NV4500 Synchronizer Ring Kit for Dodge Ram 5-Speed

A Dodge Ram 2500 or 3500 with the NV4500 five-speed that grinds going into second, crunches on the 2-3 shift when it is cold, or needs a double-clutch to get into a gear is telling you the synchronizer rings are worn. This Motive Gear RK4500D is the Dodge-application synchronizer ring kit for the New Venture NV4500, the heavy five-speed bolted behind the 5.9L Cummins and gas V8 engines in 1994-2005 Ram trucks. It is the parts list for the most common NV4500 rebuild there is.

What the synchro rings do in a Dodge NV4500

Every gear in an NV4500 is always in mesh with the countershaft. Shifting is done by sliding a sleeve over the dog teeth of the gear you want, and that only works quietly if the gear and the mainshaft are turning at the same speed. The synchronizer ring is the brake that matches them: its cone drags on the gear cone as the sleeve moves, and its teeth block the sleeve until the speeds are equal. All five forward speeds are synchronized, and the NV4500 uses a triple-cone synchronizer on first and second, with an inner ring, a center friction ring and an outer ring stacked to give extra holding power for that big ratio change. On the Dodge NV4500 reverse is synchronized as well. A worn ring loses its grip, so the sleeve reaches the dog teeth before the speeds match and you hear it as a grind.

Symptoms of worn NV4500 synchronizers

• Grinding on the 1-2 or 2-3 upshift, worst on a fast shift or with a loaded trailer.
• A box that is stiff and notchy until the gear oil warms up, then shifts better.
• Gears that will only go in if you pause in neutral or double-clutch.
• Grinding into reverse with the truck fully stopped and the clutch on the floor, once clutch drag has been ruled out.
• A gear that pops out under load. That is usually worn dog teeth, sleeves or shift forks, so plan to inspect those parts alongside the rings.

How to confirm before you tear it down

Rule out the clutch first. If the clutch is not releasing fully, every gear grinds from a stop, and new rings will not fix it. With the engine running, pedal down and the box in neutral, wait a few seconds and select reverse; a clean engagement means the clutch is releasing and the grind you hear on the move is synchro wear. A grind on one or two specific gears at speed points at those rings. Check that the box is full of the correct lubricant too, since the wrong fluid can make a healthy box shift poorly. Our manual vs automatic transmission repair cost guide breaks down what a manual rebuild like this involves.

Fitment

RK4500D is the Dodge ring kit for 1994-2005 Ram 2500 and 3500 trucks with the NV4500, covering both the diesel and gas V8 combinations listed. It is not the GM kit. Chevrolet and GMC NV4500s take a different set, the RK4500A synchro ring kit for Chevy and GMC. NV4500 ring kits are also split by ring count, because boxes with a synchronized reverse use one more blocker ring than boxes without it, so count the rings in your transmission as it comes apart and compare them to this kit. If the case came out of an unknown truck, send us the tag number or the year and VIN of the donor vehicle and we will confirm. More NV4500 parts are in our rebuild kits and hard parts categories.

Install notes

• Keep each old ring with the gear it came off so you can read the wear pattern and confirm where each new ring goes.
• Seat each new ring on its gear cone and check the gap between the ring and the gear dog teeth with a feeler gauge before assembly. Compare it to the factory minimum for your unit; little or no gap means the gear cone is worn too.
• Inspect the sleeves, hubs and keys while the shafts are apart. Rounded sleeve teeth or worn keys will grind on new rings. Check shift fork pads for wear as well.
• Lightly oil the rings with the same lubricant you will fill the box with, set endplay to spec on reassembly, and fill at the side plug until it runs out.
• If the shifter is sloppy after the rebuild, a curved NV4500 shifter stick kit and fresh tower bushings make the new rings easier to feel.

Will RK4500D fit a Chevy or GMC NV4500?

No. This is the Dodge Ram application. GM NV4500s use a different ring set, sold as RK4500A.

Which Dodge trucks does this kit cover?

1994-2005 Ram 2500 and 3500 trucks with the NV4500 five-speed, behind the 5.9L Cummins or the gas V8. Confirm with the tag on the transmission or your VIN if the box is not original to the truck.

Do I need to replace all of the rings or just the one that grinds?

Replace them as a set. A rebuild means the shafts are already apart, and one new ring among worn ones only moves the grind to another gear a few thousand miles later.

My truck grinds in every gear from a stop. Is it the synchros?

Probably not. Grinding into every gear from a stop points to a clutch that is not fully releasing, from low hydraulic fluid, a failing slave or master cylinder, or a worn release bearing. Fix that first.

What else should I replace with the synchro rings?

Inspect and replace worn sleeves, keys and springs, shift fork pads, and bearings and seals while the case is split. Worn sleeve teeth will chew up new rings.

• Automatic vs. Manual Transmission Repair Cost: What to Actually Expect