Today coming home from a camping trip, I noticed a shudder a couple times, on 2 seperate small hills, but as went on I did'nt notice it, I have never felt it before, but last nite, I put the smarty on Tow, default timing and default torque, coming from Towing, timing 1, and torque 1, it has 32000 miles on it, going to change trans filters/fluid, hopefully this week, fuel filter with 4500 miles on it. The shudder happened, when entering the hill, 6th gear, untill downshifting to 5th. About 55-59 mph speed. I did'nt use the auto-stick, let the tranny do the downshifting. Other then that, good mpg, exhaust brake works great. Not a great big shudder, but you could notice it, just did it a couple hills, warm motor/trans. Thanks

 

I just got back from a towing vacation today as well. Another nice work-out for the machine. I hardly ever let the truck shift for itself. The computer will keep that thing in 6th forever and the EGT's get quite hot. Anytime I see the EGT get up over 1100 for long, I downshift it myself and the EGT's drop at least 200 degrees.

I haven't felt any shudder in high gear though.

 

I normaly do the shifting also, when coming into a hill, also teached my wife how/when to do it when she is doing the towing. I can't really positive say its the tranny shuddering, I have been thru 8 states with this fuel filter, might have go some bad fuel, I'm going to drain some out today, and look at it, might have some water.
Now the day before I noticed the shudder, I had a message come up for see dealer but I don't know what it was for, and it went away while I was checking the overhead out. I put the smarty on when I got back to the campsite, to see any codes, nothing, thats when I set the levels to default for the timing/torque, left it in tow level. It run ok, during the overhead message. it done it on only a couple hills.

 

Oh ya wanted to mention, this is the highest levels I have had with the smarty, tow, torque 1, timing 1. Never even spun the tires on it, I drive it pretty resonably

 

The shudder is the lockup clutch in the converter slipping. It's not like the old 48RE. When those slip they are junk immediately. The 68RFE is a woven clutch and will take alot of abuse. Basically the line pressure at low RPM in 6th is too low to hold the torque of the engine. Downshift it and it will be fine. More RPM = more line pressure.

 

Sounds good, thanks

 

I took my truck out for some WOT shifts today after changing fluid and adding my Mag Hytec pan and noticed that there is a slight bit of shudder when it downshifted from a higher gear. Not much though and it most likely the converter unlocking such as Whitesport says...

 

Had the same shudder last year , felt like running across a rumble strip.
I was towing 11m lbs. at low speed in 6th and accelerating.
I changed to level 2 from 3 on my Hypermax and solved the problem. The answers provided previously seem right to me.

 

Thats what mine sounded like, like running on a very well worn rumble strip, I'm at towing, default torque/timing, now. When happened I was tow/timing 1 and torque 1. I'll be quicker on the downshift button.