Frigidaire front-load stackable washer has violent shaking cycle

did you check the power cord?

I am currently having the same issue with my Maytag A482. Not sure if you have found a fix yet, or if you have replaced your washer. My washer runs fine until it nears the end of the cycle, when it begins to spin and shake violently, enough to loosen the leveling feet and rock back and forth. I pulled the front panel of the machine off (two screws near the base in the front, and two clips at the top) and ran a load through it. It ran fine until the end, when the machine started shaking violently. I did notice a few small pieces of roundish felt looking material sitting on the bottom, which after some research looks like it may be the damper pad. I found these online:
Damper pad 203956
Replacement Damper 203725 for MAYTAG Laundry Appliances A482

I am hoping this will resolve the issue, I will order them this afternoon and install them once they arrive. I really hate to replace such a good washer with a new high efficiency unit, which all seem to have terrible reviews after a few months/year of use.

When you put on the clothes inside the spinner make it equilibrium to prevent shaking violently.

I had this problem with my front loader as well. It is probably the mounts or "level shocks" on the bottom of the unit under the tub. I have a Kenmore by Frigidaire and had to replace the "level shocks". I only paid about $43.00 and was not that hard to put on. Look under your machine and see if the shocks are connected to the tub. Check under the top panel also to see if that particular model has mounts up there too.

There are 2 shock absorbers/springs attached to the drum. If one of them breaks it will cause a loud banging noise when you wash heavy loads. This is an easy fix. The part is about $22.00 and it is accessed throught the front bottom panel.

Because front load washers are VERY HEAVY, they shake if you have a wooden floor. If your front loader sits on concrete and it still shakes, then you have to make sure all is balanced. If it still shakes, then inside the system there are shock absorbers that need to be checked.

You will have harmonic inbalance about 800 rpm on most front load machines, causing them to shake termporarily as it ramps up on the spin cycle. Be sure to check if the shipping bolts have been removed. This is the most common mistake most people make while installing front load machines. If you don't remove the shipping bolts, it will cause most machines to shake violently and can cause damage.

On something like this you will need to remove the washer wrap to inspect the suspension springs & base assembly. Please see the link provided for accessing the inside of the washer. Be sure the shipping pins have been removed. The tub should float freely.

When the washer goes into spin cycle it is suppost to start at a slow speed and continue to increase speed (to a maximum of 800 RPM) as the water leaves the clothes. Your washer is going directly to 800 RPM which causes the washer to shake and stop giving you the E4 code. The control board that controls this speed increase must be replaced.