Is this an argument for having shock absorbers fitted?Will they reduce the likelihood of wheelnuts losing their torque on alloy wheels?
Possibly, yes. I could imagine that the presence of shock absorbers could conceivably reduce shock loads to the axle. As I said, it's just a thought, but it seems plausible enough to me.
If the theory that I put forward in my previous reply is true, indicators would not show that the bolts remain sufficiently tightened, although they would still confirm whether the wheel is in imminent danger of coming off or not. I would welcome further comments from experts regarding the validity of my statements.
I would put money on it that the vast majority of lost wheels are on the n/s. Anyone ever had an offside wheel come off?
The easy answer to the problem is for the axle manufacturer to fit a hub with left hand threads on the near side. The extra cost would be almost nil.
As a matter of interest, "lost wheels" on HGV's is almost always on the n/s/r. This problem has been extensively researched by various bodies including VOSA, the conclusion pointing towards contaminated mating surfaces, incorect initial torque and the failure to recheck the torque after 30 or so miles or half an hour if the vehicle isn't moved.
The easy answer to the problem is for the axle manufacturer to fit a hub with left hand threads on the near side. The extra cost would be almost nil.
As a matter of interest, "lost wheels" on HGV's is almost always on the n/s/r. This problem has been extensively researched by various bodies including VOSA, the conclusion pointing towards contaminated mating surfaces, incorect initial torque and the failure to recheck the torque after 30 or so miles or half an hour if the vehicle isn't moved.
There is clearly a problem of some sort with some caravan wheels, and the apparent propensity for them to work loose. Unfortunately, none of the evidence we have has been scientifically tested so we are working in the dark. Perhaps the caravan manufacturers don't understand this matter either.
When a wheel does detach, then the ensuing damage or difficulties can be quite traumatic for those involved. There is uncertainty as to the cause and that is probably one of the worst situations to be in.
Is it a design fault that means these wheels are pone to working loose?
Is it workmanship error where someone has failed to fit the wheel and tighten the bolts correctly?
Should the caravan owner be expected to recheck the bolts after short distance, and if the owner finds them loose then what is the cause?
In the absence of a proven reason and a fitting protocol that prevents these incidents, it makes good sense to adopt a belt and braces approach. I recommend that owners do check the bolts.
I also think that some proper research should be done into these incidents to try and identify the cause(s). That would enable an effective response to be produced to eliminate or at lease reduce the incident rate.
When a wheel does detach, then the ensuing damage or difficulties can be quite traumatic for those involved. There is uncertainty as to the cause and that is probably one of the worst situations to be in.
Is it a design fault that means these wheels are pone to working loose?
Is it workmanship error where someone has failed to fit the wheel and tighten the bolts correctly?
Should the caravan owner be expected to recheck the bolts after short distance, and if the owner finds them loose then what is the cause?
In the absence of a proven reason and a fitting protocol that prevents these incidents, it makes good sense to adopt a belt and braces approach. I recommend that owners do check the bolts.
I also think that some proper research should be done into these incidents to try and identify the cause(s). That would enable an effective response to be produced to eliminate or at lease reduce the incident rate.
I am also surprised that the problem appears to have reached the dimension suggested by this and similar threads without any insurance companies showing any interest in establishing the root cause. I would have expected them to try to recover the costs for any claims from the 'perpetrator' so it would be in their own interest to do some investigating. That they don't, and in fact, no-one really knows much about the cause, suggests that the problem must be a very isolated one.
Quote from super gluing wheel nuts:
As I see it, it is a waste of time discussing anything to prevent wheel nuts/bolts coming loose until wheel balance is addressed.
Vibration is undoing the nuts/bolts, eliminate obvious forms of vibration and only then address what's left if anything?.
I don't know about 'no one' but just in case you missed it Lutz, not once here or in the thread I originally posted this, is wheel balance mentioned!
What else can it be? or all nearside caravan wheels would fall off, but this discussion ignores the obvious like it will spoil the debate?
