Torque on nuts.

[BufordBoone]

You guys helped with my blade issue. Now, in reading the manual (yeah, I do that), it says to torque the nuts to 644 ft. lbs.

The nut requires a socket that is 1 11/16" so is a large nut.

I have a torque wrench that only goes to 150 ft. lbs.

I found wrenches that go up to 700 ft. lbs. but they are expensive.

I have a DeWalt cordless 1/2" impact wrench that says it has max torque of 700 ft. lbs. However, the manual does not say how one can figure out how much torque one is applying.

I'd assume that any nut designed to handle 644 could also handle 700 so wonder, do I just use the DeWalt till it "seems" like it has applied all it can apply?

I'd really rather not have to spend $400 on a torque wrench. Last resort would be a breaker bar, cheater pipe and "farmer tight" but that may be the end result.

Thanks.

 

[CincyFlyer]

Actually, you can use a pull-scale (little crane scale), or even a bathroom scale, and a cheater of a given length: on a six foot bar, put ~107 lbs. of force and you'll be good.

 

[prichard]

Breaker bar with a pipe. 640lbs is 100 lbs at 6.4' if I did the math right. You can use a fish scale to to verify the 100 lbs.

Of course, I'd just use the Dewalt.

 

[BufordBoone]

Thanks, to both of you.

Prichard, I totally understand the math of the answer you posted. That will serve me well in the future, even if I do "just use the Dewalt".

 

[TimberHole]

Calculate the the length of the wrench so that your full body weight on that arm provides 640ft/lbs. Very simple and very accurate. That's a lot of torque. I don't think there is any chance that a 1/2" electric impact is going to even come close to that figure. To give you a point of reference a 3/4" high strength bolt used in steel structures will require approximately 350 ft/lbs of torque to achieve proper tension. In other words, make sure you are reading your manual correctly.

 

[Gary Fowler]

I did indeed see a Dewalt 20V 1/2" impact that stated max torque of 700 Ft. lbs but I would take that with a grain of salt. For sure it isn't going to hurt your 644# requirement by hammering it to the max.

 

[bcp]

Buy/rent/borrow a torque multiplier.

Here's one:
Klutch Torque Multiplier | Northern Tool + Equipment

Bruce

 

[747driver]

Most auto parts stores will rent you a torque wrench.

 

[prichard]

A 644 lb/ft toque wrench at an auto parts store? Last time I rented a torque wrench at an auto parts store it was broken.

 

[BufordBoone]

The idea of calculating how long to make the arm so that my full body weight would provide the 640 ft. lbs. would certainly make it easy.

But then, turning the bush hog on its side so that I could hang from the wrench might just make things more difficult.

I do like the line of thinking, though.

I'll also look at torque multipliers.

Inasmuch as these bolts also have lock washers, I think that whatever torque my DeWalt actually puts on the nut will probably be fine. I doubt that most farmers apply 640 ft. lbs. even when going "farmer tight".

Thanks, to all, again.