motor mount lag bolts

[Jeff Kaplan]

last spring i posted that i was experiencing vibration when motoring. all posts came back suspecting the motor mounts. found one stripped bolt, 3/8"x2", which i just removed . just got thru reading past posts on this subject and want to be sure i can use a 3" bolt, couldn't find a 2 1/2" one. it appears that there is plenty of stringer to go the extra 1". the past posts mention only 2" and 2 1/2". if any one has used a 3" bolt or verify to me no problem, i would greatly appreciate it. our short 5 month season is over, boat's on the hard, mast down, having all the rigging standing replaced....jeff

[Craig Illman]

Jeff - You could always stack a few extra flat washers. I'm surprised you can find 2 1/2" lag bolts.

Try http://www.fisheriessupply.com, but WM usually has good selection of fasteners.

Craig

[Jeff Kaplan]

craig, i put on 3 extra washers plus the loc washer to no avail. i was at wm first than lowes and each go from 2" to 3". i have all winter to find a 2 1/2", but if i can use a 3" bolt, all the better...jeff

[Michael Algase]

Jeff,

You say there is plenty of stringer, but I expect there is a piece of wood backing that surface and that the stringer you see is not solid.  When I went from the original mounts to the Vetus mounts, the mount flange to the stringer was very different (much thinner on the Vetus mounts).  It did not appear to take significantly more torque to go that extra 3/8 of an inch into the stringer, so  actually wondered if I was breaking through the back side of whatever backed that surface.  I admit I did not measure the length of the bolts.

If you really wanted to be safe, you could epoxy fill, drill and re-bolt.

I often wondered if it would work to coat the bolt with soap (acts like a mold release), use thickened epoxy to put it in place, then torque a little further after the epoxy cures.

Just a few thoughts . . . .

Michael

[Jeff Kaplan]

mike, thanks for the imput. the depth of the stringer is exactly what i'm looking for. it looks like there is a lot but you don't know exactly what's under the fiberglass. you might be right that a really long bolt will just go thru the stringer. that's what i'm looking to find out...jeff

[Mike and Joanne Stimmler]

Jeff, You could also run this past the folks at Catalina Yachts. Their usually pretty good at helping with questions like this.
Their number is 818-884-7700

Mike

[Jeff Kaplan]

mike, i just sent a post to kent at catalina tech. to see if he can shed any light on this subject. thanks...jeff

[Mike and Joanne Stimmler]

Jeff, the folks at Catalina seem to respond better to direct contact such as phone calls rather than email. I guess you could call them "old school" but their one of the few large companies that you can call and talk to the president of Catalina , Frank Butler if needed and that impressed the hell out of me. Try that with Hunter or any other major boat builder.

Mike

[Ron Hill]

Jeff :  The engine bed stringer that the lag bolts go into, are made of wood.  Can't tell you the kind of wood, but suspect it's plywood stacked on top of itself and then glassed over. 
The only issue that you might get into replacing those lag bolts, is the clearance between the lagbolt head and the bottom of the engine mount bracket that's attached to the engine. 

[Stu Jackson]

Keep it simple.  You simply can not re-epoxy the holes, because that would require either twisting the mounts or removing it.  Drilling the hole out is impossible.  Literally impossible.

What we did was this:  remove existing lag bolt, take a bunch of toothpicks (cut in half) and silicone them together, insert into hole, repeat as necessary, let set a bit, re-install lag bolts.  Silicone will ooze out a bit, let it set before you trim it off.

Seems to work for awhile, like two or three years.  Gets me back into the engine compartment to clean, clean, clean again!   

[Ed Shankle]

Jeff,
when I replaced my engine mounts 2 years ago with the Vetus, I was able to use the same lag bolts. I don't recall any significant resistance when tighening down the last 3/4".

Ed

[Jeff Kaplan]

ron, good point, i will have to see if a longer bolt will even fit under the engine into the hole. stu, i seem to recall now you mentioning this fix. could you share a little more detail of this proceedure, meaning did you silicone enough pieces together to fill the 3/8" hole and push down to bottom or just maybe 1/4" thick and drop down into hole and add anothe bunch on top, knowing the hole is 2" deep. once in, the lag bolt will penetrate the new wood for a tight fit. thanks...jeff

[Stu Jackson]

Jeff, a little bit of both.  Made up a "bundle" about the diameter of the hole.  Stuck 'em down the hole with the back of a pencil.  If they "disappeared" I made up another bundle.  Only one hole needed two bundles.  I only needed to do this to two holes, and these two holes were not on the same mount foot.

[Jeff Kaplan]

thanks stu, i will try the fix next weekend. 7 months till sailing season. i'm jealous of the longer season many of you enjoy...jeff

[Steve Sayian]

All the more reason to burn high-carbon fossile fuels to increase global warming here in the N.E.