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hordos

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I have a 26ft boat with twin 4.3V6 GM engines. This is a cabin boat that I fish the salt chuck with. I just put new engines in and am thinking on new drives. What works best for this setup, duo prop or single and what legs.
 
I'd have the same questions as Chris. The year and drive model will determine what you can go with.

With the AQ series drives, you're pretty much limited to this series, of which is actually a better drive.
If you now have one the later Gimbal system drives, you could go either way.
By enlarging the transom cut out, an AQ series drive can be installed.
With the AQ series, no more rubber hubbed drive coupler, no annual engine coupler alignment, no gimbal system.
You'll have main suspension fork/pivot tube geometry, easy drive shaft bellows change out, etc.
The DP-C or C1 or C2 would be my choice.


Duo Prop hands down.
I have a 28 foot SDN F/B boat with twin 5.7's and Duo Prop drives. When I made the change from single props to Duo Props, the boat became a completely different boat.
Fuel economy, getting up on step, staying on step, top speed, etc, all improved drastically.
I've installed quite a few of them over the years, and all have been very pleased.


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OK I have OMC drives that I have had no trouble with, but they are getting old and sooner or later I will have to do something.My wife gets a little upset when I spend a lot on the boat but they boys I take fishing help pay so I like to keep it in good condition.
 
OMC= Oh My Christ. ;)

The holes in the transom will be too big unless you are talking about a Cobra. Don't think you can find transom plate adapters for the old OMCs. You would have to properly fill the transom (or replace it altogether) and cut new holes. This should be done by a professional and I think you may be looking at spending big bucks.
 
Yes they are Cobra. The boat is a 1986 Zeta CB 10ft beam beautiful condition never saw salt water until I bought it. Last summer we did the inside passage Vancouver island to Alaska. My wife a couple of her frends and I spent a mounth on it.
 
Since these are OMC Cobras, you could do the Volvo Penta DP-S conversion. It's become quite popular among OMC Cobra owners.
The Cobra transom unit and gimbal ring are re-used. A new gimbal bell (aka "pivot housing") replaces the OMC Cobra unit.
The DP-S bolts to this unit.
There's a modification that must be done the ram cylinders.

This conversion ends up looking similar to this.



Or.... pull them out, enlarge the cut-outs, and install DP-C, C1 or C2 drives.
(shown with diesel engine.... but the drive will look the same)




The AQ series, IMO, is a far better drive than the later gimbal system Volvo Pentas.
The appearance of the AQ series is not as modern looking as the later drives, but don't let that fool you.

Like said earlier, these are main suspension fork and pivot tube geometry.... apposed to a Gimbal system.
Again....... No rubber hub drive coupler (in lieu of an all steel B/W coupler), no annual engine coupler alignment, no thru prop exhaust, easy drive shaft bellows replacement (upper transmission only needs to be removed), no gimbal bearing (in lieu of a PDS bearing), no upper gimbal ring pivot point to worry about, and I'm probably forgetting a few bullet points here.



In all fairness, your easiest installation will be the DP-S conversion.


Edit:
I forgot to mention that with either Volvo Penta drive, you'll get to rid yourself of the OMC Cobra ESA system, all ESA brackets and ESA linkage, and the second lower shift cable.


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Sorry Rick. With the Volvo DP conversion he would have to take a home equity loan.

You can purchase a bell housing conversion kit for your OMC Cobra transom assemblies and install a Mercruiser Alpha 1 Generation 2 drive. Cheap and reliable.
 
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Chris, he did ask the question! I just followed his lead.

Doing an SEI drive drive, would be swapping one dog clutch drive for another!
I have to ask, why bother?


