Torqueing and Checking Wheel Bolts.

[Anseo]

Even though my van is new and wheels haven't been off yet , you's have got me a bag of nerves here , so when we go away tmrw , I'll be checking them before we go, I haven't got a torque wrench I've just got a normal spider spanner so that will have to do for now. :huh:

Not sure if this is of interest Craig, but Halfords have an offer on their Professional Range of torque wrenches.

I am tempted by this one http://www.halfords.com/workshop-tools/tools/spanners-wrenches/halfords-advanced-torque-wrench-model-300

I have one of their Pro Range 3/8 drive torque wrench's and it is well made and has lifetime warranty.

For heavier duty I have an old but little used 1/2" drive Draper, I have checked it against the Halfords 3/8" drive (within the range permitted by the limitations of the 3/8" drive) and it gives very similar readings.

It is this thread that has made me edgy with all this talk of wheels coming off and made me look at a new wrench .

 

[CustardAvenger]

...Or was your previous torquing up done after the wheels had been refitted after removal, or was it a retorque after they had been refitted earlier?

The wheels were torqued in Dorset at the end of weeks break; made the trip home with no re-torque en route, the van was then put on the drive for 2 weeks then checked today. The wheels haven't been off. Expansion from the recent mini heatwave was my first thought. But other plausible explanations have been posted by Hutch.

 

[Hutch]

Even though my van is new and wheels haven't been off yet , you's have got me a bag of nerves here , so when we go away tmrw , I'll be checking them before we go, I haven't got a torque wrench I've just got a normal spider spanner so that will have to do for now. :huh:

Not sure if this is of interest Craig, but Halfords have an offer on their Professional Range of torque wrenches.

I am tempted by this one http://www.halfords.com/workshop-tools/tools/spanners-wrenches/halfords-advanced-torque-wrench-model-300

I have one of their Pro Range 3/8 drive torque wrench's and it is well made and has lifetime warranty.

For heavier duty I have an old but little used 1/2" drive Draper, I have checked it against the Halfords 3/8" drive (within the range permitted by the limitations of the 3/8" drive) and it gives very similar readings.

It is this thread that has made me edgy with all this talk of wheels coming off and made me look at a new wrench .

The Halfords Professional range of tools are extremely good, I bought some metric ones for home and when I compared them to my Snap On tools they were almost identical . But at a nicer price to the pocket.

 

[ProfJohnL]

These are my thoughts on one possible explanation for trailer wheel loss This would be so much easier if I could post diagrams!- So Its long and involves some good mental agility - so if your easily board by such things don't read it.

I don't know if other countries see the same percentage loose wheels, but I'm guessing that our friend Lutz would have been more vocal on the subject if it were a significant problem abroad. - but there could be a reason why we seem to see more wheel loosening in the uk.

It is quite common to create vibrations to help loosen a tight nut or bolt by applying a torque to the fixing whilst hitting the assembly with a hammer. This works becasue of the percussive nature of the hammer blow sets up a vibration in the assembly, and the vibration effectively momentarily reduces the thickness of the component being clamped by the fixing, and the reduced tension in the fixing allow the torque to actually start to move the hexagon. The same process is used to enable higher tension to be set up in fixings during Assembly.

The process could be happening with trailer road wheels. but it's less obvious how the torque is being applied to the nut or bolt to cause it to loosen.

As a trailers wheel are never driven, they are always being 'dragged' and that means the wheel hub will always be trying to resist the wheels rotation, especially under braking. Any play in the wheel studs or bolts would mean that if insufficient clamping force had been generated, the fixings could allow a shimmy between the wheel rim and the axle hub. Such a shimmy could be caused by the amount of punishment the wheel receives by going over potholes, or the severity of breaking.

Presuming the shimmy described above is a rotational and on the same centre of rotation as the wheel hub, The bolts or nuts would receive a torque becasue the contact area of each hexagonal head will sit on a radius from the centre of the wheel, and that gives different radial lengths between the side of the hexagon facing the centre of the wheel and the face nearest the rim of the wheel. This means for any shimmy of the wheel, the angular displacement will set up a differential torque on either side of the hexagon, but there will be a net bias in favour of the side of the hexagon furthest from the centre of the wheel.