Certainly shorten it!
As I see it, it is a waste of time discussing anything to prevent wheel nuts/bolts coming loose until wheel balance is addressed.
Vibration is undoing the nuts/bolts, eliminate obvious forms of vibration and only then address what's left if anything?.
I don't know about 'no one' but just in case you missed it Lutz, not once here or in the thread I originally posted this, is wheel balance mentioned!
What else can it be? or all nearside caravan wheels would fall off, but this discussion ignores the obvious like it will spoil the debate?
Certainly shorten it!
Maybe some of the caravan insurers will wish to answer Lutz question??
I had the Wyoming serviced a few weeks ago and there on the Service Schedule in bold type it says " Wheelnuts must be checked after 30 miles or before your next journey, whichever is the earliest".
Graham Ponty took a lot of stick on this subject. Until we lost the nearside wheel on the Sorrie this summer I didn't believe it was possible.
Chrisbee put forward a very credible reason why it happens. Balancing has also been mentioned but the car wheels were all perfectly balanced prior to the journey.
I have no idea how often the problem has happened but suspect it is not as uncommon as even I thought. Why else do all the tyre people and repairers emphasise the need to retorque?
Anyway as I said before, the torque wrench is in the boot. It doesn't take 5 minutes to check both car and caravan. Belts and braces now I've been "bitten".
Cheers
Dustydog
I had the Wyoming serviced a few weeks ago and there on the Service Schedule in bold type it says " Wheelnuts must be checked after 30 miles or before your next journey, whichever is the earliest".
Graham Ponty took a lot of stick on this subject. Until we lost the nearside wheel on the Sorrie this summer I didn't believe it was possible.
Chrisbee put forward a very credible reason why it happens. Balancing has also been mentioned but the car wheels were all perfectly balanced prior to the journey.
I have no idea how often the problem has happened but suspect it is not as uncommon as even I thought. Why else do all the tyre people and repairers emphasise the need to retorque?
Anyway as I said before, the torque wrench is in the boot. It doesn't take 5 minutes to check both car and caravan. Belts and braces now I've been "bitten".
Cheers
Dustydog
Wheel balancing, or lack thereof, could be a contributing factor, but no-one has actually confirmed that it makes any difference. At this point in time, it is only an assumption.
Sorry?
Vibration is undoing the nuts/bolts...
That is a fact
eliminate obvious forms of vibration and only then address what's left if anything?.....
ie, wheel balance, it does not need confirming, it's plain commonsense to start with the most likely and indeed simplest to eradicate
It has been suggested that vibration is a possible cause for wheels becoming loose.
I am certain that vibration or motion is a significant factor in causing loose wheel bolts to work free, but I am not sure it is the cause of them becoming loose in the first place.
A correctly tightened bolt holding two components together to prevent relative movement of the components, has no turning force to cause it to come undone. By comparison if the bolted components do have some relative movement, it may include a rotational component that can release the bolt.
I am convinced that balancing wheels on trailers and especially caravans will reduce vibration to the super structure and that can only be a good thing, but the unsprung mass (which includes the wheels) are not so well off.
Towing a trailer over a bumpy road surface will use energy as the trailer lifted up and set down again after the irregularities. A trailer without shock absorbers will tend to bounce around more as a whole, than a trailer with shocks, yet the same energy must be being dissipated by the trailer, but where is it going? The answer is that the body of eth trailer is steadier, but the suspension is actually working harder. It is therefore more likely that a wheel subjected to the action of a shock absorber is likely to experience more violent vibrations than a wheel without shock absorbers.
Consequently I would expect caravans fitted with shocks to have a greater number of wheel losses if vibrations are the most significant cause of wheel loss, but then why isn't the same characteristic causing wheels to fall off other road vehicles?
To my mind there is more to this problem that we don't understand, and I said previously it really needs proper investigation.
I am certain that vibration or motion is a significant factor in causing loose wheel bolts to work free, but I am not sure it is the cause of them becoming loose in the first place.
