A known weak spot in the Torqshift transmission are the solenoids that cover 3-5 shifting. Upgrade these two solenoids to deliver twice the fluid in half the time to the direct clutch!
IF YOU ARE EXPERIENCING 'FLARING' between gears or have the dreaded P0766 code, do this upgrade before you get the VERY dreaded P2703 code! If you already have the P2703 code, this upgrade MAY solve your issues, but it might be too late.
While you're at it, consider replacing the unused dummy pressure switches with plugs and migrating to a deeper transmission pan as what came with the Torqshift transmission. If you move to a deeper plan, note that this pan depth is the same as what is mated to the 6.4L to support a full flow pleated filter over the screen that the factory provided in the 2003-2007 models.
If you tow more than 10,000 pounds or have a penchant for boosted launches, consider choosing a 3/8 aluminum double deep pan over the tin pan provided by the OEM to DRAMATICALLY increase your transmission cases' stiffness and limit the chance of your transmission case cracking.
To install the solenoids, just remove the drain plug from the pan, remove the pan once draining is complete, and you are staring directly at the filter and solenoids to be replaced! Pull the cir-clips out, remove the electrical plug from the solenoid to be replaced, tap out the old one, slide in the new one, rotate it to replicate how the old one was, reinstall the electrical plug and cir-clip. Viola!
For more information on transmission upgrades and filtration benefits, check out this thread on FTE! While we, of course, cannot provide any warranty as to any part of the accuracy of these directions and thus EXPRESSLY disclaim all liability for damages of any kind arising from referencing or using the information, some have also seen benefits in the writeup at http://www.dieselhub.com/maintenance/5r110w-torqshift-solenoid.html.
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