how hard is it to get a 400 trans in a 3rd gen with the motor already in the car. im not sure if it matters but the motor in my car is a LS. the reason im asking is i dont have the trans yet. i just test fitted the motor tonight and got everything clearanced. the motor is going to the machine shop now and im putting it right in when i get it back so i can start my turbo piping. when i get the trans i was hoping to have the motor in the car already. is it going to be a pain to bolt the trans up with the motor in already? any tricks?

 

Not hard at all. Weighs about the same as a 700 in fact, so about the same difficulty. Just eat a good breakfast first.

 

Thanks. i just didnt know how hard it was to get to the motor to trans bolts. i didnt look at the clearance when i had the motor in.

 

Why a TH400? Parts are available now to build a 700R4 to handle 1000 horsepower. Or what about a 4L80E. These units could handle 800 horsepower stock and with upgrades we were building these units to handle 1200 horsepower 12 years ago. I would guess that with continuing technology, they've surpassed that by now. The TH 400 was old news back then.

 

Same as any other trans; they're in the same place.

Not hard at all, especially if you just put "hard" out of your mind and instead put "I'm going to DO THIS" in it instead.

 

well 400 are relatively cheap to build, this will be a full manual trans, i do not need overdrive, this is just a race car that will see minimal street use. i haven't even figured out a way to make the 400 live "yet" with what i plan on doing to it. im still looking for answers.

what im building a a 1000hp drag car that is street legal and i might take it to one or two HPDE per year. that said i need to set this up as a full manual for drag strip use and still be able to down shift it at the road coarse. every trans builder i have spoken to so far keeps saying it wont live if im down shifting it.

 

I remember a couple of 400 builds back when. One was for an Alcohol big block 8 second car. Just like the motor, if you race seriously, the trans will need to be refreshed regularly. I also remember a 4L80E that was every bit as strong.

 

I agree, there is no reson in this day and age not to use a 700R4 or even a 4L80E like was said. Sure the 400 cost less to build, but I would rather have a 700 over a 400 any day.

 

I remember when everyone was saying " You can't build a 700R4 for performance. You need to build a TH350 or 400". I was hearing this in 1999 when I was looking for someone to build the same 700R4 I'm building right now. (By the late 90s, guys like Dana at Pro Built Automatics were already running the 700R4 in 9 second cars). A few years later I was involved in a transmission shop, not as a builder though I did end up doing a few units and lots of in car repairs. At that point, guys were still asking for TH350 builds. Some that came in needed new cases and good cases were getting harder to find as so many were being ruined. I remember a good TH350 case going for $160. About that same time the 700R4 was gaining momentum with many great upgrades and solutions to the unit's flaws available. Now with high strength parts and real solutions to all of the unit's traditional weaknesses, the 700R4 can easily be built to handle serious power. The 4L80E is a brute even in stock form. Throw in a few upgrades and they are a serious high performance unit.

I understand the interest in the 400 as a less expensive and lighter weight alternative. As long as cases and hard parts continue to be easily available they will continue to be a viable option. If as the OP says this is going to be a track only car, he may as well skip the OD.

 

very true this is a track only car with no need of a over drive. i also will not have a computer to run a 4L80 and a 4L80 is nothing more than a 400 with a overdrive many internal parts are interchangeable. as for the 700r4, im just not sure you understand what i will be putting this trans threw. this will be in a turbo car making 1000+hp when all said and done. it will get beet up on at the drag strip and it will see some road coarse action where i will be down shifting it from high rpms. i nor ANY of the big name shops think the 700 will even come close to taking the abuse i will be putting it threw, and even the big name shops think ill be pushing the 400 to far.

 

Yeah, the highest rating I have seen for a 700R4 is 1000HP and how well that trans will handle abuse at that power level is anyone's guess. Just the shafts, housing, and planets for that trans will beat the heck out of $2,000. As far as high rev downshifts we are doing that all the time with no real issues. Many of the issues people think of with the 700 have been ironed out.

I have seen the 400 used behind 1,500HP for drag racing applications. These units generally need to be refreshed each racing season just due the abuse the clutches see. If you are in serious competition. It's nothing to pull the motor and trans at least one a year for overhaul.

As far as the road course goes, I don't know if I would want to do this to any serious level with a 3 speed. But hey, it's your deal.