Ford 4F27E, FN4A-EL & J39A Transmission Superior Shift Correction Kit This Shift Correction Kit from Superior will improve all 4F27E, FN4A-EL & J39A Transmissions. This Shift Correction Kit helps eliminate the following problems: Soft shifts & flairs, premature band failure, code P0741 (TCC slippage), broken solenoid pressure regulator valve spring, worn or damaged accumulator bores, the shift kit also includes newly designed accumulator pistons, can increase line pressure by up to 12% and will improve overall performance. The 4F27E kit includes Superior's patent pending billet 1-2 and neutral/ drive dual sealing ring accumulator pistons. This kit also contains one of our patent pending Accumulator Buddy brushes so no other tools or fixtures are required. The pistons and brush allow you to reuse previously discarded cases that would not have sealed due to premature ware. The 4F27E kit also includes a new, stronger solenoid pressure regulator valve spring to replace the frequently broken stock spring. This Shift Correction Kit will come with installation directions in English and illustrations. We offer a wide range of Superior Shift kits, rebuild kits and everything else you may need for your rebuild! Please see my other listings!