A correctly tightened bolt holding two components together to prevent relative movement of the components, has no turning force to cause it to come undone. By comparison if the bolted components do have some relative movement, it may include a rotational component that can release the bolt.
I am convinced that balancing wheels on trailers and especially caravans will reduce vibration to the super structure and that can only be a good thing, but the unsprung mass (which includes the wheels) are not so well off.
Towing a trailer over a bumpy road surface will use energy as the trailer lifted up and set down again after the irregularities. A trailer without shock absorbers will tend to bounce around more as a whole, than a trailer with shocks, yet the same energy must be being dissipated by the trailer, but where is it going? The answer is that the body of eth trailer is steadier, but the suspension is actually working harder. It is therefore more likely that a wheel subjected to the action of a shock absorber is likely to experience more violent vibrations than a wheel without shock absorbers.
Consequently I would expect caravans fitted with shocks to have a greater number of wheel losses if vibrations are the most significant cause of wheel loss, but then why isn't the same characteristic causing wheels to fall off other road vehicles?
To my mind there is more to this problem that we don't understand, and I said previously it really needs proper investigation.
"Parksy (Moderator)
7 Oct 2009 11:35 AM Our caravan is in for it's second service on Monday afternoon at Davans in Weston where we bought it from.
We are going to make a weekend of it and return home to the midlands on Monday evening after we pick the caravan up from Davans.
One thing is for certain, I will be taking the torque wrench and giving the nuts on the alloys a quick check when I reach Michael Wood services.
Better safe than sorry"
Hi Steve,
You will be pleased to know that Davans have two torque wrenches to hand in there service reception, one for steel wheels and one for alloy wheels, I guess they come out and walk round the van with you to check the torques.
7 Oct 2009 11:35 AM Our caravan is in for it's second service on Monday afternoon at Davans in Weston where we bought it from.
We are going to make a weekend of it and return home to the midlands on Monday evening after we pick the caravan up from Davans.
One thing is for certain, I will be taking the torque wrench and giving the nuts on the alloys a quick check when I reach Michael Wood services.
Better safe than sorry"
Hi Steve,
You will be pleased to know that Davans have two torque wrenches to hand in there service reception, one for steel wheels and one for alloy wheels, I guess they come out and walk round the van with you to check the torques.
Quote JohnL:
I am certain that vibration or motion is a significant factor in causing loose wheel bolts to work free, but I am not sure it is the cause of them becoming loose in the first place.
A correctly tightened bolt holding two components together to prevent relative movement of the components, has no turning force to cause it to come undone....
---------------------------------------------------------------------------------------------
My point is what is a correctly tightened bolt?
A size is picked to enable an adequate clamping force to be applied without undue stress on the bolt, typically 7/16" or 12mm and also typically a fine thread at 14TPI
Depending on grade of steel and it's correct torque, this produces 4 to 5 ton of clamping pressure per bolt!
Therefore the wheel is being clamped to the hub by a significant force, it should then take considerable vibration to get the two parts to move against each other and therefore set up a turning motion.
The size picked then and the combined pressure is deemed adequate and has proved in general use to be so, without wheels coming loose in vast numbers.
However wheels do fall off caravans with somewhat alarming regularity, not cars which by definition often have twice as many nearside wheels therefore chances than caravans?
It could be said you will feel the car wheels early, but when was the last time anyone felt their car wheel come loose, never in my case, never check them either!
Infact is there any difference in incidence between S/A and TA vans? I doubt it.
So back to my point, if around 25ton of pressure is generally adequate for all purposes, but caravan wheels fall off, then 25ton cannot always be adequate for caravans due to some issue or other.
Vibration we know loosens nuts but only if it can overcome the clamping force and make the wheel move against the hub.
Well that must be happening, the vibration then is outside the design capabilities of the bolt/clamping force/applied torque.
Do we then believe fitters are always to blame for not applying the correct torque or the correct torque is more often applied but it's not great enough?
