Hub Nuts

[Jon Bradbury]

Terry, could you explan the math behind that please?

 

I have purchased a 1/2" drive breaker bar (that is, a long metal handle with an attachment for a socket) for this purpose that goes up to 350 lbs/ft. It is about 3 ft long and has stamped on it "Do not use extension tube"..wonder why? It looks like it may not be long enough to apply the kind of torque I need.

 

Whatever, I need to measure it, and come up with the required amount of weight to hang on the end to get the torque, but I don't know the formula.

[Guest SteveL]

Terry, could you explan the math behind that please?

I'm not Terry, but I'll have a go!

 

In the simplest case (where the force is being applied at 90 degrees to the axis of rotation, torque is simply the product of the force applied and the distance from the point of rotation.

 

ie. If you have a hub nut to tighten up, you attach a socket/bar so that the bar is horizontal, you weigh 100 lbs, and stand at a point 1 foot away from the nut, you're applying 100lb/ft of torque.

 

Torque = weight * distance, or distance = torque / weight

 

So, weigh yourself (in lbs), and divide the required torque by your weight.

 

ie. You weight 175 lbs (not saying that you do! ). This gives the distance in feet as 350/175, or 2. Stand 2 feet away from the nut, and that's 350 lbs/ft of torque.

 

Steve

 

PS. I've ignored cases where the force is applied at an angle other than 90 degress to the axis of rotation, as I don't know how that's worked out!

 

PPS. If I've got this wrong, please feel free to call me an idiot!

[Guest daveg]

All

 

Steve has the maths right....but, IMHO 350 lbs/ft = bloody tight, so use your breaker bar and do the nut up tight!

 

Dave

[Guest TerryBarry]

Hi Jon,

Yes - Steve has explained it as I would have done ( probably better)

According to my Haynes manual the required torque is 229 to 258 lbs ft - 350 is in Nm ( Newton metres - I just about understand what they are).

I would add that when doing the agricultural repairs we were using a 3/4" socket set coupled with the scaffold pole.

Terry

[Guest SteveL]

Just re-reading this made me think. If you're going to start standing on scaffold poles attahed to sockets, be carefull!

 

I remember trying a similar thing (on a smaller scale, trying to get a wheel nut undone after it had been tightened up by a gorilla!) a long time ago, slipping, and the pole hitting my leg, hard. The result was a lump on my shin the size of an apple! I couldn't walk properly for days...

 

Steve

[Jon Bradbury]

Well, first I'll see what length I need to be from the nut with my weight standing on the breaker bar. As I said, the manufacturers stamped a "do not use extensions" warning on the handle, so I hope it is long enough...

 

As to the socket itself, it is a (specially bought) high impact socket, supplied in a kind of matt black finish (as opposed to all those nice chrome plated ones which are probably not so strong.

 

I was thinking that in order to prevent the wheel from turning whilst applying the force, I could bolt a long piece of angle iron to the hub (using the hub nuts) at one end and have the other end touching the floor directly below the handle of the breaker bar.

 

Cheers

 

JonB

[Mat-Moo]

I had to do something similar not long ago, and came up with an interesting method to stop the wheels turning while I did the nut up... I got someone else to put there foot on the brake, but it does depend on the car of course, this was a vw Polo, not sure if you can do that on the Sierra hubs...

[Jon Bradbury]

Nice one Mat..

 

But if you check out my site here you'll see I haven't got the brakes finished yet, sadly.

 

Anyway I reckon I'm gonna have my hands full with some crackpot idea I had for some database work...

 

Heh

 

JonB

[Guest DaveB]

Hi All

 

Just realised I put the wrong figure in my earlier post should be 80lbs pull at 4 foot for 320 foot lbs, sorry for any confusion

 

Dave