Importance of a torque wrench?

I recently installed a Curt class III hitch on my rig. I do not have access to a torque wrench and used the 'ol "calibrated elbow" to do so. I have turned many a wrench before and am guessing i am around 5lbs either way of spec.

Anyone see a problem with this?

I could break em free and re-torque, but fighting Loctite with hand tools sucks...

Thanks

 

crank em up, if they start to come loose again, you've gone too far.

 

i believe advance autoparts has torque wrenches as part of their free loaner tools program...i'd take advantage of that if you can...you could even do it in 2 minutes right in their parking lot

 

thats a good idea..Advance has some good tools for loan. Although, with how much I use a torque wrench at my house with wheels and such, I found a cheap snapon one on ebay, and had our snapon dealer at work calibrate it..No problems

 

Great idea, but the loctite is gonna be a b*t*h...

as far as crank em till they come loose and you're too far, come on?

i am just curious of the importance of being spot on...

 

you can tighten something so much, you strip the threads and it loosens up meaning you went to far.

Honestly, the average joe using hand tools aint gonna strip out a bolt for a hitch, there pretty hefty.

What color locktite did you use? I think your supposed to use blue on stuff you dont want to be permantly tight.

 

I know that if you over tighten you will either strip threads or shear the bolt...

i guess what my question is in regards to if i were to go over torque spec by a gross amount (say 15-20lbs) , have i effected the shear or tensile strength of the bolt to a point that it is unacceptable?

Red loctite is what i slathered on it...

I also understand that loctite or anything else can act as a lubricant and through off an otherwise accurate torque reading, much the way surface rust or other contaminates may cause drag giving an incorrect reading as well (in the converse)

probably just the OCD taking over...

 

it all affects the tensile strength. As you tighten that nut down, the threads on that bolt are stretching. If you over tighten that nut, it creates more stress on the bolt then the proper torque setting does. In actuality, will it be detremintal(sp)? no, probably not. Think of the idiots who just gun on lug nuts all day without torquing them. if you get a few lbs here or there off the spec, you will not die from it.

 

true...I personally have seen guys jut bang away with the impact gun. That's why you never see my ride in a shop, unless it NEEDS to be. Like i said just, my OCD and wild thoughts of my hitch grenading (sp) and losing my cargo. I doubt i will ever pull more than 3800#. Like I said before, i know what it "feels like" to get something close to spec, just wanted some reassurance i guess.

Who knows what would of happened if i had it installed? Dude would of prob just zipped it on with his air ratchet and called it macaroni...

 

can someone look up the specs on the install guide...my machine won't run acrobat for some reason...

http://sitepro12.sitepro.com/masterlibrary/13323/installsheet/CM_13323_INS.pdf

thanks guys

 

specs please?

 

Torque supplied 12mm hardware to 65 ft-lbs, existing 12mm hardware to 65 ft-lbs and and existing 10mm hardware to 36 ft-lbs.

 

thanks beef

 

if the bolts have been over torqued, is it essential to replace them? just get them to spec?

Am I over thinking this? installed with 1/2 inch drive ratchet. 22mm socket with 11" handle..."snug" average strength guy

 

The torque specifications are based on generating enough preload to statically secure the assembly and low enough to ensure all the components in the assembly are operating in the elastic region of the material. If you over-tightened a bolt there is a good chance the material has yielded and it should be replaced because its strength has been compromised.

 

torque really doesnt mean that much. some engineer figured a bolt of some size needs so much tension to hold some part. the only real way of getting you in the ballpark is by using a torque wrench. technically, some would argue, that using the locktight could act as a lubricant, and get you an innorrect bolt tension, with the specified torque anyways.

tire shops usually have a (forget what it is called) an adaptor rod on their impacts that crank down to a specified torque.

 

Correct - torque wrenches are assumed to be +/- 25% according to Marks' Standard Handbook for Mechanical Engineers and the Machinery Handbook. The most accurate ways to get to the correct values would be with a strain gauge (+/- 1%), or more easily, by measuring the bolt's elongation (+/- 3%). The deformation in the bolt (measured as strain or elongation, which are different measurements of the same property) is the factor said engineers are concerned with. Torque is just a way to indirectly measure it, but as mentioned above, friction varies greatly with many factors. For example, a zinc plated bolt into steel with no lubricant will have twice the friction coefficient of a black oxide bolt with oil on it (however, it should also be noted that friction with respect to tightening torque is not a linear relationship).

 

this makes me feel better...Someone who knows what they're talking about and in a way i can understand

I don't think there is any way I got the grade 8 hardware tight enough to really effect the strength of the fastener with hand tools. I got em tight but didn't "hulk out" on them either.

 

I agree. I have no experience with imperial hardware but just looked up SAE Grade 8 and those are some serious bolts. I would imagine anything of considerable size will require a cheater bar. But if in doubt, replace them.

 

this has me confused as well...

The four bolts they send are 22mm and everything existing is 18mm

damned overthinking...