5r70w?

[2000StreetRod]

Has anyone investigated the possibility of modifying the 4R70W so the overdrive is engaged at the same time as 1st gear to provide an additional gear ratio between the existing 1st and 2nd gears. Ford modified the 4R55E to provide a 5 gear ratio transmission (5R55E) by engaging 1st gear and overdrive.

The forward gear ratios for the 4R70W are:

1st - 2.84:1
2nd - 1.55:1
3rd - 1.00:1
4th - 0.70:1

There is a wide gap between 1st and 2nd resulting in maximum performance degradation on the dragstrip (dropping out of the power band) and fuel economy degradation on the highway (dropping out of the torque band).

The ratios with the overdrive modfication would be:

1st 2.84:1
2nd 1.99:1 (2.84*0.70)
3rd 1.55:1
4th 1.00:1
5th 0.70:1

PCM modifications would also be required to properly utilize the additional gear ratio. It might be possible to utilize a custom 5R55E load to control a 5.0L/5R70W.

 

[BrooklynBay]

There is a company which makes a stand alone controller for the 4R70W. You could ask them to make a custom 5 speed module. They might make it a production item if it works well.

 

[IZwack]

But on the flip side, overdirving first gear could result in more stress and shorten the life of the transmission.

 

[techieman33]

my thinking right now is just to switch to a TKO600 or T56 (preferably from a viper)

 

[2000StreetRod]

Compushift?

Thanks for the suggestion! I just searched the internet for "4R70W controller". Would you be referring to HGM Automotive Electronics that makes Compushift?

 

[BradR]

And thus cause a "5"r70w 2-3 shift flare? lol.

 

[techieman33]

He's probably referring to the Baumann unit

http://www.becontrols.com/

 

[BrooklynBay]

I think Baumann Engineering makes one.

 

[Mbrooks420]

Isn't overdrive the weak point in the 4r70w?

 

[swetrid]

Isn't overdrive the weak point in the 4r70w?

Yes