• 4L80-E
• 4L85-E

GM 4L80-E and 4L85-E transmissions may have 2nd gear starts and no upshifts, which can be accompanied by trouble codes 68, 85, 86 and/or 87. These problems can oft...Read More

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• 4L80-E
• 4L85-E
• Fits units '95-later.

Vehicles with '95-later GM 4L80-E and 4L85-E transmissions commonly exhibit wear in the Reverse checkball sleeve located in the 3-4 shift valve bore. This issue is...Read More

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• 4L80-E
• TH400
• For output and reaction planetaries, fits all TH400 and '98-earlier 4L80-E with .750" wide pinion gears.

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• 4L80-E
• 4L85-E

In 4th Gear, signal A oil force must overpower the 1-2 shift valve spring and opposing signal B pressure in GM 4L80-E and 4L85-E transmissions. If the 1-2 shift va...Read More

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• 4L80-E
• 4L85-E
• Output & reaction planetaries, '99-later

The output and reaction planetary pinion assemblies in '99-later 4L80-E transmissions frequently wear out and must be rebuilt or replaced. New replacement assembli...Read More

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• 4L80-E
• 4L85-E
• Output & reaction planetaries, 1999 & Later

The output and reaction planetary pinion assemblies in '99-later 4L80-E transmissions frequently wear out and must be rebuilt or replaced. New replacement assembli...Read More

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• 4L80-E
• 4L85-E

The actuator feed limit (AFL) valve in GM 4L80-E and 4L85-E units has a large reaction area and is greatly affected by side loading, which wears the valve body bor...Read More

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• 4L80-E
• 4L85-E
• Fits '91-later units with factory-style sleeve, no O-rings. Can be retrofitted to '89–91 units. See instructions for details.

Common problems in vehicles with GM 4L80-E and 4L85-E transmissions are uncontrollable line rise (upward of 500-600 psi), high line pressure in Reverse, buzzing no...Read More

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• 4L80-E
• 4L85-E
• TCC & PR Valves

OE end plugs are designed to prevent critical pressure loss by capping the bore, while also functioning as a valve stop. Repetitive spring motion, valve impact and...Read More

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• 4L80-E
• 4L85-E

Sonnax Sure Cure kit SC-4L80E, fully compatible with '91-later GM 4L80-E and 4L85-E units, is a comprehensive reconditioning package featuring the best Sonnax prod...Read More

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• 4L80-E
• 4L85-E
• TH400
• Updated 3-tang style shim fits all units, including '97-later 4L80-E and 4L85-E units.

It is often difficult to reduce front unit endplay on GM TH400 or 4L80-E and 4L85-E units with excessive spline wear. Normal component wear allows excess forward a...Read More

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• 4L80-E
• 4L85-E

GM vehicles equipped with 4L80-E and 4L85-E transmissions may exhibit problems such as TCC shudder, burnt converter linings, TCC apply and release concerns and rel...Read More

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• 4L80-E
• 4L85-E
• O-Ring style. Kit can be retrofit to back to '89 units. See instructions for details.

Common problems in vehicles with GM 4L80-E and 4L85-E transmissions are uncontrollable line rise (upward of 500-600 psi), high line pressure in Reverse, buzzing no...Read More

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• 4L80-E
• 4L85-E

GM vehicles equipped with 4L80-E and 4L85-E transmissions may exhibit problems such as TCC shudder, burnt converter linings, TCC apply and release concerns and rel...Read More

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• 4L80-E
• 4L85-E
• Fits TCC shift valve bore with .497" dia.

OE end plugs are designed to prevent critical pressure loss by capping the bore, while also functioning as a valve stop. Repetitive spring motion, valve impact and...Read More

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• 4L80-E
• 4L85-E
• With encapsulated relief valve. O-Ring style

Common problems in vehicles with GM 4L80-E and 4L85-E transmissions include uncontrollable line rise (upward of 500 psi), high line pressure in Reverse, broken dir...Read More

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• Powerglide
• Powerglide, TH350, TH400 (258mm) Performance Converter
• TH400 (3L80), AT-540

Sonnax 258mm performance converter kit GM-RK-358 for 35-spline GM Powerglide and TH400 258mm applications allows builders to assemble a high performance converter ...Read More

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• 4L80-E
• 4T65-E
• TH400
• For output and reaction planetaries, fits all TH400, 4T65-E and '98-earlier 4L80-E with .750" wide pinion gears.

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• Buick TH350
• Chevy TH350
• Powerglide
• Powerglide, TH350, TH400 (258mm) Performance Converter
• TH400 (3L80), AT-540

Sonnax 258mm performance converter kit GM-RK-308 for GM Powerglide, TH350 and TH400 258mm applications allows builders to assemble a high performance converter wit...Read More

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• 4L80-E (Dual Stator)
• 4L80-E (Early Single Stator)
• 4L80-E (Late Single Stator)

GM-O-10V is an oversized version of GM-O-2V. It can be used in GM 4L80-E torque converters with worn piston bores.

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• 4L80-E
• Fits '96-later

OE cast aluminum servo pistons can be brittle and are prone to breaking. Sonnax heavy duty low/reverse servo piston 34914-02 for GM '96-later 4L80-E transmissions ...Read More

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• 4L80-E (Dual Stator)
• 4L80-E (Early Single Stator)
• 4L80-E (Late Single Stator)
• 4L80-E, 4L85-E, Multi-Plate Performance Converter
• Street/Strip applications only.

A performance torque converter is highly specialized based on the performance characteristics of the specific vehicle. Sonnax has several levels of kits to ensure ...Read More

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• 4L80-E (Dual Stator)
• 4L80-E (Early Single Stator)
• 4L80-E (Late Single Stator)
• 4L80-E, 4L85-E, Multi-Plate Performance Converter
• Street/Strip applications only.

A performance torque converter is highly specialized based on the performance characteristics of the specific vehicle. And Sonnax has several levels of kits to ens...Read More

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• 4L80-E (Dual Stator)
• 4L80-E (Early Single Stator)
• 4L80-E (Late Single Stator)
• 4L80-E, 4L85-E, Multi-Plate Performance Converter
• Street/Strip applications only. For use with GM 258mm early-style stators only.

A performance torque converter is highly specialized based on the performance characteristics of the specific vehicle. Sonnax has several levels of kits to ensure ...Read More

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• 4L80-E (Dual Stator)
• 4L80-E (Early Single Stator)
• 4L80-E (Late Single Stator)
• 4L80-E, 4L85-E, Multi-Plate Performance Converter
• Street/Strip applications only. For use with GM 258mm early-style stators only.

A performance torque converter is highly specialized based on the performance characteristics of the specific vehicle. Sonnax has several levels of kits to ensure ...Read More

Learn More