How much angle can a driveline handle??

I am converting my 42' boat from fixed surface drives to Arneson surface drives. The problem is that the current gears have a 10 degree down angle, and the suggested angle of the Arneson drive input shaft is 7 degrees. I can possibly raise the rear and drop the front of the motor some, but not much. Then install the drive with an 8 degree angle. This may or may not be enough for a straight and true shaft alignment. Question: Can this cause problems? I realize that you can have offset if the angle matches, but I may be off one or two degrees.

Steve H

 

The worst problem is that the oil pan is designed for that angle installation. It may run the oil pump dry.

 

I was asking about drivelines, not oil pans. Anyone?

Steve Hixson

 

Steve,

Believe it or not, two factors determine shaft line angle. One is the engine oil pan and oil suction. Most engines will not pick up oil in the pan if the crankshaft angle (and prop shaft angle??) is larger than 15 degrees. The other factor is drag created by the prop shaft--the more angle in the shaft line, the more drag and flow separation going into the prop. Ideally, the prop shaft angle should be zero degrees. Up to 4 degrees is very nice, up to 7 or 8 degrees is OK. You are talking about a 1-degree increase from 7 to 8 degrees, which should not cause a problem. You may find that the boat trims a bit differently, and that the trim tab settings may change when you are maneuvering onto plane.

Eric

 

Thanks Eric for the reply. The engines are currently in line with the bottom of the boat. Since the boat sits bow high when stopped and under way I think the rear of the motor can come up some without causing any oiling issues.

The Arneson drives are fully trimable while under way. They will trim up or down 18 degrees, instead of the constant 10 degrees I have with the current fixed surface drives. I am getting stern lift and bow steer when I approach speeds over 45mph with the current set up. The Arnesons should take care of that.

There is not and will not be a prop shaft under the boat. Everything is behind the boat. I will be installing a driveline with u-joints between the output flange of trans and input shaft of the Arneson that will be mounted to my transom. I need to know how much angle if any I can have with out causing problems later. If I have to I will purchase transmissions with a 7 degree down angle to match the Arneson drive. But I dont' want to do that unless I have to.

Thanks again

Steve Hixson

 

I would be surprised if there is not some kind of guideline on the Arneson drive about an offset angle of the input shaft. Universal joints usually like some angle to operate smoothly, 2 degrees is a minimum, 4-5 degrees should be OK. Even the U-joint manufacturer should have some specifications about the maximum angle allowed. With the ability to tilt the Arneson's up or down 18 degrees, I can't see that your installation would really be a problem.

Eric

 

Contact Arneson directly. I used to work for Arneson, and they have application specialists that can work with you and provide the parts.

 

Email manufacturer...

Hello...

Take some photos - some tape measurements - and contact Arneson DIRECTLY - their engineers will get back to you same day...

SH.

 

I called Ric at Arneson Industries lastnight. Very nice guy. He told me to set the inputshaft of the Arneson drive at 10 degrees to match the transmission. Thanks everyone who commented. I will post pics of the project as I soon as I get started.

Thanks,

Steve Hixson