eagle sg style engine mounts

[TomMoorehouse]

I made my tub sides for a new .12 boat project. I drilled the holes for an eagle sg style engine mount and now i can't help to think...... those are some BIG holes! That has to be a weak point on the tub.

You guys think I could get away with the same idea but use 4 1/8" nylon bolts because it is a lighter .12 engine? (compared to a .21)

What ya think?

tom

 

[Terry Keeley]

How 'bout some 10-32 or 3/16" nylon bolts?

 

[Don Ferrette]

"I made my tub sides for a new .12 boat project. I drilled the holes for an eagle sg style engine mount and now i can't help to think...... those are some BIG holes! That has to be a weak point on the tub."

Actually it's not as weak as you think. If it's going to break it will be where the front wall of the radio box & engine well meet. :blink: :blink:

 

[Eric Perez]

I used 1/4-20 nylon bolts (cheap and light-weight) for this home made .12 engine mount. The mount is made of good-old aluminum angle. Only worry about the engine fitting in between the angles. You can make some light weight wood blocks that will take up the space between the outside of the mount and the inside of the tub. If you wanted to you could epoxy the filler pieces to the hull to stengthen the engine bay even more. I ended up doing this on my BBYB .12 rigger and it was solid like a rock!

In case of a major catastrophic problem then your sol...

The other wooden .12 engine mount was used to convert a plastic ABS hydro to use a nitro engine. The hull floor was reinforced with ply/CA/Epoxy and this wooden mount was bolted into place. The mount never failed -boat is still in one piece too. The wooden mount is made with hard-wood strips and has a 4-40 brass insert epoxied into place for the engine bolts and for (2) of the 4 screws that held it into place to the hull. For engines that are mounted parallel (or close) to the tub like hydros and cats this may be an option.

 

[Eric Perez]

If you use a small fly-wheel like the one on miss-bud or the original aluminum flywheel on the Traxxax Nitro-V you can actually mount the engine directly on the hull bottom. If you use a pull-stater all you need is to raise the entire mount 1/16 from the hull bottom.

For .12 engine I usally epoxy (2) 1/32 plates together or go with 1/16 ply and it provides enough strength to actually bolt the engine on the floor in the engine bay. This allows the use of inexpensive .12 mounts made for RC cars like the Traxxas T-Maxx, Nitro-V and Nitro 4-TEC. Okay -so I'm a Traxxas fan -It just happens that I have all these mounts in my parts-bin.

In the picture I also included the Ofna engine mount. It's like $10.00 and you can slide the engine back and forth and make minor adjustments to the engine to help getting it perfectly linned up to the drive-line.

Some times it's best not to re-invent the wheel when it comes to mounting .12 engines.

 

[Mike Hughes]

I thought about that when I built the mount for you. I seen a few of those riggers run at SAW events. I have seen them crash too. I was worry that you might pitch the motor out of the hull at that speed. Hence the reason I decide to stay with the 1/4. A little extra insurance with next to nothing in weight gain. I have never see a boat come apart at the mount unless it drove straight into a piling. I thinking you will try and avoid doing this.

Mike

 

[warlokboats]

hey mike if the collet is tight on the prop shaft that should keep the motor from getting chucked. i use a similar mount with 6/32 nylon bolts with no problem. oh ya its a 21.

jon

 

[TomMoorehouse]

I can't find grommets to work with smaller bolt sizes that still works with a 1/8" thick tub side. Can someone help me out with a source?

 

[Don Ferrette]

This is THE place! http://www.mcmaster.com/ Do search for "rubber grommets" & it will take you right there, they have what you are looking for. Be warned! - You can spend hours cruisin' the website, they have tons of very cool stuff!!

This should be the part #9307K14

 

[Don Ferrette]

hey mike    if the collet is tight on the prop shaft that should keep the motor from getting chucked. i use a similar mount with 6/32 nylon bolts with no problem. oh ya its a 21.
jon

Well that didn't work back at the '99 Internats when Stu (Barr) cut Andy & John's (Brown) SG45 in half when he shot across the front straight from way outside to bouy #1 at the start of the heat. It was the most gut wrenching crack of wood on wood I've ever heard! Took about 20 minutes of people wading thru the water to find each sunken 1/2 of the boat. Amazingly enough Andy & John had the boat glued back together for the next round only to be thwarted by a dead reciever......

 

[MikeP]

Tom,

If you are using 1/4" bolts I will send you some grouments.

Mike

 

[TomMoorehouse]

i'm looking at using 1/8" bolts.... no correct grommet size for that.

i did see 3/16 sized correctly..... what bolt size would that be?

 

[Don Ferrette]

i'm looking at using 1/8" bolts.... no correct grommet size for that. i did see 3/16 sized correctly..... what bolt size would that be?

10-24 or 10-32 would work.

 

[Ron Olson]

Tom, if you're worried about strength, I can cut you a couple of pieces of Carbon Fiber sheet to the sizes that you need to reinforce the tub walls. Just say the word!

 

[TomMoorehouse]

Mike H.... your mount is going in my 20 SAW..... that's perfect and perfectly made i might add

now im trying to make a .12 mount. I bought the stuff today from mcmastercarr for 3/16 bolts should be a little better i hope

 

[Mike Hughes]

The light bulb has turn on. I understand now. I completely forgot that I set it up for a 21. Duh. Well if you get stump on the 12, you know who to call.

Mike

 

[TomMoorehouse]

here is the size difference:

View attachment 1475