What are peoples favorite choice on FE Outboard lower units

Mike Luszcz · May 4, 2009

I am doing an FE tunnel, and would like some input on peoples choice on lower unit/ conversion adaptors. I see fullers carbon version, and hyperformance has the aluminum adaptor for the k&b lower unit, and bby's lower unit. Any thoughts would be greatly appriciated. I will first be converting my VS1 then doing one of my own hulls. Thanks, Mike

lohring · May 4, 2009

The highest quality and most expensive lower unit is the OS 3.5. It takes a special adapter while all others use the standard K&B bolt pattern. The weak point of all lower units except for the OS is the K&B design propeller shaft. The bearings wear instantly, leaving a sloppy shaft. Nitro racers have lived with this for years and have tried ball bearings in custom units with limited success. The OS propeller shaft stays good for years with reasonable lubrication.

Lohring Miller

Mike Luszcz · May 4, 2009

Lohring,

Thanks for the advise. Who makes that special adaptor to mount the electric motor? Or is it a custom part you have to make. Any pics? Thanks, Mike

Darin Jordan · May 4, 2009

I agree with Lohring about the OS units... nice pieces...

The REK Lowers work well for FE, and they make adapters for the FE motors...

Hyperformance Products makes a really durable and nice unit called a "Bullet Drive", both in 3.5 and 7.5 sizes: http://hyperprod.bizhosting.com/3_5_bullet_drive.html

They also make a solid stub shaft assembly, which is not only durable, but also has a longer prop shaft so it'll better fit the props needed for an FE boat, which tend to be considerably bigger than a similiar Nitro version.

http://hyperprod.bizhosting.com/psa35.html

Also, recently, Hyperformance Products came out with a nice FE conversion kit: http://hyperprod.bizhosting.com/cgi-bin/im...LEC-OB-CONV.jpg

I personally use the Lawless 3.5 sized drives for the P-Spec sized boats. It's what I had when I started this journey and they've worked very well for me... I custom modify them for my purposes, so my flexshafts have to be custom made, etc, but the basic unit works just fine as well. It's like a piece of art work on the back of your hull!

I think the Hyperprod adapter would fit just about any 3.5 sized lower, so basically you can take your pick and buy or make an adapter.

Mike Luszcz · May 4, 2009

Might as well ask...Does anyone have any of those parts used for sale??? lol

raptor347 · May 4, 2009

So far I've run the REK and the Bullet Drive. Both work great, the bullet drive is tougher and has quite a bit less drag. Either way, I like the Hyperformance stub shafts, the bearings don't give up the first time you run them (mine have 2 seasons on them and are still wobble free). Both have adaptors and drive collets for 5mm shaft motors available so it's a bolt together item. I think the Hyperformance adaptor will work with any K&B style lower unit, the REK puts the collet a little too deep in the lower unit to work with an unmodified K&B style.

K&B, Lawless and OS lower units work great as well, but take a little more work to adapt.

Mike Luszcz · May 4, 2009

Wow, That is very clean looking. So is the bullet lower heavy, or does it just look heavy? What motor, and speed control are you using? I am going to be using a turnigy 120a marine esc and the UL-1 motor. Thanks for all the help everyone. I have a feeling I am going to really like the FE on my small boats!

Flyguy55 · May 4, 2009

I have had a different experience with the REK prop shafts wear . I have an early version with tubing spacers between the lower unit and the motor adaptor plate. I fill the area around the cable adaptor with oil before each run. The oil seeps down during the run and lubes the cable and prop shaft bushing, working like an oiler . I have used synthectic motor oil and STP , and now I'm using Mercury gear oil and Prolong

I don't get to race it often but have been to 7 races in the last 2 years, the prop shaft bushing has no noticeable wear in probably 30 to 40 runs including practice.

I'm converting an OS lower unit now and plan on doing the same thing

Dick

Grimracer · May 5, 2009

Lets face it.. the lower unit is your grip.. get the OS.. its more then well worth it. It also has the longest lasting stub hands down. Seems to produce the least lift and is easy on cables.

The bolt pattern is such that you just need a simple plate and a set of standoffs. Get the hyper or fuller collet and your ready to ROCK.

Grim

ACTION JACKSON · May 6, 2009

so how long does a shaft last. 1 month 2 or less & what is the top running hull out their that runs in some rough water. where do you get this boat

Flyguy55 · May 6, 2009

When I raced nitro tunnels , I always carried a spare. Some lasted a couple seasons , some not even a race.

With smooth running electrics and good maintance I don't know if you'd ever wear one out. I take my cables out and dry it , inspect and lube it after each race , and check the prop shaft for wear then too.

