Wedge bolts sheared.

[Fffrank]

Didn't hit anything.  Ignore the prop (I've got a spare but it's somehow still balanced and the water level is low.)  

 

Bolts on the bottom left sheared and it bent due to the "wedge" effect.  

It's nibral so not that hard to bend back although I did break my #4 vise.  Planning to replace the stainless screws with Grade 8 or ARP so this doesn't happen again but anyone have a hot tip how I can mangle this back to straight?

[Ronnie]

I've bent several of them back years ago. I could bend them with a press or even by driving over it with my  truck (carefully). I got in the habit of making sure these bolts were secure before launching the boat every time. I used a hand held impact driver. There were two different styles, the ones with two screws through the wedge plate were more apt to break loose. The three bolt ones held better but were not bullet proof. I recall people drilling and tapping the two bolt arms to make them three bolt. I also changed to stainless phillips head bolts to make the impact driver hold better than the socket head.

[Nitrousbird]

Or convert to a floating wedge.  That's what I did, before my (3 bolt) manual ever had an issue.  That way, I got top dollar for mine on resale and got a better looking, easier to deploy, and more sturdy unit in the process.  

[Fffrank]

16 hours ago, Ronnie said:

I've bent several of them back years ago. I could bend them with a press or even by driving over it with my  truck (carefully). I got in the habit of making sure these bolts were secure before launching the boat every time. I used a hand held impact driver. There were two different styles, the ones with two screws through the wedge plate were more apt to break loose. The three bolt ones held better but were not bullet proof. I recall people drilling and tapping the two bolt arms to make them three bolt. I also changed to stainless phillips head bolts to make the impact driver hold better than the socket head.

Funny -- I considered driving over it with the truck thinking "what do I have to lose."

Bolt tightness is not the issue.  The bolts sheared.

This one only has 2 bolts in it.  Makes sense that 3 bolts was stronger.  But -- it has stainless hardware in it.  Stainless has very poor shear strength.

[Bozboat]

How fast were you going when it sheared?

[justgary]

35 minutes ago, Fffrank said:

Bolt tightness is not the issue.  The bolts sheared.

If the bolts were lose or they bottom out in the holes without allowing the heads to pull tight against the foil, the tiny amount of play would definitely allow shearing action a lot easier than if they were tight.  I would make sure that the mating surfaces are smooth and clean so that tight means tight.  Adding a third screw won't hurt.

As for bending it back, I would think that cold forging using a hammer and even a tree stump would bring that into shape.  You may need to get your big boy purse out of the bottom of the tool chest, though.

[Ronnie]

3 hours ago, Fffrank said:

Funny -- I considered driving over it with the truck thinking "what do I have to lose."

Bolt tightness is not the issue.  The bolts sheared.

This one only has 2 bolts in it.  Makes sense that 3 bolts was stronger.  But -- it has stainless hardware in it.  Stainless has very poor shear strength.

 

2 hours ago, justgary said:

If the bolts were lose or they bottom out in the holes without allowing the heads to pull tight against the foil, the tiny amount of play would definitely allow shearing action a lot easier than if they were tight.  I would make sure that the mating surfaces are smooth and clean so that tight means tight.  Adding a third screw won't hurt.

As for bending it back, I would think that cold forging using a hammer and even a tree stump would bring that into shape.  You may need to get your big boy purse out of the bottom of the tool chest, though.

IME, I believe bolt tightness is the issue. With the angular force put on the wedge plate and the comparatively small heads of the screws, a little flutter of the wedge plate will help loosen the bolts. Once they get a little play between the plate and the screw heads, the plate puts more and more pressure on the small screw heads until they shear off.

[Fffrank]

On 9/2/2022 at 11:07 AM, Bozboat said:

How fast were you going when it sheared?

10.5. Surf speed.

[granddaddy55]

1 hour ago, Fffrank said:

10.5. Surf speed.

they are trying to tell you this is old news and extremely common,  Nitrousbird is giving you the best solution though it costs a lot more ,  the “auto set wedge” has two settings, one for about 1100 lbs of drag snd one for about 1400, easy change on land to your preferred setting ,  snd a permanent fix with very little maintenance if any

[justgary]

@Fffrank, please post a photo of the broken bolts when you get them out.  I'm just curious from a materials standpoint to see what went on.

[Bozboat]

21 hours ago, Fffrank said:

10.5. Surf speed.

Idk, I have used mine for years at wakeboard speeds. Seems like 10.5 should be safer. 

[Slurpee]

Old problem. Happened to me once. It was a result of the bolts loosening. I didn’t check every time I trailered, but at least once a year. I always found at least one bolt that needed some care. But I liked to use a dab of anti-seize after the first time I couldn’t get a bolt back out easy again. 

[Fffrank]

On 9/3/2022 at 5:31 PM, justgary said:

@Fffrank, please post a photo of the broken bolts when you get them out.  I'm just curious from a materials standpoint to see what went on.

These suckers were definitely not lose.  Heads sheared off even with the wedge.  Tried a few different things but had to heat it up quite hot with a oxy acetylene before using a left-hand drill bit to extract.  I've straightened the bent wedge arm about 80% but having trouble taking out the propellering.  Any ideas?  I've got a 20-ton press with some 1" steel plates that I've been pressing it with but it springs back once out of the press.

[Brad B]

Wow. We used to just drive over them with a car to flatten them back out.

[blk93jeepzj]

Just because they were tight and you had an issue removing them after they sheared off doesn't mean that the heads of the screws were not loose to the mating surface of the wedge.  The biggest problem from the past research/discussion was that the threaded hole depth was not deep enough for the length of the screws.  This created the ability for the screw to be tight but there was wiggle room between the surfaces.  Compound that with vibration, trailering, prop thrust, corrosion, shear strength of stainless and the screws weakened over time.  Finally enough micro fluttering and the screws popped.  

 

On a side note what is a 2 bolt, non-bent, wedge arm worth to you?

[justgary]

You'll have to press it beyond flat so that it is straight after it springs back.

[Fffrank]

8 hours ago, justgary said:

You'll have to press it beyond flat so that it is straight after it springs back.

I just can't figure out how to press (twist) it beyond flat. This was possible on the longitude to over "arch" it.... But twisting has eluded me.

[justgary]

48 minutes ago, Fffrank said:

I just can't figure out how to press (twist) it beyond flat. This was possible on the longitude to over "arch" it.... But twisting has eluded me.

Put it in a vise and twist it with that big wrench you hardly ever get to use.

[Fffrank]

12 minutes ago, justgary said:

Put it in a vise and twist it with that big wrench you hardly ever get to use.

Lol already broke my vise trying that.

https://imgur.com/zMG4C2E.jpg

[justgary]

9 hours ago, Fffrank said:

Lol already broke my vise trying that.

https://imgur.com/zMG4C2E.jpg

You could always use your press stand as a vise, I suppose.

[Fffrank]

Did exactly that. Used the girlfriend as human ballast, got out the BF wrench and a pipe and went to town. Back together and seems good as new.

As far as thread depth it was plenty. I used some blue loctite and new SS hardware. Was going to go with something harder but figured that just makes it more of a pain in the a** if it breaks again.

Next time I'll either get a machine shop to add a third bolt or upgrade to a floating wedge. Have already added an ebay watch in case one comes up over the winter.