Transmission shifts hard once it gets warm

MKFARREN

MEMBER
2007 PONTIAC G6
3.5L
6 CYL
2WD
AUTOMATIC
142,000 MILES

My daughter's car shifts hard after you drive it about fifteen to twenty miles. Before that, it is smooth. There is about 142,000 miles on it and sometimes it will put out an 1811 code for too long to shift, but only once it is warm. It also drops really hard into drive and reverse after it is driven, but not when it is cold or warming up. Has about 28,000 on the fluid and filter. Shift solenoid? Dirty fluid?
Thanks in advance.

9 Replies

ASEMASTER6371

MECHANIC
52,797 POSTS

Good afternoon.

Yes, I would start by changing the trans oil/filter.

It sounds like a valve body issue. Possibly a servo spring may have broken.

Roy

Transmission Shifts Hard

Diagnostic Aids

An intermittent hard shift may be caused by an intermittent clutch condition.

Test Description

The numbers below refer to the step numbers on the diagnostic table.
3. A static shift test is performed by shifting into all of the gear positions with the engine not operating. While performing the test one should note how the shift lever movement is felt. Also while shifting from one gear to the other feel for binding in the shift rails. You should be able to feel the detent plungers operating when coming out of a gear and going into a gear.
6. A dynamic shift test is performed by shifting into the gear positions with the engine operating. Test for the correct mesh of the synchronizers and for the clutch releasing correctly. When shifting into and out of a gear, feel for the shift detent plungers and for the synchronizers sleeve for moving freely.
8. The transaxle uses a Castrol BOT 0063 (P/N 21018899) transaxle fluid that allows proper synchronizer operation. The incorrect fluid may cause hard shifting by varnish build-up, or not enough lubrication for proper synchronizer operation.

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