It would be standard engineering practice to use some copperslip or light grease on the thread.

I was told when at college doing my apprenticeship that you only ever lubricate a thread if it was specified with the torque settings. Obviously with less important fixings exposed to the elements copperslip is fine and can be useful on steel bolts that screw into aluminium to reduce the chance of seizing.

And just don't get me started on using copperslip on brake caliper moving parts

ah OK. I put the copper spray on the bit that fits into the alloy wheel (that's potruding about 1 cm from the hub, perpendicular to the brake disc). I don't copperspray the actual surface that the alloy meets the hub (the one in line with the brake disc) since the alloy doesn't jam on that part.

cheers

That sounds fine and is probably a good idea to stop the wheels sticking

I've seen it written that torque should be reduced by 10% if copper slip or similar is used.

I seem to recall this stuff from my motor bike days, which is somewhat before Noah's Ark, and can't recall having any trouble with it used in moderation.

 

I suppose one question would be how much lessening of torque would risk a nut actually be likely to undo itself?

E.g. if the normal correct torque is 88 ft. lbs, would the nut be in danger if it were tightened to, say, only 83 ft. lbs?

 

Probably would need some serious experimenting by a laboratory to find out!!

 

Meanwhile, I'll just stick with The Book   88.5 ft. lbs or 120 NM

My understanding is that the torque setting is to control the deformation of the fixing s it tightens. Thread friction shouldn't be relevant to torque as there is minimal rotation after the bolt face seats.

yOur partly right,torquing up a nut gives the bolt the correct amount of strech so its not overtightened, resulting in it breaking,more than one bolt on a component would be torqued down in a sequence to prevent deformation, the torque is worked out depending on the lub on a bolt,dry bolt will need more turning force(torque) to tighten down, than a lubed one,

This is why you should re tighten after a few hundred miles, as the bolt or nut would have stress relaxed and therefore loosened.

I won't bother doing a million quotes but:

• locktite on a wheel nut isn't something I've come across. I think if you were having persistant issues with wheel nuts coming loose I'd check for other reasons and use locktite as a last resort.
• 120Nm is a suprisingly small amount of force compared to how tight you would do a wheel with a cross-brace.  Since realising how tight I've done wheels in the past (and how unevenly), I've become a torque wrench convert.
• My wheel bolts always seem to have a coating of white coloured corrosion which I try & remove with a wire brush.  I usually put the tiniest (a quarter of a match head) smear of black moly grease on the threads to compensate for any corrosion I can't remove.  Maybe it means I do the wheels up a fraction too tight but it's still less than what I would using a cross-brace.

 

My understanding is that the torque setting is to control the deformation of the fixing s it tightens. Thread friction shouldn't be relevant to torque as there is minimal rotation after the bolt face seats.

yOur partly right,torquing up a nut gives the bolt the correct amount of strech so its not overtightened, resulting in it breaking,more than one bolt on a component would be torqued down in a sequence to prevent deformation, the torque is worked out depending on the lub on a bolt,dry bolt will need more turning force(torque) to tighten down, than a lubed one,

This is why you should re tighten after a few hundred miles, as the bolt or nut would have stress relaxed and therefore loosened.

 

ta

I always thought the thread had stopped rotating when the final torque was reached but seems I was wrong again.  I asked my boss at work - engineering professor - he had to look it up too!

Just recently had a go changing a wheel over and putting on a new spare wheel that I bought about a week ago. Have to say I was amazed at how easy it was to loosen all 5 wheel nuts; a gentle push with the wheel brace and each nut came loose. I've never experienced that on any other car before, many a time I've struggled with garage tightened wheel nuts, even standing or jumping on the wheel brace to loosen the nuts off!

Think I need to spend a bit of time soon and check all my other wheels too. I see mention here of not using grease on the hubs, any issue using a little grease on each wheel nut as I take them off and re-tighten again? It's just something I remember my grandfather being very keen on doing, so that the nuts would be easy to remove and not get seized up or stuck somehow!

I always used to use a little  Copperslip, and it never resulted in a nut coming loose so long as it was tightened to correct torque in the first place.

I always used to use a little Copperslip, and it never resulted in a nut coming loose so long as it was tightened to correct torque in the first place.

If you torque the bolt to the "correct" torque with grease on the threads you are in fact over torquing it which is the issue with such practice

If you torque the bolt to the "correct" torque with grease on the threads you are in fact over torquing it which is the issue with such practice

But if you torque it to the correct torque & there's a bit of corrosion on the threads then you're under-torqued.  I think I'd prefer to be slightly over than slightly under. 

