Da Burb
04-09-2007, 06:47 AM
Hi All,
here's a pretty good explanation of why a 4L80E is better than a 4L60E and why the guys in the US are doing the swaps.
Found this on another forum and thought it was interesting.
Just as a reference, the writer drives a 98 Tahoe with a BIG Whipple and 383.
This truck spins through most gears and lifts the front wheels 12" off the ground. It's also a daily driver!
First of all, a 4l60-E is a 2-speed trans plus overdrive. There are two planetary gear sets in it.
A 4L80-E is a 3-speed trans plus overdrive. These have three planetary gear sets.
The 4L60-E input shaft goes to a huge aluminum drum that houses all the clutches. This drum spins within two thinly stamped out components making up the reverse-input and reaction sun shells. These are brittle. All this large-diameter spinning mass also has no center support. It's all held by the pump bushings and the tailshaft bushings. Also, the way these components are designed, when certain clutches are applied they impart a spreading force between the front and rear of the transmission. The worst feature of all - it shifts the overdrive with a band. (Second gear is really overdriven Low and fourth gear is overdriven Direct.) All the major torque-transferring components inside a 4L60-E are aluminum. The pump in a 4L60-E is a cheesy vane-type pump, and of course it is fragile.
The 4L80-E has drums too but they are self-contained clutch packs and pistons. None of them has a foot-long thin input shaft fused to them either, and these drums are all steel. There are no "shells" or any comparable bullshit stamped parts spinning in a 4L80-E. The 4L80-E, like a TH400, has a center support separating the main geartrain from the clutch drums. Neither of the two bands in the 80 are used for forward shifing, they are only for manual low-range overrun and for reverse. All the torque-handling parts in a 4L80-E are steel. The only aluminum torque-related parts are the clutch pistons and the overdrive piston housing. The 4L80-E uses a gear pump that is so powerful it's been known to crack the early-model 4L80-E's in half when their pressure solenoids got stuck.
The reason a band has no business shifting a heavy-duty transmission is that bands do not respond well to increased demand. If you try to apply a band too fast or too hard it will pick up torque from the drum it's in contact with and self-energize causing violent engagement. A traditional clutch pack has a very linear response to increased apply force. They do not have any tendency to grab like bands do. In a 4L60-E there is one band used to engage "second" and again to engage "fourth". This band is undersized and over-worked. If it has to shift too much torque the shift becomes jarring and violent and that leads to breakage, not to mention being unpleasant.
There are plenty of other reasons, but I've got other stuff to do today.
Besides use with 4 or 5 cylinder engines, and perhaps the 2.8L V6, there is only one other place a 4L60-E belongs:
http://img.photobucket.com/albums/v35/hquick/dump.jpg
here's a pretty good explanation of why a 4L80E is better than a 4L60E and why the guys in the US are doing the swaps.
Found this on another forum and thought it was interesting.
Just as a reference, the writer drives a 98 Tahoe with a BIG Whipple and 383.
This truck spins through most gears and lifts the front wheels 12" off the ground. It's also a daily driver!
First of all, a 4l60-E is a 2-speed trans plus overdrive. There are two planetary gear sets in it.
A 4L80-E is a 3-speed trans plus overdrive. These have three planetary gear sets.
The 4L60-E input shaft goes to a huge aluminum drum that houses all the clutches. This drum spins within two thinly stamped out components making up the reverse-input and reaction sun shells. These are brittle. All this large-diameter spinning mass also has no center support. It's all held by the pump bushings and the tailshaft bushings. Also, the way these components are designed, when certain clutches are applied they impart a spreading force between the front and rear of the transmission. The worst feature of all - it shifts the overdrive with a band. (Second gear is really overdriven Low and fourth gear is overdriven Direct.) All the major torque-transferring components inside a 4L60-E are aluminum. The pump in a 4L60-E is a cheesy vane-type pump, and of course it is fragile.
The 4L80-E has drums too but they are self-contained clutch packs and pistons. None of them has a foot-long thin input shaft fused to them either, and these drums are all steel. There are no "shells" or any comparable bullshit stamped parts spinning in a 4L80-E. The 4L80-E, like a TH400, has a center support separating the main geartrain from the clutch drums. Neither of the two bands in the 80 are used for forward shifing, they are only for manual low-range overrun and for reverse. All the torque-handling parts in a 4L80-E are steel. The only aluminum torque-related parts are the clutch pistons and the overdrive piston housing. The 4L80-E uses a gear pump that is so powerful it's been known to crack the early-model 4L80-E's in half when their pressure solenoids got stuck.
The reason a band has no business shifting a heavy-duty transmission is that bands do not respond well to increased demand. If you try to apply a band too fast or too hard it will pick up torque from the drum it's in contact with and self-energize causing violent engagement. A traditional clutch pack has a very linear response to increased apply force. They do not have any tendency to grab like bands do. In a 4L60-E there is one band used to engage "second" and again to engage "fourth". This band is undersized and over-worked. If it has to shift too much torque the shift becomes jarring and violent and that leads to breakage, not to mention being unpleasant.
There are plenty of other reasons, but I've got other stuff to do today.
Besides use with 4 or 5 cylinder engines, and perhaps the 2.8L V6, there is only one other place a 4L60-E belongs:
http://img.photobucket.com/albums/v35/hquick/dump.jpg