Drive line drag O.B vs straight shaft?

[Andris Golts]

Hi all im using a R.e.k composite lower unit on my outboard tunnel hull im interested has anyone ever figured out how much power loss or frictional loss there would be with the flex shaft having to almost make a 90 o bend as opposed a straight flex drive ? E.G my mono where the flex shaft may roll upwards to the flex hex a 1/4'' over a 6'' length . Do many fe boaters still use teflon liner? On my new rigger im just using a brass stuffing tube and Mercurys 2-4-c marine grease to lubricate the flex shaft. Andris Golts.

[sailr]

I am no longer using teflon but you have to on the outboard unless you can fabricate a brass tube for the shaft to run in.

[Andris Golts]

Thanks sailr for your input. Regards Andris Golts.

[AlanN]

I am no longer using teflon but you have to on the outboard unless you can fabricate a brass tube for the shaft to run in.

HUH????? I use only the brass liner in my REK. I would not put teflon in it. The grease Andris is using is fine to use. I would re-lube every 1-2 runs. I used to do this but for heat racing days, I shoot some aerosol lube like corrsion x inbetween heats.

[RaceMechaniX]

Andris,

The drag in a flex shaft can be signifigant in the range of 3-4% for an OB, but it really depends on many factors. Some to consider are:

1. Stiffness of flex shaft
2. Friction between shaft and liner (teflon, brass or other)
3. Driveline speed
4. Angle and/or radius of bend(s)

IMO, teflon liners work very well for smaller applications with shaft diameters below 3/16". In high power applications the teflon liners have to be closely watched and lubed to avoid burning up. You won't think burning up a liner would be so bad, but its the extra load it places on the motor and which ultimately leads to failure. This will rarely happen with brass, so its prefered over teflon particularily for 1/4" drivelines. Brass liners with good grease are perhaps the most reliable solution.

Tyler

[sailr]

I'm not running an REK. Are you saying that unit comes with a brass tube in it? If so, then that is what I would use and would not add teflon. I run K&B lower units which use teflon...no brass. You have to fabricate your own brass liner which is tricky to get just right.

HUH????? I use only the brass liner in my REK. I would not put teflon in it. The grease Andris is using is fine to use. I would re-lube every 1-2 runs. I used to do this but for heat racing days, I shoot some aerosol lube like corrsion x inbetween heats.