Sierra driveshafts - Handed nuts?

[thescamper]

Comadis said:

"just had a look at my nuts,lol left hand threaded one has small "nicks" like small saw cuts on the outside"


everybody who has a "little" knowledge about engineering should know that the above mentioned "nicks" indicate a left handed thread.

i´m always wondering how many unskilled people think they can repair their cars themselves, without having any clue about basic mechanical knowledge!!!

Planet Comadis must be a perfect place to live, where everyone knows everything, nobody is wrong and everybody is afraid to ask anyway.

[LaurenceFrost]

Ok so I did a little research on this, and it seems there is a 50/50 split on which side should have the left handed thread.

One argument is that braking generates more force than acceleration, and so when you brake, by slowing the wheel you are making the wheel resist the rotation of the driveshaft, so the left-handed thread should be on the near-side.

Others say that they should be the way I have mine, for the reasons I have outlined in a previous post. Imagine what's happening in a standing start, where the torque of the engine is multiplied almost 3 times to the prop because of the 1st gear ratio, and then another 3 or so times at the drive shafts (depending on the final drive ratio).

If the average car puts out 150 lb/ft at launching rpm, and you just drop the clutch, you have 150 lb/ft x 3 on the prop (1st gear), and then the multiplication of your diff ratio / 2 at each drive shaft.

So 150 lb/ft x 3(ish), x (3.6 / 2) = 810 lb/ft of torque on each drive shaft on a car with a 3.62 diff. A lot more than the 250NM that has been used to torque up the drive shaft nut.

So therefore, I'm happier knowing that the torque put through the drive shafts will actually be tightening the nut, and not loosening it. Braking forces I don't think would be nearly as high would they?

[GreenV8S]

LaurenceFrost said:

So therefore, I'm happier knowing that the torque put through the drive shafts will actually be tightening the nut, and not loosening it. Braking forces I don't think would be nearly as high would they?

You're thinking about this the wrong way. The problem is not the nut being turned by the wheel. The problem is the nut 'walking' round the stub axle. It's a problem common to all rotating assemblies. The inner diameter of the but is bigger than the outer diameter of the stub axle. If the nut moves at all relative to the stub, it will tend to roll around it in the same direction the axle is turning. Because of the difference in diameters, this has the effect of turning the nut very slightly in the opposite direction, relative to the stub. You could visualise it as a spirograph with two circles that are *almost* the same diameter. Anyway, the bottom line is that the nut will tend to turn itself in the opposite direction to the rotation of the shaft, and it'll do this regardless of the direction of torque applied to the splined fitting that it is securing.

[Mr2Mike]

GreenV8S said:

Anyway, the bottom line is that the nut will tend to turn itself in the opposite direction to the rotation of the shaft, and it'll do this regardless of the direction of torque applied to the splined fitting that it is securing.

It will tend to turn in the same direction as the shaft, hence the nut should tighten in the normal direction of rotation. Left hand thread on left hand of car, right hand thread on right hand side.

[GreenV8S]

Mr2Mike said:

GreenV8S said:

Anyway, the bottom line is that the nut will tend to turn itself in the opposite direction to the rotation of the shaft, and it'll do this regardless of the direction of torque applied to the splined fitting that it is securing.

It will tend to turn in the same direction as the shaft, hence the nut should tighten in the normal direction of rotation. Left hand thread on left hand of car, right hand thread on right hand side.

You're right, stupid typos!

[andygtt]

mattstead said:

Hi there, The sierra / granada have handed nuts on the end of the driveshafts. The nyloc on these are coloured green or white depending on which side they are from.
My problem is that I've had some new driveshafts made and can't remember which colour / hand goes on which side and I don't want to get it wrong in case the end result is a wheel falling off.

Does anyone know?

thanks.

handed threads on hub nuts! which side you put it on depends on what you want from the car!... do you want them to undone under acceleration or under braking?

Ford decided to have them so they cant undo under acceleration and then torque them up so high they cant undo under braking either!... on an Ultima (that uses the ford hubs) they reverse this and have them so they cant undo under braking as the loads are higher than under acceleration.
Porsche dont bother having handed nuts and fit right hand threads all round!

[Mr2Mike]

andygtt said:

handed threads on hub nuts! which side you put it on depends on what you want from the car!... do you want them to undone under acceleration or under braking?

Ford decided to have them so they cant undo under acceleration and then torque them up so high they cant undo under braking either!... on an Ultima (that uses the ford hubs) they reverse this and have them so they cant undo under braking as the loads are higher than under acceleration.
Porsche dont bother having handed nuts and fit right hand threads all round!

Please read the rest of the thread! Whether a nut is self tightening depends on the rotation of the shaft with respect to the direction of the thread, it has nothing to do with accelerating and braking.

[andygtt]

Ive read the thread thanks