v8 rx7 what tranny should i use th350 or th400
 

ok guys
this is not a question about mpg or anyother tranny that would be better.
as a few of you know i'm putting a sbc in my rx7, i just bought a motor and got a free tranny with it.
the tranny is a th400 and according to the kid i got it from it needs a rebuild. when i say kid i mean 17-19 year old kid.

he said that he bought the tranny from a guy that said it was good. he put the tranny in and found out it needed a rebuild.
he says that from a start he would have to give it a lot of throttle to get the truck going.
now my wife had a 70 c10 that was the same way. her tranny had a leak and was low on fluid.
also the motor i got from him is rated at about 200 hp. combine that 200hp with a heavy ass 74 pickup and you will need to gas it a little to get the truck moving.
he said once the truck is going the tranny shifted fine, it just wouldn't start from a stop good.

ok so to my question
this v8 swap i'm doing is going to be done as cheap as possible, but not ghetto rigged. i could rebuild the th400 for about the same price as a used th350. or i could just drop the 400 in and see if it does need a rebuild. or i could buy a used th350.

now i know the gears are different, but not that much different
my rear end is 4.10

th350
1st - 2.52
2nd - 1.52
3rd - 1.00

th400
1st - 2.48
2nd - 1.48
3rd - 1.00

so what should i do
sell this th400 and buy a th350 used
rebuild this th400
or just throw the th400 in and find out if it needs a rebuild



oh and the kid installed the th400 himself and didn't seem to know much about working on cars. i think he didn't refill the tranny all the way after the install.
which could be bad for the tranny.

Re: v8 rx7 what tranny should i use th350 or th400
 

400 = bulletproof.

350 = a few lbs lighter.


find a 5spd trans from a 4.3 s10. problem solved.

Re: v8 rx7 what tranny should i use th350 or th400
 

also, get some low ass gearing or find a cheap 8.8" rearend with airplane gears from a f150 if you stay automatic. 4000rpm @ 60mph = not fun

Re: v8 rx7 what tranny should i use th350 or th400
 

I would think the t350 would be alot easier to get to fit in the rx7's trans tunnel. If it was rebuilt with a shift kit it would be way stronger then you would ever need but.........................

bingo

Re: v8 rx7 what tranny should i use th350 or th400
 

thats what i was thinking too

Re: v8 rx7 what tranny should i use th350 or th400
 

i'm either using the 400 or the 350.
no other tranny will be used.
the th400 will fit with no problem.

i should also be at 4k rpm @ 70 mph

i guess i should have asked my question different

are the shorter gears of the th350 that much better then the gears in the th400?
i'm not too worried about the weight of the tranny or with the strenght of the tranny. i'll be blowing rear ends before i blow up a transmisson.

as for a 5 speed trans from a s10, i want to stay automatic. if i was gonna get a manual i'd get the t56 6speed tranny

Re: v8 rx7 what tranny should i use th350 or th400
 

dude, .04 gearing in low gears in a trans isnt going to make a difference.
get a new rearend. youll thank us later.

Re: v8 rx7 what tranny should i use th350 or th400
 

does anyone make some cheap rearend gears for a n/a rx7? cause i'm not swapping my rear end for another cars rear end.
seems like the rear end and the th400 tranny will be perfect for the 1/8th mile.

so i guess the answer is to just throw the th400 in.

like i said in my build thread, i'm doing this cheap to see if i like the car or not. if i like it then i will either build the motor or drop in an ls1 and make it smog legal in cali.

Re: v8 rx7 what tranny should i use th350 or th400
 

if its between a th350 and th400 then I would go with the 400. That rx7 is light and I bet the taller gears will be better.

Re: v8 rx7 what tranny should i use th350 or th400
 

there is no taller gear. at 5500rpm with a 235/60/15 tires and stock rx7 gearing, that .04 gearing difference in first wont show a difference in mph vs shift point, secone gear will show 1mph more.
redline speed speed


5500 41 42

3.08 gearing will be:

5500 55 56

Re: v8 rx7 what tranny should i use th350 or th400
 

2004R or 700R4

OD ftw

Re: v8 rx7 what tranny should i use th350 or th400
 

there is a reason i learned to drive 55mph on the freeway. doesn't take much longer to get there and you save a ---- load of gas when you only have 3 speeds

Re: v8 rx7 what tranny should i use th350 or th400
 

OD bullshit, I ------- hate those tranny's....I'd use a th350 with shiftkit and a higher stall than stock

Re: v8 rx7 what tranny should i use th350 or th400
 

Automatic second gen. 7s have 3.90 open rears

5speeds n/a's use 4.10 open or LSD(model dependent)

S4 GTU, and S5 GTUs' use 4.30 LSD

Turbo models run 4.10 LSD, have beefier ring and pinion, thicker stub-shafts, and bigger axels (need hubs also)

You can get TALL First gen. ring and pinion from mazdaspeed, but the pinion shaft has to be lenghend


I THINK that instead of lengthening the pinion, you might be able bold the first gen center section into a second gen rear end housing. I have never tried it, but it looks like it should work

Re: v8 rx7 what tranny should i use th350 or th400
 

Either the th350 or the th400 are both quite literally the easiest auto trannies in the world to rebuild.

