chevrev

iTrader: (2)

i have an LS1 and a th350 transmission going into a 1957 chevy belair w/ c4 corvette suspension in a pro touring type setup. i have purchased a custom harness for this application but have not yet purchased the ecm. will a harness that is setup for an ls1-th350 also work with a 700r4 or would it need to be modified? also what are your opinions between the two transmission...any other suggestions?

thanks,

Indyjc

iTrader: (1)

I think your custom harness will work. What gears are you running? I have 373's the turbo 350 just didn't work well with those gears. It made a world of difference with the overdrive. Good luck

chevrev

iTrader: (2)

the stock c4 suspension has about 2.75 gears. would there be much of an advantage of going with the 700r4 as opposed to the th350 in my case?

Indyjc

iTrader: (1)

You may be better off with the 350. If your gonna use it for crusin.

AmericanMuscle313

iTrader: (5)

My preference would be to have overdrive with the 700r4 for a cruiser. For a mild performance build I would go with the th350 if you dont mind not having overdrive. Have you looked at t56's or tko600's?

chevrev

iTrader: (2)

i dont know much about the t56's or tko600's, but maybe i should look into them. i have also been told by a couple companies that the ls1 pcm wont control the th350, th400 or 700r4...but i know that people have made these conversions? what role will the pcm play in controlling these units, or the t56/tko600? what about other manual units such as borg warner t5..any good? will they bolt up to the ls1 ok?

here are a couple quotes of the replies i got form companies that make harnesses for ls1 applications...

"The PCM will only handle a 4L60E the 700r4 will need to be handled by a
standalone controller. See B&M transmissions and look for a lockup kit for
700r4"

"The LS1 PCM can not control the TH400 or 700R4 transmissions. It can only control the 4L60E, 4L65E, or 4L80E. There are no necessary modifications to your harness".

Wardrum

What size rear tires are you going to use? Total gear ratio (transmission ratio x rear axle ratio) will determine what speed your combination will provide if the tire size is known. If you know what RPM you want when cruising, select the transmission that will provide that RPM at your desired cruise speed. There are several calculators available on-line that you can plug this info into to provide the speed for you. Or if you want, post the info and I can calculate the results for you.

BTW, nice combination. I am building a similar car with an Art Morrison chassis.

bczee

iTrader: (12)

With a TH350, TH400 or the 700R4.. you don't need to control them with your ECM/PCU.. For the 700R4.. I beleive that you only need a lock up controller (can use a simple switch) and a TV cable.

The 700R4 is the same as a 4L60, the 4L60E is the electronically controlled with the the ECM/PCU would utilize or a standalone controller. I think the 4L60 (w/o E) was only used in some Truck in the late 80's early 90's and before the 4L60E came out.

So, depending on how much you plan to cruz' or how much power you planning on. A Built TH350/400 may be better choce for more higher HP street/strip usage, else go witha 700r4/4L60 (or better 4L60E/4L80E) for the Overdrive.

Another choice is a built 200R4.. Lighter and just as strong if built correctly. Use on the Buick GN/X turbo V6's

Eskimo

iTrader: (9)

Wasn't mentioned, but the 700R4 has a 3.06 first gear, as opposed to the TH350's 2.52.. Another benefit to the 700R.

If it was me and I didn't have a bunch of cash wrapped up in the 700R4, I'd find and run a 4L60E in a heartbeat. It'll save you a TON of headaches.. (Flexplate spacers, making a TV cable bracket, standalone lockup harness, etc...)

chevrev

iTrader: (2)

i really appreciate all of your input! my tires are 245/40/17 if i remember correctly. i am looking for a setup that will give me the best of both worlds so to speak. i want to be able to cruise @ 70mph at about 3000 rpms and yet still have a descent launch.

if i were to go with the 4l60e, my harness would need to be modified correct? can i use a 4l60e that came form a v6 application or does it have to be from the ls1?

i am familiar with the TV cable on the 700r4(my truck has that setup), but how would i rig that up with the throttle body of the ls1(cable operated)...do all 700r4's utilize a TV cable, or only certain years?

thanks,

Wardrum

With 2.75 axle ratio and 245/40/17 rear tires, the rpms and mph are as follows:

TH350 = 1.00 direct ratio = 70 mph @ 2699 rpm
TH350 = 1.00 direct ratio = 78 mph @ 3000 rpm

700R4/4L60E = 0.70 overdrive ratio = 70 mph @ 1889 rpm
700R4/4L60E = 0.70 overdrive ratio = 111 mph @ 3000 rpm

IMO, cruising at 1889 rpm is much better for fuel economy, noise and wear & tear than at 2699 or, worse yet, 3000 rpm. And, as stated above, 3.06 low gear in the 700R4/4L60E will also provide much better launch than the TH350.

Hope this helps.....

chevrev

iTrader: (2)

so, bottom line is that with the 700r4 i will not only have better cruising speed rpms but i will also have better launch...sounds like thats the way to go.

how will i setup a TV cable with the ls1 throttle body?? any ideas? do all 700r4's require a tv cable?

thanks

njkid

a 700r4 has the same gear ratios as a 4l60e. its just the 4l60e is electric. i would got with a 4l60e that way it plugs in but if u have a budget or have the 700r4 go with it

chevrev

iTrader: (2)

my harness is not setup for the 4l60e. it would cost about $180 to get it setup for a 4l60e, so i have to factor that into my budget.

bczee

iTrader: (12)

Many of the Aftermarket and performance Trans shop (check the sponsers) has kits to convert your T/B to utilize a 700R4 TV cable. just search the internet and this forum under the Transmission sections. Others have this setup and they can give you all of the info you need to drop it in and be cruz'in in no time ! Lov them 57's.. wish I still had mine !

chevrev

iTrader: (2)

thanks,
so far i have found 1 company that sell a kickdown cable/bracket for the 700r4/ls1 application. www.bowtieoverdrives.com the cable+brackets is ~$150.

bczee

iTrader: (12)

TCI is a sponser on this forum.. maybe try them.

Eskimo

iTrader: (9)

TCI is a no-go.

X2 on the bowtieoverdrives being the ONLY one I've found..

$150...

bczee

iTrader: (12)

Just saw on S&P site/catalog, they have a T/B CAM setup for the 700r4 for $35.00

check it out.. hope you get something that will work for you..