I'm very much the latter, there will of course be fitter error as will there be dirty mating surfaces and a few other possibles, but all those rely on vibration to finish the job if it does not start it in the first place.
I believe excessive vibration 'beyond the correct applied torque can cope with' is the main reason for wheels coming adrift.
And the main, if not only reason, for that is out of balance wheels
Reason is my tyre fitter tells me an unbalanced wheel is generally 50-60grams out, I have discovered just 30grams on a 600mm dia wheel at 60mph is generating 7kg of force and that's hitting the road 12 times a second! doubling that generates I believe far more than double the force and that's common out of balance?
Badly out of balance wheels are well in excess of 100grams so what force does that generate? More to the point what vibration does it create?
I've no idea and don't care to find out, my caravan wheels are balanced! My simple attitude is get rid of the obvious, it costs about a fiver a wheel
I am certain that vibration or motion is a significant factor in causing loose wheel bolts to work free, but I am not sure it is the cause of them becoming loose in the first place.
A correctly tightened bolt holding two components together to prevent relative movement of the components, has no turning force to cause it to come undone....
---------------------------------------------------------------------------------------------
My point is what is a correctly tightened bolt?
A size is picked to enable an adequate clamping force to be applied without undue stress on the bolt, typically 7/16" or 12mm and also typically a fine thread at 14TPI
Depending on grade of steel and it's correct torque, this produces 4 to 5 ton of clamping pressure per bolt!
Therefore the wheel is being clamped to the hub by a significant force, it should then take considerable vibration to get the two parts to move against each other and therefore set up a turning motion.
The size picked then and the combined pressure is deemed adequate and has proved in general use to be so, without wheels coming loose in vast numbers.
However wheels do fall off caravans with somewhat alarming regularity, not cars which by definition often have twice as many nearside wheels therefore chances than caravans?
It could be said you will feel the car wheels early, but when was the last time anyone felt their car wheel come loose, never in my case, never check them either!
Infact is there any difference in incidence between S/A and TA vans? I doubt it.
So back to my point, if around 25ton of pressure is generally adequate for all purposes, but caravan wheels fall off, then 25ton cannot always be adequate for caravans due to some issue or other.
Vibration we know loosens nuts but only if it can overcome the clamping force and make the wheel move against the hub.
Well that must be happening, the vibration then is outside the design capabilities of the bolt/clamping force/applied torque.
Do we then believe fitters are always to blame for not applying the correct torque or the correct torque is more often applied but it's not great enough?
I'm very much the latter, there will of course be fitter error as will there be dirty mating surfaces and a few other possibles, but all those rely on vibration to finish the job if it does not start it in the first place.
I believe excessive vibration 'beyond the correct applied torque can cope with' is the main reason for wheels coming adrift.
And the main, if not only reason, for that is out of balance wheels
Reason is my tyre fitter tells me an unbalanced wheel is generally 50-60grams out, I have discovered just 30grams on a 600mm dia wheel at 60mph is generating 7kg of force and that's hitting the road 12 times a second! doubling that generates I believe far more than double the force and that's common out of balance?
Badly out of balance wheels are well in excess of 100grams so what force does that generate? More to the point what vibration does it create?
I've no idea and don't care to find out, my caravan wheels are balanced! My simple attitude is get rid of the obvious, it costs about a fiver a wheel
I can't believe that this is still dragging on.
Do the bl**dy bolts or nuts up and they don't come off.
Cars lose balance weights and how many lose a wheel?
I agree, have wheels balanced but they come off when you or the fitter screw up or rather, don't screw up correctly!
Do the bl**dy bolts or nuts up and they don't come off.
Cars lose balance weights and how many lose a wheel?
I agree, have wheels balanced but they come off when you or the fitter screw up or rather, don't screw up correctly!
ps: Do not grease the threads of the wheel bolts or studs. The torques specified apply to a dry condition and any reduction in friction due to the addition of grease could result in the tensile strength of the thread being exceeded.
Hello gary,
We seem to agree about the fundamentals concerning the wheels bolts.
