New Impact Wrench and Lug Nut tightening

[leehljp]

1. IMPACT WRENCH
I have been interested in an 18V Ryobi Impact WRENCH for a while and I just purchased one. I purchased the 3/8 inch Brushless one that has 160 ft-lb of torque. Since I don't work on large engines or tractors or farm equipment, I figured the 160 ft-lb would do well for me. IF I run across any large bolts or nuts that are rusted, I have my 24" breaker bar and a pipe extension if needed.

Rod from down under made a post once that he did not like 14V or 18V cordless drills/impact drivers because they were too heavy for him to use comfortably. Now that I am 74, I understand. I picked up the 1/2 inch impact wrench (without the battery) and it was quite heavy. That was one of two points that pushed me to the 3/8 inch impact wrench.

About the only thing I will use them often on - will be rotating tires on two cars and working on the lawn tractor or 8ft light weight trailer. WHICH brings me to the next question:

LUG NUT TIGHTENING:
I was deciding on the two and the second factor was - "did it have enough power to tighten the lug nuts". In two different places I saw people referring to 150 ft lbs for tightening. I thought that would be the limits of the 3/8 inch, and then I did a search in several places on automobile and SUV lug nut tightening (specifically Toyotas.) 76 - 80 ft pounds recommended. I have all my life been giving it the final heave ho for tightening and have been over tightening.

WHAT DO YOU DO for tightening lug nuts?

3. I found these at HF: Torque Limiting Extension Bar Set, 10 Pc.

https://www.harborfreight.com/12-in-...-pc-69870.html

Anyone use these?

[LCHIEN]

I think i got a 1/2 torque wrench at HF for $20 some years back and a 2-foot 1/2" drive breaker bar some years back but never used them for the intended purpose of removing a car tire.


Which brings me to the Murphy's special corollary that having the right tools means you not ever need them
Which is similar to but different from the corollary that if you have spares they you will never need them.

[mpc]

I use cordless impact drivers and guns to remove lug nuts, or fasteners in general, but rarely use the impact guns to install nuts onto bolts or to install bolts into metal threaded items... too much torque. Impact drivers (those using the 1/4 inch hex bits) are typically rated at 60 ft-lbs to 100 ft-lbs so I often use those to snug up the fasteners - just enough to make them snug, I don't let the tool tighten fasteners as much as the tool allows. I'll follow up with a regular socket wrench for small fasteners or a proper torque wrench for lug nuts, cylinder head bolts, bolts into aluminum stuff, etc. that really should be torqued to specific values.

Passenger car lug nuts, especially for cars with aluminum wheels, typically specify around 65 ft-lbs. Pickups, especially 3/4 and 1-ton rated models, generally specify something higher; 75 ft-lbs to as much as 110 ft-lbs for 1-ton trucks with steel rims. On most disk brake equipped vehicles the wheel studs hold the brake rotor in place... overtightening the lug nuts puts extra stress on the rotor. That can in turn lead to warping the rotors especially after the brakes have been used quite a bit - when they get hotter than normal (downhill braking, emergency stops, etc.). Once the rotors warp you will feel two symptoms in the vehicle:
1: the brake pedal travel from "no brakes" to "brakes beginning to apply" will increase - i.e. the pedal free-play will increase. Why? A warped rotor pushes the brake pads further away, when the brakes are off, from the rotor so the pads have to travel further before they can do their job when you press the pedal.

2: you likely will feel a pulsing in the pedal, especially at lower vehicle speeds, as the warps/waves in the rotor pass the pads. This is different than the feel when the antilock brake function activates; that's usually a more rapid on-off vibration feeling.

One thing few folks do with lug nuts: look at the threads in the nut and on the lug studs. Any corrosion or grit? It should be wire-brushed away to get proper torque. Otherwise that junk creates extra friction leading to not-quite-tight lug nuts. Folks that do a lot of auto engine repairs know to use "thread chasers" on many bolts or in bolt holes to clean out crud for the same reason, especially for cylinder head bolts/head studs.

If you have to change a flat tire - using whatever lug wrench tool came with the car - you will have no way to measure lug nut torque. The safe thing to do is to tighten pretty much as high as you can with these generally-crappy wrenches; then re-torque with a proper tool when you get home. On the road it is safer to have lug nuts over-tightened rather than under-tightened!

I've never tried the torque limiting extension bar sets such as the HF set linked in the original post... so I don't know how well they do or don't work.

