Walters V-Drive Bolts Sheared Off

[Wainui]

I have a Perkins 4108 driving thru a R10 Walters V Drive to a Max prop. I was motoring for 6 hours at 2,400 rpm when the 4 (#8) bolts holding the flange to the prop shaft sheared off. I did not run over anything and the shaft turned easly by hand. This is the second time that this has happened.
Is the prop too heavy for this unit?
There has not been any rapid forward to reverse changes!
Any help would be great
Thanks
Mark

[perchance]

Have you checked your coupling alignment?

[Jesse]

Was there any noise? Did the bolts shear simultaneously? Do the bolts show any wear on their sides above or below the break?

[btrayfors]

Mark,

This is a pretty common occurrence. It happened to me once on the ICW while awaiting a bridge opening, with wind and current behind me (great fun!).

What happens is that the bolts get loose, and back out one at a time. Sometimes there's only one left and the coupling pulls apart just enough so the bolt will sheer. Be sure to use the right bolts, too. All bolts are not created equal, and you need steel bolts of the proper type....not stainless bolts.

First, check your alignment.

Next, get a good set of bolts, and replacements. Get them long enough to put fibre nuts on the back end. Snug 'em up tight.

Then, every so often -- with the emphasis on "often" -- check to be sure the bolts/nuts are still tight.

I did this some 15 years ago, and nary a problem since.

Oh, yes, I also have a 4-108 and a Walther V-drive.

Good luck,

Bill

[Chief Engineer]

Regular bolts are not coupling bolts.

[Wainui]

The alignment was correct.
Chief Engineer, what are the correct type of bolts?
Many thanks
M

[Chief Engineer]

Try these folks....I can't remember the exact grade of hardened bolt.

Ya can't get'em off the shelf at West Marine, Lowes or Home Depot

Buck Algonquin® Marine Hardware - Motor Couplings - Transmission Couplings: Deep Blue Yacht Supply

[SkiprJohn]

Originally Posted by btrayfors

Mark,

This is a pretty common occurrence. It happened to me once on the ICW while awaiting a bridge opening, with wind and current behind me (great fun!).

What happens is that the bolts get loose, and back out one at a time. Sometimes there's only one left and the coupling pulls apart just enough so the bolt will sheer. Be sure to use the right bolts, too. All bolts are not created equal, and you need steel bolts of the proper type....not stainless bolts.

First, check your alignment.

Next, get a good set of bolts, and replacements. Get them long enough to put fibre nuts on the back end. Snug 'em up tight.

Then, every so often -- with the emphasis on "often" -- check to be sure the bolts/nuts are still tight.

I did this some 15 years ago, and nary a problem since.

Oh, yes, I also have a 4-108 and a Walther V-drive.

Good luck,

Bill

I don't know what fibre nuts are but if they are like nyloc or aircraft nuts then I do not recommend them for this application. The very best quality steel bolts with matching steel hex nuts with lock washers will keep them in place.

regards,

[SkiprJohn]

Chief, aren't they grade 8 bolts?
regards,

[cburger]

And maybe a little Locktite on the treads during assembly?

[motion30]

I would think real grade 8 bolts. Try mcmaster carr

[imagine2frolic]

Is it possible to run them through the flange, and set a nut on the other side? Placing locktite on the nut only?.........i2f

[Wainui]

The bolts do not go all the way thru the flange.
Still trying to find out what is special about the correct bolts.
Thanks
Mark

[SkiprJohn]

Aloha Mark,
I'm not certain either but grade 8 bolts and nuts are hardened steel and will not sheer as quickly as regular steel. As you know there is a lot of vibration and different directions of twist and torque on those bolts so anything other than lock washers and nuts torqued to the proper load have a habit of working their way loose. Once one gets a little loose then they can all follow suit.
regards,

[btrayfors]

Mark,

Bolts are graded according to their material and strength. In the US, they are usually coded, with marks on the head.

I think you need Grade 8 steel bolts for the coupling.

See this chart: Bolt Depot - Bolt Grade Markings and Strength Chart

Get them long enough to put a lock washer and nut on the end. Depending on clearances, you may not be able to fit both, but just a nut and some Locktite will help.

Bill