4r70 clunk
 

Good morning all. I've searched and read and still ... '04/ 4.6l / 4R70 3.73 posi rear, 71,000 mi., mild Troyer tune, has the dreaded downshift clunk.(4 to 2 downshift) If I switch it out of OD it won't do it. It did not start doing it until I added an additional trans cooler in the spring.(about 62,000) The cooler is inline with the return line after the factory cooler(tow pkg.). It seems now to do it more in the morning when when it's cooler out and before the trans really warms up. I do have a trans temp gauge with the probe in the test port and normal use the gauge is showing 150/160 and towing the horses 180/190. I've had the clutch packs and fluid changed I've greased the yoke on the D/S. Has any one really solved this problem ? Am I runnig too cool ? or a bad inline trans tstat? Anyway thanks to all for any replys.

A couple things come to mind. When you changed the clutches, did you flush the cooler lines or replace it all together? I've seen bits and pieces get stuck in the lines after clutches fail which drastically shortens the life of the new clutches and trans. Junk in the lines might be the reason the additional cooler was needed. Did you install a shift kit, adjust the screw on the EPC or get a tune? Any combination?

Does the trans clunk ALL THE TIME or just at WOT? If it's only at WOT, you have a some time left.

Bottom line, blow out or replace the stock cooler, do the same for the second cooler and replace the clutches, bands, inspect the screens, clean the magnet, etc...