Quote:
Originally Posted by 68c10airstream
clinebarger can chime in on this one also but the 80 in 4l80 as well as the 90 in the 6l90 is the load rating. The higher number the more load it can handle.
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That is correct.
There are 3 different versions of the 4L80E..
4L80E, All Planet carriers have 4 helical cut pinions.
4L80E-HD, 4 Straight cut pinions in the front & rear Planet carriers, O/D planet uses helical cut pinions.
4L85E, 5 Helical cut pinions in the front & rear Planet carriers, O/D planet...Same as the others.
Any of these unit will work good in high HP applications with minimal modifications, Most already have a 32 element Intermediate sprag from the factory (I have seen some with the weaker Roller Clutch). The Direct Clutches are really the only weakness. Double Feeding them fixes that.
These unit's shift "Straight Through"....Meaning one clutch doesn't have to disengage for another to apply for a oncoming shift.
1st gear, Forward clutch applied
2nd gear, Forward clutch, Intermediate clutch applied
3rd gear, Forward clutch, Intermediate clutch, Direct clutch applied
4th gear, Forward clutch, Intermediate clutch, Direct clutch, O/D clutch applied
A 4L60E for example has to knock the 2-4 Band off & simultaneously apply the 3-4 clutch pack for a 2-3 shift. The presents several problems when performance is concerned. You will almost ALWAYS end up with a "Flare" or a "Tie-up". You may not feel it...But it's there
"Flare" meaning during the 2-3 shift the band was released but the 3-4's have not fully applied, This would put the trans in 1st gear for a split second.
"Tie-up" meaning the band didn't fully knock-off before the 3-4's applied. This would put the trans in O/D for a split second.
Both these events are very hard on the 3-4 clutch pack.
The 6L90E Planet Pinions, Carriers, Sungears are longer/taller than the 6L80E, Other than this & the actual case being longer, Not many differences between the 2.
Every Up-shift & Down-shift requires "oncoming" & "offgoing" Clutch in these units. It's called "Clutch to Clutch". Again...Not really good for performance applications where torque & horsepower are uprated. I still don't like the Stamped drums but they seem to be holding. Bad tuning seems to be their biggest enemy...(Burnt Clutches).
For now, the 4L80E is still the best choice for high power applications.