Safeguard performance GM TH400 and 4L80-E vehicles on the street and track with reliable, high-strength servo upgrades from Sonnax – the leader in transmission innovation.
New for fall 2021, Sonnax billet aluminum Low/Reverse servo pistons prevent failure at any power level — a critical safeguard when cast OE pistons are brittle and prone to breaking. Part No. 34914-01 fits all TH400 and ’95-earlier 4L80-E; Part No. 34914-02 fits ’96-later 4L80-E.
Also new for TH400 and ’95-earlier 4L80-E applications is an adjustable servo pin kit (Part No. 34912-01K) that gives builders easy access to five of the seven pin options discontinued by GM. The pin covers the five longest lengths for accurately setting Low/Reverse piston travel. It features an O-ring groove to prevent leakage of line pressure past the case pin bore.
Visit www.sonnax.com for details on these and many more Sonnax upgrades.
This story was originally published on December 17, 2021. 
