Another prop slipping thread

[beech2000]

I know they're are many threads of the like. I have history of shredding this boats Alpha One Gen 2 so I decided to post a fresh one.
The boat is way overpowered. (Big mistake with Alpha's) 1st failure was due to improper upper gear ratio being a V6 1.62. Replacement was a new OEM with 1.47 gear ratio.
So all has been fine for years.. Yesterday three Girls and I pulling 2 males on slalom under way when she all of a sudden she went into rev limiter mode.
Throttled back and we were able to return back but only at idle power. I pulled the Prop and the flo Torque plastic center was perfect. I reinstalled the prop and tried to rotate in both forward and reverse and unable to fight the engine rotation by hand. I pulled the drain plug on lower unit and while some light metal.... nothing major. I removed the top cover from upper unit and all looks perfect. We went out again late and same thing. Bad Coupler? If yes wondering why?

 

[Scott Danforth]

if the coupler is bad it is usually from not checking alignment every year

you do pull the drive every year to check alignment and u-joints per the manual, correct?

common things that lead to the drive being out of alignment:

• rear mount bushings fail and motor sags
• transom is rotten and motor transom plate moves
• motor mounts failed, and motor moves
• stringer mounts are rotten and motor moves.

doubt the boat is overpowered.

 

[Bt Doctur]

V6 usually pushes 200 hp and the 1.65 is the correct ratio, You wont spin a 1.5 up to rated rpm unless you running a 14 x 11 P prop

 

[ROY WILLIAMS]

you was the on the land of the boat ... do the fwd /neutral/reverse of that prop ... locked it left fwd, right rev .... neutral spin it ...

the gear ratio is dropping it today ..prop is the of the gears issue wearing it .. 1.47 ratio

 

[beech2000]

if the coupler is bad it is usually from not checking alignment every year

you do pull the drive every year to check alignment and u-joints per the manual, correct?

common things that lead to the drive being out of alignment:

• rear mount bushings fail and motor sags
• transom is rotten and motor transom plate moves
• motor mounts failed, and motor moves
• stringer mounts are rotten and motor moves.

doubt the boat is overpowered.

I haven't been checking the alignment every year. In fact last time I did was when I installed the new out drive. Engine dyno brake tests at 390 hp and 405 ft lbs of torque at 3900 RPM. Engine is a 5.7 litre engine with a stroker kit. Displacement at 383. I was told Alpha weak past 300 horse so assumed I'm the sorce of my own problems

 

[beech2000]

V6 usually pushes 200 hp and the 1.65 is the correct ratio, You wont spin a 1.5 up to rated rpm unless you running a 14 x 11 P prop

My power plant is a vortec V8 engine (383cid) with 14X21 Pitch propeller and 1.47 gears. WOT equates to 4400 RPM so I feel the prop (screw) as our english folk call them seems perfect for the size weight and WOT RPM.

 

[beech2000]

you was the on the land of the boat ... do the fwd /neutral/reverse of that prop ... locked it left fwd, right rev .... neutral spin it ...

the gear ratio is dropping it today ..prop is the of the gears issue wearing it .. 1.47 ratio

Drive was new and stamped 1.47 which is what I ordered from mercruserparts.com several years ago.

 

[alldodge]

Prop hub not spun
Drive locks up and doesn't spin
Only thing left is the coupler

Remove drive and look at the coupler thru gimbal. Look to see if rubber has stripped mostly away from center. If drive doesn't slide off easy it's not aligned

The extra hp is ok so long as the boat is light and throttle is not hammered

 

[Scott Danforth]

I haven't been checking the alignment every year. In fact last time I did was when I installed the new out drive. Engine dyno brake tests at 390 hp and 405 ft lbs of torque at 3900 RPM. Engine is a 5.7 litre engine with a stroker kit. Displacement at 383. I was told Alpha weak past 300 horse so assumed I'm the sorce of my own problems

your fine with the power assuming you dont mash the throttle for a holeshot and most importantly, run a rev limiter to kill the engine should you launch from one wave to the next. that instant loading of the drive as you come onto the second wave will grenade the drive.

coupler should be good for a lot more power than you are putting in. however if they are mis-aligned, they go quickly.

