gear oil drain bolt - thread damage - help!

[OldRider]

Some one who knows what they're doing can weld it up and you would be good to go.

 

[Mzee]

Hope you solve this problem. It has generated much interest in me. I once had a similar problem on an old bike and had the hole retreaded.

 

[Koinz]

Not sure if this was mentioned, but I've seen a repair like this before.

Weld up the crack first, then weld a nut over top of the damaged hole and use a new bolt with washer. Might be an easy cheap way to go. Just a thought

This way you're not putting any pressure or force on the old casting.

 

[AlsoRan]

There is another option but it would require a good welder and a decent manual machinist.

Simplified version:

1. Bore the threads out to a clean diameter. A "counterbore" or step may be machined as well in order to provide a linear stop for the sleeve, this may be configured for weld also.
2. Machine a "sleeve" to replace the material that was bored out. The internal diameter will be the "minor diameter" for the new thread. The outer diameter is slightly larger than the "major diameter" of the new thread.
3. Press the sleeve and have it welded to the housing.
4. Thread the new sleeve diameter using the same thread spec as standard.

There is more to it than that but the machinist will know what to accomplish to prep the sleeve for weld since it will be a standard procedure. It even could get rid if the crack if it's not too deep. Also, the whole process is not difficult to do so cost should not be out of line.

I would do it this way if it was my bike, once complete it's a done deal. Just use the torque spec from then on.

I see from your pictures that the crack is over the entire "face" of the seating surface (where the crush washer is applied), but I can't tell how far down into the threads it goes? Can you see it on the outside of the housing past the seating surface? If it's not past that point and not too deep I would go back to this original thought (see above). BUT, with step #1 you will have to machine the seating surface farther down until the crack is completely gone. Hopefully there is still enough material to work with especially since there is not much outside of the thread major diameter in the first place. But if the crack continues there will not be anything left anyway.

I like this approach because once it's done there will not be any additional stress on the housing and an OEM drain plug can sill be used. Otherwise it seems like it's going to be a constant chase.

Maybe take some close up pictures and find a machine shop / welder and show them. If they want to see more, then ride the bike over there so they can get a visual and give you a yes or no. And hopefully not too much $$$ to get it done.

 

[yellowpaper]

I had this same problem of stripping the thread on the aluminum housing of the drive shaft that the gear oil drain bolt goes in to. This does not solve the 'crack' in the drive shaft that this post originated from but I did want to share that I used a 'm14x1.50 single oversized drain plug' from Autozone or O'reillys. Looks like this: http://d.pr/i/tSLD

So for those that have stripped the thread on the drive shaft housing - no worries! You don't have to take anything apart or redrill/retap the hole. Start with a single oversize and it will rethread as you screw in the new bolt, nice and slow! You can even order online double oversized and/or triple oversized.

Hope this helps someone else in the future.

 

[OldRider]

I think those oversize plugs are meant to be screwed into a steel pan. Could get into a lot of trouble trying to stretch the threads in an aluminum housing. JMHO.

 

[Kelvininin]

I am sure its been said, but I am too lazy to read the whole thread...

Some rules of thumb when working with aluminium housings and steel bolts.
* Never, ever, force it. The bold should thread in easily, resistance is bad.
* If you are experiencing resistance, and are confident that everything is ok, get a tap and trace the threads.
* Never over tighten, most bolts are not holding down heads on a diesel engine, if you are not confident in your ability to tighten properly, use a torque wrench. You will probably be surprised how "loose" the bolt is. Triple check your torque setting and make sure you selected the correct units.
* When in doubt and frustrated, take a break and come back to it.

I am a big fan of people doing their own maintenance, I have stripped plenty of threads, so I hope to pass along my experience.