How to Solve Borg-Warner Velvet Drive Problemsby Chris Stevenson
The Velvet Drive transmission, founded by Regal-Beloit in 1948, was purchased by Borg Warner in 1995. The transmissions were and have been particularly suited to the marine industry, for installation on many watercraft, including sailboats, fishing trawlers, inboard cruisers, sport runabouts and large yachts. The Velvet Drive transmission line offers smooth and quiet performance, using the highest grade components manufactured to industry standards. However, the Velvet Drive transmission can be problematic if certain systems are not checked and maintained on a regular basis. A boat owner can solve and remedy many of these problems if he knows what to look for.
Check the transmission oil level prior to starting and running the engine. Pull the dipstick and wipe the probe end with a rag. Insert the probe and pull it to read the level. Low or no transmission fluid oil will cause an overheating condition due to low pressure and inadequate lubrication.
Look for any discolored oil, which has browned or blackened. Smell for a burnt odor. Poor performance, overheating and noisy operation result from dirty transmission oil. This problem requires a fluid drain, replacement and new filter installation. Fill the dip stick inlet tube with type F Dextron, to the full mark.
Start the engine in neutral with the boat in the water and let it reach normal operating temperature. Place the shift selector in forward, at no more than 1,000 engine rpm, and wait for the detent ball at the shift base to pop into socket. The shift indicator needle should rest directly over "Forward" and the boat should begin to move. If the shift indicator rests on either side of the forward position and engages, you have a shift linkage misalignment.
Use the proper end wrench to loosen the lock nut on the linkage and turn the other linkage rod nut to extend or shorten the lingkage throw, so it aligns properly with the indicator needle and the shift mechanism. Check the forward, neutral and reverse positions. Once aligned properly at the linkage adjustment rod, all positions will line up.
Remove the shift case housing with a screwdriver and check the detent ball and poppet spring, if the shift lever slides without engaging in a gear with a click. Make sure the ball has not been lost and the spring is strong enough to keep the ball in the socket, in gear. Apply a small dab of marine grease on the ball and ball groove to insure smooth shifting operation. Replace the poppet spring if it looks broken or stretched.
Measure the engine, transmission and shaft angle where it sits in the bulkhead, relative to a horizontal plane or the boat's bottom surface. Establish the horizon plane with a string or board, and measure the angle between it and the angle of the transmission shaft. Use a simple protractor for this. Velvet Drive transmissions can not operate if the angle exceeds 15 degrees with the boat at rest, or 20 degrees with the boat under way in the full bow-up condition. If the angle is exceeded, you will need to loosen the engine mounts with a socket and wrench, then subtract shims to decrease the angle.
Read the transmission cooler fluid temperature on your gauge. Excessive transmission fluid temperature, coupled with abnormally high pressure after a hard, extended engine run, results from a transmission cooler that does not have adequate capacity to keep the system at recommended specifications. The transmission fluid temperature range should read between 140 and 190 degrees F. Hotter temperatures cause excessive back pressure. Change your cooling system to a larger capacity unit that allows increased flow and faster cooling.
Measure the distance, or air gap, between the transmission coupling and the propeller shaft coupling, if you experience heavy vibration, hear grating noises or see premature bearing seal failure in the through-hole prop transom fitting. Use a socket to remove the coupling bolts, connecting both flange plates. You need a feeler gauge with a .003 inch blade for testing purposes.
Rotate the propeller shaft coupler, then the transmission coupler. Take a measurement at 0 degrees (top), and every 90-degree rotation until you make a complete rotation, for a total of four measurements. The thickness of the gauge blade inserted into the seam can not exceed .003 inch, in any rotational position. If any measurement exceeds this limit, it points to a bent propeller shaft, bent coupling, broken, worn or out-of-alignment motor mount. Install a flexible coupling plate, if your out-of-alignment condition can not be remedied.
Listen and feel for heavy vibrations when at full throttle, or from accelerating from a standing start. Also listen for a metallic clanking sound when the shift lever is placed in forward or reverse, at recommended rpm. Vibrations and heavy metal or gear noise can indicate a defective vibration damper. On the Velvet Drive, this can lead to complete transmission failure.
Use a socket to remove the transmission coupler to the shaft coupler; then remove the bell housing bolts. Remove all cooling lines with flare wrenches, and unsnap wire connectors. Pull the transmission back and inspect the damper.
Look for broken mounting bolts on the damper, which will be attached to the flywheel, on a rear damper configuration. For a front mount crankshaft damper, remove the main damper bolt with a socket and pull the damper loose for inspection. Front-mount dampers can be split at the seam or have a scuffed, marred or worn inner race. Rear flywheel dampers will have broken weld seams or internal component breakage. Replace the damper in either of these situations.
Items you will need
- Transmission oil (type f dextron)
- Marine grease
- Socket set
- Ratchet wrench
- Feeler gauge
- Flare wrenches
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