ACTION JACKSON said:
so how long does a shaft last. 1 month 2 or less & what is the top running hull out their that runs in some rough water. where do you get this boat

lohring · May 9, 2009

How long a K&B prop shaft "lasts" depends on your standards. If you want it as tight as an OS shaft the answer is one or two runs. I ran mine around a season for club races, but always put in a new or rebuilt one for important races. Garry Preusse sells bearings, so rebuilding is an option. However, I have had the shaft break. In comparison, I have never replaced an OS propeller shaft on either a nitro or a fast electric boat.

Lohring Miller

DPeterson · May 12, 2009

Hey Brian or anyone else. Where do you purchase the white tunnel stand that is in the photo of Brians tunnel? Would like to purchase a couple.

Doug

properchopper · May 12, 2009

DPeterson said:
Hey Brian or anyone else. Where do you purchase the white tunnel stand that is in the photo of Brians tunnel? Would like to purchase a couple.
Doug

Doug, It came with the TS-2. Tower Hobbies, p/n LXMN3, $ 10.99 , Late June [

]. Handy to set drive trim; easy to make- I'll send you the dimensions if you want. Just 2 pieces of ply & 4 dowels, really.

Tony

Ed.R · May 13, 2009

I have heard of some people that had to add weight to the back of ther boats when using a REK lower unit . If anyone has had to do this please comment. I heard a K&B 3.5 may be better has a little more weight so you won't have to add anymore . I would think the back of a FE tunnel is going to be lighter than a nitro boat anyway .

Any comments ...

Ed

Kris Flynn · May 13, 2009

Ed, This is probably due to the boats being setup with an Aluminium Lower unit (IE K& B) then switched to a REK which is much light, this would upset the CoG. Adding weight to the rear would then help balance the boat properly.

Advantage with FE is that you can move the battery packs around to adjust CoG(constant total hull wieght), not add weight as we do with the Nitro ones

Cheers

Kris

Flyguy55 · May 13, 2009

That depends a great deal on the hull and motor your using. On my HTB 290 and TS2 P spec I had to buld a radio box with the 4S1P 5000 lipo as far back as possible with the ESC on top of the Lipo and the Servo in front .

I have a Leecraft TX 460 with a NEU 1521 that has the lipos as far forward as possible, and I have 6 OZ of lead on the pickle forks to balance the hull at 28% .

My villian has the lipos about in the middle of the radio box .

You have to put all the equip ment in the hull and move it around till the cg is where you want it , giving it some room to adjust the CG when its running.

I have heard of some people that had to add weight to the back of ther boats when using a REK lower unit . If anyone has had to do this please comment. I heard a K&B 3.5 may be better has a little more weight so you won't have to add anymore . I would think the back of a FE tunnel is going to be lighter than a nitro boat anyway .

Any comments ...

Ed

lohring · May 14, 2009

Electric tunnels have batteries that can compensate for CG issues. The best way to get the XT-460 CG right without lead is to cut into the cockpit area and extend the radio box forward. By the way, the Leecraft XT-460 is a great P Tunnel. It's big enough (barely) to stay on the water and uses the 7.5 size K&B lower unit with the 3/16 shaft to take the torque. The 3.5 size lower units are too small for real P motors.

Lohring Miller

DPeterson · May 14, 2009

Lohring

The 3.5 size lower units are too small for real P motors.

Hi Lorhing, Curious as to why you say this?

I am not overly experienced with tunnels yet but am getting there. I run both a spec tunnel and what I call a P tunnel. Both are Woodstuffs. My P tunnel is 32" long. 4S 2P, Hydra 240, Lehner 2250/8, Lawless 3.5, 447/3. I haven't pushed it yet but it handles real nice and it isn't slow.

So why do you say the 3.5 lower is too small and what characteristics or issues is telling you this? The 7.5 lower would look really out of place on a 32-34 inch hull.

Thanks - Doug

Darin Jordan · May 14, 2009

DPeterson said:
So why do you say the 3.5 lower is too small and what characteristics or issues is telling you this? The 7.5 lower would look really out of place on a 32-34 inch hull.
Thanks - Doug

Doug... Even with something fairly mild, like a 1515 1.5D on 4S, the 3.5 lowers, with only a .150 flex, get torn up pretty badly... I know several people that have torn up flexshafts with similiar setups...

The 7.5 unit looks great on the LeeCraft Lohring is talking about... It's a BIG boat... much wider than my 30" LeeCraft. Maybe Brian can post some pics of it... the 7.5 looks just fine back there... as does the big 580 Fiegao motor... WAY too much power for even this hull...

What are peoples favorite choice on FE Outboard lower units

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