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Drivetrain› Automatic Transmissions and Components

Sonnax

R Ratio Servo Piston Kit

$197.61 $141.79 Save $55.82

SKU: K36528R

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Special Order
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INSTALL DIFFICULTY
DIY PRO SHOP

Moderate — 2–4 hours

Overview

The Sonnax "R" Ratio Servo Piston Kit is designed to increase band apply force in Ford C6 automatic transmissions. This kit, part number K36528R, is for mid-1968 and later units. It features a no-leak servo pin design that uses an O-ring and a PTFE ring to prevent leakage, even in worn case bores. The kit also includes two selective return springs to allow for tuning of shift quality.
Show original supplier description
The Sonnax "R" Ratio Servo Piston Kit K36528R is a performance upgrade for Ford C6 automatic transmissions, specifically for mid-1968 and later models. It features a no-leak servo pin design that utilizes an O-ring and a PTFE ring. This innovative design effectively eliminates back pressure and leakage, allowing the servo piston to function correctly even in transmissions with worn case bores. The kit includes a cover, servo assembly, PTFE seal ring, O-rings, a gasket, and two selective return springs. The selective return springs allow for fine-tuning of shift quality to match driving preferences or specific performance requirements. Sonnax also offers a replacement seal kit (K36528R-SK) for this servo. Proper installation requires ensuring that the exhaust passage and both oil feed passages in the transmission case are unrestricted. Any previous modifications that blocked these passages must be removed for the servo to operate correctly.

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

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Specifications

BrandSonnax
Part NumberK36528R
CategoryDrivetrain
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Returns & Fitment

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

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Shipping

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