I'm relatively new to boat transmissions, they must have much stronger innards then automotive/trucks transmissions as you can't get away with any kind of load of this kind on the output shaft.
Volvo Seal, Replaced With PSS.
- Thread starter BrianRobin
- Start date
Consider that the thrust of the prop shaft (in forward and reverse) is applied directly to the transmission. IOW, the boat is being shoved around by the thrust bearing in the transmission. I think the spring compression is pretty small in comparison.
The shaft seal bellows ride on a graphite surface, there is no real load from the seal as evidenced by how happy your shaft is to roll if you have a fixed prop in neutral. The real damage potential is locking up your transmission and allowing the shaft to turn against stopped transmission plates/cones. That will kill a Kanzaki.
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Essentially the load is just your applied pressure on the bellows, when you set it, per PYI instructions.
There is a very small bellows compression [spring] when you forward thrust your boat.
Your engine mounts take the thrust load.
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Note: If those rubber bellows took the 50+ horse power thrust to move you boat, there would be no gap between the ribs on the bellow.
Tip: Measure the rib to rib gap when it is brand new, no engine on. Log that. In say 6 months, check the gap again. Log it. Repeat that seasonally for sure. Change in gap, change in seal effectiveness over time. Adjust if necessary.
Jim...
Have the same boat ,also feeds raw water pump at sink , I just changed the out the Volvo dripless with new one no leakage whatsoever ,but I did add a flexible coupling. I machined a bushing to fit on the 25mm shaft and an od of 40mm to go into tube . With this setup the coupling halfs were out 1/8 " loosened motor mounts of engine pulled over until coupling haves mated, then installed flexible coupling in between.