shudder at 55mph. shakes truck. possible converter or tranny issue
 

hi - i got our 2006 escalade 2 - 3months ago. love it. tows great. 6.0 Liter/ 4L65-E transmission.
yesterday wife says she feels truck shaking.
i drive it and at cruisng speed on highway, when converter locks up, its shakes the truck really hard. Its stays like that until I either tap the brake (unlocks converter), release the gas (coast) or drop it down a gear and accelerate.

I have 6 month power train warranty (fidelity gold check); will drop truck off at local aamco shortly.

anyone else have this issue? The car had electronic brake controller on it when I bought it so I know previous owner towed with it. I have towed my stuff about 5-6 times so far (5000 lbs total, car and open trailer).

I'm curious if warranty company will just replace converter or I will push for new tranny.

thoughts?

How does it act going up a grade with a load on the engine?

Engine misfires or a worn tcc isolator bore in the valve body would be my guess as to why you are having this issue. If you caught this in time and the issue is trans related then you might have not totally destroyed the torque converter clutch and fixing the valve body might solve your issue.

^ I was starting to think misfires as well. Our trucks at work had issues with misfiring up a grade (before downshift) or when getting into the throttle. Basically anytime the engine was under a decent load.

hi - actually it happens on slight inclines at 55 mph+ only. Cruising speeds on highway going up slight inclines. Is that when the converter locks?

Anyone else have further input? This is more or less what I am currently experiencing with my 4l60e.

Some misfires are most noticeable after lockup and under load. Shop will be able to tell. It's either misfire or converter. When they test drive your vehicle they will watch misfire graph while at freeway speeds when in lockup. If not misfiring, they can command full TCC PWM and see if that makes converter stop shuddering.

And if its just converter they may just replace converter and put new filter in it. Unless you have a warranty that doesn't do tear downs. I know some of those are like that. They come through dealer quite a few times.

Some misfires are most noticeable after lockup and under load. Shop will be able to tell. It's either misfire or converter. When they test drive your vehicle they will watch misfire graph while at freeway speeds when in lockup. If not misfiring, they can command full TCC PWM and see if that makes converter stop shuddering.

And if its just converter they may just replace converter and put new filter in it. Unless you have a warranty that doesn't do tear downs. I know some of those are like that. They come through dealer quite a few times.