This is why the wheels direction of rotation becomes important. Given that as far as I know all caravan wheel nuts or bolts are right hand threaded, the wheel that rotates in an anticlockwise direction will try to undo the fixings, whilst those having a clockwise rotation will actually try to tighten.

As we drive on the left in the UK that means the near side trailer wheel will turn anticlockwise and thus will be trying to undo the wheel nuts. Where as driving on the right,as on the continent the wheel in the gutter will be rotating clockwise and thus doing more to tighten the nuts rather than loosening them.

It can easily be seen that in the UK most of our potholes do occur on the near side of each carriage way, and we seem to have more potholes than many other countries so it seems we are more likely to see wheel loosening.

Caravans tyres are often have to carry a greater load than individual car wheels so they may be worked harder. Many are closer to a commercial tyres with stiffer side walls, which might transmit more vibrations into the wheel.

What can we do about it? The most important thing is to ensure that when a wheel is to be fitted all the surfaces are free from debris, and to ensure the correct torque is used on the nuts or bolts. And Its just good practice to check the wheel nuts after a few miles in case there has been any loosening.

It sensible to check the pressures & nuts before any journey as part of the pre trip routines.

Making sure trailer wheels are fitted with dampers, to reduce harmonic resonances in the wheels.

It seems that trailers may be more susceptible to these issues than cars, so perhaps the trailer manufactures should be following the lead of the car manufactures in design details.

 

[GD485]

Hi Prof

I think you theory is a valid one. The idea that stiff side walls make wheel loss more likely is possibly correct. Most trucks have left hand threads one side to oppose the effects of differential torque.
LH threads used to be far more common place but I think the increase in use of spigot mounted wheels deceased the need.
Of course the wheel construction, material, and load would all have effects on the “differential” effect.
On LHD caravans the problem should still affect the left wheel more due to it’s anti-clockwise rotation.
As always a great theory and has sound reasoning behind it , thanks ProfJohn

 

[Dustydog]

Morning Prof,
Not boring at all. When I lost a wheel a few years on the car, the nearside rear many on here said it couldn't happen. A number of theories were put forward, you included , which I see you have concisely encapsulated in your latest post. An excellent affirmation imo that wheels for various reasons do come loose and for me regular checking the car and caravan wheel torques is still an important check before departure
My torque wrench will remain in the tug.

 

[GD485]

Just about to set off for Devon. Wheel nuts torqued, air pressures checked, oil,water,roof lights, road lights, Milk in the fridge and weather checked.
But its all worth it for peace of mind.

I’ve been thinking a bit. Could simply the direction of rotation and loading of an individual part of the wheel (radially). It is subjected to varying load through out a revolution. In fact the direction of this load reverses through the rotation.

 

[Dodger524]

One other point that may be relevant. Most caravan wheels are asymmetrically loaded; on my own van the off-side carries several hundred kilograms more weight than the nearside. This is because all the heavy items are mounted on the off-side.

 

[VicMallows]

Since we are speculating on why UK caravans might loose wheels disproportionately to other countries ........
two thoughts:

1) Is the obsession with torquing to a specific value -rather than just doing up tightly by feel - more prevalent in the UK. Maybe wheels which come loose have been grossly under tightened because of absolute reliance on the wrench, rather than an intuitive feel for whether the slip point seems reasonable. (Wrenches may be faulty, user technique wrong).

2) The vast majority of UK caravans have alloy wheels. Casual observation abroad suggests that a high proportion of even brand new foreign caravans have steel wheels. (Maybe alloys are an extra, rather than included in standard spec; maybe other countries are not so impressed by 'bling').

 

[otherclive]

Thank you Prof for what is a very logical explanation. I once saw a large fastening self loosening under vibration on a marine turbine, which is normally a well balanced equipment. It was undoing faster than a human could undo it.
You touch on the subject of dampers and Ive noticed that with continental vans many makes have dampers fitted as standard. Even my small Trigano pop top had them fitted and it only maxed at 1000Kg MTPLM. Car wheel/hub assemblies is much more robust than caravan ones and the suspension and damping is too. The consideration of the differences between LHD and RHD is a good one as you say in UK our nearside road conditions may well exacerbate any problem and lead to loosening. My tyres sit at 60psi nearly twice the car's sol pressures, and are C rated commercial tyres too. (OEM)

As others have said I too will continue my routine or retorquing the wheels shortly after service, tyres and prior to journeys. May even consider fitting some dampers too as our roads will not be improving any time soon.

