4L60E 2-3 Shift Flare: Causes and Fix

4L60E 2-3 shift flare — engine RPM rises briefly before grabbing — points to the 3-4 clutch or pressure issue. Here's the fix.

What flare means

• Brief RPM rise during shift
• Clutch isn't grabbing fast enough
• Pressure or clutch issue
• Read our transmission shudder vs slip

Common causes

3-4 clutch wear:

• Most common
• Stock 4L60E uses 4 frictions only
• Wears with miles or HP
• Read our 4L60E 3-4 clutch pack failure

Low line pressure:

• PR valve wear
• Pump wear
• Read our 4L60E PR valve symptoms

Apply piston seal failure:

• TCC apply piston worn
• Read our 4L60E TCC apply piston

Solenoid issue:

• Shift solenoid timing off
• Read our 4L60E shift solenoid B

Diagnosis

• Pan inspection (burnt material = clutch)
• Read our transmission pan inspection
• Pressure test
• Read our transmission line pressure testing
• Code pull

Repair options

Sonnax PR valve fix:

• Restores line pressure
• $300-$600 fix
• Read our Sonnax PR valve install

Full rebuild with HD 3-4 pack:

• Add 5th friction to 3-4 pack
• HD apply piston
• Sonnax sun shell
• $1,500-$3,500
• Read our best 4L60E rebuild kit

Prevention

• Quality fluid, regular service
• HD upgrade if performance/tow use
• Aux cooler
• Read our transmission cooler installation

Need 4L60E 3-4 clutch parts? Shop our 4L60E catalog. HD clutch packs, Sonnax kits, rebuild kits. Free shipping over $70.

Related:

• 4L60E 3-4 clutch pack failure
• 4L60E no 3rd or 4th
• Best 4L60E rebuild kit