Are heli-coils encouraged ?

[orlandoclippertim]

Noticed that one of the 3 little holes in my flywheel might be questionable. (the 3 you use the puller on - and holds the ratchet)
would it be OK to install helicoils in those holes ? It looks like it would be easy. I cant think of any reason why not-- I just want to ask before I strike just in case since Im a newbie to outboards........ (its an RDE-17 25 hp)

Tim

 

[Crosbyman]

I think you drill it out and retap to the next size up hopefully it wont unbalance the fw

 

[boobie]

Install the helicoils. They are actually stronger than the original threads.

 

[orlandoclippertim]

Its not academic now--- tried pulling the FW tonight and all the threads in one hole just came out with the bolt.
when I looked down into the other two -- 1 other is about 1/2 way gone.
I have use helicoils before and know they are strong. Some of the companies that make aluminum racing car
blocks put them in from the beginning. Detroit wouldn't dare do that :-(

In the meantime-- I am going to have to make a puller that straddles all the way across to the edges of the ring gear
just to get the flywheel off. The vary idea of using 1/4-20 bolts into aluminum to mate up with a puller--- is kind of
assanine. But these things were make kind of cheap back in the day.maybe 1 level above briggs and Stratton
I suppose.

Tim

 

[F_R]

Pulling on the outside rim of the flywheel is a very good way of destroying it. May bend it or pull it right off the hub

Heli-Coil is the way to go.

Don't be tempted to tap the flywheel for larger bolts. You will find the recoil ratchet is just about impossible to drill to accommodate them.

They only made a few million of them with 1/4-20 threads. But eventually they made them to thread into the steel hub flange on the Big Twins.

 

[racerone]

Agreed-----You will be looking for a good used flywheel if you try that method !!!

 

[oldboat1]

Grease on the drill bit to minimize shreds in the magneto.

[Edit. As an alternative, you might check Ebay for a replacement flywheel for $40/$50. If you decide to try the grabber, I think you can use it above the ring gear on yours, which may be better. I've pulled many flywheels using the grabber style -- points about potential damage are good, but have to add that I haven't damaged one as best I can determine. Some that aren't stuck too tight in particular are less likely to be damaged -- can try it to see how tight yours is.]

 

[F_R]

Just a couple of the many "easy-to-get-off" flywheels that I've encountered. They don't give any warning before they break.

 

[oldboat1]

Can also try using a big flathead screwdriver or pry bar to pop it — flywheel nut loosened up to the top of the shaft, and whacked with a hammer while prying from underneath. Don’t hit the flywheel or unprotected top of the shaft.

I haven’t used the “grabber” in many years, but always used about a three inch piece of iron or steel under the hook to spread the stress — might be why I didn’t bust any flywheels (not visibly, anyway).

 

[orlandoclippertim]

I tried prying with double screwdrivers. Nothing. So I made a puller out of 3 inch steel chanel-- with 2 angled legs
which went under ring gear about 2 inches inboard from outer edge. When I started screwing in puller bolt-- nothing happened for a few turns. Then -- unexpectidly KABLAM--- off it cam- but this time the wheel and the puller went
about 12+inches in the air when it broke loose. That tells me one of the two was flexing. Im guessing it was my puller
because it was so wide- and not stiff enough to be rigid. Dont want to do that again !

Anyway--- got it off -- looks OK--- drilled it and installed the helicoils with some locktite. Dont know if I needed to glue them in-- but in that weal aluminum casting I figured I dont want then vibrating out later. Looks like they worked perfectly.
Drilled and tapped the wheel in the milling machine to keep the holes centered and square. I was impressed at how weak the aluminum was. Must be they used an aloy that casts easy . Like drilling and tapping a bar of soap.

Tim

 

[F_R]

Ah, so you have a milling machine. That tells me you aren't just the average bear. Be sure to torque the flywheel nut to 60-65 ft lbs. And make sure the tapers are clean and dry.

 

[oldboat1]

Keeping the flywheel nut in place near the top of the shaft is meant to both protect the shaft and keep the flywheel from flying off. The puller will pretty much stay in place using the screw-type, but not so much with a grabber.

Sounds like you came up with a creative solution -- interested in a pic of the puller you came up with.

 

[Tim Frank]

If you are ever doing this again you might consider using a thread forming tap rather than a thread cutting one.
Results are better in soft metals like brass and aluminum and chips are pret much eliminated.
Tap drill size changes...so verify that.

 

[orlandoclippertim]

Never tried a thread forming type tap. Im guessing that the radius at the bottom is rounder so the threads have higher shear strength ??? (guessing here) (like rolled threads...)

I grew up doing machine work and restoring antique cars. Now Im more into airplanes. Boats and motors are new to me
but fun.

Id be happy to post a pic of the puller but I cant remember how to use the photosharing place (Pain in the azzz)
I know it isn't heavy enough--- but I wont be using it again unless I strip other flywheel holes...

T

 

[boobie]

What's the difference between a thread forming tap and a thread cutting one?? Guess I'm stupid. Too old !!

 

[orlandoclippertim]

gee---I cant remember -- I think its in the MSC catalog at the beginning of the tap and die section.
I DO remember there are cut threads and rolled threads. I think when you cut threads you leave behind tiny tears along
the surface of the threads and a sharp V at the bottom. Cracks can start at these defects. Rolled threads are formed
upsetting the surface and flowing the material laterally to "mash" the threads into the shank. This forms a microscopically
smooth surface and a well controlled circular radius at the bottom of the V. I think all the expensive NAS high strength bolts
are rolled. jet fighter wing bolts--- important stuff. some of there are 50-200$ per bolt.

I think the threadflower taps do something like that where they don't remove material - they just re-arrange it.
Someone can correct me if Im talking out my porthole here.....
Tim

 

[Tim Frank]

^^^ Nope....great explanation.
Sounds like you have a better grasp than I do.
They are easy to find online and particularly pricey.

I have a Clipper as well. Had to replace the transom and used a theadformer for a bunch of spots.
Great old boats.

 

[orlandoclippertim]

Boobie--- I think the way it doesn't "cut" the threads. I think it mashes them in kind of. Upsetting VS. cutting away metal.
Kind of like rolled threads.

In the helicoil kits--- the taps supplied are non-standard taps--- so you cant get a thread flower in those off sizes.
Like for 1/4-20 helociols--- they give you a 5/16-20 tap Also the helicoil material is a square cross section wire.
Probab;lly the supplied tap matches the cross section of the wire. i think a threadflower has a round radius at the bottom
of the V.