Transmission bushings are much like engine bearings. For example, engine oil pressure is heavily reliant on proper bearing fitment/clearance. Automatic transmission bushings are very similar(if not the same) to engine bearings. These bushings help to route lubrication to the planetary gear sets, among other tasks.
The 700R4/4L60/4L60E are known to have a relatively loose fitting bushing and hub, due to poor OEM bushing design. This results in less lubrication to the rear planetary gear set. Sonnax, an aftermarket company, has designed a wider bushing. This wider bushing helps to better distribute the axial loads, and improves oil flow to the gear set.
Note: This upgraded bushing is included in our Blueprint-in-a-Box kit.
- Blueprint-in-a-Box: 700R4/4L60.