 

[Lutz]

Since we are speculating on why UK caravans might loose wheels disproportionately to other countries ........
two thoughts:

1) Is the obsession with torquing to a specific value -rather than just doing up tightly by feel - more prevalent in the UK. Maybe wheels which come loose have been grossly under tightened because of absolute reliance on the wrench, rather than an intuitive feel for whether the slip point seems reasonable. (Wrenches may be faulty, user technique wrong).

2) The vast majority of UK caravans have alloy wheels. Casual observation abroad suggests that a high proportion of even brand new foreign caravans have steel wheels. (Maybe alloys are an extra, rather than included in standard spec; maybe other countries are not so impressed by 'bling').

I think you have a very valid point regarding alloy wheels. I suspect that many UK caravan manufacturers are using alloy wheels without obtaining prior approval from the chassis manufacturer. They aren't obliged to get approval but they do carry full product liability if they don't. The chassis manufacturers, on the other hand, producing in much larger numbers, have the resources to check compatibility of wheels with their chassis, which is something the caravan manufacturers with their much smaller volumes, do not.
You are right that Continental caravans don't normally have alloy wheels and probably the steel wheels are also sourced from the chassis manufacturer, so one can be sure that they are compatible.

Another possible reason is that virtually all Continental caravans are fitted with shock absorbers, so obviously the loads and vibrations to which the wheels are subjected will be different to caravans not fitted with shock absorbers.

I'm not saying that wheels never come off Continental caravans, but it is certainly not as big an issue as it seems to be in the UK.

 

[Dustydog]

Vic,
You raise a very interesting point. When we were young we couldn’t afford torque wrenches.
The tyre fitters in those days taught us to tighten, all nuts FT! We never lost a wheel but obviously technology and design have moved on considerably.
It now raises the question when using the OME tools how do you tighten the spare
FT or Murder Tight perhaps

 

[Hutch]

Vic,
You raise a very interesting point. When we were young we couldn’t afford torque wrenches.
The tyre fitters in those days taught us to tighten, all nuts FT! We never lost a wheel but obviously technology and design have moved on considerably.
It now raises the question when using the OME tools how do you tighten the spare
FT or Murder Tight perhaps

Dusty D, I think the Majority of people call the Breakdown outfit they are with, more to the point though , How would you get the wheel nuts/ bolts Off with Original equipment tools.

 

[Dustydog]

Vic,
You raise a very interesting point. When we were young we couldn’t afford torque wrenches.
The tyre fitters in those days taught us to tighten, all nuts FT! We never lost a wheel but obviously technology and design have moved on considerably.
It now raises the question when using the OME tools how do you tighten the spare
FT or Murder Tight perhaps

Dusty D, I think the Majority of people call the Breakdown outfit they are with, more to the point though , How would you get the wheel nuts/ bolts Off with Original equipment tools.

:woohoo: :blink:

 

[Parksy]

Around 18 months ago I changed all four tyres on the caravan because they'd passed the age where they would be safe to use.
I bought the tyres from 'Tyres on the Drive', one of the many mobile tyre sales and fitting services accessible via the internet.
On the appointed day the fitter duly changed the tyres and I then asked for my wheels to be (re) balanced.
The tyre fitter seemed very surprised that I wanted the caravan wheels balanced, he said that it was something that he'd never been asked for before and that caravan wheel balancing was rare in his experience.
Of course I insisted in spite of the fitters protestations, and although I regularly check the alloy wheel stud torques with the torque wrench that lives in the tug the wheel studs are always ok.
I wonder if the fitter was trying to avoid the extra work or if caravan owners genuinely don't bother with wheel balancing and if this could loosen the wheel nuts or studs?

 

[Craigyoung]

Someone says on a previous post that they don't hear of it happening overseas on the continent but the roads over here are crap, the roads over there are superb for driving on , lovely tarmac motorways , no pot holes

 

[Lutz]

Someone says on a previous post that they don't hear of it happening overseas on the continent but the roads over here are crap, the roads over there are superb for driving on , lovely tarmac motorways , no pot holes

I have not seen any evidence that there is a direct link between the condition of the roads and the likelihood of a wheel falling off. I have done many miles with my Continental caravan in the UK and on unsurfaced roads elsewhere and have always returned home safely. Besides, wheels coming off does not seem to be a problem across the board. It appears to be most frequent with certain models.

