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  #1  
Old 11-15-2006, 09:08 PM
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Argh! Broken rethreading tap

I have been working on the front brakes of my TD, when I ran into a problem. The bolt holes that hold the caliper to the steering knuckle were cross-threaded and galled, so I bought the Craftsman rethreading kit and got to work.

Working with a ratchet I would run the tap in 1/2 - 1 turn then back out a few. Every once in a while I would remove the tap completely, clean it off and re-oil. Standard tap techniques (I thought). After cleaning out the upper hole, I went to work on the lower one. Just as I had the tap almost all the way through, it broke off as I was backing it out! I guess it will be a trip down to the machine shop for this knuckle.

Is it recommended to heli-coil these holes, or should I be looking for another knuckle?

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Old 11-15-2006, 09:14 PM
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Quote:
Originally Posted by OldPokey View Post
I have been working on the front brakes of my TD, when I ran into a problem. The bolt holes that hold the caliper to the steering knuckle were cross-threaded and galled, so I bought the Craftsman rethreading kit and got to work.

Working with a ratchet I would run the tap in 1/2 - 1 turn then back out a few. Every once in a while I would remove the tap completely, clean it off and re-oil. Standard tap techniques (I thought). After cleaning out the upper hole, I went to work on the lower one. Just as I had the tap almost all the way through, it broke off as I was backing it out! I guess it will be a trip down to the machine shop for this knuckle.

Is it recommended to heli-coil these holes, or should I be looking for another knuckle?
I dont see why you cant go the next tap up, isnt the hole on the caliper a clearence hole anyways?

NEVER use a rachet for threading. Use a tap handle, as it lets you "feel" the tap. TapMagic (or and other high-sulfer oil) is a must. I stay far away from craftsmen threading tools, as tools bought from a tool supply house (IE production tool supply) are usually cheaper and a bit more robust. Just be sure to ask for a hand tap, as they usually try to sell you a plug tap. NO spiral flutes tao either. You want a HSS tap (NOT carbon.) and you may also need a "bottoming" tap, to get those last few threads set.
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Old 11-15-2006, 10:41 PM
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Taps

This wasn't a standard tap. It had a hex head on one end and the rethreading cutter on the other. Not the usual square head that goes into a proper handle.

Here's a link to the set:

http://www.sears.com/sr/javasr/product.do?cat=Mechanics+Tools&pid=00942275000&vertical=TOOL&subcat=Automotive+Specialty+Tools&BV_UseBVCookie=Yes
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Old 11-15-2006, 10:47 PM
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The quality of a tap can vary all over the map. The cheap Chinese taps certainly meet the hardness requirement, but, when you have to apply some torque, the brittle steel simply snaps.

However, when you use a high quality tap, it's amazing how much force you can apply without breaking it. You can actually feel it torque up slightly........the tap is very hard, but does provide some yield before it fails.

The Chinese taps never provide any notice..........one minute you're working along fine and the next, it's in two pieces.

Don't know about those Craftsman taps, but, from the sound of your experience, they can't be very high quality.
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Old 11-16-2006, 07:28 AM
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Taps, and tools....

G'mornin',

There is a tool.....Tap Extractor.....however I don't own one, and I am unsure if it will grab your "Rethreading Tap".....

Rethreading taps are a bit different from your usual "Machine Taps".....they are designed to do just what their name says.....rethread.....or chase and clean up old threads without removing any extra material......I own a set that I purchased from MAC.....Snap-On has a good set as well.....

Note, my set has 3 different M12 taps, different thread pitch, my car required M12x1.5

Argh! Broken rethreading tap-mvc-332l.jpg

Argh! Broken rethreading tap-rethread-set-small.jpg

I've owned my rethread set for some 10 years, and have one broken Tap....1/4" 20 NC.....it snapped along the shaft between the hex and the barrell shaped cutting head.....I think I got that out with some needle nose pliers, patience, anti-anxiety drugs, and if you screw your mouth up just right....

Personally, at this point, I would look for a used steering knuckle and replace ...

SB
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Last edited by Shorebilly; 11-16-2006 at 07:55 AM. Reason: Add Photos
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  #6  
Old 11-16-2006, 07:49 AM
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I second the motion for a new knuckle. You already know the present one has some bad threads (reduced metal).
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Old 11-16-2006, 08:39 AM
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Quote:
Originally Posted by OldPokey View Post
This wasn't a standard tap. It had a hex head on one end and the rethreading cutter on the other. Not the usual square head that goes into a proper handle.

Here's a link to the set:

http://www.sears.com/sr/javasr/product.do?cat=Mechanics+Tools&pid=00942275000&vertical=TOOL&subcat=Automotive+Specialty+Tools&BV_UseBVCookie=Yes
It seems to me that Craftsmen comes out with "gimmick tools" every so many years. The sockets with the plastic band around them with the sizes printed on the bands comes to mind, but because of the bands you could not get them into a tight hole.

But this set sure does look like the MAC set from shorebilly. But then again, if you look at the Klann spring compressor vs. the aftermarket copy they tried to make it look identical. I agree with Brian that the quality of the tools is not as good as it could be.

I know it is more work than cleaning up the threads of what you have, but I think you should replace the knuckle too. You know you have been wanting to do some suspension work and now is your chance.
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Old 11-16-2006, 09:17 AM
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Quote:
Originally Posted by Shorebilly View Post
I think I got that out with some needle nose pliers, patience, anti-anxiety drugs, and if you screw your mouth up just right....
SB
That is very good advice. Last week I was drilling out a broken off bolt from the Tecumseh 6HP engine on my Troy Built Horse roto tiller. I had drilled my pilot hole which is typically the hardest part and was just about done with the next size up and it broke off. I was able to get it out and then broke another one off It tool me a while and a pair of Swiss needle nose tweezers and a pin punch and a hammer to get it out. Finally got it all done, but it was a 2 hour job that turned into a 5 hour job.
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Old 11-16-2006, 10:29 AM
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That's what I thought.

Looks like I have to head down to PGA and get one, unless someone has one they'd like to sell...
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Old 11-16-2006, 11:23 AM
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Quote:
Originally Posted by Brian Carlton View Post
The quality of a tap can vary all over the map. The cheap Chinese taps certainly meet the hardness requirement, but, when you have to apply some torque, the brittle steel simply snaps.

However, when you use a high quality tap, it's amazing how much force you can apply without breaking it. You can actually feel it torque up slightly........the tap is very hard, but does provide some yield before it fails.

The Chinese taps never provide any notice..........one minute you're working along fine and the next, it's in two pieces.

Don't know about those Craftsman taps, but, from the sound of your experience, they can't be very high quality.
Craftsmen is known to use some import stuff nowadays.

I like taps/cutters from Poland - affordable and good. "Pro-Cut" is a good brand for the price.

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