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Game-Changing New TH400 Drum Upgrade from Sonnax

Posted By: Evan J. Smith

Game-Changing New TH400 Drum Upgrade from Sonnax

TH400 drag racers seeking a radical edge over the competition will get the total package of performance, consistency and safety with the new Smart-Tech® drum module from Sonnax. It’s the first and only Turbo 400 upgrade to deliver a big boost in transmission efficiency for more power to the ground, improved traction/stability on the shifts and unmatched protection against catastrophic drum failure.

There’s a hard limit to what traditional aftermarket upgrades can do for the TH400. It’s burdened by an inefficient drum system that involves starting/stopping/restarting a heavy direct drum on the 1-2/2-3 shifts. At racing rpm this consumes a huge amount of energy and puts a lot of strain on the transmission, which is why parts fail when they hit their limit. The common method of installing lighter components to improve performance won’t overcome this basic inefficiency.

Sonnax — the leader in transmission innovation — took a revolutionary new approach to the problem, re- engineering the entire forward/direct drum system with a unique configuration of lighter and stronger parts. Weighing 3.3 lbs less than an aluminum direct drum, with weight concentrated at the center, the module’s direct clutch components take 68% less energy to operate than an aftermarket aluminum drum. This is a huge advantage no matter vehicle power level or what type of racing you’re doing. The Smart-Tech drum module is track-proven to increase wheel horsepower, improve acceleration, reduce shock on shifts and ramp up durability. Plus, direct drums that explode due to over speeding are simply no longer a threat thanks to the module’s custom design.

“We are used to seeing converters and gear ratios have a noticeable effect on track performance,” said Sonnax High Performance Product Line Manager Gregg Nader. “Now you can do it just by replacing the drum system in the transmission. It’s not often one product makes a race car faster, more predictable and safer, too!”

As an all-in-one kit, the Smart-Tech drum module 34555-01K is a great value. It includes all-new, top-quality components for upgrading the forward/direct drums and everything else from intermediate sprag to back of the pump. The module is easy to assemble and install with compatible 28-spline input shafts, including Sonnax heavy and extreme duty shafts. Due to its design, the module is for use only in drag racing applications that do not use a front band.

To learn more about the groundbreaking new Smart-Tech drum module, visit

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