Help Identifying Currently Installed Lower Unit

My new to me boat, a 2007 Tr-210 with 2007 250 pro xs serial 1B465109, had what I was told was a torque master lower unit put on to replace the original that locked up. I do not believe it to be a torque master because the oil drain is on the bottom starboard side of the bullet instead of inside the prop cavity. I also do not see the cast in swell on the skeg.

I am wondering because I need to know the gear ratio. Current prop is a 26p Tempest Plus. I turn ~5200 rpm @ 68 mph. It seems as though the prop may be too tall for the current setup. If I base my slip Calc on 1.62 gears I get 14% which seems unrealistically high and based on 1.75 I get 7% which seems unrealistically low. I have not confirmed tach accuracy but will be putting smartcraft SC1000 in soon. If I have a 1.62 gear case I want a 24p Tempest but if it is a 1.75 I want the 25p Tempest.

I will post pictures tonight but is there any quick way to know the gear ratio based on the information I have?

What is the diameter of the prop shaft?

99% chance that you have 1.75 gears.

Always check the Commonly asked Used Posts a the op of the forum page.

Click on this>>>>Determining your Gearcase "Gear Ratio"- Without removing Gearcase

Thanks Savage. I saw the link I'll set up a camera tonight and try it, I was just trying to avoid pulling the plugs to answer this question (read: it's hot and I was being lazy).

Is the prop shaft diameter measurement taken at the bearing support where it enters the bullet or at the prop nut end?

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Originally Posted by Jtreed99

Thanks Savage. I saw the link I'll set up a camera tonight and try it, I was just trying to avoid pulling the plugs to answer this question (read: it's hot and I was being lazy).

Is the prop shaft diameter measurement taken at the bearing support where it enters the bullet or at the prop nut end?

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Don't even bother with measuring propshaft, if your fill screw is where you say you either have a standard merc unit or more than likely a SEI. You can tell if it's SEI by looking at the low water pickups in the nose SEI holes are staggered mercs are inline.

http://www.bbcboards.net/attachment....d=290983&stc=1http://www.bbcboards.net/attachment....d=290985&stc=1Thanks bassman. So mine would be a standard Merc unit?

10 flywheel rotations revealed 5 and 2/3 prop rotations. That's close enough for me to believe Savage was correct. Thank you all. Any help identifying if the unit I have is the standard optimax lower would be appreciated.

Maybe it's a fleet master with the low water pick ups added? Looks like a fleet master with all those pick up holes on the sides. Tourquemaster only has 4 or 5 I believe.

Not sure Triton, doesn't the fleet master have the LU drain behind the prop? This one is between the bullet and skeg.

An additional possibly very stupid question: Is there any sort of timing relationship between the compressor and flywheel? If so I definitely messed that up because I took the belt off to perform the gear ratio test.

That is not a Torque master or Verado case. Guessing its a fleetmaster which would be considerably cheaper than a TM. Pretty sure you have 1.75 gears.

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Originally Posted by Jtreed99

Is there any sort of timing relationship between the compressor and flywheel? If so I definitely messed that up because I took the belt off to perform the gear ratio test.

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No.

Thanks!

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Originally Posted by NKY TRITON

Maybe it's a fleet master with the low water pick ups added? Looks like a fleet master with all those pick up holes on the sides. Tourquemaster only has 4 or 5 I believe.

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So much misleading info, guy's a Fleetmaster is the exact same as a Torquemaster less the torque tab.

So standard Merc 3l case? Like would come on a regular opti instead of ProXS? Any negatives of running this case?

And to end all guesses this is a verado style LU (servicemaster) And if y'all don't believe me hopedully Don or Savage chimes in. The only two LU's that come factory on a Merc is service master or torque master on earlier models and the Gene 2 torque master is is easy tell because it has an extra wing just above the upper watee intakes which helps it with water in high engine applications so no more filling in yhe upper holes. If you see a merc with a sport master it's because it was special ordered that way or purchased separately and id its an XS motor it will have the torque master or sport master

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Originally Posted by Jtreed99

So standard Merc 3l case? Like would come on a regular opti instead of ProXS? Any negatives of running this case?

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None at all on a standered opti motor. That is an older verado style gear case. The newer verado style has the drain plug behind the prop at the bottom of the bearing carrier

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Originally Posted by fishfarm

None at all on a standered opti motor.

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What about on my 250 pro xs?

Looks like a Standard/ Servicemaster Lower unit .Look's like the same one as minds on my 2004 225 EFI motor.

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Originally Posted by Jtreed99

What about on my 250 pro xs?

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What rchavis just said. A service master is what came on your pro xs. I don't have a experience with the SEI lower units so I can't honestly tell the difference. When it coms to my Merc it always gets OEM parts. These are expensive motors and I just don't take the chance with after market stuff unless your doing reeds then its TDR reeds or Chris Carson reeds