Lost reverse: overheated or shattered reverse clutches
What Chris sees on the bench
- Shattered reverse plates that took out all the reverse springs, including the pressure plate separator plate, which often warps too.
- Strawberry milkshake in the sump, a thick goo that makes the pump work harder and the transmission overheat.
- A clutch hub on the input shaft with grooves in it, gone black from overheating.
- On one 71 1.91:1, a previous rebuild had put a Speedi-Sleeve on the input shaft when the shaft should have been replaced, and reused a worn bronze washer.
- A reverse plate starting to wear next to a brand new one: the notches and teeth get skinnier and narrower.
What causes it
Ski boats are the classic setup for this failure. A hard port turn can tilt the transmission enough that reverse briefly sucks air, and slamming into reverse right after that is what shatters the reverse clutches. Wear plays into it too. As a reverse plate's notches and teeth wear down, eventually you'll shift into reverse one hard time too many, the cavities that hold the reverse springs blow apart, and the springs go everywhere and get into the pump.
Fix and prevention
When the reverse plates shatter, you have to replace all the springs, including the pressure plate separator plate. A lot of times that separator plate warps too.
To keep from getting here, take your time shifting. Chris's rule is five seconds from forward to neutral to reverse, instead of banging it into hard reverse. See the five-second shifting rule.
When to call
If reverse is gone, call (804) 333-3677, Monday through Friday 9 to 3 Eastern, or email sales@halemarine.com.
Related reading: the five-second shifting rule and Velvet Drive torque specs.