Stellings Ext. Box Experts.....
 

I'm in the process of working a deal on a Stellings Ext. Box and components from a board member and have a couple of questions. I know the box will work with my Bravo outdrive. I'm not to saavy on how the hyd. rams mount on a Stellings application. From what I saw the IMCO has a couple of wing plates. The Stellings application looks like it calls for some ext. arms that bolt to the back of the transom for the rams to bolt too. I want to purchase the ext. arms from the OSO member also, but want to make sure their going to work with my application. The Ext. box is coming off a Active Thunder and I'm installing it on my 29 Scarab.

I'm attaching a picture of the components. Could one of you steering experts shed some light??

I hope to gain 3 to 5mph . Does this sound possible?

Also , besides some longer hydraulic lines and a few through hull fittings, what else will I need to complete this upgrade?

Thanks for any input!

here's another pic

Before you mount that box, consider taking it to a machinist. He can connect each of those holes. That way you can adjust your x-dim with a floor jack and don't have to tear everything apart. When I mounted my box, I had some super thick stainless washers cut so they wouldn't deflect when the bolts are tightened.

I put vasaline on the transom to make sure the gasket wouldn't stick. I didn't want it tearing when I moved the box.

Also make sure those transom bolts are really tight. I actually had the box move all the way up on me once and lost water pressure. Do keep an eye on your pressure. I found that mine fell to zero shortly after planing.

I see a couple of items missing from your pics. I don't see the water outlet pipe. This piece will be required to connect the 1-5/8" hose to the drive. I also don't see the inner transom plate. The stock merc plate cannot be used without hacking the hell out of it. Stellings makes a rather nice inner plate that I'd recommend. This plate does not allow for the stock steering valve to be used. There is also a piece of steel that will bolt to the back of the crank shaft. This is the adapter that goes between the crank and the drive shaft. Grade 8 bolts, lock washers and blue lock tight are a requirement. Wire ties are recommended, but not required.

You will also need some bolts to go through the transom. It would proably be the easiest to put the nuts inside the box. You proably have to do that for the bottom 2 holes anyways. I used standard grade bolts and nylon lock nuts. The first time I tightened them, I torqued it to the capacity of the bolt. Unfortinatly, I crushed the transom which moved the two mounting ears together so the engine couldn't be installed. The transom is still crushed to this day and I had to add some shims behind the plate to make up for it.

I see that somebody dissassembled the center bearing. That's very dissapointing. After assembling everything, I was unable to get the drive to align with the center bearing. I ended up tearing the whole thing apart and sending it back to Stellings for alignment. There are some shims that go below the bearing that are custom machined for every application.

Hydraulic steering is a requirement. I used the imco brackets which mount off the box. This has a significant advantage over the transom brackets. First they look cleaner. Second when you change the box height, the steering rams stay centered on the drive pivot. This is very critical as a bind condition will result with dual steering rams. I ran both of my steering lines into the box below the brackets. This makes it really easy to pull the box off, but makes for very tight packaging. That box sure is crouded in there! The one thing that I did not like about the imco brackets was their mounting system. You drill 6 holes in the box and then thread in some beefy studs. The problem is that you cannot get 6 nuts on the studs inside the arm. There just isn't enough room. I ended up with 6 studs but only 4 nuts. I hand drilled these holes, but it would be better if there was some way to do it on a mill. If you already have steering rams, just make sure they are compatable with the imco brackets.

I would attribute 3-5mph to the box and much improved planning. Don't forget that this box will effectivly lower your x-dim by 1". This is a function of the transom angle. Stellings says they adjusted for this in the design of the box, but just be prepared to raise the drive a little. They say that you can keep the engine at the stock location for all but the top and bottom 1" of travel. I've had the box all the way up and down and have never felt a drive shaft vibration.

Cord,

I forgot to mention I already have an external pickup tube for the water inlet. They put that on when they installed the Whipple Charger.

I didn't know you had to change transom plates? I'm not sure I want to buy the steering brackets if the IMCO's will work better as far as possible bind.

