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Old 29 July 2012, 16:24   #1
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Counter-rotating Gearboxes

Being totally thick, why are they generically weaker than standard right hand units??

It is the same power/torque going through them and as our engines are electronically sync'ed, they are being used almost identically. The components are machined from the same quality metals and assembled with the same tolerances. Are the internals that different and therefore that much weaker??

3.5 years on right hand gearbox, 4th unit coming up on the left hand side! The longest lasting 363 days.

What are your thoughts on using right hand units on both engines?

Regards
Steve
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Old 29 July 2012, 16:30   #2
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Why not swap them over and see what difference that makes

Peter @ Boatsandoutboards4sale ~ askboatsandoutboards4sale@sky.com ~ 07930 421007
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Old 29 July 2012, 17:56   #3
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Looking at the Evinrude gearboxes, the CR version looks to have about 20% more parts in it than the standard rotation. Bearing (pun) in mind that the powerheads all rotate the same way, the CR has to reverse the direction of rotation inside the same space, so the components have to be crammed in. More parts, more friction, more complex = more scope for failure I suppose.
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Old 30 July 2012, 02:33   #4
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swap them over not that easy on a verado as they have to be set up with a computer, counter rotating g/h run hotter
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Old 30 July 2012, 05:06   #5
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I think if you have two right hand ones you might find the boat wanting to lean due to the increased prop torque, so you might have to weight one side.

There is a verado forum which may have more insight into the problems you have experienced ..Your Source for Verado and 4S Information - Index
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Old 30 July 2012, 07:20   #6
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Mine are both right hand as the engines are not the XL shaft which certainly at the time were the only leg which they offered CR on. It is noticeable in big waves if the boat has too much weight aft, as you crest a wave you can feel the hull being pushed over, not massively but noticable. If the boat is well balanced its not an issue.
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Old 30 July 2012, 07:32   #7
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Never had any problems with CR outdrives but then you probably do more hours in a week then I do in a year!
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Old 30 July 2012, 09:29   #8
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Quote:
Originally Posted by 250kts View Post
Being totally thick, why are they generically weaker than standard right hand units??

It is the same power/torque going through them and as our engines are electronically sync'ed, they are being used almost identically. The components are machined from the same quality metals and assembled with the same tolerances. Are the internals that different and therefore that much weaker??

3.5 years on right hand gearbox, 4th unit coming up on the left hand side! The longest lasting 363 days.

What are your thoughts on using right hand units on both engines?

Regards
Steve
I think on a righthand gearbox that the "fwd" gear is the one in the front of the gearcase. One thrust bearing can take the thrust from the prop shaft and also the loading produced by the gears meshing.

On a CR gearbox the "fwd" gear is the one at the rear of the gearcase. Therefore the prop shaft thrust will be taken by the bearing at the front of the casing but there will be loading forwards from the gears meshing.

Maybe this is difficult to shim up at build or you have to have some sort of floating gear.
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Old 30 July 2012, 12:43   #9
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Interesting from suzuki

New Suzuki DF300AP with Selective Rotation wins a NMMA Award for Innovation at the Miami International Boat Show
Feb 2012
Suzuki has been honoured with yet another prestigious Innovation Award at the 2012 Miami International Boat Show for its new DF300AP model, which features a world first in outboard technology - Suzuki Selective Rotation.

This new technology enables Suzuki to do what no other outboard manufacturer can and combine standard and counter rotation operation into the same outboard. This is done by switching an electronic circuit to change the gear-shift mode and adding a counter rotation propeller.

In counter rotation mode the power is transmitted through the reverse gear, which has been upgraded and improved to give it the same characteristics as the forward gears. In fact, the specifications and materials used for forward and reverse gears have both been optimised, as well as improving the layout of the bearings.

All of this now means that there is now no need to buy a dedicated counter rotation outboard.

The award was made on February 16, by the National Marine Manufacturers Association (NMMA) and Boating Writers International (BWI), recognising the DF300AP as the most innovative new product in the Outboard Motors Category.

It was voted for by a panel of esteemed marine journalists and marks an unprecedented seventh time that Suzuki's Marine Division has received the coveted NMMA Innovation Award, with six out of these seven awards going to models from its market leading fuel-injected four stroke range.

Ed Sherman, Educational Programming Director at the American Boat & Yacht Council, (ABYC) said, "This is a brilliant ground-breaking design and will save dealers money in inventory, and consumers selling their used twins will now be able to sell them one at a time and make them into whatever the buyer needs."

Yasuharu Osawa, Group Manager for Suzuki's Marine Division in Europe said, "We are always looking to enhance our range of outboard motors, whether it be with new models such as the new DF20A and DF15A or technical innovations such as the new Suzuki Selective Rotation. We are very proud to have won this award and I must pay tribute to the engineers that were responsible for this innovative new feature which we believe will be very popular with boat builders, dealers and boaters alike."
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Old 30 July 2012, 13:11   #10
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There yer go then Steve, you need a pair of Bi-directional Suzi-wongs to keep yer junk goin'
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