084 STARTER ALTERNATIVE

[buster]

Duane,

You don't think I would have the guts to post my project for all the world to see if I couldn't get it to work, do you

Read the comment caption on the picture with the jumper cables clamped on. It works good, the first time too I didn't even have to make any adjustments this time

Dave

[Duane Scarborough]

Buster,

Looks like I need to start visiting some of my local "Automotive Parts Recycling Facilities".

Thanks,

Duane

[Duane Scarborough]

Buster,

Between your success, and the discussions we've had about the advantages of a bendix style starter, and using the OE alternator, I have become convinced that you are on the right track.

I called all of my my local "Automotive Parts Recycling Facilities" today, and none of them had a take off Legacy AT Subaru starter,or flexplate with ring gear, but they'd all be glad to order them for me. Prices ranged from $100 to $400 or more. There just don't seem to be a lot of junk Subarus in North Carolina.

I found a new starter on EBAY for $75, so I've ordered it. Now to find a compatible flexplate and ring gear. I found several AT flexplates cheap, but none had a ring gear.


So, the search continues.

I'd like to use the larger diameter OE flexplate so I can position the starter lower, and to the starboard side of the oilpan. This would give the starter even more torque, and keep it from blocking airflow to the cylinders.

Thanks,

Duane

Edit: I discovered that the reason none of the Subaru flexplates had ring gears was because Subaru puts the ring gear on the torque converter.

[buster]

Duane,

Don't confine your search to Subaru. Ford, Madza, and probably others have ring gear tooth profiles that are compatible with Subaru on at least some of their cars. You just have to check it out. I'll let you know if I find out anything helpful.

Did you get my PM?

Dave

[Duane Scarborough]

Buster,

When the starter shows up I'll go shopping with it.

I did get your PM, and replied twice. They're both still showing up in my outbox. Papee tells me that's because you have not read them yet.

Thanks,

Duane

[Duane Scarborough]

Buster,

There seems to be a snag with the PM messaging. Please contact me at my regular email address:


Thanks,

Duane

[Duane Scarborough]

All,

Buster and I got the PM snag figured out, so he knows where I'm at. this is for anyone else who may be interested.

I received the new starter yesterday. It is a Nippondenso OE replacement for several years / models of Subaru AT vehicles. It is CCW rotation, and has a 9 tooth gear. I have not weighed it, but it's very light weight.

I found a place on the web that makes it seem to be a good match for the 14" Chevy small block 168 tooth flexplate. My "old chevy" friend from work is going to bring me an almost new flexplate Tuesday. For free !

I'll let you know how it works out.

Thanks,

Duane

[chuckitt]

Hey Duane, The problem with the 9 tooth, it is a 10/12 pitch which we call a course tooth. The GM 168 tooth 14 inch flex plate is a 12/14 pitch which is what we call a fine tooth. you will have to change the pinion gear on the starter to a 11 tooth. We have to do this all the time. The Toyota starters we use on aircraft engines come with the 9 tooth and we have to change it if the motor has a fine tooth gear. I can send you one if your local auto electric don't have it but they should have it.
Thanks, Chuck

[Duane Scarborough]

Chuck,

That's a good heads up.

You do know how much I appreciate you sharing your experence, and advice, don't you?

But, I don't think that I could use the 11 tooth Toyota pinion gear on the Subaru starter. If I'm not mistaken, the Toyota starters are all CW rotation.

Buster chose (and I'm following his lead here) the Subaru starter because it is CCW rotation. This is because the starter, flexplate, and ring gear are mounted on the rope pulley/alternator end of the 4A084, with the pinion gear facing toward the front of the boat. Looking at the 4A084 from the front of the boat, it rotates CW. So, using a bendix style starter pointing toward the front requires a CCW rotating starter.

I thought that I read that the older Chevy small blocks (1955-1985) used a 10/12 pitch ring gear, and the newer ones use a 12/14 pitch. Going back to look at it again, I realize that I may be mistaken. (sure won't be the first time).

It'll probably be hard to find a 10/12 pitch pinion gear to fit the Subaru starter.