It looks like have some more investigating to do on this project.

Cord,

Thanks for taking the time to explain in detail. I think I'm going to print this page out.

Shawn

You don't have to change the plate. The problem is that merc designed the plate for a small splined shaft comming off the drive. You now have to pass the large knuckle of the drive shaft through that small hole. A sawzall will do the trick, but there is a lot of webbing that would need to be cut. It would just be a hack job which will significantly weaken the plate.

I'm going to talk with my mechanic about the plate.

Do you know how much that transom plate would be. Also is there a website I can look at a parts list for the Stellings ext. box conversion.

Stellings isn't on-line. I think I paid around $100 for the plate (unpainted) a couple of years ago. There's not much too it, so they are really making a killing at that price.

When you do call, don't be suprised if they do some head scratching at seemingly simple questions. A couple of years ago the owner died and left everybody in the dark.

Thanks Cord!!!

Anyone have any pics with both types of set-up.

Stellings with transom steering ext arms.

IMCO with wing mounted plates. ?????????????

Well said. The flange that goes thru the bearring carrier is where I can put my dyno/strain guage.

The real home run is to get the X dimension right. The new high 'X" on an extension box with a four blade prop will get the speed. I would try and find out what is ideal for your boat. I good place to start is JimV an this board. He has solid experience with high X on a single engine 27-30 boat with an extension box. I would be surprised if you can't get +5 mph.

Here is a poor pic...

I have another question.

Those holes in the box look like for adjustment. When I put the box on how do I know what set of holes to use?
I know you want a optimum X-dimension, but how will I know where the right ones are.?

Where will the box put my outdrive compared to when it was bolted straight onto the transom. Do I take measurements before unbolting my outdrive with it parallel to the ground or what?

You guys are heading me into the right direction, but if there's some more info out there, I sure would appreciate it.

I want to tell ya thanks for the info so far, but keep it comin'.

Take a straight edge and run it along the bottom of the 'V' back to the nose of the bullet of your drive and measure it, how far below this straight edge the nose is. When you bolt on the box I would use the hole that will put the nose 1" higher than you measure stock. Probably it will be the middle set of holes.

Yea, before you take the drive off, I'd measure your x-dim. Take a straight edge off the bottom of the hull and run it back to see when the prop is. We can all talk the numbers up, but it's that alignment that matters. Now ask yourself how the boat is handling, how it planes off. If you get blow out or slippage the box will help improve that. If you can get on plane with a 3 blade mirage then you can go higher. Ultimatly, the box will allow the x to be set at least an inch higher. I honestly don't know anything about the scaarab setups so I can't offer much more help there.

Those holes are for adjustment. If you machine them into slots then you'll be able to adjust the box without tearing everything apart. I'd highly recommend the modification.

cord
 

You should see the block of plate thur or fri/sent 3 day service

I'm doing mine with the IMCO ears, rams, drive cap and going to run the hoses into the side of the box and not thru the transom to keep a cleaner look. I'm thinking of tapping the bottom for a drain plug- What does everyone think?

The IMCO ears I used before used hex head bolts and use a long allen wrench to get down in the ear with the nuts on the inside of the box. No studs or nuts in the ears.

454-thanks!

Cobra-definetly tap the box. Mine came that way so I never mentioned it. I replace the pipe plug that mine came with a brass mercruiser block drain plug. Hopefully they changed the mounting system for the ears. Those studs and nuts really sucked!

That brings up another question.

Is there one ext. box better than another? What makes one better if so? What are the advantages?

What is the story on the drive shaft of the Stellings compared to the torsional driveshaft of the IMCO box. Is one better than the other. Is there an advantage of buying one new compared to used??

Just a couple of questions for inquiring minds......

Thanks

Your PM box is full... Send me an email (I can't get into OSO at work). I might have a steering system that would be perfect for your setup.

I cleaned out my p.m.......

Sorry about that/...

a shot of the wing plate steering

I have a setup like you are talking about. Stellings with imco steering/wing plates and lines run through the box.
PM me and I will send some pictures