Ford E4OD/4R100 Transmission Overdrive Spiral Snap Ring Update This is a great update from Sonnax to correct Fords poor design on this snap ring. Fords first and second design retaining rings are known to pop out of the retaining ring groove, causing initial failure or costly comebacks. The Sonnax retaining ring mechanically locks itself into place. This is pretty inexpensive modification that will insure a strong rebuild. This design ensures that tabs are mechanically locked into place. The retaining ring will not expand; it will stay in place. Installation Instructions 1. Using a spring compressor, compress the overdrive return spring. 2. Remove and discard the OEM return spring retaining ring. 3. Install one end of the Sonnax Sure Lock™ ring into the retaining ring groove. It is NOT recommended to use a screwdriver to install, force or pry the spiral snap ring into place. 4. With the ring end fully installed in the groove, work the ring into the groove one wrap at a time (see Figure 1). 5. After the ring is fully installed, make sure that the locking tabs are engaged with the cut-outs in the retaining ring as shown. It may be necessary to bend the locking tabs up to get a secure lock (see Figure 2). Do not bend the cut-out ends.