A/T - 700R4 Forward Sprag Design
BULLETIN # 234TRANSMISSION: 4L60/700-R4
SUBJECT: Forward sprag
APPLICATION: GM
4L60/700-R4
FORWARD SPRAG DESIGN
You may from time to time encounter a 4L60 forward sprag that looks a little different than what you are used to. This type of sprag assembly has only one cage ring instead of the usual two cage rings (figure 1).
The single cage type of sprag element has been known to fail, even when new.
You may encounter harsh forward engagements, a "neutral" condition during a 4-3 or 4-2 kickdown or even a catastrophic "flaring" failure of the reverse input drum. All of these concerns can be attributed to a worn or defective forward sprag.
If you encounter a "one cage" type sprag assembly, replace it with the two cage style.