Where we diverge somewhat is in your description of "However wheels do fall off caravans with somewhat alarming regularity". And the assumption that it must be down to incorrectly tightened assemblies.
I fully agree the incidence is alarming, but I disagree that it is regular, and I wonder just how often it does happen.
It is in the nature of people to complain when an incident like this happens, and I do not blame them for that, but the complaint is often repeated which can make one incident appear to be many, thus distorting the apparent numbers.
When it does happen it is alarming and disconcerting for the owner, and I in no way wish to diminish the severity of the event and its implications, but looking at the numbers of reported incidents and comparing it to the number of caravans and other similar sized and weighted trailers, the incidence is quite low. Despite that I still believe the numbers are sufficiently large to warrant a proper investigation.
As you point out in your comprehensive post there are many factors that might have a bearing on the issue, no just how tight the bolts are, or mechanisms that might cause the bolts to loose their hold.
We seem to agree about the fundamentals concerning the wheels bolts.
Where we diverge somewhat is in your description of "However wheels do fall off caravans with somewhat alarming regularity". And the assumption that it must be down to incorrectly tightened assemblies.
I fully agree the incidence is alarming, but I disagree that it is regular, and I wonder just how often it does happen.
It is in the nature of people to complain when an incident like this happens, and I do not blame them for that, but the complaint is often repeated which can make one incident appear to be many, thus distorting the apparent numbers.
When it does happen it is alarming and disconcerting for the owner, and I in no way wish to diminish the severity of the event and its implications, but looking at the numbers of reported incidents and comparing it to the number of caravans and other similar sized and weighted trailers, the incidence is quite low. Despite that I still believe the numbers are sufficiently large to warrant a proper investigation.
As you point out in your comprehensive post there are many factors that might have a bearing on the issue, no just how tight the bolts are, or mechanisms that might cause the bolts to loose their hold.
Chrisbee said:-
When wheels are fitted the mating surface between the wheel and drum/hub needs to be spotlessly clean. If this is the case then correctly torqued wheels will not "fall off". The problem arises when dirt, grit etc gets trapped. As the vehicle is in use sideways forces, especially when cornering, can crush this dirt effectivly decreasing the clamping effect of the nuts. That is why it is recommended that the torque be rechecked after 20/30 miles.
As said previously I watched the fitter set up his torque wrench to the manufacturers specification. He checked all four wheels twice. I never double checked after 50 miles and the rest is history. The wheels were quite hard to remove due to corrosion between the steel and aluminium surfaces. He wire brushed them, no grease. Some will say copperslip should be used others nothing. I prefer nothing but am I right?
Will grease between the surfaces intefere with the torque?
I for one will take no chances in the future. Hence the T wrench is in the boot.
Cheers
Dustydog
When wheels are fitted the mating surface between the wheel and drum/hub needs to be spotlessly clean. If this is the case then correctly torqued wheels will not "fall off". The problem arises when dirt, grit etc gets trapped. As the vehicle is in use sideways forces, especially when cornering, can crush this dirt effectivly decreasing the clamping effect of the nuts. That is why it is recommended that the torque be rechecked after 20/30 miles.
As said previously I watched the fitter set up his torque wrench to the manufacturers specification. He checked all four wheels twice. I never double checked after 50 miles and the rest is history. The wheels were quite hard to remove due to corrosion between the steel and aluminium surfaces. He wire brushed them, no grease. Some will say copperslip should be used others nothing. I prefer nothing but am I right?
Will grease between the surfaces intefere with the torque?
I for one will take no chances in the future. Hence the T wrench is in the boot.
Cheers
Dustydog
When a caravan or trailer wheel comes off it has recently been near a dealer or somebody has had the wheels off and refitted them in most cases!
All this drivel about thread pitch and vibration etc.
JUST DO THE BL***Y THINGS UP CORRECTLY AND THEY DON'T COME OFF!