My best bet may be to start looking for a Chrysler style flexplate and ring gear. If my information is correct, they all are 10/12 pitch.

Thanks for keeping me on my toes,

Duane

[buster]

You guys are makin' me jealous, calling those starter gears by numbers. I had no idea. I figured ya just had to compare 'em side by side 'til you found something that would work!... Who'da thunk???

Dave

[chuckitt]

It wouldn't hurt to ask the auto electric shop guy if he had or could get a 11 tooth pinion for the CCW starter. Thanks for pointing that out.
Chuck

[Duane Scarborough]

Chuck,

I may do that if the almost new early Chevy small block flexplate that my buddy has offered me doesn't look like a match for the teeth on the Subaru starter.

Depending on which internet source I look at, either it's a perfect match, or a total mismatch. Hopefully, I can eyeball it that close.

Thanks,

Duane

[Duane Scarborough]

O.K. guys, I'm making an about face. I will not use the Subaru starter, and here's why:

I've spent some time discussing this idea with Les Smoot, from the Yahoo 4A084 users group. I've chatted with him on Yahoo, and in person. He lives about 10 miles from me. Small world, huh?

Les has been using these engines in experimental aircraft for 20+ years.

Here's part of what he has to say:

"There are still issues with the setup, #1 that starter
is going to die a horrible death, the starter motor is
really close to the cylinder ......that will be a problem
at some point. Without cooling sheetmetal these
engines run borderline high temps ......that starter
does not stand a chance.

#2 those 4 small screws screwed into that cast aluminum
alternator will not hold up if that engine kicks back
one time .......also the extremely small keyway on
that end of the crankshaft is very fragile and the crankshaft
is small ........with that running right behind you
it won't be pretty when it flys apart .......it's not a matter
of if it will fail ...but when.

The original belt driven version and starter will simply yield
and slip if the engine should kick-back, nothing is stressed,
the belt "chirps" and everything stays together."

And:

"Those four small bolts he has bolted the ring gear on with
will never handle (for long anyway) the constant jolt from the
starter ...it threads into aluminum, and if it ever "kicks Back" it
might / will shear them or crack the
aluminum alternator / magnet assembly, then one day while you
are cruising around that 10 pound chunk of alternator with a gear
on it will come loose .......who knows where it will go!

Basically if any of that assembly comes loose ....at speeds ...you
will feel it ...good or bad!

The belt driven version ........nothing but a belt fly's off! If you don't
like the 3:1 ratio ...get a bigger for the start/gen pulley and go 2:1
.......the belt driven version is much safer as far as flying apart ...
the starter/generator is in a heavy steel case ...
nothing will fly out of it, if it locks up you simply destroy a $12 serpentine belt ........
the engine keeps running, and you come home!"

Les has had friends using a siimlar arrangement to Buster's design that had in flight engine failures because it all suddenly came apart.

I'm not putting down your idea Buster, but it doesn't sound like something I want to have just a few inches behind my head. You might want to rethink it too.

My idea of using a larger diameter flexplate to be able to move the starter out from in front of the cylinder would only add to the risk.

So I've wasted $75 on a new Subaru starter.

I'll let it go cheap, if you promise not to use it on an airboat.

Duane

[chuckitt]

Thanks Duane, We will come up with the ideas and you can do the research for us. .
Chuck

[buster]

Duane,

Are you really gonna let a little thing like that scare ya?

Well, What the heck was I thinking anyway HUH???

OK, believe it or not, I'm not quite ready to give up on this idea just yet! I have one slight modification I had mentioned before, that I just haven't gotten around to yet I am quite sure it will prevent the problems you fear, at least I am willing to trust it!

You know those rope slots in the alternator pulley? Well I have been meaning to drill holes in the flywheel/flex plate, and install 3/8" bolts and nuts in them. After reading your post, I may even safety wire them! That pulley was designed to turn the engine with one of those slots at a time, this way both will share the torque of starting. They will also assure that everything stays together a lot better.

I know I probably should have done that up front, but I had not thought out the possible problems to that extent. Somehow the inheirent danger present with an airboat itself, an engine winding to it's Max RPM's, and a 60" three blade propellor spinning just behind me, tend to make an unlikely errant starter ring gear pale by comparison.


