Any *cheap* way to repair threads?

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Thread on the exhaust manifold of the lawnmower has stripped for a longtime. It is M6x1.0 thread. Fortunately, it is a through thread, so I had access to the other side. I was able to mcguiver by using a long skinny stud and put nuts on the both side to hold the muffler in place.

I would like to repair that thread. It is not a requirement to keep it at M6x1.0, so I could re-tap it be standard (rather than metric) thread and use a standard long bolt. I would prefer to keep it M6x1.0 but I am not willing to pay $30 to buy the Heli-Coil kit. The repair is not necessary as the mcguiver method is working fine but I would like to learn the technique of thread repair.

I have no tools such as taps or thread chasers. I could use this as an excuse to visit Harbor Freight but you guys would probably prefer that I avoid that approach :)

Any advise?
- Vikas
 
I'd go buy a Harbor Freight metric tap set and have a go of it. Is the manifold Cast Iron? That would explain the first set stripping with a steel bolt and that shouldn't be a challenge for a cheap tap. Even if it's steel it must not be very hard. I doubt you'll be able to chase them with the same size, you'll probably have to go up one.

But to be honest your first fix is probably fine.
 
i bought a tap & die set harbor freight, 60-piece i think, years ago and it is great. drill it out and go bigger on the thread. download a tap chart from the internet so you use the correct drill for the thread pitch & diameter you're going to.
Pick up a small bottle of cutting fluid too if you can find it, otherwise use some lightweight penetrating oil.

http://www.shender4.com/thread_chart.htm
http://www.kramerusa.com/DrillTapChart.htm
google drill tap chart.
 
Just crossthread a bolt in and dont worry about it. It will be no worry unless you need to work on it in the future.
spankme2.gif
 
Yeah Id turn it into a stud, but that doesnt feed you desire to learn.

Actually, Id fix it as you have, but that doesnt either.

So Id buy the one tap that you need to go up one size, buy the bolt, and run with it. Worst that can happen is that you re-macguyver it.
 
Only if Heli-Coil were reasonably priced :-( I suppose when one really needs it, he would be willing to pay the price.

At first the muffler shield corroded and fell off. When I tried to tighten the nut on the stud, the other must have stripped or it was already stripped before. I am still perplexed as to why Honda used stud and why the hole was through. They must have updated the design because now Honda only sells flanged bolts instead.

The manifold is still nice and silvery. If it is not aluminum, it is plating is still intact after 12 years :)

- Vikas
 
Originally Posted By: pcoxe
JB weld a stud in the hole and use a nut instead of a bolt to hold it on.


This is an exhaust stud, JB weld will melt from the heat
 
JB Weld is merely a chemical,2 part man made product.It does not "weld" pieces back together,cannot take high temps,or stress loads.People brag all the time how it pieced back connecting rods,cylinder cracks,head cracks,etc etc.Hooey! Someone online did a long bar test one time,and just minor pressure on the end of that bar snapped the "bond".It was concluded that more contact area made a stronger bond,but whats the cross section of a small crack or a connecting rod? I laughed when I read on the label of a JB tube back awhile,where a "testimonial" stated that a guy repaired an 80 ton bottlejack with it.OK...how would JB support 80 tons? Bet it was used on the pump handle bar,not the jack itself.
 
You can make a poor mans tap using a grade 8.8 or 10.8 bolt and cutting 4 lengthwise flutes in it with a dremel fitted with a small cutting wheel, you can taper the end on a bench grinder.
The 8.8 will do aluminum but not steel to well. Just drill the hole about 1mm smaller than the bolt.

Don't do this if you intend on using a helicoil only to go up in size. You can just flute a 7mm bolt (hard to find but they are made) and tap the stripped 6mm hole without drilling.
 
Originally Posted By: Trav
You can make a poor mans tap using a grade 8.8 or 10.8 bolt and cutting 4 lengthwise flutes in it with a dremel fitted with a small cutting wheel, you can taper the end on a bench grinder.
The 8.8 will do aluminum but not steel to well. Just drill the hole about 1mm smaller than the bolt.

Don't do this if you intend on using a helicoil only to go up in size. You can just flute a 7mm bolt (hard to find but they are made) and tap the stripped 6mm hole without drilling.


Fluting grade 8/10.8 hardware into homemade taps! Genius!

I'm seriously going to give that a shot next time I'm at work. Bet it'd work like a self-threading machine screw.
 
Quote:
Bet it'd work like a self-threading machine screw

Exactly. I cant tell you how many times one of these little home made buggers has saved the day in a pinch.
 
I am just going to leave it alone. I have got to tackle the power output of this lawn mower before doing anything else.
 
Originally Posted By: rpn453
A good tap and die set is part of any decent tool collection. I've used mine many times.


Agreed
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