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View Full Version : Is re-torquing nuts & bolts a good or bad idea?



jerry598
10-23-2010, 14:09
I've always been paranoid about not torqueing rod and crank fasteners properly after throwing a rod through the side of the engine block on my 54 Olds 98 after less than 500 miles. It was my first rebuild and I was just 19 with no mechanical training.

I don't know if it's right or not, but I do like to go back over any bolts or nuts after they have already been torqued down and set for awhile, and then retorque them just once more to the same value. Right or wrong, it makes me feel better, anyway.

I had a conversation with a couple of 80+ year-old retired CEOs from UHaul the other day. Seems that years ago UHual was having some issues with the wheels falling off trucks & trailers now and again. They called in a group of mechanical engineers to study the issue and one old guy proceeded to tell them what the problem was like this.

He said he could give them a 2-hour lecture on how certain fasteners hold their torque - or he could show them in 1 minute how to fix the problem. He took a few minutes instead to tell stories and finally showed them what was needed. He wiped his finger across the side of his nose and then rubbed the residue on the wheel stud and then fastened on the nut. That's all there was to it.

They performed multiple tests to measure any lost torque after the stud and nut had been in service for different lengths of time, and sure enough the old guy was right - apparently there needed to be a smidgen of oil or grease in those grooves to keep it tight.

I used to think that using brake cleaner on wheel stud nuts was a good idea. Not anymore. And I won't even try to understand why crank and rod bolts and studs have to be oiled to get the right torque. I'm just not an engineer.

More Power
10-24-2010, 11:35
There are many opinions out there regarding wheel nut torque and whether to use a lubricant.

Aluminum wheel manufacturers recommend re-torquing wheel fasteners after the new wheel has been in service for about 50 miles or so. The new aluminum wheel will relax a bit, they say, and a re-torque can be a good idea....

The GM service manuals clearly indicate that we shouldn't lubricate the wheel lugs or nuts, and that the friction between the nuts and wheels helps them to remain tight.

However, the steel nuts will gall into the aluminum, wrecking the nice 60 degree bevel, which can upset the uniform clamping load around the circumference of the nut. I use a tiny dab of anti-sieze on the bevel, but nothing on the threads. The nuts maintain torque over time and none have come loose - in hundreds of thousands of miles and more than 24 years of driving a GM diesel pickup... Jim