Sx-m to dp prop conversion question.

kccoe

Seaman
Joined
Jul 4, 2015
Messages
62
I found a 1996 rebuilt dp-s lower duoprop unit. Serial # 3868164 . 1.95 ratio. Will it fit a sx-m 3868891 upper unit ? I am trying to get my lower unit repair or find one. It is hard to find one . I have a 2250 regal cuddy with a 5.0 gxi and a duoprop would be nice to have for docking.
 
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evantful

Petty Officer 3rd Class
Joined
May 11, 2014
Messages
90
Your upper unit is a 1.60 ratio (which is common for the SX in a V8 application), so it would not work with that DP-SM lower.
The 1.95 ratio in the DP-SM drives is the correct ratio for your application, so realistically your looking at finding a SX lower with a 1.60 ratio or selling your current upper and buying a complete 1.95 ratio DP-SM drive.

The Duoprop for your application would be a nice addition for many aspects.
 
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89retta

Senior Chief Petty Officer
Joined
Jul 18, 2010
Messages
772
I have to disagree with evantful. The gearing is done in the lower unit. As the sx-m units come in 3 different drive ratios and all 3 lowers will bolt up to the same upper. But as to your question to mounting a duo drive lower I think it would but cant say for sure.
 

evantful

Petty Officer 3rd Class
Joined
May 11, 2014
Messages
90
89Retta is correct in regards to the gearing. My mistake.

The serial number that you listed for your upper unit is for a complete, 1.60 Ratio SX-M Drive. Based on that it is of the same generation has the DP-S lower you listed. The SX-M and DP-SM drives of that era used the same upper gear housing (this can be confirmed via Volvo Penta's parts diagrams, same serial number used). The lowers can be swapped.

The 1.95 ratio would be the correct ratio for your size boat and weight. Either the F-5 or F-6 prop set, but there are charts to help be sure.
 

kccoe

Seaman
Joined
Jul 4, 2015
Messages
62
89Retta is correct in regards to the gearing. My mistake.

The serial number that you listed for your upper unit is for a complete, 1.60 Ratio SX-M Drive. Based on that it is of the same generation has the DP-S lower you listed. The SX-M and DP-SM drives of that era used the same upper gear housing (this can be confirmed via Volvo Penta's parts diagrams, same serial number used). The lowers can be swapped.

The 1.95 ratio would be the correct ratio for your size boat and weight. Either the F-5 or F-6 prop set, but there are charts to help be sure.

Thanks and I understand that will have to get a stud kit to mount the lower Dp unit because it uses lock nuts instead of bolts.
 
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