I was towing a big wakeboard boat yesterday, and as I got to 50mph the truck shifted from 4th to OD, but studdered really bad, felt like a mis-shift, then it locked in and continued to drive fine. this was on a hill, the boat weighs less than 8k...should I have had the OD locked out? or is my tranny goin bad, and was just more noticeable with something being pulled?

 

Probablly should have had OD locked out. Upshifting on hill with enhanced performance is perhaps more than stock Lock up can handle. Say the tranny is designed to handle 400 #FT torque, at that shift condition. However due to enhancments the engine is delivering 550 #ft to the tranny. Get the ideal of overloading. Fix would be trans enhancements to handle extra torque.
You probablly need to change ATF+4 also. Additives in fluid break down and aggravate lockup shudder.

 

awesome, thanks. I am planning on changing fluids soon.

 

4th is Overdrive. You are having a converter lock-up shudder issue. If the fluid is old, fresh fluid/filter may be all it needs. If it is fresh and ATF+4 add 1/2 bottle of Lube Guard. It is a friction modifyer and will allow a little bit more of slip before grabbing. 50 MPH is not good to be in OD and locked-up. Let it run up to 60-65 before od.

 

you mean while towing right? because 50mph is the point where it always shifts, no matter what, I thought that was the case for everyone?