 

[Brasso530]

Vic,
You raise a very interesting point. When we were young we couldn’t afford torque wrenches.
The tyre fitters in those days taught us to tighten, all nuts FT! We never lost a wheel but obviously technology and design have moved on considerably.
It now raises the question when using the OME tools how do you tighten the spare
FT or Murder Tight perhaps
When I was an apprentice,tight meant 1/4 of a turn before it snapped :lol:

 

[Anseo]

I note VicMallows comment on "tighten intuitively", and I agree that there is a lot going for this approach.

However, although I am handy with the spanners now, I do recall the rather long learning curve where I went through the 'tighten until spins freely' phase.

All in all, a torque wrench is useful for removing some of the guesswork; with the caveat that hardly anyone will have a torque wrench re-calibrated after the initial purchase.

Youtube has some videos on re-calibration that are useful.

 

[ProfJohnL]

I agree with Vic that alloy wheels may be part of the problem. Compared to steel, alloy is relatively malleable meaning it can be formed and shaped more easily - its requires less force to leave a permanent mark. so any additional force on the wheel induced by vibrations allows the nut or bolt to bruise the alloy, this could permanently reduce the thickness of the alloy being clamped, and that will reduce the tension in the fixing. Then as I previously postulated there is more potential for the nuts to work loose.

It could also be the case as Lutz points out that caravan manufacturers own wheel designs may not be as thoroughly tested as those supplied by the trailer manufacture.

We have to work with what we have, so its up to drivers to make the necessary checks.

 

[Gafferbill]

.....for me loose caravan wheels are solely down to human failure to carry out due diligence.

That is a failure to fit the wheel correctly after removal and a failure to recheck the wheel fastenings for correct tightness after the initial bedding in mileage.
It has long been known that best workshop practice is for a fitter to torque the fastenings to the manufacturers settings and then to get a second fitter to recheck the settings.
Then on hand over of the vehicle to the user........ the user is told of the importance of checking for tightness after a set number of miles.

It would be simple engineering to fit wheel fastenings that could not come undone, so ask yourself why 99.99% of all wheel fastenings since their invention do not have a locking mechanism.
The reason is that they are not needed provided the human carries out the correct procedure.

 

[Lutz]

.....for me loose caravan wheels are solely down to human failure to carry out due diligence.

That is a failure to fit the wheel correctly after removal and a failure to recheck the wheel fastenings for correct tightness after the initial bedding in mileage.
It has long been known that best workshop practice is for a fitter to torque the fastenings to the manufacturers settings and then to get a second fitter to recheck the settings.
Then on hand over of the vehicle to the user........ the user is told of the importance of checking for tightness after a set number of miles.

It would be simple engineering to fit wheel fastenings that could not come undone, so ask yourself why 99.99% of all wheel fastenings since their invention do not have a locking mechanism.
The reason is that they are not needed provided the human carries out the correct procedure.

It's not as simple as that. If your assertion were true, then the problem of loose wheels would apply across the board, but that is apparently not the case. It is hardly likely, for example, that Bailey owners or dealers (or any other make for that matter) work less diligently than others.

 

[Craigyoung]

I've just been away this weekend I had a look at the wheels, both still on , fine and noticed the little information plate that is beside my door with all my weights etc it tells you what to tighten wheels up to both steel wheels or alloy wheels , think it 86 for steel wheels and 13o for alloy wheels.

 

[Buckman]

Neither of the breakdown services offered by either the CMC or C&CC will torque up an alloy wheel. They will simply tighten it as tight as possible.

 

[Hutch]

Neither of the breakdown services offered by either the CMC or C&CC will torque up an alloy wheel. They will simply tighten it as tight as possible.

Sorry buckman , that doesn't make sense. The breakdown company's have torque figures for wheel bolts / nut and torque appropriately , they always use torque wrenches for their final fiment. .
It is normally the Fitter / mechanic/ engineer being interrupted whilst the final procedure that causes a problem. Thats why a duplicate inspection is required.