Torque wrench max question...

Joined
Dec 23, 2015
Messages
75
Location
NY
I have a CDI torque wrench that is capable max of a 100ft pounds. Recently I purchased a Toyota Tundra that requires 97ft pounds for the lug nut torque. Should I upgrade to a larger capacity wrench or is my current one sufficient? The only reason I am asking is because I read somewhere years ago that when you get to the max torque specs it's not as accurate... And I cringe at the idea of the dealership or mechanic using a impact gun to tighten. My step dad lost a tire on a suburban doing 70 one time...no thank you.
 
I've read to not use in 10% from either end. Maybe it 20%...

But on my Tundra I use my 150 ft-lb wrench at its 150 rating. It's a lug nut not a rod bolt. I don't know what the designed tolerances are that the OEM uses (do they figure out the optimum value and then pad it by 20%? 50%?) but whatever error my wrench has is likely well within that. If it was a critical level then most tire shops would have gone out of business eons ago.

But if you spy a wrench with a higher rating while out and about, and it's on sale... snag it. It'll likely be longer and easier to use to cinch up to the final value. Don't forget, you're not supposed to use 'em to loosen the lugs either, only for tightening.
 
Thanks! That's what I was thinking... I guess I will just have to purchase a larger wrench. Yeah luckily I had a mechanic tell me that years ago...never loosen with a torque wrench.
 
Originally Posted by Oey12
I have a CDI torque wrench that is capable max of a 100ft pounds. Recently I purchased a Toyota Tundra that requires 97ft pounds for the lug nut torque. Should I upgrade to a larger capacity wrench or is my current one sufficient? .


That depends on the answer to this question- do you have a TW with a break away or a beam?

If you have a beam- throw it away, if not ( and its within specs) it will be good through all ranges of torque. ( they are tested and certified through all ranges)

They tell you not to max it because people often have the tendency to want to use them as a pull handle and stress them and that will throw it out real quick.

Most of those time honored tales are about the beam wrench with the pointer- they are all but worthless in terms of accuracy- we don't even accept them for calibration and certification because even if they work, they don't at all ranges for very long.
 
20% of the lower range only, max is okay. A spit beam is ideal for this sort of work and there is no need to set it back to zero after use, you can use this type to loosen then also if you want, its not an issue.
Some manufacturers like Stahlwille and Norbar on some models bake the 20% into the cake so it can be used full scale. This is a good one for what you want to do with it.

https://www.amazon.com/Precision-Instruments-PREC3FR250F-Silver-Torque/dp/B002XMSFIM
 
If there was a calibration certificate with it, use that to get closer to an actual 100. No need to buy a bigger one, it's likely no more than 3-4 off.
 
The proper range for a torque wrench is 20-90%

Source: MIL-STD-1312-31

//

In your case, I would NOT buy a new torque wrench. As has been posted, being off by a little won't matter much for something like lug nuts. Just make sure to pay attention to the torque, so you don't go over by a lot. You might want to test it by using the crowbar supplied with your vehicle and then using the torque wrench. It should immediately click OR not need much additional rotation to click.

I used a bad torque wrench at the end of its range once and it never clicked. I ended up pushing the threads and had to replace the fastener/nut.
 
Both of my CDI came with a calibration certificate it will tell you how far off it is at 100. It is in the slot with the lenders manual.

Agree though that for a lug nut it isn't that critical.
 
Originally Posted by Oey12
I have a CDI torque wrench that is capable max of a 100ft pounds. Recently I purchased a Toyota Tundra that requires 97ft pounds for the lug nut torque. Should I upgrade to a larger capacity wrench or is my current one sufficient? The only reason I am asking is because I read somewhere years ago that when you get to the max torque specs it's not as accurate... And I cringe at the idea of the dealership or mechanic using a impact gun to tighten. My step dad lost a tire on a suburban doing 70 one time...no thank you.


Torque wrenches (click type) are rated for accuracy (3% or 4% of setting) from 20% of range to 100% of range. So, a 100 ft/lb wrench is perfectly fine for a 97 ft/lb lug.
 
Originally Posted by redbone3
...Torque wrenches (click type) are rated for accuracy (3% or 4% of setting) from 20% of range to 100% of range. So, a 100 ft/lb wrench is perfectly fine for a 97 ft/lb lug.


I agree 100%.

My lightly used 45 year old 100 ft-lb Snapon click-type torque wrench was recently calibrated and adjusted (for the 1st time ), and is within 2% at its max of 100 ft-lb. Before adjustment and replacement of some parts, it was 8% high at 100 ft-lb.

But calibration companies advise that a wrench that is frequently used at the max value will require more frequent calibration.
 
I got one of those HF 1/2" drive wrenches on sale just for doing things like this. I got tired of accidentally stepping on or dropping my good wrench when I was wrestling tires or having to lay it down in the grass when I was working on the trailer. They are cheap on sale and I check it against my calibrated wrench every once in a while and its always close enough +- 5%.
 
Awesome! Thanks again for all the information and it's good to know I don't have to get another one...
 
Originally Posted by Chris142
Originally Posted by Trav
Originally Posted by Oey12
https://www.amazon.com/CDI-1002MFRMH-8-Inch-Handle-100-Ft-lbs/dp/B002LA19P2

This is the one I own.


Quote
CDI 1002MFRMH Torque Wrench Features:
Accuracy: ± 3% clockwise ± 4% CCW of indicated value, CW, from 20% to 100% of full scale

So its off on the low side and accurate on the high.


Yes, for that reason some manufacturers advertise their tool as 12-50nm even though the scale is 10-50. They take the low end inaccuracy into account.
 
Back
Top