Another thing about torque wrenches: the "clicky" style that are popular - and easy to use - are supposed to have their calibrations checked each year. Who does that? A home mechanic might use a torque wrench only a few times a year so I can't see it wearing out enough to require annual calibrations. One pro mech I knew avoided the issue by simply replacing his clicky wrench each year as there are several fairly inexpensive models. That was easier for him than sending a tool somewhere, paying and waiting for re-calibration. The older "deflecting beam" style torque wrenches (those with a fat main bar and a skinny bar for just the needle/pointer) don't need recalibrations... unless they get physically damaged (nicked/cut or something hammers on the main bar which alters its stiffness) at which point they should be replaced. I have one of each style: deflecting beam and clicky... so I connect them together with the clicky set at 65 ft-lbs... and see what the deflecting beam wrench reads at the click. If the clicky is not accurate I tweak its adjustment. I've had to adjust my clicky model once and that was because the adjustment lock-nut got loose somehow. It's been a while since I did this check; probably time to repeat it.

mpc

[Slik Geek]

Great advice!! Thank you.

[leehljp]

Well, I rotated the tires. The light weight impact wrench did not budge the lug nuts for loosening on the front, but did on the rear. The front were so tight that I had to use a 2 ft breaker bar over the 4 way wrench and I was afraid that I was going to twist the bolts off. I felt like I was loosing an 18 wheeler wheel.

I ran by HF and picked up the torque limiting torsion bar set after reading reviews on HF and on Amazon. I don't understand how they work exactly but I tried the 80 ft-lb set all the way around.

MPC - Thanks for the comments on the ft-lbs. That kind of knowledge doesn't seem to exist in most auto service centers.

[LCHIEN]

How do the torque limiting extensions work. Do they just get soft and spongy if you try and push them too far?

Doesn't look like they slip or click. Looks like they have precision machined thickness which has a lot of give at the torque limiting point.

oh, I got it. It works when you use it with an impact wrench. At some point (the rated torque) the impact loads it up and releases it before the opposite end rotates any, thus limiting it to the amount where the torque stick yields the amount of the impact stroke.

Costs $60.



Isn't a HF torque wrench at $20 a lot cheaper than a set of these?

[capncarl]

Someone gave me a used deflection beam torque wrench in 1970, I’m not sure how old it was then. I used it quite a bit “as is”. Sometime around 1990 I had our plants calibration shop check it, and they found it spot on. I still use it today mand have compared it to bolts tightened by my klickety torque wrenches and still don’t see much difference. Not bad for a 50+ year old tool.

[woodturner]

I tighten lug nuts to the torque specified by the manufacturer. That is in the range of 100 ft-lbs for our mid-sized GM sedans and 120 ft-lbs for the pickup truck.

[Condoman44]

FYI: If you buy tires at COSTCO you may see them torqueing the lug nuts. The wrenches they use are tested monthly as part of a routine. They also will use one wrench to torque the nuts, then another person will perform the same thing with a different wrench.

[d_meister]

The amount of torque specified is determined by the grade, diameter, length, screw pitch, head contour (countersink/flat) and companion material. Torque specs are usually for clean, dry, unlubricated threads.
Much of the time, torque specs are provided to ensure even pressure over the joined materials, as is the case with staged and pattern torqueing, like the criss-cross pattern. If a single lug nut or bolt is jammed home at full force before the wheel is settled in place, it can be deformed by tightening the other lugs.. As Condoman points out, professional tire outlets torque lugs every time.
Impact wrench ratings are deceptive. Part of the problem with impact wrench set bolts is inertia. More tightening force than the wrenches rated capacity can be applied when threads and adjoining surfaces are cleaned and lubed. The spinning mass of the impact motor, impact socket, and nut/bolt can drive the fastener to a higher torque value than intended.
I bought my Snap-On 1/2" torque wrench 42 years ago when I was a dealership mechanic. I have used it every time that I tightened a lug since then. It's important that a wheel can be changed at the side of the road with ordinary tools. Measuring the torque when installing is the best way to be sure that's possible reliably.
Applying pressure with screw threads is an interesting subject. There are a few variables that can affect the amount of pressure applied when joining materials with screw-threads. In the final analysis, the amount of force applied can't be measured during final assembly. Only the amount of force applied to the fastener is measurable. Modern torque-setting methods include torque-to-yield, where torque is applied to a fastener where it is stretched to just under the breaking point. Those fasteners are single use. Angle torqueing is a method of applying torque with a torque wrench, and then turning the wrench another number of degrees of arc to stretch the fastener to a calculated amount. Those fasteners are either discarded after one use or measured for length to determine if elongation limits have been exceeded and re-use is permissible.

[Carlos]

I use Dewalt's largest impact to remove and replace any large bolts/lugs on the Jeep. Still haven't broken one or had one fall off. Every time I double check it with a torque wrench I'm close enough. Cars aren't aircraft or rockets. Close is good. I also did spend some time testing the feel and breaking some fasteners on the bench when I first bought it.

Be careful driving anywhere in AZ. Those overhead signs and light posts were put together by a crew that just uses battery impacts to install almost everything.