I have the tranny lined up for purchase...


Lex- Thanks for the TH400 article, and yes I have considered the TH400 for along time, however they are not comfortabel to drive...With no overdrive they really are not what I am looking for in a Lexus tranny swap...I really don't think I will ever push much more then 450rwhp on this Sc400 of mine so the Supra tranny makes the best sense to me... They also can be built to handle more hp if needed...

Again, the Supra TT auto tranny "performs more effeciently then the SC400/LS400 tranny's) What I looking for is not only Hp holding capacity but also tranny performance with an uprgraded tranny swap......

Thanks fellas...

 

[WDoherty]

maybe your bellhousing will fith the supra transmission?

 

[jibbby]

6 cylinder motor block to an 8 cylinder 1uz-fe block bellhousing fit, I dought it......It seems that no-one has tried or knows much about this swap, unbelievable.. with an extra 100whp holding capacity, better shifting, longer gearing, stronger internals, etc it seems like a no brainer for the price.....If you still need require more HP holding capacity you can always beef up the Supra Tranny later on down the road... With a built Supra TT Auto tranny you will still retain the benefits of better gearing, shifting, etc.........I really don't get it? ...The V160, and the R154 trannies are a hit, but the Automatic TT version is not even thought of....Hmmmmmmm...

What is wrong with you people, wake up an smell the coffee.....(just kidding guys)...

 

[WDoherty]

jibby, the reason people ditch the supra auto is because if you mod a supra its likely you will make way more than 500rwhp plus lots of people like a stick in a sports car for control, but you live in l.a. traffic and seem to prefer automatics. I think if you mis-understood what i was saying about the bellhousing. If the transmissions are the same outside physically and they are used with the v-8 and the i-6, then would the v-8 bellhousing bolt to the supra tt transmission if the external transmission is the same? Another question, you say better shifting, how will the shift points change if your sc400 ecu is still controlling the solenoids?

 

[jibbby]

The Supra has internal electric shifting points and I believe it to be independant of the Sc400 ECU...That is what I read on two different forum threads...It is compatible but independant...Shifts are more timely, 1 st gear is longer....more clutch plates, longer shaft, etc...I have driven an auto tt Supra tranny stock and I remember it shifted nice...Nicer then the SC's if I remember correctly...I test drove a new 1997 Supra TT auto in 1997 and it was pretty darn fast.... That is what I know...

Combine that tranny with the supra LSD and basically your SC is Supra...Right? Driveshaft and tranny bolt patterns are identical...The bellhousing fitment is a bit of a question mark...One extra tranny fluid line needs to be worked out and that is it....I hope..

 

[Lextreme II]

I have heard from a person with TT tranny and he is not too impressive with it. I think its better to spend $1,800 for a fully rebuild transmission then a $1,000 for a used transmission.

 

[WDoherty]

i don't know about "internal electric shift points", the sc400 has a tranny ecu so i am assuming the supra is the same.

 

[jibbby]

Lex - Thanks for the input and I carefully considered what you say, and reading up on the Supra forums the Auto TT is not all that and you are right to some degree.....However it is a step up from the SC400 stock tranny...right?

I think the stock SC400 built tranny will still lack the improved shifting and gearing that is in the Supra TT tranny...Again stock those TT supra trannies do mid 4 second range 0-60mph with just under 300whp or so...How bad can that be at stock? With 400whp I think you may achieve the high 3's or low 4's possibly with a good traction setup...Boost logic trannies get good and bad reviews.... HP holding capacity is increased but everthing else remains the same pretty much.....People are dumping those boost logic built tranny's alot. Ryan (sc400tt) says he dumped his and didn't like the feel at all...One other guy said the same...Supra TT auto trannies are smoother and perform pretty well at stock...Not all that but an upgrade for under $1000 hopefully...Got it down to $800 cash now...Trying for $600 cash and making this guy sweat. He has no bits as this tranny has been sitting dry around his yard for over 2 years now..The crashed car has 73,000 miles.........

I just think Toyota made that tranny to support 300whp and not 200whp (like our SC400's) so it has to be better.....I just want to know if it will take well to the Sc400...Not much info to go off of when pertaining to this proposed tranny swap...

WD - Independant transmission codes is what I read...Longer first gear, more clutch plates, swap is doable and easy from what has been said...Hope it is all true as I am about to find out....