A universal torque wrench setting

[Shayne]

For the boat which of course has no repair manual and having just been told by real marine engineers the boat had to travel a week to find that pretty much everything pretend marine engineers in the Isle of Man fitted or repaired umpteen times in the past 2 years is loose .

I'm thinking maybe there should be a torque wrench aboard permanently set to "tight" but what setting when it might be used on anything from M6 to M14 ?

Tell a fisherman to make sure its tight pretty much ensures he will snap the bolt so i hope to save both him and me some headaches .

Your thoughts please .

 

[Towpack]

Way too many variables really to give a universal figure for bolts of such a size difference and that's before you get onto bolt ratings, what use it's being put to, what vibration it'll be subjected to etc.. What about some non permanent threadlock?

 

[Rob Cowell]

Those plastic arrows you put on tractor or truck wheel nuts? Torque them properly, then a plastic arrow pointing to a painted mark.

 

[Shayne]

This looks promising ?

 

[David]

We always used a chart like that when no settings were available

 

[Jon_Tallis]

Target torque is fairly closely driven by the bolt dia / threadform / material grade, rather than the use its being put to (with a few notable exceptions like a diff crush tube), as it's driven by the load required to put the bolt into yield, but not plastically deform it. Therefore if you don't have anything better, it's fine to use generic figures - see link below, but remember to select the right material grade.
It's also worth noting that lubrication, surface finish, use of washers etc can significantly change the bolt loading for a given torque input - usually (but not always) reducing it.

Torque Specifications for Metric Bolts: Maximum Values & Tables

Recommended thightening torque metric bolts.

www.engineeringtoolbox.com

 

[Jon_Tallis]

And if that fails, "FT" usually works

 

[Bob]

For many applications, we use T or FT... o do use proper settings for head bolts, flywheels etc, but FT is done by feel and I've never had a bolt back out of anything

 

[Towpack]

I had 2 wheel studs shear off during some routine maintenance a good while back after years of using the FT approach. With two replacements fitted I decided to get the TW out and use the correct setting and was amazed how easily the required 70lb/ft is reached. I must've been wacking them down to close on 100 which obviously stretched them to eventual failure .

 

[Shayne]

I bust one bigger than this as a young man when the skipper told me with the wrong attitude to make sure its tight so i'm always cautious of overtightening . Never had anything come undone though .

 

[chapel gate]

without a torque wrench ime youll over tighten small bolts and under tighten larger ones.

back in the day before stretch bolts, it would be all about the length of the bar to get the "correct" torque.
6" 1/4 drive for the small stuff, 18" 1/2 drive for the medium and 36" 3/4 drive for the larger stuff for example.
the mechanic would apply roughly the same force and the extra leverage of the longer bars gives the increased torque.

one of the major reasons for torque wrenches being used was wheel nuts coming loose on commercial vehicles.

ive started using a torque wrench more and more over the years. its surprising how much physical effort 400nm takes even with a 36" bar, and im 16 stone. equally its very easy to over tighten bolts in aluminium, 80 series water pump for example.

 

[Jon_Tallis]

Prompted by Chapelgate's point I should add to my post that generic torque tables only apply to bolt & nut arrangements, or where the bolt is threaded into a blind hole in a material of similar grade. Bolting into aluminium / brass / plastic / dodgy Chinese casting then all bets are off - consult the manual or go by feel

 

[outdoordan]

As per everything everyone else has said with the added complication of the strength of the material that the bolt is made from.

Depending on what job the bolt/stud is doing, how systems critical it is, how accessible it is, what it is attached to (going into), how much vibration it is subject to... all these and more mean there's no 'one stop solution'.

On our boat I reasonably regularly inspect anything that is critical to make sure it hasn't loosened. Caught something yesterday hour out of harbour on routine engine check.

 

[Shayne]

Never mind , after Ramsey Shipping Services LTD cost me 5 grand a month for over a year (not including lost earnings) i decided to ignore covid rules and take the boat to professionals who actually want to fix it .

First question up "why does everything have new bolts in it and why are they all loose" ?

The answer "because everything is a new part fitted by people who claim to be marine engineers"

So lets hope it gets fixed and i dont need a torque wrench .

 

[IRLGW]

Sounds to me like your not getting enough saltwater down below Shayne.

 

[chapel gate]

Never mind , after Ramsey Shipping Services LTD cost me 5 grand a month for over a year (not including lost earnings) i decided to ignore covid rules and take the boat to professionals who actually want to fix it .

First question up "why does everything have new bolts in it and why are they all loose" ?

The answer "because everything is a new part fitted by people who claim to be marine engineers"

So lets hope it gets fixed and i dont need a torque wrench .

the term engineer is very much over used nowadays.

 

[Shayne]

Aye some well set up cowboys about

Will salt dissolve the bodies then ?

 

[IRLGW]

No but it will nicely corrode and expand all the bolts so that they will never come loose! Durlac does a nice job of anti rust, size and threadlocking all in one.

 

[Shayne]

Today's conversation with professionals lets me know alignment was impossible while only replacing the part that broke this week basically confirming everything i've known and repeated and again for over a year . She's just been rattling herself to bits .

 

[Towpack]

the term engineer is very much over used nowadays.

My Dad used to say the same about mechanics. "Many so called mechanics are just parts fitters".