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Need V/P DuoProp 230 gears

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FleetMech

New member
Hi all,

I just repowered from a VP V8 to an AQAD31a so I need to regear my Volvo Penta DP-C with 195 gears, to the 230 or 232 used on most 4cyl and some 6cyl applications.

I just know there is someone out there pulling his four banger out and sticking in a V8 that is facing the opposite scenario. Maybe we should do some talking. Thanks, John
 
I assume that you're not wanting to change gear sets and bearings, but rather find a complete working ready-to-go 2.30:1 lower.
That makes sense due to set-up time for a Duo Prop gear ratio change.

I may have a good 2.30:1 lower unit as I rarely use this ratio.
It may not be a "C" lower, but all of these interchange with the difference being that the "C" and later requires the long vertical shaft spline coupler .... and I have plenty of each.


Here's my take on this, for what it's worth.

Correct....... the 2.30:1 Duo Prop ratio works for some V-6's in some hulls, and works for the OHC 4's.
The V-6 and OHC 4 have a higher operating RPM than the diesel will...... ( i.e., a WOT RPM of at least 4.4K rpm. )

The AQAD 31 Diesel will be 110 +/- horse power and offers a WOT RPM of approx 3.7K rpm.
I cannot find the AQAD 31 Diesel torque but I'd think that it will be equal to (or more than) the OHC 4 cylinder gasoline engine.

While going from a taller ratio to 2.30:1, we're going numerically higher (lower in ratio).
This works with the higher RPM of the V-6 and OHC 4 and keeps the prop shaft RPM up and allows for a lower prop set #.
However, with the lower RPM Diesel and the 2.30:1 ratio, the prop shaft RPM will be less.
If relative prop set pitch is increased, we may loose on the propulsion dynamics end.
I don't know for sure, but if Volvo Penta suggests this ratio, then they must be correct.
You'll also switch to the A series props if memory serves me.


One other note re the 2.30:1 ratio:
when going from 1.78:1 or 1.95:1..... to a 2.30:1, the gear contact changes between the three gears.
The "drive" gear becomes smaller, and the two "driven" gears become slightly larger.
This lessons tooth contact at any one given time (not much/but some) basically making the 2.30:1 gear set NOT quite as strong as the other two ratios.
Not an issue with the AQAD 31 as it wil be plenty stout for this little engine.

I'll take a peek and see if I have a 2.30:1 lower.


.
 
Hi Rick,

Thanks for the response and further info. You are correct on all counts. Volvo recommends the 230 ratio for the Duo Prop and 215 for the single in this application, and I have a friend with this same duo prop package in his boat and he is getting great results.

Let me know if you have a good lower, you are pretty close to us here. Thanks, John
 
John, there is a 2.30:1 in a C drive listed on e-Bay today..... seller is in Michigan.
The C transmission driven gear bearing diameter is the same as what you now have.
Basically, you could use the entire drive, not just the lower unit.
I'd sure ask if the seller will pull the props and prop shaft bearing carrier and expose the gear set for you.
Cost = two new O-rings and his time to do so.
These look like B props on it. Make sure that they can removed.

http://www.ebay.com/itm/VOLVO-PENTA...728127&pt=Boat_Parts_Accessories_Gear&vxp=mtr
 
Ricardo, there is a set of DP lower gears listed on e-bay that say they are for a 1.95:1 or 2.32:1 both.

I questioned the seller asking how they could be both and he replied "the lower gears are the same and the difference was in the upper gears". Is this possible? I don't believe it is. I know the overall ratio is a combination of upper and lowers but I think we may be talking "apples and oranges".

NEW Volvo DP dual prop gear set 3851309 1.95:1, 2.32:1 #110790431216

Thanks, John
 
FleetMech said:
Ricardo, there is a set of DP lower gears listed on e-bay that say they are for a 1.95:1 or 2.32:1 both.

I questioned the seller asking how they could be both and he replied "the lower gears are the same and the difference was in the upper gears". Is this possible? I don't believe it is. I know the overall ratio is a combination of upper and lowers but I think we may be talking "apples and oranges".

NEW Volvo DP dual prop gear set 3851309 1.95:1, 2.32:1 #110790431216

Thanks, John
Click to expand...
This thread implies that we're talking about an AQ series drive.
All AQ series transmission reduction is the same. The ratio change occurs in the lower unit.

The tooth count between the "drive" gear and the two "driven" gears determines this ratio.
The smaller drive gear and the larger the driven gears = a greater reduction.... and visa-versa.

These gears cannot be mixed and matched.... even with the same ratio part number, as they are factory matched (as a set) during fabrication.... just like an automotive ring/pinion gear set.

Is this the auction?
http://www.ebay.com/itm/NEW-Volvo-D...431216&pt=Boat_Parts_Accessories_Gear&vxp=mtr

He lists more drive numbers than what the gear set will work in, so perhaps he has many to choose from... AQ and DP-S styles perhaps.

FYI: the set up time can require anywhere from 6 to 8 hours, and special tools and skills are required, not to mention the cost of bearings/seals.
Often it's not cost effective to change a perfectly good working gear set to another ratio.
Instead, off the one that you have, and pick up a good one with the correct ratio.

Re-shimming of the vertical shaft bearing race must be done when swapping any lower unit from one Intermediate to another. No exceptions!

.
 
Ricardo, Thanks for responding. I checked the lowers that I have here this morning and answered my own question.

The listing on e-bay was incorrect in the drives listed for the ratios listed.

Thanks, John
 
Just a note and clarification for you re; the ratio combinations.

When/if you get into the "E" drives (i.e., DP-E), you will find an alternate upper gear set.
When the alternate upper gear set is used, the 1.95:1 lower unit gear set is used to come up with a 2.3:1 over-all ratio.
This makes for a more stout lower unit due to the gear contact that I mentioned earliy.

As far as I know, this is the only alternate combination that we can use for the higher HP and higher torque diesel engines that require an over-all 2.3:1 ratio.

.
 
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