Sevice wheelnut tightening
Comments
-
Where have I said the bolts snap?
I have said no such thing nor have I said here in our case the bolts are taken into yield.
What I am saying is the wheel will be on its way off, long before the bolt and its tell tale ever rotate. Any rotation happens at the very end long after the wheel is shuffling about unretained just held loosely on the bolts.
Vital in wheel retention is retaining adequate tension in the bolt, that can be lost, and typically is, without the bolt turning at all.
0 -
I think he might argue that point. I can’t argue if he is right or wrong because what I have read on here might be wrong. Every caravan service I have had the person torquing the wheel nuts has never slackened them off 1st. I have had my vans serviced at various ncc workshops just for warranty purposes. Maybe the ncc should send out instructions of how do do this task proper especially if from what I read on here it is wrong.
0 -
but when checking wheel bolts/nuts, you're checking them for being slack and assume that when they were originally fitted they were torqued up correctly. If when checking them 20 miles up the road after a tyre change etc you slackened them first you'd end up in ever decreasing circles of slackening & tightening bolts/nuts every 20 miles.
I get the slackening bit when the wheel was originally fitted. I tried to reason this point at a high street tyre place after he'd fitted a wheel to my car using a windy rattle gun. The torque wrench did not move the bolt at all ...... it went completely over his head.
1 -
As a blanket statement without history that's rubbish.
If a bolt has been torqued correctly it will have been 'stretched' to within safe limits along its length, and will return to its original length when loosened, allowing re-use.
However without knowing its history the bolt may have been overtightened, in which case its elasticity has already been ruined and no correct torquing will bring that bolt back to its original shape.
If you are not certain then replace the bolts, as loosening and re torquing means nothing without knowing what went on before.
1 -
And if he had first slackened over torqued up bolts with it without resetting way above the required value he would most probably negated the calibration.
If on the road you just check the bolts have not relaxed enough for the torque wrench to advance them, you will have IMO done all that is sensibly necessary.
Bolts in this application that are not renewed each tightening, as the plating condition has an important influence on their friction so the tension developed, don't have the degree of precision others are implying. It is therefore all a bit academic if they need loosening or not, just rechecking they are that tight is all that IMO is necessary, and without carrying a breaker bar as well as a [break] torque wrench all that is sensible to do at the roadside.
I have never seen an Al-Ko published technique statement that the re-torque requires loosening. Where have others found this mandated?0 -
In fifty odd years of driving, I've only been torquing wheelnuts on caravan or cars in the last five years, not having owned a wrench previously. The only time I ever had a problem was after a tyre replacement by a garage who obviously hadn't tightened the nuts properly and became evident when the steering was all over the place. I stopped and used my wheel wrench to tighten them and continued on my journey. I think we can get a bit too paranoid about this.
5 -
It was the one and never again Eldiss but as I was advised by the motorway patrol the off side was also loose but the wheel rotation on the near side "assists" in studs ,if loose, undoing,it was all down to the dealers,"pre delivery "? check not being carried out,
The Bailey problem has been sorted by fitting security studs to the wheels, but then i have since found out that other makes also had the same problem when on Alko chassis, always it seems the nearside wheels, as above probably
Since fitting tell tales on our last two Bailey caravans ,I have not used our torque wrench and we did ,just under 3000 miles towing on UK roads last year
0 -
Another "theory"put forward as to loose wheel studs is that it has been more prevelent since alloy wheels have been fitted and the different metals steel brake drums expanding differently ,how that pans out compaired to cars I do not know unless caravan wheels are more suseptable to higher heat and stress when traveliing
, 1 -
"So you are saying the threads on wheel bolts are so short that it will not show on a tell tale untill to late, that sounds a bit of poor engineering"
No again I am not saying that at all.
I am saying bolts don't turn, so tell tales don't move until it is too late, in that they only self turn when the required tension is too low to stop them turning. By which time with just 5 bolts, so no spare players, it is way too late to retain the wheel firmly clamped in place.
-------------------------------------------------------------
The short issue is separate, it is not limited to the threaded section, but the bit of every bolted together application that is elastically strained. Typically the section strained is between the underside of the head and the start of the "nut's" thread, it fits into.
Bolts just like rubber rod "stretch" [in the pre yielding sense] and it is that strain stretching that generates the clamping force that hold the wheel to the hub in our bolting application. If it did not store that clamping energy, as soon as you stopped turning the bolt the force would disappear.
Here you need to understand the wheels are clamped to the hub and it is the interplay of the clamping force and the friction between the clamped bit as the only thing holding the wheel in place normal to the bolts. Here as is almost always the case with vehicle wheels, pre, the wheel starting to come free, and moved onto the bolt shanks the bolt serves no physical retention role. It just applies that required force for the friction to do all the holding.
Where the length plays a part is in the amount of energy it can hold. Think if you had two elastic bands, one of about 3 times the length of the other. Pull each apart with the same force, then relax each by a couple of inches, you will find that the force on each is very different, the third length band will lose far more than the longer band.
Exactly the same will happen with the elastic energy in the wheel bolt, with equal levels of clamped surface settlement between the wheel and the hub. The shorter the bolt the greater the loss in its clamping force. Hence, why to best retain wheels the stretched length of the bolt is an important player, and the longer that is the higher the margin is on retaining an adequate clamping force.
It is nothing to do with “poor design” as long as the length is adequate to accommodate the settlement that could occur. Increasing the length brings increased tolerance to settlement, hence WSL marketing bolts using the age old technique of collars; they are simply safer should settlement ever occur, some always does.
Our standard bolts, as well proven, are adequate as long as we re torque as the makers mandate, so ensuring they are fully recharged with energy once any initial settlement has occurred. WSL are very much more tolerant, but I with our van don't see a need for them as I know what I should be doing.0 -
Because, maybe like me, unless the wheel(s) have been removed I don't bother.
Most know the reasoning behind it all, but in reality it is a rare occurrence.
Take cars for instance, you go into a garage for new tyres. Wheels put back on and air gunned, then torque wrench applied and they always click but never turn so already over tightened, but never lost a wheel yet.
0 -
I am sure that is because most people who lose a caravan wheel will at least pick the wheel up?
IMO they are a bit too valuable as well as posibly needed, just to leave them there "littering" the verge. Then there could be needed of it in support of an insurance claim.
So, not seeing the roads littered with them is no great surpise, and no indication it never occurs.
That caravans do lose wheels is a fact, I have actually seen it a few 10s of metres in front of me. We have friends who have had it happen, plus on forums it has been reported, a little seaching could well find cases.
A product was even brought to market to mitigate against wheel lose, and one manufacturer adopted them as a standard build feature. I suspect not simply to make their build cost higher but because of a need.
0 -
I don't own a torque wrench but I wouldn't trust the little wrench that comes with the van. I have a socket on the end of a 1ft bar (about the same length as a torque wrench). In the motor trade we had a highly technical universal setting called "FT". I leave you to work that one out, but it basically means that as long as you're not standing on the end of a 6ft scaffold pole, one hard shove on each nut before every trip will pretty much guarantee your wheel will stay put. One serious point though, a nut/bolt/stud that constantly needs re-tightening is a clear pointer that either the thread is worn or the bolt/stud is over stretched and should be replaced.
0
