RE: tractors & torque wrenches - help for a newbie

[garchib]

RE: tractors & torque wrenches - help for a newbie

I am new to torque wrenches and while reading the instructions to my new torque wrench I read that you should never torque bolts that are already tight, but rather you should loosen them and then torque the bolts. This begs the question.....if my goal is to ensure that my frame bolts for my FEL are tight and my wheel bolts are tight, can I just set my torque wrench to the amout of foot pounds listed in the manual and torque them !? How does everyone else out there check the bolts on their CUT(s) ? Thx ! /forums/images/graemlins/grin.gif

 

[Boomerang1]

Since you are only checking the bolts, you can set your wrench to the specified torque and see if any of the bolts are loose. If you find a loose bolt then you must loosen it and then torque to the correct spec.

 

[garchib]

Cool...thanks !

 

[Jibber]

Interesting that I should come on this note this morning. Just yesterday I was working with the PTO chipper and noticed that a couple of the bolts holding my backhoe subframe onto the tractor were a few threads loose. They may have been that way from the dealer.. I just had never noticed it. I used the torque wrench on them and it worked fine on the loose bolts but just spun on the tight ones. I figured I probably would have to loosen them first to get a correct torque but decided to just leave them alone.

 

[Bird]

The way I understand it is this: If you just use the torque wrench to "check" to see if a bolt is tight, you'll know that it's as tight as the torque wrench was adjusted for or tighter. In other words, it may be too tight, so if you loosen it, and then tighten it with the torque wrench, you stop tightening at the right time.

 

[Pilot]

Here are a couple rules for using a torque wrench:

Torque values listed in manuals are usually for clean, dry bolts--no oil.

Sometimes there will be significant drag or resistance even before the nut starts to get tight. A couple wheel bolts on my Yanmar are like this. In theory, you measure the drag, then add that value to the torque target you are trying to reach. So if you are supposed to torque to 90 lbs. and there is 10 lbs. of resistance, then torque to 100 lbs. Hard to do with a clicker wrench, not a problem with a beam type.

 

[hobbyfarm]

garchib,

Occasionally, torque specs are called for as "angle after torque" such as 35lb/ft + 30 degrees.
Please read the torque chart carefully. This type of spec is called for more and more, especially when bolts are used, then discarded. Cylinder head bolts are one example. And there are tools used in conjunction with a torque wrench.
Such as:
<font color="red">Snap-On Torque Angle Guage</font>

 

[MicroPilot]

I've also seen specs that say something like "90 ft Lbs, + 1/4 turn"

 

[garchib]

Great info guys ! Thx ! /forums/images/graemlins/grin.gif

 

[hobbyfarm]

MicroPilot,
That's what they're talking about. Sometimes you can get by, by eye, but the mission-critical parts (like head bolts) you really need to be as accurate and precise as possible.

I've also seen torque specs listed like above, but with the addition of lubricated, AND the lubricant specified! /forums/images/graemlins/smile.gif