 

The trouble is that some people go a bit OTT with grease / copperslip.

But if you torque it to the correct torque & there's a bit of corrosion on the threads then you're under-torqued.  I think I'd prefer to be slightly over than slightly under. 

 

The trouble is that some people go a bit OTT with grease / copperslip.

Yes, only a tiny smear is needed. And in any case, the torque figure of 120 NM is rarely going to be reached exactly. Probably every torque wrench varies a little. I can't imagine you'd be in trouble if the nut was say 117 NM or 123.

Yes, only a tiny smear is needed. And in any case, the torque figure of 120 NM is rarely going to be reached exactly. Probably every torque wrench varies a little. I can't imagine you'd be in trouble if the nut was say 117 NM or 123.

This is also true, there are probably plenty of people out there with cheap or old torque wrenches that haven't been checked for calibration in years...

I must say I've not really ever had an issue with corroded threads on wheel bolts or nuts though, even on some of my vintage vehicles

I would second the comments about cheap and uncalibrated torque wrenches -  in my experience they can be wildly inaccurate.

 

I have torque “adjustment” tables which indicate the adjustment to be made to the torque figure where the thread and/or fastener is lubricated – try Googling this for more information. There is variation between the tables but in general they say 10-15% reduction if the thread is lubricated with light engine oil (ie 10W) up to 50-60% reduction if the lubricant is moly based. Use of light engine oil apparently gives the most consistent torque results. The tables assume that the threads are otherwise clean.  Where copperslip sits within the number range is open to question.

 

Be very clear - I’m not recommending reducing the torque by 60% - I’m certainly not brave enough and would never do so myself, but the figures are food for thought.

 

I would suggest an alternative for consideration which is ACF50. This is primarily a corrosion inhibitor much used by us in the motorcycle fraternity who face a much bigger battle with corrosion (especially on salty roads) than just with the wheel nuts on a car.

 

ACF50 was originally developed by the aircraft industry and is especially good with corrosion on alloy parts. So it is ideal for where your alloy wheels mate with the hub.   

There are 2 problems with ACF50. Firstly it can “creep” from the area where it was originally applied (this is by design). So it MUST only be applied SPARINGLY particularly avoiding brake components.  Secondly it can be difficult to find suppliers in the UK.

 

They claim that ACF50 does not affect torque settings – I specifically asked this question and got assurance from them over this. But I remain slightly sceptical – although it is primarily an inhibitor, it does have some lubricity characteristics, so a small torque reduction by the purists may be in order.

 

Finally I would suggest the purchase of an appropriate tap and die from Halfords or wherever. All torque numbers assume clean threads and it’s only a matter of moments to use these to clean the threads.   

 

Happy torqueing!

I would second the comments about cheap and uncalibrated torque wrenches - in my experience they can be wildly inaccurate.

I have torque “adjustment” tables which indicate the adjustment to be made to the torque figure where the thread and/or fastener is lubricated – try Googling this for more information. There is variation between the tables but in general they say 10-15% reduction if the thread is lubricated with light engine oil (ie 10W) up to 50-60% reduction if the lubricant is moly based. Use of light engine oil apparently gives the most consistent torque results. The tables assume that the threads are otherwise clean. Where copperslip sits within the number range is open to question.

Be very clear - I’m not recommending reducing the torque by 60% - I’m certainly not brave enough and would never do so myself, but the figures are food for thought.

I would suggest an alternative for consideration which is ACF50. This is primarily a corrosion inhibitor much used by us in the motorcycle fraternity who face a much bigger battle with corrosion (especially on salty roads) than just with the wheel nuts on a car.

ACF50 was originally developed by the aircraft industry and is especially good with corrosion on alloy parts. So it is ideal for where your alloy wheels mate with the hub.

There are 2 problems with ACF50. Firstly it can “creep” from the area where it was originally applied (this is by design). So it MUST only be applied SPARINGLY particularly avoiding brake components. Secondly it can be difficult to find suppliers in the UK.

They claim that ACF50 does not affect torque settings – I specifically asked this question and got assurance from them over this. But I remain slightly sceptical – although it is primarily an inhibitor, it does have some lubricity characteristics, so a small torque reduction by the purists may be in order.

Finally I would suggest the purchase of an appropriate tap and die from Halfords or wherever. All torque numbers assume clean threads and it’s only a matter of moments to use these to clean the threads.

Happy torqueing!

Very sound advice. ACF50 is excellent stuff. Used to use it loads on my old motorbike winter hack.