Dave

[buster]

Duane,

About the heat problem with the starter. That may be an issue if I leave the starter where it currently is mounted. I did however mention that I intended to make up a shield to divert more air to the front cylinder,(and the starter) if heat was a problem. I did not know if it would be or not, since I have not even had the 084 running yet!

However, the idea to use a larger diameter ring gear and mount it lower than the cylinders, would certainly prevent any heating problem. It will get unheated air before it even touches the cylinders. Automotive starters have been mounted in confined areas, between hot engine blocks and exhaust systems, and usually last many years. I don't think the starter will "DIE A HORRIBLE DEATH".

If an airboat starter does fail due to heat, chances are no one will have to parachute back to earth!

Dave

[Wildfowl]

Hey Dave and Duane good info! Grand Dad said "if you ever think your having a bad day try missing one." Than again he drove home-made planes on the river so that makes sense. I always wondered if he missed one?

Any way I like your resume Dave...good candidate for BigIsland Engineering

Duane,

I did not know if it would be or not, since I have not even had the 084 running yet!
This "could" lead to premature starter failure but we like the way you have been running with the options...if at first you dont succeed...Pick up a welder or someting other powered.

I don't think the starter will "DIE A HORRIBLE DEATH".

This is generally tool true but I did see a guy turn one to mush trying to jump it with a stick welder...At least he was responsible and at the last second, looked over his shoulder, and told us kids we should step back. Looking around the adults were standing way back (That's how they sort out the stupid ones on BigIsland). He was ok because of the leather gloves and helmet but I never saw that boat again????? Mom was angry about something and we were told to go play in the river. She must of thought that was safer than where she was standing?????

If an airboat starter does fail due to heat, chances are no one will have to parachute back to earth!

Chances are.....but take a look at the bluff overlooking BigIsland...We have directions to the other side and have determined we "can" get there from here. Plus...I have matress straw and bank sticks for sale...so that shouldnt be a problem anyway...I mean the heat.

Dave

The above is entertainment only...below is not.


Seriousley....If you go ring-gear or belt-drive...PLEASE>>> PUT A COVER ON IT...!!!!!!

Would hate to see a scarf, a hand, piece of rope, or sweatshirt hood sucked into either one of them.... NO SMILY FACE...these things we build have no soul.

imho

[Wildfowl]

Somehow the inheirent danger present with an airboat itself, an engine winding to it's Max RPM's, and a 60" three blade propellor spinning just behind me, tend to make an unlikely errant starter ring gear pale by comparison.

Dave

All of those thoughts will go away once you drive under your first bridge!

[Papee]

Kickback, what kickback? I can attest to the kickback. These motors will kick back. I've had it happen more than I can count just using the pull rope. It's instant blister when it happens, it pulls the rope right out of my hand every time. Keep up the work and don't work without a net.

These motors are VERY easy starting we just need to figure out what will turn them. I've never pulled mine more than 3 times before start since I've been using mine.

[buster]

Wildfowl,

Are they hiring at Big Island Engineering? I'm quite sure I'd fit right in! I have references. I have been told I am exceptionally talanted with bailing wire and duck tape

By the way, If you read my post on April 13, '09, I stated that I intend to instal a guard over the ring gear. I think the drag racers would call that a scattershield! Please note, I am not finished with it, it is a work in progress! Just as an observation, except for prop guards, I have not noticed many carmotor airboats with protection of any kind over the pulleys and belts on the front of the engine

I do not know Duanes friend Les. I'm sure he is a great guy, but he is a airplane guy. My experience with them is that they tend to analyze everything to death, and usually come up with the WORST CASE SENARIO, most often, it will never happen.

If I were a pilot, I probably would be the same way,.....Na,.. I doubt it! If a guy wants to avoid all situations that may be dangerous, he would have to stay in bed... then pray that a metorite didn't crash through the roof.

Anyway, I usually don't abandon a project because a few problems become obvious. There usually are ways to overcome just about any flaw. If all else fail, use more duck tape

Hang in there,
Dave