Bolt for a Gibbs Ascender

They come in 2 sizes: for the 1/2" capacity Gibbs, the bolt measures 1 3/4" (not counting the head) x 3/8". For the 3/4" capacity Gibbs, the bolt measures 2" x 3/8" (again, not counting the head). Got to be grade 8 as well.
it has a smooth shank thats slightly larger than the threaded part so you can cinch it tight with out distorting the body of the gibbs. like this
Its called a shoulder bolt. You can buy them from good hardware stores or bolt companies.
The nylock nuts are longer because of the nylon ring pressed into the top of them.

The bent thread nuts are a bit more streamlined. Bent thread nuts have the last thread pressed a bit so the nut threads are very tight and will not loosen.
Used on interior engine parts or applications where their is alot of heat. I use the bent thread nuts on my chipper blades, for example.

Grade 8 bolts are very hard and strong, but also are brittle. Grade 5 (plow bolts) are slightly softer so they distend before shattering or shearing.

A high strength all-metal lock nut that gets its locking feature from deformed top threads. Very reusable and good to 450 degrees F. Used on grade 8 cap screws and other high strength fasteners.


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I have some ART rope guide mini-blocks and those things use the bent threads AND the bolt is about 4mm too long and has a hole in it for a little pin. That sucker ain't coming out.

A socket head cap screw works nicely for Gibb's too. The head drops down inside the plastic plate on the side and sits on the shell of the ascender.

Has anyone had a spring pin from a Gibb's open accidentally? sometimes I wonder if this is a case of urban mythology. I sure can't argue with the idea of bolting when using it for a lanyard but I do wonder if the triple autolocking/unlocking of the spring pin isn't enough safety.
I wouldn't be that surprised if you never heard from anybody who had this happen. Most likely they'd be dead.
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I can't figure out why they need to come apart, anyway. I've never taken my pin out.
Push center button
Grab pin at the same time
Pull the whole works out

If you don't do all three things at the same time I can't see how it would come apart. Pushpins are used in many similar applications with no problems.

This is more just a discussion rather than saying that a bolt isn't a good idea for a lanyard application.
I see what you mean by three different motions now. Another overkill method I have noticed is the use of grade 8 bolts.

Even the sheer strength of a 3/8 soft steel bolt is higher than any force a climber could generate.
You're probably right there Frans. The problem is, what if you're wrong? Why take a chance when the grade 8 bolt is only a few cents more?
I use grade 8, for just that very reason Bounce. But I have looked at charts that list the shear strength of 3/8 shank bolts of various grades, and the lowest grade is huge!

We tend to over build in certain things, but not in others.
That's for sure...the darn tree will fail on us way before that bolt will...and that goes for a triple handful of other stuff we go big on breaking strength, too.

Doesn't mean I'm gonna back off on any of it though...I'm fearless when I'm tied in, and that's all because I KNOW the gear is bombproof.