Stuck bolt, possibly crossthreaded - how to proceed?

[stickshift]

I've got a stuck bolt I could use some help diagnosing. This bolt secures a pivot rod, around which a pulley spins, to a frame. There's a bolt on either end of the pivot rod. I started both by hand, then ratchet, then impact driver (hex shank driver with socket adapter). On prior removal, the bolt on the left required more effort to remove. And it required more effort to fasten, and then it become very difficult to fasten further, so I tried backing it out and it's also very difficult. Tried rubbing some grease on threads to see if I could get that between the bolt and the threads in the frame (though now that I'm writing this, I realize wd40 or similar would be better b/c it can wick in even without me turning the bolt, so I'll go do that).

It feels like it's binding, and I'm afraid the bolt is going to snap. I'm not sure what's going on. I started by hand, then ratchet, then impact, so I'm not sure how it could be crossthreaded. But then again, the only explanation I can think of for the binding is crossthreading. Any ideas? Maybe there was some thread damage from earlier, which would help explain why it was more difficult to remove this bolt than the bolt on the other end of the pivot, and that damage got worse even without crossthreading?

How can I get this bolt out? It's critical that I do not damage the frame (prohibitively expensive to replace), which includes the frame's threads - which hopefully I can preserve such that the threads can be cleaned up with a tap.

 

[LXCam]

I doubt it’s cross threaded but there’s no doubt it’s galled. At this point I would suggest not using WD40 but a good penetrating fluid such as PB blaster...etc. also I’d heat the thread area up if possible before you try again. One thing about a galled thread, when it starts getting tight, try rotating the opposite direction a turn or so and then try again. I’m sure that doesn’t make sense but it damn sure works.

Once you get it out use a thread chaser on both pieces to restore the threads. And lastly unless this part needs some type of thread locker, use anti seize on it and you’ll be fine in the future.

 

[stickshift]

Got the bolt out. I ran copious amounts of Liquid Wrench down the threads, then pulled hard on the ratchet - there was a snap very similar in sound to when you break a fully fastened bolt free, except in this case, the bolt was only halfway fastened. I'm guessing this was the sound of thread breaking off. After that snap, the bolt was no longer binding and it loosened, not easily, but not very difficult as before; it definitely was not crossthreaded.

Here's a pic; the bolt is a hot mess; the good bolt from the other end of the pivot is included for comparison. Notice the missing threads, as well as the bit of thread I was able to pull off with my fingers.

Going to get a tap and hopefully the frame's threads can be cleaned up.

I doubt it’s cross threaded but there’s no doubt it’s galled.

Doesn't galling require time? This got stuck while I was fastening it.

 

[LXCam]

Nope, galling can happen at any point.


Glad you got it out.

 

[EOC_Jason]

^^^

Also, Stainless on Stainless is very prone to galling. Something to be aware of...

All it takes is just a little bit of material tearing to start gumming things up and it all escalates quickly...

 

[Selo]

You may not want a "tap" but maybe a thread "chaser" designed to clean up threads not to cut threads. There is a big difference in the two.

Good luck,

Selo

 

[larry_g]

It is also possible that spinning the bolt in with a power driver contributed to the problem. It was tight to begin with then the speed of the bolt caused heat and wammo, welded threads. Also looking at the bracket it has a punched hole in it that was threaded. I would guess that the hole was a bit small for the thread used also. If all else fails, drill it to a clearance hole and use a nut on the bolt.

Why is the bolt so long? Do the extra threads have a purpose?

lg
no neat sig line

 

[stickshift]

^^^
Also, Stainless on Stainless is very prone to galling. Something to be aware of...

All it takes is just a little bit of material tearing to start gumming things up and it all escalates quickly...

Guess so. Definitely learned something new. I had previously thought galling required lots of time.

I'll follow LXCam's advice and use anti-seize.

