Monday, February 3, 2014
Tips for Rebuilding a 4L60E Transmission
The 4L60E transmission is an electronically-controlled version of the 700R4 four-speed overdrive transmission. The engine control module controls and shifts the transmission for precise control of the shift points and lockup torque converter. Manufacturers used the transmission in light- and medium-duty rear-wheel drive and four-wheel drive vehicles, such as trucks and sport utility vehicles, and in full-size rear-wheel drive passenger cars such as the Caprice and Impala.
Proper Workbench
The 4L60E transmission has numerous parts internal to the case assembly. Professional transmission re-builders use a very large worktable with plenty of room to keep the parts in order, clean and organized. The worktables have ledges to prevent losing small parts and components and a screened drain to capture transmission fluid. Lay out the internal components of the 4L60E during disassembly in order on an adequately sized workbench to keep the components organized.
Clean Workspace
Clean the worktable prior to use. Transmission re-builders worktables are stainless steel and easy to clean. Dirt and grit picked up during the rebuilding process significantly reduce the life of a transmission. In a pinch, secure wood strips around the outside edge of the table to create a ledge to retain small parts. Drape a plastic drop as a resourcecloth over the table to provide a clean surface and catch excess transmission fluid.
Visual Aids
Obtain an exploded view diagram of the 4L60E from the transmission parts supplier. Suppliers keep diagrams on hand to identify the exact parts customers are attempting to purchase. The diagram indicates the order and placement of the components. Experienced technicians use the diagram while rebuilding to jog their memory and speed the assembly process. Often overlooked as a resource, cell phones can be invaluable during the rebuilding process. Take numerous pictures with a cell phone during the disassembly process as a erence to help during re-assembly of the 4L60E.
Additional Componets to Consider Replacing
The 4L60E transmission has several known weak points that are prone to failure. Upgrade the sun-reaction shell with a hardened steel sun shell to prevent it from shearing at the splines. Upgrade the 2-4 servo to increase the holding power of the band, preventing slipping and burning of the band. Install a rev-kit or new springs in the 3-4 clutch pack to prevent engagement at high rpm that will burn and damage the new clutch pack.
High Horsepower Modifications
With proper modifications, the 4L60E transmission will easily handle 600 foot-pounds or more of torque from highly-modified powerful engines. Upgrade the input shaft and output shafts from mild steel to hardened steel shafts. Replace the stock three-gear planetary gear sets with four- or five-gear planetary sets. Use racing clutches, bands and steels. Use synthetic transmission fluid to handle extreme heat and stress and extend the life of the transmission under abusive conditions.
Modifying Shift Quality
The springs of the accumulators under the valve body of the 4L60 E control the crispness of the shifts. The servos control shift quality by purposefully slowing the buildup of fluid pressure in the clutch servos. The clutches slip, creating a smooth transition into the next gear. Softer springs result in softer shifts. Stiffer springs result in crisper shifts. Install the servo piston and spring in the upside-down position to lock them out completely, for the harshest and crispest shift possible.
Great tips! Thank you! If you don't mind I'd also like to recommend this manual which was recommended to me and downloaded here. http://www.4l60eguide.com/. It is a complete guide and it has helped me a lot. It has a ton of information in it that helped me rebuild/repair 4l60e transmission. It also includes useful diagrams and pictures, plus diagnosis and repair solutions.
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