What is the stock stall speed for...

billyw · #1 03-15-2007, 07:34 PM

... 4R70W tranny in a 97 F150 with a 4.6L engine?

The tranny is being rebuilt as you read, and they are putting a torque converter with a 1400 RPM stall speed in. The tech says that is the stock number and that the 5.4 version is around 1100. Is this the case? These numbers are MUCH lower than the numbers being bandied about around here.

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Bluegrass · #2 03-16-2007, 12:26 AM

The stall is dependent on the load it see within limits.
The stock off idle is closer to 1500 +/-.
I have a custom build with a diesel converter and it hooks just off idle at about 1000 to move the truck empty.
This was done to help keep the temp down when towing and out of lockup running plus a heavy TCC clutch.
The is not the hot set up for drag racing but works good for towing application.
A lot of RV motor homes types use this kind of setup.

billyw · #3 03-16-2007, 11:44 AM

After chatting with the tech for awhile late in the day yesterday, we are going to go a few hundred RPMs higher. I'm assuming this will make city driving a little more enjoyable without negatively affecting highway cruising or towing. Thoughts?

jmt0645 · #4 03-16-2007, 12:34 PM

my understanding of converters is this:
High stall speeds allow the engine to rev to its torque peak to achieve a better launch, this is not good for towing 'cause your engine will have to rev just as high to get the load rolling.

Low stall speed converters engage thier clutches alot lower on the Rpm band getting you rolling alot sooner meaning the engine has no need to rev as high to get you and you trailer rolling. this is why lower stalls are better for towing.
stall speed on my truck(stock) is between 1500-2000rpm depending on the load according to the dealership mechanic.

dirtyd0g · #5 03-16-2007, 07:41 PM

5.4'S are capable of having 2 different stalls. They came with either the 1200-1500 straight blade pump or the 1500-1800 pitched blade. The 4.2's got a higher pitch but you cannot tell the difference from the outside. Vehicle weight, power, gearing and tire size all play a major role in what stall you will actually see.
Alan