Light weight nuts & bolts sources, Hollow and aluminum?

Richard/SIA · Jul 2, 2019

Tried an on-line search for hollow and aluminum bolts with no luck.
The keyword algorithms have gotten so bad that no matter what you try to find all you get are unrelated Amazon links.

I no longer have my EDM machine to make my own hollow bolts so will have to buy them.
Anyone have a good source?

If I have to I can still make aluminum bolts on my lathe but lose out on any heat-treat for toughness or plating.
Anyone have a good source?

I know the knowledge base here is far better than any search engine, probably a manufacturer or two here as well.

Milland · Jul 2, 2019

I don't recommend Al for bolts, at least any that are under stress. As for lightweight, there's a few series of NAS/Mil Ti fasteners, lots to be found on Ebay and elsewhere.

For hollow bolts, almost all can be drilled, no need to EDM them. I recommend a proper strength and fatigue analysis for any critical use, and also suggest a two-diameter hole, with a smaller hole through the threaded section to create a uniform tensile profile over the full length of the bolt/screw.

A fine finish in the holes is important for fatigue life, slight compression of the surface through ball sizing or shot peening will help.

BillE · Jul 2, 2019

One of the race shops over here used to sell hollow bolts, which I'm sure were sourced out the States as they were exclusively imperial, marketed as "chrome moly" - so I might add that term to your search?

Aluminium bolts seem to be the domain of superkarts or go-karts and MX bikes, lots of garish anodised finishes and doubt you'll find anything beyond metric.

One job at Boeing over here, we were given a few thousand nylon AN style bolts and nuts for ultimate light weight....and Darwin award prospects.

Graham Gott · Jul 2, 2019

McMaster-Carr shows aluminum coarse thread hex head cap screws.

Here's a link for hollow bolts: Race Bolt They're a popular alternative to titanium fasteners for sprint car racers.

WizardOfBoz · Jul 2, 2019

If you want to have lower weight, wouldn't you just use a smaller bolt rather than a bigger bolt with a hole? Or is it that you have a drilled and tapped hole of a specific size, and the titanium bolt is too expensive or unavailable, so you get a cromoly bolt and drill out the center?

Graham Gott · Jul 2, 2019

bosleyjr said:
If you want to have lower weight, wouldn't you just use a smaller bolt rather than a bigger bolt with a hole? Or is it that you have a drilled and tapped hole of a specific size, and the titanium bolt is too expensive or unavailable, so you get a cromoly bolt and drill out the center?

It depends on the application. In tension, absolutely that's what you would do if starting with a clean sheet of paper. In shear, particularly single shear, running a hollow larger diameter bolt gives you a stiffness advantage vs. a smaller diameter solid bolt.

Richard/SIA · Jul 2, 2019

Building a custom '68 El Camino and looking to reduce as much weight as possible without an unlimited budget.
Many of the fasteners will only be holding non-critical items.
Engine is only a fast revving 327 so less torque than a 350+.
Tired of hearing the "No substitute for cubic inches" canard and trying to do something about it.
Have already taken some other fairly extreme measures to reduce weight, such as a 40# fiberglass front clip.
If hollow or alloy bolts can save another five pounds I will use them.
Ti is just too expensive.

Mud · Jul 2, 2019

McMaster is the goto source for Super Stock guys to get aluminum fasteners for fender brackets and such. With your lathe you can drill most bolts, once the shank is drilled use a large drill and run the 135° point into the head to reduce it's height and hollow it out at the same time, that saves more weight than than drilling the shank.. A friend took 15lbs off an XR750 during a winter by doing that to all the fasteners. A ball endmill works nicely also, you can make the heads look sort of like titanium bolts with one. Use 1/2 height jam nuts where you can. Lots of bolts on a cars are sized for convenience and wrench size rather than strictly strength.

"The easiest way to save 100 lbs on a race car is to find 1600 places to save an ounce."

Once you think you have a part light enough, take it outside and throw it up in the air. If it comes down, it's still too heavy.

Mud (former car builder)

Milland · Jul 2, 2019

For many of us (like me), the best way to remove weight from a car is to diet.

