drive shaft length question

**Blue89turbo** · 08-20-2020, 04:31 PM

Hey guys, so my new to me Vector came with the stock drive on the engine and a nice nose cone drive.

I went to swap them out the other day and the drive shaft lengths are way off.

The stock drive measures 28 1/4 from the water pump to the top

The nose cone drive measures 23 1/4 from the water pump to the top.

Does any one have a 28 1/4 shaft that I can buy?

I dont want to tear apart 2 drives but would rather just rebuild the nose cone unit.

Does that sound like the right measurement to start hunting for?

Any other ideas or opinions?

Thanks for the help!

**Aaronhl** · 08-20-2020, 05:32 PM

So seems like the stock lower unit is a 25" and the nose cone lower unit is a 20". To use the shorter lower unit on the engine, it might require you to change the mid section. Hopefully you will have a spacer on the mid section to make it a little easier (and probably easier than changing a lower unit driveshaft). Post some pictures of your engine and the lower units, that will help me see things a little better. Try to keep that nose cone unit with the shaft it has in it because 20"ers are a pretty popular size, and what you will need for that Vector...

**vnemous** · 08-20-2020, 06:20 PM

http://www.baymfg.com/kits/mercury/

**Blue89turbo** · 08-31-2020, 07:43 AM

Thanks Aaronhl.

I took some pictures.

**Blue89turbo** · 08-31-2020, 08:02 AM

Cant upload pictures right now...

**Blue89turbo** · 08-31-2020, 12:54 PM

pictures were too big. Had to shrink them down.

**Aaronhl** · 08-31-2020, 01:18 PM

Originally Posted by Blue89turbo

pictures were too big. Had to shrink them down.

nice engine you go there, so the engine is a 25” long mid section, if you want to convert it to a 20” you will need to pull the powerhead off- to some it’s a lot of work to do

You can get a 5” drive shaft extension from a few places like cris carson marine to use that 20” nose cone lower unit on the 25” engine

Does your boat need a extra long shaft or would a shorter one work better?

**Dave S** · 08-31-2020, 01:36 PM

Shorter is better......TOOL up.....

**nitro_rat** · 08-31-2020, 02:00 PM

Boat is a Vector. Will be a much happier with that combo. You need to get a 20" leg which is this part:

Click image for larger version.

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Make sure the one you get is 20" which is considered "long." Your 25" unit is considered "XL." There are 15" (short) units available but they were race only. 20" is most common.

You will need a shift shaft and water tube to go with your 20" leg.

You will need a set of solid motor mounts, these are a big safety item for a rig like a Vector. You can get them from bobsmachineshop.com for around $100.

You will need a few gaskets, the powerhead base gasket, the exhaust divider gasket, and the gasket between the exhaust adapter and can. Best to get these from your local Mercury dealer or boats.net. Don't get cheap aftermarket ones, the exhaust will burn them out.

Don't be startled when you find the extra "liner" piece inside your 25" leg, most high performance applications don't run one.

Hope your 25" motor didn't come from a salty environment...

**Blue89turbo** · 08-31-2020, 05:02 PM

Originally Posted by Aaronhl

nice engine you go there, so the engine is a 25” long mid section, if you want to convert it to a 20” you will need to pull the powerhead off- to some it’s a lot of work to do

You can get a 5” drive shaft extension from a few places like cris carson marine to use that 20” nose cone lower unit on the 25” engine

Does your boat need a extra long shaft or would a shorter one work better?

Thanks. Yes i really don't want to get into swapping parts and pulling the power head. At least not at this time.

I think i may just do the shaft extension for now.

Knowing that this is an XL now I wonder how high the engine will go with the jack plate...I will need to check this out.

What is ideal again? 2.5 below the hull center line? and what PSI should i see minimum?

And what is the advantage of the shorter drive compared to the one that I have on the boat now?

Thanks for the help.

**nitro_rat** · 08-31-2020, 05:13 PM

You're probably going to end up +1.5" from even with bottom of pad. That's going to put your 25" motor WAY up there! That is going to upset the balance of the boat especially with rubber motor mounts. You're not going to be able to drive it. A Vector is a handful anyway, no sense in stacking the deck against yourself!

What kind of steering do you have?