 

[beech2000]

Since the original 5.0 litre engine was a 2bbl carb with 1.61 gear ratio upper drive... will the coupling replacement be different? Are the coupler splines aluminum on the original? I've identified the part number for the original engine to be 18643A5. Best price found for the OEM is Nuwave. Does iBoats sell the OEM?
I'll let you know what I find when I pull the drive off this week.

 

[beech2000]

Prop hub not spun
Drive locks up and doesn't spin
Only thing left is the coupler

Remove drive and look at the coupler thru gimbal. Look to see if rubber has stripped mostly away from center. If drive doesn't slide off easy it's not aligned

The extra hp is ok so long as the boat is light and throttle is not hammered

I'll remove the drive this week to inspect and report back. Thank you

 

[alldodge]

Use same coupler as removed, splines will be aluminum and should have squared edges not rounded or pointed.

 

[Scott Danforth]

I'm glad my drive has a drive plate vs a coupler.....lol

A good flashlight will tell you the health of the coupler. If you see rubber bits and it looks like the center sleeve is being pushed out a sphincter....the coupler needs replacement

 

[nola mike]

if you can see the driveshaft behind the engine, it won't spin if the coupler is bad. Have you greased the coupler ever?

 

[ROY WILLIAMS]

Drive was new and stamped 1.47 which is what I ordered from mercruserparts.com several years ago.

the boat 19-21 feet ... the gear ratio 1.47 the prop is 14X19 also the 15.75X17 ... boat is the 3000-3500 lbs ....

 

[beech2000]

the boat 19-21 feet ... the gear ratio 1.47 the prop is 14X19 also the 15.75X17 ... boat is the 3000-3500 lbs ....

My boat is 19 ft 1.47 and prop is 14X21 new stainless vengeance. WOT was 4400 for years. that is until now.

 

[beech2000]

if you can see the driveshaft behind the engine, it won't spin if the coupler is bad. Have you greased the coupler ever?

I gooped It with black high pressure moly grease when I installed the drive many years ago. I see the couplers have grease fittings.. opps

 

[ROY WILLIAMS]

I gooped It with black high pressure moly grease when I installed the drive many years ago. I see the couplers have grease fittings.. opps

I did the moly grease of the shafts and grease fittings ....bushings ..
I did every year ..
I was my 4runner I was the moly grease of the drive shafts .. great !

 

[tank1949]

I know they're are many threads of the like. I have history of shredding this boats Alpha One Gen 2 so I decided to post a fresh one.
The boat is way overpowered. (Big mistake with Alpha's) 1st failure was due to improper upper gear ratio being a V6 1.62. Replacement was a new OEM with 1.47 gear ratio.
So all has been fine for years.. Yesterday three Girls and I pulling 2 males on slalom under way when she all of a sudden she went into rev limiter mode.
Throttled back and we were able to return back but only at idle power. I pulled the Prop and the flo Torque plastic center was perfect. I reinstalled the prop and tried to rotate in both forward and reverse and unable to fight the engine rotation by hand. I pulled the drain plug on lower unit and while some light metal.... nothing major. I removed the top cover from upper unit and all looks perfect. We went out again late and same thing. Bad Coupler? If yes wondering why?

Before pulling OD and examining coupler, I'd lock the motor (best way) and then install a couple of jam nuts on prop shaft. Then with breaker bar see if you can turn over motor by hand via breaker bar. If everything is ok, install prop with motor turned off and use a 2x4 to see if you can move prop on shaft. If something easily moves, replace it.

 

[beech2000]

Before pulling OD and examining coupler, I'd lock the motor (best way) and then install a couple of jam nuts on prop shaft. Then with breaker bar see if you can turn over motor by hand via breaker bar. If everything is ok, install prop with motor turned off and use a 2x4 to see if you can move prop on shaft. If something easily moves, replace it.

To late. Drive off boat. I had a moment to do so between travel trips.