• 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

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• 4L80-E
• AT-540
• TH400
• Fits AT-540/543/545.

Sonnax forward and direct clutch inner snap ring 34577-01 is a direct replacement for GM 4L80-E, TH400 and Allison® AT-540 forward and direct piston return spring snap rings.

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• 4L80-E (Dual Stator)
• 4L80-E (Early Single Stator)
• 4L80-E (Late Single Stator)
• 4L80-E, 4L85-E, Single-Plate Performance Converter (Mounting Ring)

Sonnax performance converter mounting ring kit GM-RK-15 is designed to work with both early- and late-model GM 4L80-E, 4L85-E transmissions and utilizes the GM 245...Read More

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• 4L80-E
• 4L85-E
• Powerglide
• TH400
• Intermediate clutch backing plate

Sonnax heavy duty clutch retaining ring 28124 can be used as an upgrade for the Reverse clutch backing plate retaining ring in GM Powerglide transmissions and for ...Read More

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