How to Remove a Stuck or Stripped Lug Nut
A Tire Shop Couldn't Get the Lug Nut Off
A rather bad experience at a nationally known automotive tire shop inspired me to write this article. I took my 2007 Chrysler Pacifica into the shop for a tire rotation. Normally, I do this maintenance myself, but I had a coupon for a free tire rotation, so I thought I could save some time and take it to the shop.
The front wheels came off without a problem. The rear passenger side wheel had a stuck lug nut. The mechanic was unable to remove it with his standard 6-point sockets and impact wrench. After he struggled for several minutes, he called me over and showed me a chewed-up looking lug nut. He then proceeded to tell me that there was no way he could get it off and that I would have to take it elsewhere to get it removed. I was quite surprised. This was an auto shop dedicated to servicing tires. One would think that this problem would be encountered and dealt with regularly.
These results were completely unacceptable. I've dealt with this situation before, and there are very systematic ways of dealing with it.
- First off, I'll share which tools are needed to get the rounded lug nut off.
- Second, I'll review the mechanics of torque and force, so we can better understand the problem at hand.
- Third, I'll go through a step-by-step guide that outlines the twist socket method.
- Lastly, I'll go over some preventative maintenance guidelines and make sure you understand what the proper torque is for your car so you can avoid the issue of over-tightening.
- ½” drive breaker bar $15-20
- 1” diameter iron pipe, 36” length $10-15
- Nut/bolt extractor twist socket set $20-100
- 3 lb. hammer $5-10
- WD-40 or alternative penetrating oil $5
- Replacement lug nut $3
- Total cost: $58-153 (if you have to purchase everything)
Along with your other emergency supplies that are stored in your car, I highly recommend keeping these items in the car as well, in case you need to repair your own tires while away from home.
The Mechanical Advantage of Leverage
The physics of leverage can be summed up as torque. In the context of removing a lug nut from a wheel, we can think of it as a simple statics problem.
- Torque = r x F
- Torque = rotational force at the lug nut
- X = Cross product
- r = length of the breaker bar / leverage pipe
- F = Force applied
I'd like to show how much torque you can generate with your body weight and compare it to the torque produced by an pneumatic impact wrench.
Impact wrenches used in auto shops range from 0-1000+(ft-lbs). Typically, between 0-400 ft-lb is more common.
Using a 24" breaker bar and a 36" iron pipe I'll show you how much force your body weight alone can produce. Assuming you weigh 180lb here is the calculation of torque:
- Torque = r X ΣF [EQ 1]
- Torque = [(24in*(1ft/12in))+(36in*(1ft/12in))] X (180lb @ 90° vertical)
- Torque = 900ft-lb with 36" iron pipe and 24" breaker bar;
- Torque = 360ft-lb with 24" breaker bar only
Of course, additional force can be generated by jumping on the end of the pipe attached to the breaker bar. I'll show the calculation I used to find how much torque is created from a 6" vertical jump on the end of the pipe. To keep this calculation as simple as possible, I'll consider a stopping distance equal to the thickness of the sole of a sneaker combined with the estimated deflection in the lever (3"), and no energy losses to the environment.
During this jumping action we can say that at the peak height of your jump the initial potential energy combined with the initial kinetic energy is equal to the sum of the kinetic energy and potential energy when you are about to land on the end of the pipe.
- PE1 + KE1 = PE2 + KE2 [EQ 2]
- PE = m*g*h [EQ 3]
- KE = 1/2*m*v2 [EQ 4]
- PE1 = Potential energy at peak of the jump
- KE1 = Kinetic energy at the peak of the jump = 0; no motion at peak of the jump
- PE2 = Potential energy right before landing = 0; the pipe height = 0, that you are about to land on
- KE2 = Kinetic energy at the end of the jump.
We can say that PE1 = KE2 from the conservation on energy principle. We will neglect the energy losses due to friction, and drag. Using this information we can manipulate the equation to find how fast you are falling right before you land on the pipe (v2).
