[Diy_efi] Using GM '747 to control TCC lockup only

[Logan Lingle]

Don Sauman wrote:
> The guy who does my transmissions believes that TC lockup causes more 
> problems than it is worth. He reckons that at certain loads/speed you 
> can get a drivetrain chatter that will quickly destroy 
> splines/bearings etc. He suggests that when I put the 4L80E in my Jeep 
> that I disable the lockup.
>
> Thoughts anyone.

He's totally, completely incorrect..

First, the 4L60/700R4 has a superior 1st gear ratio. If you can use it, 
you should.

Second, lockup helps the transmission to run cooler and it uses less fuel.

And there's no "chatter" in a 4L60/TH700 TCC clutch unless you've got 
internal pressure control problems.

It's an simple, on/off clutch and 100% duty solenoid.

If it's slipping or chattering, then you don't have enough pressure to 
hold it on properly. Something is leaking.

The last car that came in to my shop wanting a 4speed unit with lockup 
was a 57 Chevy with an LT1 Corvette engine and a TH400/3L80. (The three 
speed cousin of the 4L80)

The customer hated it because it ran hot, used allot of fuel and had a 
lazy launch.

With a performance 4L60/TH 700R4 behind it, he's thrilled.

It's more responsive, the transmission runs cooler, the engine turns 
1600 RPM on the highway, it gets 21 MPG and it will still rip the tires 
through third gear.

IMO? Find a new transmission shop.