engineering type question...tight nuts /heat

[steveo3002]

right

we all know a bit of heat onto a rusted on nut often makes it easy to undo

what about fresh fastners that are just really really tight , would heating the nut make it easier to undo if you were unable to undo it cold?

im thinking no , but im no expert

 

[jugs]

right

we all know a bit of heat onto a rusted on nut often makes it easy to undo

what about fresh fastners that are just really really tight , would heating the nut make it easier to undo if you were unable to undo it cold?

im thinking no , but im no expert

Have they been Loctite'd if so with what - nut-lock or retainer ??

Heat will help (heat destroys Loctite ) Apply heat quickly so nut expands faster than bolt


Edit - could they be left hand threads ?? - they'd be realy tight

 

[tigler]

It probably would be easier with heat, but you would need to be careful as too much would ruin any heat treatment on high tensile fasteners.

 

[steveo3002]

lets say no loctite

its nothing im struggling with , on another car forum theres talk of a certain fixing thats just always really tight , someone has said heat it up but i was thinking it still needs x amount of force to undo it

basicly a big breaker bar shifts them ...but will heat and a smaller bar do the same job?

 

[tomb]

Depends how you heat it, If you put just enough heat into the nut and not the bolt it will expand and reduce the required torque to undo it. You can also cut a nut from a bolt without damaging the threads if you are careful!

 

[bigbadbugga]

lets say no loctite

its nothing im struggling with , on another car forum theres talk of a certain fixing thats just always really tight , someone has said heat it up but i was thinking it still needs x amount of force to undo it

basicly a big breaker bar shifts them ...but will heat and a smaller bar do the same job?

Like rear hub nuts on old VW's,?
I wouldn't heat them, I'd use a large breaker bar or a torque multiplier.

 

[astro_al]

The coefficient of thermal expansion is isotropic (the same in all directions), so heating, whether or not you heat the bolt in the middle, will always loosen the nut (the path length expanded circumferentially is significantly greater than the path length expanded radially).

Hope that makes sense. Personally, I'd just use a bigger bar though. Al.

 

[Ducati]

lets say no loctite

its nothing im struggling with , on another car forum theres talk of a certain fixing thats just always really tight , someone has said heat it up but i was thinking it still needs x amount of force to undo it

basicly a big breaker bar shifts them ...but will heat and a smaller bar do the same job?

Lots more use being made of distorted thread type nuts on cars these days and greater torque settings which does require the intake of more spinach when using hand tools.

If the nut is not corroded, locktight not used and it " takes a long strong-arm " to shift them, then they were designed to be that tight for a purpose.

Rather than heat, which as mentioned above may not do the fastenings the world of good, best to keep to the long bar, or use a rattle gun, or a nice bit of kit a torque multiplier

If heat was used to make it easier to undo them, would heat also be used to tighten them , to the correct torque setting of course ?

If the nut is not designed to be re-used and presuming there is sufficient working space, a tweak with a nut splitter sometimes works wonders.

 

[Ducati]

Like rear hub nuts on old VW's,?
I wouldn't heat them, I'd use a large breaker bar or a torque multiplier.

You also had access to 12 foot of scaffolding pole and 2 x 20 stone pals I presume.

 

[tigler]

Snap-On guys carried 60", 3/4" drive breaker bars and the appropriate socket on their vans as a standard stock item at one time, just for that application !

 

[mm289]

Can't even get the damm wheel nuts of on mine let alone the hub nuts. Sheared off 1/2" t bars trying - looks like I will have to invest in a 3/4 breaker and socket

MM

 

[eddie49]

I can definitely recommend the use of a 3/4" breaker bar for high-torque situations. It makes a huge difference, regardless of whether the bar is longer or the same length as a 1/2 inch one. Even if you reduce down to a 1/2" drive socket, the additional stiffness of the 3/4 bar, compared to a soft bendy 1/2" one, means that more of your effort goes into torque on the socket, rather than bending the bar.

 

[astro_al]

I had this with a Unimog wheel nut. Bought a right angled 1" drive bar for about a tenner on ebay and welded a shaft on the end opposite where the socket fits on (so changed the L shape bar to a T shape). I could then support the back of the bar by putting a screw jack under the new shaft (at the same height as the offending wheel nut). Then I could really jump up and down on the end of the 12 foot bar without fear of the socket slipping off the nut.

Al.

 

[piman]

Hello all,

I do not believe that heating up a tight fastener will significantly reduce the force required to undo it. Just use the right tools for that application. With the increased use of stainless fasteners, heating those might make it significantly worse.

Alec

 

[jugs]

Hello all,

I do not believe that heating up a tight fastener will significantly reduce the force required to undo it. Just use the right tools for that application.
With the increased use of stainless fasteners, heating those might make it significantly worse.

Alec

Like religion, belief has little to do with fact

I've played with nuts (mine & other peoples) for yrs, if I have a stiff one, properly applied heat will usually provide instant relief.

With the increased use of stainless fasteners, heating those might make it significantly worse.

The main problem with SS threads is galling - (a form of friction welding) normally caused on assembly but only discovered when removing.

SS threads should be treated with an anti-galling treatment (graphite is one)on assembly. If a SS fastener has galled, replace both nut & bolt.

 

[astro_al]

Another way to avoid stainless galling is to use dissimilar grades for nut & bolt. Not ideal, but...

Al.

 

[mk1richiep]

peanuts, nylocs etc

Nut related and a bit nerdy but I think its interesting!

http://www.youtube.com/watch?v=mgwmuZuJ02I&feature=channel_video_title

(comparison of resistance to vibration on bolt types)

 

[Wedg1e]

The rear hubs on my TVR are held on by Nylocs - M22 x 1.25 thread I think. They're supposed to be 250lb.ft., I've undone them before with a 30" bar and 1/2" drive socket, gawd knows what those VW ones must be torqued to!

 

[bigbadbugga]

The rear hubs on my TVR are held on by Nylocs - M22 x 1.25 thread I think. They're supposed to be 250lb.ft., I've undone them before with a 30" bar and 1/2" drive socket, gawd knows what those VW ones must be torqued to!

They are supposed to be 270ft/lb IIRC, but most people don't torque them up properly and just swing on a 6 ft extension instead.

So usually, the same is needed to remove the buggas

 

[darran sandwich]

Heting the nut before assembly will help you out quite a lot, even heating the nut and cooling the bolt or vise versa will help to an extent, thats more commonly used when inserting bushes to be honest.

An impact driver will also do a better job than a long bar as the shock propigation will help pass any startup friction more easily.