well im gonna be building a motor to put in a 87 iroc and i am wondering what to do about the transmission wether to go to a th350 or build a 700r4
now what i would like to do is build the motor and put it in the car and be able to drive it with the stock 700r4 untill i am able to get a new tranny which would only be a few months but what i really want to know is how much power can a stock 700r4 hold
also what are the advantages and disadvantages of a 700r4 compared to a th350 stuff like mileage, 1/4 miles times, drivabillity and durabillity

 

 

The power a 700 can hold is neither here nor there. It all depends really on the condition of the transmission and driving habits. If you make 350hp and 400 tq, probably not long if you drive aggressively. Get that th350 as soon as you can, you;ll be happy.

 

If you like mileage low rpms while cruising, then the 700 will be your friend. If you don't care, then it doesn't matter which one.

 

my next question is how what has to be done to a 700r4 to make it handle at least 400hp and is it worth the money to do it or would it be a lot cheaper to just get a turbo 350
and one other thing is i really dont like turning high rpms when going at highway speeds so i would like the overdrive unless going with the 700 will decrease performance a lot

 

Going to the 700 is going to degrade performance. At least not directly. If you are willing to pay 3x as much, you can have a 700 as strong as a 350. If you are not willing to pay that you will have to sacrifice some reliability. I agree, if you are into long distance cruising with the car, the OD is nice, but I have no problems doing without it, after all, people drove cross country a long time ago without OD, and still do I am sure.

 

Sure, but what was the price of gas then?

 

Yeah, they do, but I've made several trips from New Mexico to IL, and I wouldn't bother unless I had a max of 2.73 overall ratio (including OD)... gas prices have gone up, and flight prices have gone down over the last 20 years and it's not cheaper overall to drive in a lot of cases.

 

what i really want to know is if there will be a difference in performce between the two like the difference in 1/4 mile times between two identcal cars except the different trannys
i would like to know this because if it istn to different i will go with a 700 for the OD
and i think it will be a little more drivable
and one other thing is how much $$ am i looking at to have my 700 rebuild to do what i want

 

I prefer the gear spacing of the TH350 because the 700 is a wide ratio trans between 1, 2, 3. You won't notice too much difference though if you put a decent stall converter in and your engine is running proper. To me, the O.D. overrrules the gear spacing though.

In MI, you should be able to find someone good w/ the 700, but ask around to see who does them right. Some places can "rebuild" them but they don't last. Some places build them and they do last. Do some research.

 

go with the 700 you will spend a little more money but it will cruise better and be faster down the track it has a lower first gear you can get cheap parts at kbs.com

 

I disagree, the 700 will be slower.
the lower first gear(3.06) will make it easier to burn off the tires, and once you get to 2nd gear(1.63) you will loose a lot more rpm than the th350.

Which has a higher first gear and a closer 2nd gear ratio, which wont make the rpms drop as much

I would still build the 700, how much time do you spend at the track compared to driving??

 

you will spend more money that is a fact ...
but ... be faster down the track because of a lower first gear is if your rebuilding stock sure then thats right but if your building a transmission thats going to handle 400+ hp then your going to be building a strong th350 .....

otherwords in my opinoin go with the th350 and be happy unless your building a highway cruiser for every day driving that your not planning on driving very agressive on a daily basis.....ive had to help change out a number of 700r4 transmissions because of this exact problem too much power + 700r4 = big bang and $$$$$

 

you are letting the wrong person build your trannys then

 

that's what I am saying. :lala:

 

We usually dont bother building a 700. If its gonna be raced, we just build a 350 for it when the 700 goes.

 

If your all done doing the 700 vs 350 comparison in the 1/4mi. I'll chime in and give first hand information.

THERE IS NO DIFFERENCE if a few minor changes are made!!!

Years ago when i first got this beast I installed a mild 350hp 350sbc. When the motor was out I went ahead and had the 700r4 freshen up and installed a 2800 stall. Was trapping 5000 rpm in 3rd gear with a 1.95 60'.

Well, thought by going to the TH350 and the lighter rotating mass and less weight I would pick up a wee bit, so had a TH350 built and installed a 9" 3500 stall-both of which are for sale right now and guess what...1.95 60', crossed the traps in 3rd gear @ 5000rpm running identical et and mph. Was I happy to get rid of the 7004r-yes, but if this will be a car that is going to only see track duty once in a great while and be your daily driver in this case I would recommend staying with the 700r4 and getting a few beefier internals to live behind a mild sbc.

 

they arent my trannys they are other peoples i am taking out to change because they are junk....:lala:

 

700's can be built up with performance parts that can withstand up to 475+ HP. The price on them is like $1500 or so.

The stock 700 is good for a stock motor. Beefing up the motor = beefing up the tranny. Or getting something better.

check out www.fearthemonster.com

They have some heavy duty 700's with top line internals meant for higher HP and torque. Starting somewhere around $950 or so.

But theres lots of places that offer heavy duty 700's.

I personally like roadtrips and would prefer an OD.

 

the th350 vs the 700r4 is a loaded question anyway and its going to be argued to the death or until it shuts down this thread ...lol...but its all in how you want to drive your car honestly or what you have laying around to work with .........

 

You find that TH350 spacer info yet?

 

I'll post it when I get the exhaust. I guess you will just have to wait till then.

 

I'm not the one waiting. The guy with the assembled TH350 w/ 700-R4 output shaft is.