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Cobra drives work just fine, IF one can find someone that knows how to adjust them before any damage is done. That's a big IF. Most young marine mechanics don't even know what a Cobra looks like let alone a AQ series Volvo Penta, thustly the bad rap and GO Mercruiser you'll never have a problem routine. If I had to depend on Volvo's to put bread on the table I'd weigh 80 lbs. Those welfare drives are what has kept most marine mechanics alive for the past 50 years. Talk about a bunch of garbage.
 
boatdoc55 said:
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If I had to depend on Volvo's to put bread on the table, I'd weigh 80 lbs. Those welfare drives are what has kept most marine mechanics alive for the past 50 years. Talk about a bunch of garbage.
Click to expand...
I have refered to us Volvo Penta mechanics as though we belong to the Maytag repairmen group.
In fact, I've attended a few of their meetings. ;)
 

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Thanks for the input I will be in Florida this January and if my wife will tolerate my obsession of messing around with boats and related stuff I will check out the Merc knock off. I know they are a lot cheaper than Volvo but I have a brother who works for Volvo and should be able to get a deal. If I am going to make a change I think DPS is what I will be happy with. I have not heard good things about the salt water composite series so I will stay away from them. I fear I won`t have enough time in Florida as I have herd there is boats every where you turn.
 
I'd probably do the SEI conversions and get lube reservoirs for the new drives- the old style Alpha reservoir that just feeds the upper fill plug so you can see trouble coming. You can buy 6 or 8 spare drives for the savings over VP, and Cobras are just not reliable. Waiting for that shift cable to inevitably go out of whack and destroy the lower is not fun boating.
 
Well I`m not shire what to say. I have had this boat for 8 years and the legs have caused me no problems. The engines, a different story. This forum helped me a lot to understand the drive system, I had a lot of stalling when shifting in and out of gear.Turned out all my problems were caused by the engine ignition system. A complete change up to Pertronics and a new Balmar charging system. The engines idle down to 600rpm with stalling and shift in and out of gear like butter. The boat is stored on a trailer, and every time it comes out of the water I check the gear oil for level and water. I don`t think OMC is as bad as a lot of people say, they probably were the one to have when the Cobra first came out and if one engineer hadn`t screwed up on the dog clutch they would still be a strong contender for the top boat drive manufacturer.
 
I'm a bit puzzled here.

Here's the first post.
hordos said:
I have a 26ft boat with twin 4.3V6 GM engines. This is a cabin boat that I fish the salt chuck with. I just put new engines in and am thinking on new drives. What works best for this setup, duo prop or single and what legs.
Click to expand...
This thread has been posted in the Volvo Penta section of the forum..... not the OMC or Merc section.
I made an assumption that Hordos may perhaps be wanting to get away from the Cobra Dog Clutch and ESA woes.

The SEI is also a Dog Clutch drive and the V/P is a Cone Clutch drive.
Duo Prop is a trade name of Volvo Penta, so there should be no confusion of this being a Merc BIII drive.
Since this was posted in the V/P section, I assumed that Hordos realized the added expense of the V/P drives.
Now we're talking about the SEI Dog Clutch drives.... of which is trading one dog clutch for another.


Have I missed something here?


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You got the question right and you gave me the answer I was looking for, not my fault other people like to read through and give their opinion. It does not hurt to have more than one view on things after all this is a discussion forum. Every one can learn from other peoples experiences and the right way to do something in one persons opinion isn`t necessarily the only way it will work.
 
hordos said:
............ Every one can learn from other peoples experiences and the right way to do something in one persons opinion isn`t necessarily the only way it will work.
Click to expand...
Very true.

I've owned and worked on Dog Clutch drives, and I've owned and worked on Cone Clutch drives.
Once you've owned a CC drive, it would be tough to go back to a DC drive.... in my opinion only.


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You are Right. My sister in-law has a Volvo drive and it has never had an issue except once when her brother, a "licensed mechanic" had the prop off to remove fishing line than replaced prop without locktite. Good thing there was a logging camp in the bay near where we were fishing. We used their phone to have a new cone sent out the next day. She carried a spare prop but no cone.
 
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