jdawg1276

I got a question I thought 700r4 transmission is supposed to have a lock up converter. Why are some people who rebuild 700r4 transmissions give you the option of locking vs not is it just a scam for your transmission to burn out so you have to buy another one?

vetteoz

iTrader: (13)

You won't burn a T700 out from no lockup ; it is only a fuel economy measure to take the slippage out of the convertor.
Of course,a non locked convertor generates some heat but millions of other trans (PG /TH350 /TH400 )
are running with no lockup function and not burning up

There is info about that the early T700 only had full fluid flow to the trans cooler when in lock up mode which may
be the origin of the " kill your trans with no lockup " myths

Many run a non lock convertor in perf apps ( hence the non lock option ) where economy is not a factor because
the tiny lock up clutch inside the convertor is not designed to handle big power under load;
if it lets go it will fill the trans with debris requiring a strip and cleanout

jdawg1276

OK thanks I don't want a lock up anyway so if I run a bigger pan and cooler I should be fine right

3rdgenmaro

iTrader: (9)

Yes you will be fine. The extra cooler is really the main thing. Deeper pans run into problems scraping the ground.

Throw a temperature gauge on it and you wont have to ever worry about it, you will know for sure what temp it is at.

Orr89RocZ

iTrader: (20)

If you bought a converter designed to be locked up under load it would be fine but likely abit pricey. I locked mine under load no issues. Some claim locking converter helps reduce et's and increase mph at the track. In my few attempts at this on two engine combos i never saw the gains. Lockup certainly is helpful on the dyno when tuning. Can maintain lower starting rpm on dyno and transmit all the power to the ground. Typically gain 10-30whp with lockup, because your taking out the losses from converter slippage. Helpful when you want high bragging numbers

If you street drive alot i would get lockup. Makes the car nicer to drive, regardless of fuel economy or not. I loved my 700r4 and 4l60e, with lockup. Dont like my th400 with open converter

David 91RS/Z28

Just curious but did you try one with the turbo setup? I recall some turbo cars benefitting from using the multidisk lockups to take full advantage of boost. I want to say it was locked at some point in 2nd gear. Not that your car isn't stupid fast already with current setup, lol. Only benefit to the NA cars is the driveability on the street as you mentioned above.

Orr89RocZ

iTrader: (20)

No when i went turbo i was also going to do t56 swap. Bought it and then realized down the road my power goals would outlast the t56 and the money required to build manuals to hold power is 4 times the cost of a th400. My buddy had one already built for 600 bucks so i got it. Sold the t56 and 700r4
My car seems to like more converter slip to spool the turbos. Never had a problem getting boost once converter was dialed in

David 91RS/Z28

Yeah, the old TH's can't be beat for cost and hp capablities! You run much stall at all?

Orr89RocZ

iTrader: (20)

5400 in the first combo due to incorrect stall by company. Had it tamed down to 4200. Same converter on new setup stalls at 3500-ish due to powerband shift. So its goin back for restall to 4500 i think

Pat Hall

iTrader: (31)

One other tip, if you plan on running a lockup style converter in a high horsepower application, make sure to go with a high quality converter, such as Yank, Edge, Vigilante, etc. These converters have a much improved, heavy-duty lockup clutch assembly. Bargain lockup converters use a stock style lockup clutch, which is quite weak when you're at full throttle in lockup mode.