Reusing 40+ year old bolts

[Neil L.]

After reading recent threads about parts failing, I wonder how safe it is to reuse 40+ year old bolts on suspension,drivetrain and steering components. Just because they clean up nicely and have the correct head markings, how strong are they. The bolts have been subjected to years of weather, heat and vibration.

[Bill M.]

Re: Reusing 40+ year old bolts

Neil
I am just completing a budget restrained chasis restoration on a 66 convertible. I am reusing every nut and bolt that shows no sign of corrosion. I also check to see if a new nut will thread on the old bolt if it does then the test is passed meaning the threads are not stretched. I use new lock and flat washers in all areas.
Bill

[Duke W.]

Re: Reusing 40+ year old bolts

Fasteners usually have a big safety factor built in, and I'm not aware of any critical fasteners on vintage Corvettes that are prone to failure due to either fatigue or insufficient design margin.

What you should carefully look for is corrosion, especially on the shank right below the head.

If you have them plated, make sure you specifiy a bakeout to get rid of embedded hydrogen from the plating process. "Hydrogen embrittlement" can cause otherwise good fasteners to fail when placed back in service.

Duke

[Clem Z.]

Re: Reusing 40+ year old bolts

if a bolt will pull up to torque i would say it is safe to use on a street driven car. if you plan on doing track day or auto crossing i would put in new bolts.

[Richard M.]

Re: Reusing 40+ year old bolts

I would prefer to use 47 year old bolts made here, than any present day asian imports that IMO are more susceptible to having hidden manufacturing defects and likely having no quality control.

[Domenic T.]

Re: Reusing 40+ year old bolts

I use all my original and find that one will stretch (especially head bolts).
You can feel a bolt stretch and watch your torque wrench move 3 times as far as it did when you start to reach the torque limit.
I think a lot were stretched by mechanics that would not use a torque wrench.
Back in the 50's my brother told me that he was in a shop watching a guy adjust 6 cylinder chevy valves and 2 of the head bolts popped and hit the hood when the engine got to temp. The mechanic jumped back when the first one popped and said "I knew they were to tight".
If they look good use them.
Some aircraft engines have rod bolts that have a machined length. You measure the legth , torque the bolt, then measure it again to see if the stretch is within limits.
I'll bet some of the hard core race engine builders do that.

DOM.

[Terry M.]

Re: Reusing 40+ year old bolts

Some aircraft engines have rod bolts that have a machined length. You measure the legth , torque the bolt, then measure it again to see if the stretch is within limits.
I'll bet some of the hard core race engine builders do that.

DOM.

Yes they do, and the tools to measure rod bolt stretch are available from Summitt, among many others. Measuring the stretch, rather than relying on a torque measurement, is a far more accurate means of tightening a fastening system.

[John H.]

Re: Reusing 40+ year old bolts

Yes they do, and the tools to measure rod bolt stretch are available from Summitt, among many others. Measuring the stretch, rather than relying on a torque measurement, is a far more accurate means of tightening a fastening system.

Using a rod bolt stretch gauge is the most accurate method of establishing and verifying clamping force in that critical joint; that's why ARP rod bolts have dimples in the ends, to accommodate the gauge contacts. That method has been around for many years - I used it back in '61-'62 on my AA/FD, and never had a bottom end failure. Not necessary on a street engine.