It is also possible that spinning the bolt in with a power driver contributed to the problem. It was tight to begin with then the speed of the bolt caused heat and wammo, welded threads. Also looking at the bracket it has a punched hole in it that was threaded. I would guess that the hole was a bit small for the thread used also. If all else fails, drill it to a clearance hole and use a nut on the bolt.

Yeah, the heat from that tight fit of thread being forced to spin via the impact driver probably contributed to the galling.

Nut is a good solution if the bracket's threads cannot be restored, thanks.

You may not want a "tap" but maybe a thread "chaser" designed to clean up threads not to cut threads. There is a big difference in the two.

Yeah, I meant chaser. Strange how you can buy taps at all the hardware stores, but none of them have thread chasers/restorers. Seems backward to me - lots more people need to clean up existing threads than tap new threads.

Why is the bolt so long? Do the extra threads have a purpose?

Good question. I was asking myself the same as I was removing these seemingly endless bolts (the good bolt doesn't have enough room above it for my impact driver, so it took forever to remove with a <90* arc for the ratchet to work with). Because the bolts secure a pivot rod on which pulleys spin, you want a little adjustability as the belts wear, but that is a few threads at most. When I looked up the part # in the parts diagram, it shows a 2-1/2" bolt. What I have in front of me is a 3-1/2" bolt. Between that and the damaged threads, I'm guessing these are not the OEM bolts and that someone has been here before me (and didn't bother cleaning up the threads after damaging them!).

 

[joel63]

Got the bolt out. I ran copious amounts of Liquid Wrench down the threads, then pulled hard on the ratchet - there was a snap very similar in sound to when you break a fully fastened bolt free, except in this case, the bolt was only halfway fastened. I'm guessing this was the sound of thread breaking off. After that snap, the bolt was no longer binding and it loosened, not easily, but not very difficult as before; it definitely was not crossthreaded.

Here's a pic; the bolt is a hot mess; the good bolt from the other end of the pivot is included for comparison. Notice the missing threads, as well as the bit of thread I was able to pull off with my fingers.

Going to get a tap and hopefully the frame's threads can be cleaned up.

Doesn't galling require time? This got stuck while I was fastening it.

From looking at the picture of the damaged bolt, I'd say you were very lucky to get it out of the pivot.

 

[6PTsocket]

^^^

Also, Stainless on Stainless is very prone to galling. Something to be aware of...

All it takes is just a little bit of material tearing to start gumming things up and it all escalates quickly...

The bolt is a grade 8 (6 lines) ao it is not stainless, which is similar to grade 2 and not very strong.

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[6PTsocket]

Here is the good news. Chaser taps and dies are mostly made by Lang, formerly Kastar for almost everybody. That includes Snap On. They are the only ones I know who have open stock. If you order online they ship free and have no minimum. I believe the chaser taps and died are under their Bluepoint label. They are pretty cheap. I think I only paid around 3 bucks for a 10 or 12 mm chaser tap. Make sure there is no broken screw thread left in that nut. That was a grade 8 bolt and not that easily messed up. Make sure you replace it with another grade 8.

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[stickshift]

That was a grade 8 bolt and not that easily messed up. Make sure you replace it with another grade 8.

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What grade are the zinc plated bolts at Home Depot? They are labeled AMD and cost $0.26 for a 5/16"-18 x 2-1/2" bolt.

 

[HotRodBoater]

Probably grade 5

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[EOC_Jason]

The bolt is a grade 8 (6 lines) ao it is not stainless, which is similar to grade 2 and not very strong.

Yeah I don't think I was clear in my post. I didn't mean HIS were stainless, I was just giving general information (because a lot of people like to buy stainless nuts & bolts thinking they are always the best in any situation).

I'll follow LXCam's advice and use anti-seize.

Good call, a little anti-seize never hurts.

 

[greenskeeper]

candle wax works good too

 

[RKA]

Look for a misalignment of the parts that bolt is passing through before it reaches the threaded portion. That’s how the peaks on those threads get flat like you see on that damaged bolt.

 

[sberry]

We spray about every bolt we install.

 

[Falcon67]

Or anti-seize.

