NV4500 Synchronizer Ring Kit for Chevy GMC RK4500A

Full set of replacement synchronizer blocker rings for the GM version of the New Venture NV4500 five-speed manual, Motive Gear part number RK4500A. This is the Chevrolet/GMC ring set - the GM NV4500 does not share ring specs with the Dodge box, so ordering the Chev kit matters if the transmission came out of a C/K 2500 or 3500, a Suburban, or a Kodiak-series truck. It covers the 1992 and up GM NV4500 gear train.

Worn blocker rings are what you are chasing when the truck grinds going into second or third even after the clutch is adjusted and the fluid is fresh, or when the shifter fights you on a cold morning and smooths out once the case warms. The ring cone loses its bite against the gear cone, the ring stops slowing the gear fast enough, and the sleeve teeth clash before speeds match. No amount of fluid changes fixes that - the friction surface is gone.

On the bench these go in with the transmission split and the mainshaft stack pulled. Check each new ring against its gear cone before assembly: seat the ring on the cone by hand, rotate it a quarter turn to bed it, and measure the gap between the ring face and the gear dog teeth with a feeler gauge. A new ring should stand well clear of the teeth; if it drops close to flush, the gear cone itself is worn and the gear needs replacing too. Rings that pass go on with the struts and springs, and the sleeve slides on last.

Note this kit is rings only. If the transmission is coming apart for a full teardown, plan on a bearing and seal kit alongside it, since the labor is already spent once the case is split.