Long story short, both my brother and I had our transmissions rebuilt by a local guy for a good price. The builder used BW clutches, a beast shell, alum accum pistons, and installed the vette servos we had. He supposedly also disabled the TCC PWM as he claims he does on all 4l60e builds.

My brother believes that the TCC piston bore is worn and bleeding fluid off. He took it back to the builder and he fixed it by "replacing parts in the valve body". Now it seems to act up intermittently on long highway trips, it feels like it isn't completely locked at times.

I believe the transgo kit fixes this with an over sized piston. There is also a Sonnax kit that keeps PWM and uses a steel sleeve. Then there is the Sonnax HP-4l60e-01 kit which eliminates PWM in a way they claim is better than other methods.

Sonnax claims using a spring to block it will cause excessive apply pressure and can lead to rivet failure inside the converter.

What is the preferred long-term fix?

 

How is your tune set up?

You can leave the valvebody alone and eliminate the PWM by adjusting the TCC Duty Cycle tables.

 

Stock tune for now, but we believe the bore of the valve body is worn and bleeding off pressure.

 

This is the correct way to fix it...it makes the trans run cooler, possible better fuel mileage, and gets rid of bang 1-2 shifts on high mileage units..

I use this valve in EVERY build stock or high performance. no reaming required, very easy install if you feel confident pulling the valve body.

This does not include new filter or valve body gaskets, purchase separate

4L60E TCC Valve Upgrade Replacement Fix P1870 Code 7 '95 '00 by Teckpak | eBay