 

[TractorJeff]

What grade are the zinc plated bolts at Home Depot? They are labeled AMD and cost $0.26 for a 5/16"-18 x 2-1/2" bolt.

I would bet the zinc plated bolts are Grade 2, not Grade 5

 

[stickshift]

From looking at the picture of the damaged bolt, I'd say you were very lucky to get it out of the pivot.

Yeah, I avoided a world of hurt.

I got a loaner set of thread chasers from auto parts store (probably made by Lang) and slowly chased the frame bracket's threads using plenty of oil, backing off a lot and periodically removing the chaser to clean it off (lots of fine metal bits, including some larger slivers). Was able to salvage the bracket's threads.

Lesson learned here for me. I felt the threads were a little difficult when removing the bolt and comparing it to the other bolt, which came out easily. But because I didn't have thread chasers, I figured I could get away with reinstalling the bolt and not bother holding off until I bought or borrowed thread chasers. When a chaser set isn't on hand, the temptation is to get the project done and not delay to acquire a thread chaser.

So I'm going to invest in a set so that I can quickly clean up threads anytime I run across rough threads. Even though this will be a low use item for me, it can save lots of time and headaches.

 

[visionguru]

Yeah, I avoided a world of hurt.

I got a loaner set of thread chasers from auto parts store (probably made by Lang) and slowly chased the frame bracket's threads using plenty of oil, backing off a lot and periodically removing the chaser to clean it off (lots of fine metal bits, including some larger slivers). Was able to salvage the bracket's threads.

Lesson learned here for me. I felt the threads were a little difficult when removing the bolt and comparing it to the other bolt, which came out easily. But because I didn't have thread chasers, I figured I could get away with reinstalling the bolt and not bother holding off until I bought or borrowed thread chasers. When a chaser set isn't on hand, the temptation is to get the project done and not delay to acquire a thread chaser.

So I'm going to invest in a set so that I can quickly clean up threads anytime I run across rough threads. Even though this will be a low use item for me, it can save lots of time and headaches.

I think you haven't learned the right lesson.

The bolt seemed secured with high strength Red ThreadLocker. It needs heat to soften the ThreadLocker first before you put torque on it. The damage was done by over torquing.

 

[stickshift]

I think you haven't learned the right lesson.

The bolt seemed secured with high strength Red ThreadLocker. It needs heat to soften the ThreadLocker first before you put torque on it. The damage was done by over torquing.

Nope, not threadlocked. I could start turning these bolts with a short-handled 1/4" ratchet. If red threadlocker had been applied, no way I could do that. If you're referring to the red goop in the earlier pic, that's just grease.

 

[Squankum]

The gall of some fasteners!

https://en.wikipedia.org/wiki/Galling


Also, a hex drive impact chuck means, well, not the greatest impact gun. Should be enough for that thing, normally... And of course, get some Kroil. And some antiseize.

(Having spent my formative years in the Salt Zone, and me always being the future mechanic who will be fixing it next time, I'm an antiseize fiend.)

_

 

[Squankum]

More fun with metal:


https://en.wikipedia.org/wiki/Spall

https://en.wikipedia.org/wiki/Fretting

https://en.wikipedia.org/wiki/False_brinelling

(I especially like the automotive manufacture rail-shipment story in the “Examples” section. Railroad cars aren’t mentioned specifically, but yes, the wheel bearings in your car can do a great many things, but a few days on the train going higgity-higgity-higgity* back and forth a teeny tiny amount instead of spinning can screw them up quickly.)



_

 

[cherrybomb]

If an assembly is even a bit out of alignment, using an impact causes side pressure which damages thread parts.You can't get a good feel,resulting in damage.Even though its slower,a short wrench or ratchet and socket you feel the tight spots and the good threads.You will know quickly what your are dealing with.Its possible the guy before you threw you a bit of a curve.I am happy when you see the head of a fastener not all boogered up,not over torqued, and some type of lube on the threads.Thats when wrenching is fun.