A technical question for any mechanics out there

#1 Postby **coriolis** » Mon Apr 21, 2003 6:21 pm

I overtightened a bolt and stripped out the threads from an aluminum piece. I have the tools to retap the hole and get a larger bolt. How many sizes larger should I go? The bolt in question is a 7M x 1.0. This is a very odd size and I had a hard time finding the bolt in the first place. I could easily get an 8mm bolt with the same pitch. Would there be enough metal left to make decent threads in the 8mm dia, or should I go to a 9mm (another odd size) or 10mm. 10mm is close to 3/8 so I could do it in english and have the best selection of replacement bolts. Any thoughts, anyone?

azsnowman · #2 Postby **azsnowman** » Mon Apr 21, 2003 7:13 pm

I think, instead of re tapping, I would go with a *helicoil*. I've done this numerous times and it saves a whole heck of a lot of work. Any auto parts store sells the helicoil, you use your tap and die set to insert the coil, it will be the same size that you stripped. :wink:

Dennis 8)

#3 Postby **Stephanie** » Mon Apr 21, 2003 7:27 pm

Way over my head guys!!!! :o

This is pretty cool though - we have alot of people here that we can tap for information and help each other out!

azsnowman · #4 Postby **azsnowman** » Mon Apr 21, 2003 7:29 pm

I was a diesel, hydraulics mechanic in the Navy and the Army National Guard, I do 99.9% of my own auto repairs, only thing I can't do, is the computer crap on cars!

Dennis

#5 Postby **Stephanie** » Mon Apr 21, 2003 7:31 pm

Sounds like you were! :wink:

azsnowman · #6 Postby **azsnowman** » Mon Apr 21, 2003 7:33 pm

I hope I have the spelling right, it's pronounced
(heal-e-coil)

#7 Postby **pojo** » Mon Apr 21, 2003 7:37 pm

Stephanie wrote:Way over my head guys!!!! :o

That's my point exactly!

#8 Postby **coriolis** » Mon Apr 21, 2003 7:41 pm

Az, thanks for the reply. I was aware of helicoils but didn't know if they hold as well as original threads.

You're right about the computer crap. I had a battery explode once (no injuries) and after that the truck never ran right again. Numerous mechanics looked at it and proposed many expensive repairs, including replacing the carberator. Finally I went to a shop with several recent grads from a local tech school. They found that the exploding battery caused an electrical surge that fried a portion of the computer. He simply disconnected that circuit and it ran fine! I only paid for about an hour of his time.

azsnowman · #9 Postby **azsnowman** » Mon Apr 21, 2003 7:48 pm

The helicoils I've used in the past are just as effective as rethreading. My first experiance with helicoils came from the Navy, I was working on a piece of equip that's used on the flight deck, I stripped a bolt, asked the shop chief what he wanted me to do, he said that the helicoils are, if not better, than rethreading. Any piece of equip that's used on the flight deck of a carrier has to be at 150% because of all the aircraft, they can suck up a bolt from 25 yards away and there goes a 15$ million dollar aircraft!

Dennis

#10 Postby **coriolis** » Mon Apr 21, 2003 8:06 pm

Yeah, I'd bet that a bolt would do a number on a jet engine. You're talking a lot of rpms. Let's see... those military engines are turbo jets ... or ... turbofans?

#11 Postby **coriolis** » Sat Apr 26, 2003 10:25 am

Well Dennis, an 8mm helicoil for fine threads just does not exist. I got a 3/16 INCH bolt and was able to get it in stainless steel and the socket head that I wanted. I drilled out the old 8 mm threads, tapped the hole and it works great! That brand new tap went through the aluminum like butter. Problem solved. Thanks for your responses and input.

#12 Postby **Stephanie** » Sat Apr 26, 2003 11:09 am

Cool!

A technical question for any mechanics out there

A technical question for any mechanics out there

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