Drivetrain› Automatic Transmissions and Components

Sonnax

Pinless Accumulator Piston Kit for GM 4L60E

$47.00

SKU: 77998-03K

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Special Order
Ships in 4–6 weeks
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$100 Minimum Order
30 Days Return
INSTALL DIFFICULTY
DIY PRO SHOP

Moderate — 2–4 hours

Overview

The Sonnax pinless accumulator piston kit is designed to address common issues in GM 4L60E transmissions, such as poor shift quality and burnt bands or clutches caused by accumulator piston wear. This kit includes 1-2 and 3-4 bore pistons, as well as the forward piston for the valvebody. Its pinless design eliminates potential pin bore leakage and uses dual seals to stabilize and seal the bore, even after extensive use. Steel balls are included to plug the existing pin bore in the case or cover.
Show original supplier description
The Sonnax Pinless Accumulator Piston Kit (77998-03K) is engineered to resolve common problems in GM 4L60E transmissions that manifest as poor shift quality, burnt bands, or clutches. These issues often stem from wear at the accumulator piston pin bore interface, leading to fluid loss and potential piston cocking which can gall the accumulator bore. This kit directly addresses these failures by replacing the worn components. This kit features a patented pinless design that eliminates the possibility of pin bore leakage. The pistons are also extended in length to provide additional stabilization, preventing the piston from cocking within the bore. Equipped with dual seals, these pistons offer enhanced stability and a complete seal for the bore, maintaining tight sealing even after thousands of operational cycles. Steel balls are provided to plug the existing pin bore in the case or cover, ensuring a secure fit. This kit is compatible with '95-later GM units featuring PWM/EC3 (electronically controlled capacity clutch) control. The installation of this kit involves dropping the valvebody, which typically requires new valvebody gaskets. The specific steel ball size to be used will correspond to the OE pin bore size.

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 Number77998-03K
CategoryDrivetrain
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Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

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