JamesC

iTrader: (5)

Theoretical question: Where's the damage occur in cross threading, for example an accessory stud, the head, or both? Or is it simply difficult to say? Possible fixes?

JamesC

wanta427

Usually whatever is softest or the hardest to repair (or most expensive). Mr Murphy always has the last laugh .

pandin

When a bolt hole is cross threaded, you are cold forming a new set of threads on an angle from the original ones. The angle causes the thread ingagement to be more then the bolts, so it gets tight real quick. If you continue to screw the bolt in, the bolt will turn to follow the hole. When the bolt is stronger, then the hole thread, the hole strips the threads out. You can sometimes see them wrapped around the bolt threads.

If the bolt is soft the threads roll over and are flattened and sometimes stay in the hole.

The cure is use good bolts. Clean out the holes with a tap. Start the bolts straight. Then stop if it does not feel right. If all else fails helicoil.

Sonix

iTrader: (1)

As mentioned, softest mtl.
From experience, both get chewed up almost equally. I can usually repair the bolt with a thread file, and the hole with a tap. Only if a NEWB really went to town on it, will it be unrepairable.
Cases where the damage isn't 50/50:
hardware store grade 2 bolt into steel threaded part. Bolt get torn up.
Grade 8 bolt or allen screw, into aluminum or cast iron part. Threaded part gets chewed up.

As mentioned, bring the bolt in by hand 2-3 threads before using tools. If you can't, that's because the threads are already damaged and should be cleaned up with a thread file/tap, or because you're parts are misaligned. Do everything you can to align them better first. Always lube threaded parts, etc etc

JamesC

iTrader: (5)

You can imagine that I'm very annoyed with myself--apparently even with some experience, you can still be a dumb butt. The bolt is a Torx into the cylinder head. Snug but not tight. Locktite from the factory. Three other bolts, torqued to spec, and a brace are holding the bracket in place. Leave well enough alone? If I remove the bolt, am I relegated to drill/tapping or is there another alternative?

JamesC

pandin

Hindsight is usually 20/20. Don't ask me how many times in past, that I knew better, didn't do better. It is real easy to, odd angles, miss made parts, in a hurry, tired, ect...

Is the head aluminum or iron? Can you get a tap in it? How far in is the bolt? Which bracket and which bolt? That all makes a difference.

BTW broken taps in a bolt hole are worst than a stripped bolt. Always stop 1/4 turn before it breaks. AMHIKT

pandin

Murphy's Law:

Nothing is as easy as it looks.
Everything takes longer then you think.
And if anything can go wrong, it will go wrong at the worst possible moment.

Also known as the Optimists Creed.

Auther unknown, but is sometimes credited to a nasa engineer, whose name I can not remember. Oh ya Murphy.

JamesC

iTrader: (5)

Maybe not. As the situation turns out, I hadn't cross threaded at all. To explain, however, what I did do, would make me and ten generations of my family look stoooooopid. At any rate, the bolt in question is torqued to spec.

JamesC

pandin

Theoretically speaking only.