WizardOfBoz · Jul 2, 2019

Milland said:
For many of us (like me), the best way to remove weight from a car is to diet.

You'd be amazed at the number of bicyclists that will spend 5000 (or more) on bike because it weighs a pound less than a 1000 bike, but won't skip the cheeseburger.

Milland · Jul 2, 2019

bosleyjr said:
You'd be amazed at the number of bicyclists that will spend 5000 (or more) on bike because it weighs a pound less than a 1000 bike, but won't skip the cheeseburger.

I was a modestly serious rider in my youth, I went from an Al frame to a Ti frame not for weight saving, but as an "up yours". The money for it came from the insurance settlement after a woman driver knocked me off my old bike.

Sure wish I weighed now what I did then...

moonlight machine · Jul 2, 2019

Graham Gott said:
It depends on the application. In tension, absolutely that's what you would do if starting with a clean sheet of paper. In shear, particularly single shear, running a hollow larger diameter bolt gives you a stiffness advantage vs. a smaller diameter solid bolt.

I used to drill my own when I was racing motorcycles. Used to use a ball mill on the head after drilling.

moonlight machine · Jul 2, 2019

Richard/SIA said:
Building a custom '68 El Camino and looking to reduce as much weight as possible without an unlimited budget.
Many of the fasteners will only be holding non-critical items.
Engine is only a fast revving 327 so less torque than a 350+.
Tired of hearing the "No substitute for cubic inches" canard and trying to do something about it.
Have already taken some other fairly extreme measures to reduce weight, such as a 40# fiberglass front clip.
If hollow or alloy bolts can save another five pounds I will use them.
Ti is just too expensive.

Reduce the weight of that 327 by replacing it with a 406, same exterior size, half again more horse power. Wait, this is for an El Camino, you won't be able to get the 327 power to the ground, the 406 will just ravage the tires!

kustomizingkid · Jul 2, 2019

There are lighter ways to fasten things than bolts... that said sometimes things can be taken to a real extreme. Assuming you aren't running a cast iron block eh...

Richard/SIA · Jul 3, 2019

Sadly I am forced to use an iron block.
One reason I went with a 'Glass front clip is that it was half the cost of an aluminum block even before machining.
Have to use a 327 as it's to be something of an "Old School" and "Day Two" themed build rather than just another common "Hey look at much I spent!" 383/LS conversion.

Some good links posted and I do appreciate them.

kustomizingkid · Jul 3, 2019

Gonna need a lot of light bolts... ever hear of the LS motor

moonlight machine · Jul 3, 2019

Richard/SIA said:
Sadly I am forced to use an iron block.
One reason I went with a 'Glass front clip is that it was half the cost of an aluminum block even before machining.
Have to use a 327 as it's to be something of an "Old School" and "Day Two" themed build rather than just another common "Hey look at much I spent!" 383/LS conversion.

Some good links posted and I do appreciate them.

Build a 406, run circles around any 327 and still looks old school. Get some nice light pistons, I used to use Ross pistons, use 5.7" rods instead of those puny 400 rods. You get a better rod length to stroke ratio for less cylinder wall loading. Any sprint car engine builders around you? Look at one of those blocks, pretty easy to get 50 lbs off an Iron block. Aluminum heads are cheap now days and flow better than any Iron head.

Richard/SIA · Jul 3, 2019

Pretty committed to the 327 with already buying an Eagle crank and rods, Brownfield aluminum heads, custom forged pistons, 4xWeber 44IDF carb system all to go on a four-bolt main block.
Smaller displacement CAN work, a friend of mine used to prove it regularly with his little Lamborghini Muira.
Didn't win drag races but no U.S. car could stay with him when he got tired of their annoying him on the road.

I will try to document how much weight I lose by modifying fasteners.

Light weight nuts & bolts sources, Hollow and aluminum?

Cast Iron

Diamond

Hot Rolled

Aluminum

Diamond

Aluminum

Cast Iron

Diamond

Diamond

Diamond

Diamond

Diamond

Diamond

Titanium

Cast Iron

Titanium

Diamond

Cast Iron

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