Wheel bolt Torque Spec

ratlee2

I recently got my 53 Hornet back on the road late last summer and was able to put about 300 miles on it since then. A couple weeks ago, I was driving to work and had the left rear tire come off. I was cruising at 55mph and heard a rubbing sound and was almost able to bring it to a complete stop before the tire came off. Fortunetly, the wheel remained within the wheel well, so the rear drum did not even drop down to the pavement and there was no body damage. The only damage was isolated to the wheel and brake drum threads. I have located a replacement drum and had an extra rim at home, but I am trying to find the root cause. I know I torqued it to the correct spec of 65 ft/lbs. and I double checked it. I went back and double checked the 3 other wheels and they were also low like the bolts are backing out. I double checked my torque wrench against another beam torque wrench I have and the 65 ft/lbs. setting is correct. I have since replaced all the lug bolts just to be safe, but do not want this to occur again. What would cause this to happen?

-under torqued bolts

-over torqued bolts (stripped)

-wheel out of balance

I had the tire shop mount the tire last summer with balance weights on the back side of the wheels because I did not want the weights showing. At the time the shop said they would not be able to do a dynamic balance on the wheel with the weights only on the inside since the wheel is so narrow. They indicated that they would only be able to do a static balance, but it would be fine. I had them spin the wheel on the balancer this morning before they transferred the tire over to the new rim and it appeared to be balanced. They told me that the torque spec of 65 ft/lbs. is really low with the heavier 225/75/R15 steel belted radial. So, my question is, do I dare torque the new bolts down to a higher value or is it likely due to not doing a dynamic balance on the tires? What do you torque your lug bolts to? The new lug bolts are grade 8, but I doubt the hubs are.

ratlee2

I stopped by the tire shop and picked up my tire the shop mounted on my replacement rim. The shop insisted that a wheel balance being slightly off would not cause the lug bolts to loosen, but rather suggested that I increase the bolt torque to 85ft/lbs. I looked up the general torque specs online for a 1/2-20 bolt and it is listed as 90ft/lbs for grade 5 (dry). What is your opinion on upping the torque value to the 85ft/lbs.as suggested by the tire shop?

54coupe

65 seems low for a 1/2-20 bolt. I would go with 85 as well.

ratlee2

Thanks 54Coupe,

That confirms what I was thinking.

railknight

Thanks for sharing your unfortunate experience on the road as apparently, we can all learn from it. Indeed, I think I'll go with 85 torque lbs. as well. "Happy Motoring!"

lostmind

When the car was built , the " torque" wrench came in the trunk.

The factory jack handle was the lug wrench.

The length was designed to use as much force tightening the bolts as you could.

Always worked for me, but I do use a torque wrench now on alloy wheels.

cheyenne7271

One thing to look at is the hole in the rim, make sure that the bolt isn’t sinking deeper into the hole, I have a set of wheels that this started happening to.