Understanding Volvo Penta U-joints

[saaristo]

According to my VP manual the normal operating trim range is +/- 6 degrees. Above that range the rpm's should be lowered otherwise there will be too much stress on the U joint. On some other place I found that the drive movement range from side to side is +/- 28 degrees...but not a word about allowed rpm range. For U-joint as such there's no differene wheter up or down. So what to make out of this? Is it allowed to "floor it" while turning?

 

[harringtondav]

Add that steering angle to trim angle and there is a larger working angle. Assuming the VP drive shaft assy uses a two uni cardan system, this angle is reduced by half for each U joint (effective uni steering angle = +/- 14 deg.) +/- six degrees likely applies to full power maneuvering. Hole shots with straight ahead steering, max trim in are OK. Full power turns at half the steering range stay w/in this limit, and seems reasonable unless someone is a hot dog.

I watch hoopleheads doing full power donuts. This makes my head hurt. But I think the unis are hurting worse.
A standard caution is to not run the drive when tilted up in trailer position. Uni stress is the reason.

 

[QBhoy]

Wouldn’t pay too much attention to the digital trim gauge and instead look at the actual angle of the drive. The trim reading is at best when the sender is set up every year and even then can easily read out of what it should.
simple answer is that at any upward angle above normal running trim, you will damage and wear the UJ for sure. Especially at high rpm.
Usually a greasing nipple to keep it in shape too.