- (m*g*h)1 = (1/2*m*v2)2
- v2 = (2*g*h)1/2 [EQ 5]
- m = mass
- g = gravity
- h = height of jump (veritcal)
- v = velocity (vertical direction)
Considering the stopping distance (d) of 3", which is the thickness of your shoe and estimated deflection of the pipe. We can generate another equation from a work-energy principle. The change in kinetic energy across the distance of the thickness of your shoe during the impact is defined as work.
- W = ΔKE(impact) where KE at the end of the jump is 0
- W = 1/2*m*(v2)2 [EQ 6]
Of course we know that Work is simply force applied over a (impact) distance:
- W = F2*d [EQ 7]
Putting [EQ 6] and [EQ 7] together we can find F2 which is the (average) force of impact.
- F2 = 1/2*m*(v2)2*1/d [EQ 8]
Combining this impact force from the jump with the force of your weight in the torque equation [EQ 1], we have the following:
- Torque = r X [Force of impact]
- Torque = r X [([2*g*h]1/2)2*1/2*m*1/d))
- Torque = [24in*1ft/12in+36in*1ft/12in] X [[2*32.17ft/s2*0.5ft]*1/2*(180lb*1slug/32.17lb)*(1/0.25ft)]..................<slug is just lb*s2/ft>
- Torque = 2160ft-lbs when you jump on the end of the breaker bar and pipe extension
And a quick recap of what we looked at:
- Torque = 900ft-lb with 36" iron pipe and 24" breaker bar
- Torque = 760ft-lbs if you jump on the 24" breaker bar only
- Torque = 360ft-lb with 24" breaker bar only
- Impact wrench = 0 - 1000ft-lbs
We see that an iron pipe with a breaker bar will be plenty enough force to overcome over tightening.
Step 1: Breaking Up the Rust
Apply targeted, liberal amounts of WD-40 to the base of the lug to allow this penetrating oil to be drawn into the bolt threads through capillary action. If it is badly rusted, then give it a few smacks with a hammer to break some of the rust free before applying the penetrating oil. Give the penetrating oil time to work, up to a day if you have the time.
Step 2: Selecting the Correct Nut Extractor Socket
The nut extractor socket needs to be a tight fit onto the lug nut. So tight that you must hammer it down tight with a 3 lb. hammer. These specialty twist sockets are really great; once seated properly, you can turn the socket and it will grip the nut tighter.
Step 3: Getting the Lug Nut Off
Attach the ½” drive breaker bar to the nut extractor socket. If you need to, slide the 36” iron pipe over the breaker bar handle to gain an additional mechanical advantage. If the correct extractor socket was used (no slippage), then this force will free the lug nut. Definitely throw it out and replace with a new one.
Getting the Bad Lug Out of the Socket
Bad Lug Aftermath
While this method usually works, there are problems that can be encountered that will require different strategies.
- If the stud is stripped: The lug spins freely but won't come off the stud. Drill through the lug and/or stud. Select a carbide drill bit that matches the size of your stud. Apply heavy pressure while drilling at low speed to drill down the center of the lug until it is not longer attached to the stud. There are some specialty drill bits available on the market that I haven't tried. The videos look promising, so if you feel like taking a risk, and spending extra money I've included a link to one of these products. Note: Drilling through the stud will require you to replace it, which can be rather tricky for some vehicles.
- Can't grip the lug nut with twist sockets: If you have access to welding equipment, then tack weld a nut to the damaged one so you can have a clean grip again. Or, split the lug with a chisel. Use a heavy 2-4 lb. hammer for this and make sure you have a sharpened chisel. Split the lug nut down the side. Careful not to damage the rim. Inspect stud for damage, it may need to be replaced.
Preventing the Problem
Careless mechanics can easily overtighten the lug nuts with their impact wrenches. Consider speaking with your mechanic to make sure the correct torque will be applied before they start working on your car. Bear in mind that different cars have different requirements for torquing lugs. Cars typically require 60-100ft-lbs of torque. Larger vehicles can require upwards of 300ft-lbs of torque. Consult your owner's manual for correct torque requirements.
Keep lugs clean and free of water. Dirt, water, and rust on the threads and mounting bolts must be removed before attempting to put your wheel back on.
If they are worn out and don’t seem to fit very well, there is nothing wrong with getting a new set.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.