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AUTO TRANS VALVE BODY KIT

AUTO TRANS VALVE BODY KIT

$152.50
$152.50
Sale Sold out

The B&M Transpak Shift Kit is a valve body recalibration kit for GM TH350, TH400, 700R4, 4L60E, and 4L80E automatic transmissions in countless Chevy muscle cars, trucks, and street rods. If you're frustrated by mushy, drawn-out shifts, the Transpak is the cure.

Each kit includes precisely calibrated separator plates, spring assemblies, check balls, and drilled orifice plates that modify the transmission's hydraulic shift timing. The TH400 kit reduces shift overlap by 50%, firming up shifts without the harshness of a full race calibration. Installation requires only basic hand tools in about 2 hours with the valve body removed. Step-by-step instructions are application-specific.

The Transpak delivers crisper, quicker shifts that reduce clutch pack slippage between gears, extending transmission life while improving performance. Firmer engagement reduces the internal heat generated during lazy shifts—heat being the primary cause of automatic failure. Multiple calibration levels let you choose between street-friendly firm shifts and aggressive race settings.

Your transmission shifts lazy. Fix it with the B&M Transpak—firmer shifts, less heat, longer life. Order your kit today.
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Frequently Asked Questions

Will this B&M Transpak shift kit improve both firmness and performance in my automatic transmission?

The B&M Transpak shift kit modifies the valve body's separator plate and spring calibration to increase line pressure and sharpen shift firmness by 30 to 50 percent compared to stock, providing crisper shifts at both part-throttle and full-throttle. The kit includes pre-drilled separator plates, springs, and check balls that override the factory shift timing to reduce clutch pack slip and heat generation. Installation improves transmission durability by reducing the time between gear engagement.

Does the B&M Transpak kit work with tow/haul mode or electronic transmissions?

The B&M Transpak shift kit is available for both hydraulic and electronically controlled automatic transmissions, with specific versions for 4L60E, 4L80E, and similar electronic transmissions that retain the factory computer control while modifying shift firmness. For electronic transmissions, the kit works in conjunction with the stock ECU or a standalone controller, and it does not interfere with tow/haul or manual shift modes. Always select the Transpak version that matches your transmission's year and control type.

What transmission models does this B&M Transpak valve body kit fit?

The B&M Transpak shift kit covers a broad range of automatic transmissions including GM TH350, TH400, 700R4, 4L60E, 4L80E, Ford C4, C6, AOD, 4R70W, and Chrysler TorqueFlite 727 and 904 transmissions. Each kit is application-specific with the correct separator plate drillings, spring rates, and valve body modifications for that transmission model. Verify your transmission model by checking the transmission pan shape and bolt count before ordering.

How difficult is it to install a B&M Transpak kit in my transmission?

Installing a B&M Transpak kit is an intermediate-level DIY project that involves removing the transmission pan, filter, and valve body, then replacing the separator plate, springs, and check balls with the included components. The entire process takes approximately 2 to 4 hours for someone with basic mechanical experience and a torque wrench. B&M provides detailed step-by-step instructions with each kit, and many enthusiasts find it easier than a full transmission rebuild.

Will the Transpak kit cause harsh shifts in my daily driver?

The B&M Transpak kit can be adjusted for mild, medium, or firm shift settings depending on which springs and plate drilling options you choose during installation, allowing you to tailor the shift feel for daily driving or performance use. The mild setting provides a noticeable but comfortable shift improvement suitable for daily drivers, while the firm setting produces a quick, positive shift feel preferred for performance applications. Start with the mild calibration and upgrade if you want firmer shifts later.

Does the B&M Transpak shift kit help my automatic transmission last longer?

Yes, the B&M Transpak shift kit improves transmission longevity by reducing clutch pack slip time during shifts, which lowers the heat generated inside the transmission during gear changes. The increased line pressure ensures the clutches and bands engage quickly and fully, preventing the slow engagement that causes premature clutch wear. Lower operating temperatures and reduced slip can extend transmission life by thousands of miles, especially in heavy vehicles and towing applications.