Was doing an oil change at 40K today and when I put the Oil drain plug back in somehow I must have stripped the threads in the case. Not sure how this happened, I started it with my fingers for the first 3 full turns and then was using a torque wrench to tighten. Anyways, I backed it out and the drain plug had some of the case threads on it at the top (by the head) of the plug.

Well damage is done and now after doing some searching on here I found a few threads and an article that Dawg posted on fixes for this using oversized tapered plugs.

The help I need is does anyone know what size the factory plug is?

This article talks (http://www.bigboyzcycles.com/showthread.php?t=85)about using a 1/2"-20 oversize plug, if the factory is 1/2"-20 then is this what I want (oversize indicating it is for a factory 1/2-20)? or do I need a different size?

 

It is a MS fitting that seats on washer face and the o-ring goes up into bevel so you get metal to metal fit for a torque value. There may be an oversize plug for it or you could go NPT tapered plug and tap it. Then you would be stuck with sealer or tape. Need to do some checking. It's 1/2-20 from my research back checking with the ms 16142 chart and the o-ring size. You have the plug out, measure the thread OD. It could be 9/16-18. Sure Harley has a oversize plug and tap. Using a tighten spec with a torque wrench on maintance plugs and threads in aluminum is way too much after a few year of normal maintance with sharp steel male threads.

 

Why don't you just re-tap (it's called dressing) the threads back to original size? That will work unless you stripped all the metal out. That's what's done in the shops. The plug will hold in that hole just fine afterwords.

 

Some options.

eBay - I have seen oil pans for $50.00 +/-
http://www.bigboyzcycles.com/showthread.php?t=85
http://www.timesert.com/html/drainplug.html

 

Once metal is removed from the thread,you can not get the thread back to it's original size.The major and minor diameters will be oversize.

 

Everybody knows that. Dressing the threads works when most of the threads are still there and just need reshaping so the plug goes in straight and holds tight.

 

The o-ring seals the oil in, the threads just hold in the plug in. As long as the threads are good enough to do that then you are good to go.
Dressing the treads with a cleanup tap will remove some metal. Nice thing about a tap is you can see if you are going in straight. Do it without the handle if you can.
A lot of times you can dress up the treads with the original plug, just make sure it is in straight, use a socket with a short extension and no wrench, it will give you a good idea if the plug is going in straight.
An oversize plug is just that, it is still 1/2 20 but machined to fit tighter and is tapered so that it gets tighter as it goes in.

 

Not all torque wrenches are created equal.

 

This happens more than most want to believe and it is very easy to strip.
The choices are pretty much what you linked to: over sized, piggy back and then what is sometimes the overlooked option of a slightly longer drain plug bolt..If you go to NAPA autoparts with your original drain plug the counter person will measure the plug for you for diameter, thread type(course/fine) and pitch.
From my experience:
1-over sized piggy back sometimes creates a clearance problem on some bikes when using a floor jack and is very deep when compared to your regular drain plug thus eating alot of good threads. Also the provided o-ring sucks.
2-the 1 time oversized magnetic drain plugs are very good IMO, do not eat away a bunch of good threads and look factory to the naked eye just in case that is important to you.
3- a longer NOT over sized drain plug would catch/hold onto deeper threads in the case but will not have a magnet and the head size of bolt will be smaller..just information not that it matters.
*Finally: none of the above choices allows for an o-ring but the use of white liquid thread sealant solves that problem....there are individuals that have ground a small o-ring slot with a dremel type tool for #3
In an emergency situation i have seen someone just remove the o-ring and put teflon tape on the original plug. removal of the o-ring allowed the plug to sit a little deeper and bite into a good thread.
But your best bet might be NAPA although they might cost $8 instead of $3 at advance/pep boys or other place but they usually have informed counter people.
Torque wrenches sometimes become an issue with drain plugs because of positioning and low torque values. Hand tight and then quarter turn with a small 1/4 type wrench.

 

I was hoping that would be the case, but I just got done looking at it again and it looks like the first 3 thread have came out, they were on the plug. I can get the original plug in but it won't tighten enough (at least for me) I would be worrying that it would eventually back out. So dressing the threads won't work to use the original plug.

You answered my real question on the oversize and this is what I thought but wanted to make sure. My plan right now is to get a solid tapered 1/2-20 oversize and run it in about 3 threads to start the new threads, then put in a piggyback oversize.


Post mortem - I am pretty sure this all occurred because I was doing a "quick" oil change on a hot bike and putting the plug back into a still hot aluminum pan, not the best idea.