Torque settings?

[vic008]

Thought I had a handle on it. But why torque when using nyloc nuts? These are instructions with R&D marine couplings. (Plastic cush) and the gearbox coupling holes are threaded, and then nylocs as well. R&D pack has 8 bolts and nylocs. Thought torque settings were more for like don't exceed these settings or else bolts will stretch etc. Otherwise do as tight as. So I should still follow their 40lbs/ft for both sets of bolts?

 

[penberth3]

Thought I had a handle on it. But why torque when using nyloc nuts? These are instructions with R&D marine couplings. (Plastic cush) and the gearbox coupling holes are threaded, and then nylocs as well. R&D pack has 8 bolts and nylocs. Thought torque settings were more for like don't exceed these settings or else bolts will stretch etc. Otherwise do as tight as. So I should still follow their 40lbs/ft for both sets of bolts?

You still need the correct torque to give the right tightness/stretch/whatever. The nyloc bit stops them coming undone - that's all.

 

[penfold]

Follow the recommended torque settings; with the likes of a shaft coupling the torque setting affects how the coupling works, if it's too loose there will be fretting and if you just heave on the wrench you could overstrain the fastener.

 

[VicS]

Thought I had a handle on it. But why torque when using nyloc nuts? These are instructions with R&D marine couplings. (Plastic cush) and the gearbox coupling holes are threaded, and then nylocs as well. R&D pack has 8 bolts and nylocs. Thought torque settings were more for like don't exceed these settings or else bolts will stretch etc. Otherwise do as tight as. So I should still follow their 40lbs/ft for both sets of bolts?

40lbs ft ?? or 40Nm

Instructions say

3/8 UNF - 40 Nm 30 lbs ft M10 - 61 Nm 45 lbs ft 7/16 UNF - 81 Nm 60 lbs ft M12 - 108 Nm 80 lbs ft 1/2 UNF - 100 Nm 75 lbs ft 5/8 UNF - 210 Nm 155 lbs ft 3/4 UNF - 366 Nm 270 lbs ft

 

[vic008]

Interesting
Not much in it, but my instructions say M10 54Nm 40 lbsft

 

[Skylark]

It's always worth searching for the recommended torque rather than adopting the "tight as possible" flawed approach. Personally, I appear to have a bit of a fetish for torque wrenches

 

[Moodysailor]

The reason for the (relatively high) tension is to allow the stiction (static friction) of the mating surfaces to assist holding against he rotational forces. If the bolts aren't tight enough, the main rotational load will be taken by the bolts, which is undesirable.
The torque is there to make sure they are not too loose.

 

[dankilb]

It's always worth searching for the recommended torque rather than adopting the "tight as possible" flawed approach. Personally, I appear to have a bit of a fetish for torque wrenches

I’m just dreading when the day comes I have to find (i.e. afford!) one big enough for our keel bolts! ?

 

[penfold]

You can hire them.

 

[RichardS]

It's always worth searching for the recommended torque rather than adopting the "tight as possible" flawed approach. Personally, I appear to have a bit of a fetish for torque wrenches

In the 70's I used to have one of those torque wrenches with a long metal pointer which physically bent and showed the torque on a circumferential scale by measuring how much you had managed to bend the bar. It was rather crude but in those days proper torque wrenches were very expensive so most home mechanics used the torsion bar version.

I wonder whether they are still sold?

Richard

 

[38mess]

I always torque nuts down, at least you know everything is equally tight and nothing will warp. Important to re do them after around a week

 

[Skylark]

In the 70's I used to have one of those torque wrenches with a long metal pointer which physically bent and showed the torque on a circumferential scale by measuring how much you had managed to bend the bar. It was rather crude but in those days proper torque wrenches were very expensive so most home mechanics used the torsion bar version.

I wonder whether they are still sold?

Richard

I’ve not seen one of that type for a very long time. I’m sure that they appear on eBay every now and then if you’re feeling nostalgic?

The one on the right of my picture is the first one I bought, probably in 1972. It’s a Norbar as I’ve always believed in buying high quality tools.

I used two of them last week, refitting the flex-o-fold ?

 

[penfold]

In the 70's I used to have one of those torque wrenches with a long metal pointer which physically bent and showed the torque on a circumferential scale by measuring how much you had managed to bend the bar. It was rather crude but in those days proper torque wrenches were very expensive so most home mechanics used the torsion bar version.

I wonder whether they are still sold?

Richard

They look proper ropey but they're still available.

 

[RichardS]

I used two of them last week, refitting the flex-o-fold ?

They look proper ropey but they're still available.
View attachment 115132

When I fitted my Flex-o-Fold for the first time I only took my higher range torque wrench to Croatia and, once there, realised that I should have taken both of them.

Interestingly, the one in the photo covers 0 -300Nm which is much greater than a normal torque wrench and would have been fine for all the bolts. However, what you gain in range you definitely lose in accuracy.

Richard

 

[thinwater]

And the blots or nuts must be lubed or not, per specification. That affects the torque requirement.

Torqueing bolts deterines the preload and elastic bolt stretch. It is only indirectly related to the fasteners loosening.

 

[vic008]

And VP say naught about coming back and rechecking. Do you?

 

[RichardS]

And VP say naught about coming back and rechecking. Do you?

Volvo Penta? Re-checking what?

Richard

 

[penfold]

Volvo Penta? Re-checking what?

Richard

Head bolt torque after ~5hrs running.

 

[RichardS]

Head bolt torque after ~5hrs running.

Which post does that come from?

Richard

 

[Moodysailor]

And VP say naught about coming back and rechecking. Do you?

That practice hasn't been required by a lot of engine manufacturers for a number of years now. The technology has moved on meaning that is no longer required - it's a good thing, not a bad thing.