Once again, I've had one wheel come off, I'd missed the final tighten when the van was off the jack. I've driven tens of thousands of miles with caravans and trailers and have family and friends who have done the same on a variety of roads with baalnced and unbalanced wheels and balanced wheels that the balance weights have come off. No other wheels have come off!
Yet again another subject raked over and over when the only issue is doing the bolts or nuts up correctly and tight!
I admit my mistake! Others just need to face up to mistakes as well!
Having just bounced around India for weeks on motorbikes, all the wheels were fine and we didn't see any wheels fall off any vehicle on rough roads and many of the vehicles are not in the best of health and probably never have wheels balanced!
All this drivel about thread pitch and vibration etc.
JUST DO THE BL***Y THINGS UP CORRECTLY AND THEY DON'T COME OFF!
Once again, I've had one wheel come off, I'd missed the final tighten when the van was off the jack. I've driven tens of thousands of miles with caravans and trailers and have family and friends who have done the same on a variety of roads with baalnced and unbalanced wheels and balanced wheels that the balance weights have come off. No other wheels have come off!
Yet again another subject raked over and over when the only issue is doing the bolts or nuts up correctly and tight!
I admit my mistake! Others just need to face up to mistakes as well!
Having just bounced around India for weeks on motorbikes, all the wheels were fine and we didn't see any wheels fall off any vehicle on rough roads and many of the vehicles are not in the best of health and probably never have wheels balanced!
Perhaps time to call it a draw??? Listen to the link below and lighten up chaps!
http://www.youtube.com/watch?v=fZ9LOPWrZwk
http://www.youtube.com/watch?v=fZ9LOPWrZwk
Two points John, most importantly, no I don't make the assumption incorrectly torqued nuts are generally to blame, rather and for the majority, I blame excess vibration correct torqued nuts cannot deal with!
How often it happens depends on what it's compared with, if compared with cars then it probably is alarming?
I said 'somewhat' it's more than somewhat to the guy/s that get the sack over it! and I personally know of one, his manager was almost a second!
The regime now is the fitter tightens them, the fitter next to him checks them and signs to say so and the manager finally checks them and sign them off yet again!, no finished yet then the owners asked to check them again after a few miles and has to sign to say he understands!!
If you compare that with your car wheels being removed and replaced, the caravan wheel rigmarole is totally ridiculous but being repeated across the country?!
Val A. you do have a point providing you have a twin axle, as they can still travel slowly on 3 wheels!
A single axle van and you're completely up sh 1 t creek if one wheel departs your wagon
A single axle van and you're completely up sh 1 t creek if one wheel departs your wagon
Dusty
If you are attempting to secure a wheel with rusty mating surfaces, then i am not surprised your wheel came off.
My wheels are not balanced, are not secured by a torque wrench, the mating surfaces ARE clean, are smeared with copperslip, the bolts are also lightly smeared with copperslip, the nuts are never checked 30 miles after the wheels have been refitted, and yes, you are correct, i have NEVER lost a wheel or nut. In over 25 years caravanning.
If you are attempting to secure a wheel with rusty mating surfaces, then i am not surprised your wheel came off.
My wheels are not balanced, are not secured by a torque wrench, the mating surfaces ARE clean, are smeared with copperslip, the bolts are also lightly smeared with copperslip, the nuts are never checked 30 miles after the wheels have been refitted, and yes, you are correct, i have NEVER lost a wheel or nut. In over 25 years caravanning.
Hello Dustydog,
This video clip shows bolts do come loose due to vibration, so I would check the torque after 30 miles as recommended by all service centres, tyre depots etc.
It is a very important safety issue, not just a get out of jail card.
Anyone who wishes to ignore it, that's their choice.
www.boltscience.com/pages/junkertestvideo.html
Regards,
This video clip shows bolts do come loose due to vibration, so I would check the torque after 30 miles as recommended by all service centres, tyre depots etc.
It is a very important safety issue, not just a get out of jail card.
Anyone who wishes to ignore it, that's their choice.
www.boltscience.com/pages/junkertestvideo.html
Regards,
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