But if youve never rebuilt an automatic before, then it will take you at least three tries before you get it right. Consider this.
There is a real good chance its gonna need a pump too. GM is sketchy on the tolerances for the stock ones. Best to start fresh.

Either trans is perfect for a light weight eighth mile car. Stock n/a rx7 rears will hold enough power to put you in the low 7's. Ive seen it with my own two eyes ---- what everyone else says. Tall tires are your friend though.

Re: v8 rx7 what tranny should i use th350 or th400
 

the rx7 is far from a light weight car, they weigh about 3000 lbs with driver.

Re: v8 rx7 what tranny should i use th350 or th400
 

thanks for the help guys.

this car will probably never see 1/4 mile tracks. it's gonna be 1/8 mile and spirted canyon driving.

Re: v8 rx7 what tranny should i use th350 or th400
 

I say 1uz with w58 trans :6

Re: v8 rx7 what tranny should i use th350 or th400
 

Actually its a bit underweight for outlaw 10.5 class. That was my comparison. And I think you will find that you will still be under the 3k mark even with the v8 in it. ;)

That is a mistake. You will skatter that trans across the track with a 1uz. Im running a w58 in my 2jz powered mk3, only because I dont care to lay in the driveway and pull the trans out every other weekend, since its easy as ---- to rebuild. Dont get me wrong, the w58 is a great trans, just wont hold up to the kind of torque that engine offers, much less the way most ppl who have that sort of swap would drive it. :P

Re: v8 rx7 what tranny should i use th350 or th400
 

If size isnt an issue TH400 hands down. As mentioned, the trannys gear ratios are TOTALLY inconsequential.

The RX has the solid rear right??

9" ford / DANA and ladder bars :6 + 3:73/4:11s.

Re: v8 rx7 what tranny should i use th350 or th400
 

do the 'glide :)

Re: v8 rx7 what tranny should i use th350 or th400
 

Glides are gay. The 400 is teh way to fly son.

Re: v8 rx7 what tranny should i use th350 or th400
 

The glide is only good when you really start getting up there with power. Having one less tire shock from a gear change helps out on a close to the edge setup.

Re: v8 rx7 what tranny should i use th350 or th400
 

Ok what about the r154 trans, cheap/easy to find >:D. BTW have you posted your car yet?

Re: v8 rx7 what tranny should i use th350 or th400
 

th400 way better gearing i would say glide if it were a race only car..

Re: v8 rx7 what tranny should i use th350 or th400
 

god damn you guys are ------- dicklickers, the 400/350 debate on gearing is POINTLESS THERE IS NO DIFFERENCE QUIT GOBBLING COCK OVER IT.

Re: v8 rx7 what tranny should i use th350 or th400
 

what about a 8-9-10 second street car? 'glides are just fine.

Re: v8 rx7 what tranny should i use th350 or th400
 

TKO 5 speed, word.

Re: v8 rx7 what tranny should i use th350 or th400
 

true, however when i think of light weight cars, i think of my 1800 lb crx

all you guys talking about manual trannys
the only manual tranny that belong in a v8 rx7 is a t56 6speed

Re: v8 rx7 what tranny should i use th350 or th400
 

Re: v8 rx7 what tranny should i use th350 or th400
 

R154's are getting rare, and expensive. Check ebay.

I came across a sweet a340e i think im gonna pick up. I want my wife to be able to drive it, so I might go that route. No I havent posted it yet, its just a pile of parts. I just bought a house and havent had ANY time to even look at the supra.

Light weight is the 1600lb 2RZ drag Starlet my brother is building. Stupid fast.

I have an aquantance who managed to destroy a t56 in his LT1 FD. Im not sure that means anything just thought id let you know.

Re: v8 rx7 what tranny should i use th350 or th400
 

Agreed, nut the planetaries in the 2004R are crap. The gearing iw mush better, but I don't know them well enough to feel comfortable with fixing all the problems.

A 700R4 is pretty easy to build to handle some good amounts of power and abuse.




Since you are trying to do this on the cheap, just use the damn TH400.

Complex, why the ---- would you recommend the weak kneed 5 speed out of the S10s? The T5 is a joke, and the NVG3500 isn't that much better. I guess the NCG 3500 would be great if you wanted to pull stumps in 1st gear with the RX7.

:P

Agreed.

Re: v8 rx7 what tranny should i use th350 or th400
 

i've got a borg warner t18 4spd if youre looking for an indestructable, abuse loving manual trans.

also have a dana44 rear axle with powr-lok diff and 3.55 gearing if the lineset was correct

Re: v8 rx7 what tranny should i use th350 or th400
 

damn you complex, i got a borg warner 5 speed i believe from a v6/v8 trans am. i love 4 speeds!!!

Re: v8 rx7 what tranny should i use th350 or th400
 

With gearing appropriate for pulling a house down.

Lol.

You might as well call that a 3 speed in a car.

Re: v8 rx7 what tranny should i use th350 or th400
 

first gear + rearend gears and fat rear tires will net about 33-34mph in first, really making use of redline

Re: v8 rx7 what tranny should i use th350 or th400
 

buy the trans. it's still conncted to an amc 258 (before jeep reworked the head and coined it their 4.0)

Re: v8 rx7 what tranny should i use th350 or th400
 

Just stay with the turbo 350. That light of a car with that trans and gear you'll be scared shitless with a sweet motor. You've got to love Old School GM.