GM 287mm 4L60E converter tips help rebuilders General Motors’ new est 4L 60E converter, used in the 2003 and newer Trail Blazer and Envoy, has become quite popular among rebuilders. This converter features the same component structure as its big brother, the 300mm; however, special attention is needed for the differences that exist between the two.
This unit is a constant slip-type torque converter and is equipped with a woven, carbonfiber liner clutch. The mating surface of the front cover must receive a ten or better micro finish for correct clutch performance. If the surface is more coarse than a ten micro finish, clutch shudder is most likely to occur.
If you are unaware of what a ten micro finish looks like, imagine the finish of a new engine crankshaft. The finish is almost as smooth as the polished crankshaft bearing journals.
Clutch damper springs are also a major concern in this unit. They usually are not broken, but are almost always weakened. At this time we have found only three different damper springs used, all being very similar. Make yourself a fixture for testing the torque with a torque wrench and pretest each damper before assembly. This will save countless hours of rework and customer dissatisfaction.
Cores for this converter are hard to find, so if you need new springs, you can use a used damper from the 300mm or contact your parts distributor and encourage them to supply them. At this time, they may be unavailable. If so, contact Dennis Sneath at 815-229-9808.
The front cover of the 287mm is identical to the 300mm version. Bearings and impeller hubs are also the same. Turbine and impeller diameter are the only major differences. Balancing is extremely important, as well as T.I.R. Using care and checking clearance during assembly will assure you a quality finished product.
Found in issue May 2005