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Carpenter193

Drive Gear Ratio

9 posts in this topic

Hello all,

Last summer I bought a 1997 1930 SS with the GM 5.7, 2 bbl with non vortex heads (I believe), and alpha one drive, 1.62 gear ratio, 19p SS prop. After only 3 trips out, totaling 6 hours total use, the drive began popping. The dealer called and said the drive was toast, and recommended a SEI unit. I will be swapping the units myself as the bellows and gimble bearing were replaced when I bought it, thus the repair should be fairly straight forward. What drive ratio is best suited for this boat/engine configuration. I have read multiple posts and cannot determine if the 1.62 or 1.47 would be best. I have read that the 1.62 is best suited for the V6's and that the added power of the V8's can lead to increased wear and problems down the road. Any advice would be greatly appreciated.

Thanks

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1.47 will give you a more top end but you will give up hole shot performance.  I'd stay with the same 1.62 if you are please with the performance.  

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I had the same boat, and it came with 1.62 ratio. Leave it there. Why not fix your existing drive?

brick

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What is causing the Popping sound ? gears bearings ?  All speeds in F N R ?

AS a note

A over heated valve or carbon build up...hot spot ...sticking valve.  can cause popping / pre ignition or subdued backfiring.

Find the cause beyond any doubt. Before pulling & replacing a drive.

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Hi, sorry to hear of your troubles. If your Alpha 1 Gen II 1.62 drive right hand rotation (standard) drive is NFG, than SEI is hard to beat for pricing. Often a dealer can't repair them for the price to buy an SEI. You could also do a search for Mercury part # 5121300TP or 5-5121300TP (same exact part; 5- in Mercury speak simply means complete drive and some dealers simply don't list the 5- on their site description)  

Some dealers purchase a large quantity of drives, and get a heavy discount as they sell so many. This is the latest number from Mercury and would bolt right up to your boat.

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Thanks all for their replies.

Brick, unfortunately no way to repair the existing drive as the gears in the upper unit are completely destroyed, missing teeth and gouged the aluminum casing. I am unsure what the best method for uploading photos or i would post them.

Cyclops, it is definitely a drive issue. All speeds in F N R, worse as RPM's increase. Engine runs smooth and will be getting a tune-up this spring. 

Shepherd, it looks like SEI is the way I'll be going, especially since they come with a 3 year warranty and I can almost buy 2 of them for the price of a mercury.

It looks like I will be sticking with a 1.62, that way I do not have to re-prop.

 

 

 

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9 hours ago, Carpenter193 said:

Thanks all for their replies.

Brick, unfortunately no way to repair the existing drive as the gears in the upper unit are completely destroyed, missing teeth and gouged the aluminum casing. I am unsure what the best method for uploading photos or i would post them.

Cyclops, it is definitely a drive issue. All speeds in F N R, worse as RPM's increase. Engine runs smooth and will be getting a tune-up this spring. 

Shepherd, it looks like SEI is the way I'll be going, especially since they come with a 3 year warranty and I can almost buy 2 of them for the price of a mercury.

It looks like I will be sticking with a 1.62, that way I do not have to re-prop.

Just as a reminder, recommend filling with Mercury or Quicksilver high performance gear oil after you've fit the new SEI drive together. Mounting gasket provided by SEI is less than ideal IMHO as it's very thin; recommend installing a Mercury or Quicksilver version part # 94996T2 or Q2

Lastly, for installing the drive, highly recommend removing the trim cylinders altogether from the forward anchor pin - let them hang right out of the way. Saves on scratching the paint on the new drive, as well as giving you greater access. And a piece of carpet or wood under the skeg...oh vey.

 

 

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Thanks Shepherd, I will definitely get the merc gasket and lube. Looking forward to getting this thing put back together and back on the water.

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The 1930 series were great boats. Hope the new drive works out for you.

brick

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