M25 motor mounts

[KWKloeber]

Ed,

I have a different looking coupling but the theory is the same, and my shaft came out easily.  But I think all you need to do it unbolt the coupling from the transmission flange, there's no need to get it off the shaft - which is the more tricky operation.

Ken

[Noah]

Usually there are studs coming out of the forward end of coupler attached to the transmission flange with nuts on the forward side of the transmission flange--unbolt there and slide coupling and shaft aft. However, those nuts may be "frozen" and require some soaking with penetrating oil--perhaps for days.  Be careful not to get any penerating oil on the rear transmission seal. Use a Q-tip or small spot/pin oil bottle applicator.

[Ron Hill]

Ed : There are 4 studs (as Noah said) that come out of your flexible coupling on the engine side.  The studs go thru the holes on the 4 fingered coupler which is on the aft side of the transmission. 
There should be 4 nuts that need to be removed so you can slide the coupling aft to disconnect it from the trans/engine

I'll guess that these nut are probably corroded to the studs and you'll need liquid wrench/blaster and maybe even heat to get them off.

A few thoughts

[Ekutney]

I made some progress.

Plan A:   I bought the 90 deg drill adapter from Harbor Freight but it is too tight a fit to get a hole saw properly positioned to drill it out.

Next idea,

Plan B step 1:  I loosened the large nuts on the stud coming out the top of the motor mount and was able to rotate the base just enough to give me access to the hole where the broken lag bolt is in the stringer. (front mount, front hole starboard side)  I then took a Dremel and excavated the hole enough to see the top of the lag bolt, it is about 1 in below the top of the stringer. My plan is to use the Dremel and either grind it down or excavate enough to dig it out..  A long tedious process but I am determined.

Plan B step 2:  I then plan to insert a thick plastic straw in the center of the hole and fill around the outside of the straw with epoxy (the void left by the straw should act just like a pilot hole).

Any thoughts on my plan?

[Stu Jackson]

.....access to the hole where the broken lag bolt is in the stringer. (front mount, front hole starboard side)  I then took a Dremel and excavated the hole enough to see the top of the lag bolt, it is about 1 in below the top of the stringer. My plan is to use the Dremel and either grind it down or excavate enough to dig it out..  A long tedious process but I am determined.

Ed, is there any room to cut a slit in the top of the "down-in-there" lag bolt and then use a screwdriver to back it out?

[Ekutney]

I was thinking the same thing, gonna stop by the hardware store tomorrow and see what type of Dremel bits I can find.  One way or another that lag bolt is leaving the boat.

Any thoughts on the idea of using a thick plastic straw to act as a pilot hole for the new lag bolt..  Just not enough room to drill an adequate hole use a variety of methods.

[Noah]

You have two threads going here. See my response on your first thread. Good luck.

[KWKloeber]

ed,

it may be too stuck for this to get it out, there are ez-outs for wood screws.  The come in multiple diameters - one \end is a left hand drill bit (drill in reverse), the other end a graduated, left threaded post that grabs onto the drilled hole and backs out a screw.   


For that matter even an EZ-Out made for a machine bolt might work.

You need to be very careful drilling because no doubt the shaft is broken off at an angle.  But you might be able to grind it flat with a dremel in order to drill it.

kk

[KWKloeber]

Ed

after 3o yrs of epoxy repairs - a caution.  Epoxy resin alone (no additive) is both very hard and dense and can be difficult to thread into.  It's like trying to thread a wood screw into a metal block -- it's difficult to get threads to 'cut in', and the density leaves no 'give' to displace material as tapered threads work their way into the hole.   You're gonna want the diameter of the pilot hole to be equal to (or ever so slightly larger than) the minor diameter of the lag. 

It might also be worthwhile to add a little West 407 low-density filler or Mas Cell-O-Fill to the resin mix.  A gob of soft wax (like from a toilet bowl seal) would help the lag turn easier.  I would do a trial run (different mixes) in say, a heavy cardboard tube like a carpet tube (a plastic solo cup might melt from the heat of reaction) to see how they accept a lag.

KK

[Ekutney]

Good news, the broken section of lag bolt has left the boat.  I used a Dremel with a tungsten carbide bit, shaved it down then the 3500 RPM vibration got it to just pop out.  I now have a hole which is as deep as the 2 in lag bolt. 

I have read the suggestions & plan to experiment with a couple of recipes to see which works best.  I plan to use a mixture of epoxy & filler to see if the straw concept works, a wooden 2x4 is going to be my test platform. 

I also had another thought since I now have a bigger hole.  Maybe using a threaded insert, just not sure if larger ones are available.  I would have to make sure it is kept perfectly straight because once set it can't be moved.  My concern is if a threaded bolt is off just a little then it will not sit flush when tightened.

I've attached a pic of a good lag bolt next to what I extracted.

[Stu Jackson]

That's great news, Ed.  Congratulations.

[KWKloeber]

Ed,

COOL! A Sonicare to floss your stringer.

By threaded insert, do mean UNC thread?  Or screw thread (e.g., like a lead shield)? 

As I said below you can get a coupling nut -- available in standard or extra-long length, stainless or zinc.  Wax up a bolt, and use it to insert the coupling nut and keep it plumb in the stringer hole.  Soon after the resin kicks, back out the bolt leaving your threaded fastener.

Ken

[Ekutney]

I was thinking a UNC thread but the largest I found at WM was 1/4 20.  I was thinking something larger that is close to the same size as the 3/8 lag bolt.  I don"t want to use something smaller because it will leave too much movement in the slot of the motor mount.

WHat did you mean by a lead insert?  I think lead would be too soft.

[KWKloeber]

I was thinking a UNC thread but the largest I found at WM was 1/4 20.  I was thinking something larger that is close to the same size as the 3/8 lag bolt.  I don"t want to use something smaller because it will leave too much movement in the slot of the motor mount.

WHat did you mean by a lead insert?  I think lead would be too soft.

When you use a lag bolt in, for instance concrete, one method is to drill and tap in what's called a lead shield. It's basically a lead anchor that expands against the hole as the tapered thread of the lag goes in.  Some are a solid cylinder, some are two halves of a cylinder, held together by wire until the lag goes into it.

Google lead shield anchor in google images.  The shield would be your "straw."

Coupling nuts come in 1/4", 5/16" 3/8" UNC ...... etc.  Look through McMaster-Carr.  You could tack weld a washer to its end to give more bite.

Or, why don't you think you could hold an upside down hex bolt/nut/washers plumb -- to make a stud? 
If you have a nut/washer atop the stringer, that would help to plumb up the bolt.

kk

[Ekutney]

I was also thinking of using a bolt inserted head first with a flat washer and another bolt to give more strength but then I.d have to remove the mount.

Gonna hit HD & Lowes in the AM & see what they have.