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WesBrooks

Causes for loss of wheel?

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Hello,

There was a recent case in the media covering an accident where a wheel came free from a modified mk1 Discovery and collided with a pedestrian. I'm not in any way interested in fault in this accident. I do however want to understand the possible route causes and mitigate the risk in my build as far as possible.

I've read in other posts in this forum in the past that certain single point component failures can lead to the wheel detaching from the vehicle. Other than the wheel bolts (which arguably are not a single point of failure) what are these single points of failure that can lead to the loss of a wheel? Differential to hub shafts? Bearing failure? Are there advised preventative maintenance/inspection tasks relating to these items or is it predominantly random failures?

Edited by WesBrooks

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A wheel coming off the vehicle in my eyes is only going to happen from loose wheel nuts on either the wheels to hubs or if spacers are fitted, the nuts holding them to the hub.

I don't think a wheel bearing failure is going to let the hub come off the stub axle completely? I'd need to have a look at one again. The other possible failures like a failed swivel ball, the wheel would be partially restrained by the half shaft, should at least stop it over taking the car.

I think the preventative maintenance stuff is just checking the wheelnuts as you should anyway, and even more so if you've got spacers fitted.

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In my experience the most common cause, other than  wheel nuts themselves being loose, is when wheel SPACERS are fitted, and the securing nuts are either not tightened adequately, and have become looser and looser over time. When a road wheel is fitted is it not possible to simply look and see if the spacer is secure.

When a spacer is installed, it is not so easy to fully tighten the nuts as absence of the road wheel means you don't have that resistance to tighten against.

Hope that makes sense.

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Alloys have a stricter process than steel wheels, requiring proper torque and at retightening after 50 miles. This could be easy to get wrong. Would probably count for spacers too if they're alloy

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Stub axle bolts too. I once bought some M10 bolts from eBay to replace with new. When tightening, they never got to the right torque. They were actually stretching before it got there. I looked closer and they weren't rated, unlike the advert said. So I put the old ones back on. If they failed the only thing holding the wheel on would be the disk to caliper interface, i.e nothing

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Thanks for the comments. I was planning on using 8J ET0 modulars which off the top of my head shift them out a further 30mm. I needed this to have the inner edge of the tyre in a similar position to a standard set up with the larger ~33" diameter tyres. I am aware that this may give the bearings a harder time but I was expecting a lot of warning signs before something as catastrophic as this would occur.

The larger tyre would however increase the torque loadings on the half shafts. I was originally liking someone else's idea of using these as a weak point to protect other more expensive items in the drive train. But I will be pouring over the axle rebuild threads to get a better idea of them!

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1 minute ago, dailysleaze said:

Stub axle bolts too. I once bought some M10 bolts from eBay to replace with new. When tightening, they never got to the right torque. They were actually stretching before it got there. I looked closer and they weren't rated, unlike the advert said. So I put the old ones back on. If they failed the only thing holding the wheel on would be the disk to caliper interface, i.e nothing

This was probably what I had picked up on, thanks. I'll make sure I have a close look at these.

So these bolts hold the hub assembly to the half shaft? If the half shaft snapped would it not have the same effect?

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I know the story you mean, very sad.

I had a wheel come off my trailer once, I wasn't towing it at the time I had lent it to someone so can't be 100% sure of the cause. They didn't know it had come off for some time as the trailer was empty. The studs had sheared and the drum was too stiff to turn by hand, when I took the drum apart the only fault I could find was the spring holding the shoe in wasn't there and the shoe had twisted and jammed in the drum. All I can assume is that this had failed for whatever reason (age maybe?), however has the driver didn't notice I can't imagine the wheel had completely locked, even if it had you wouldn't expect it to shear the studs, so I think it must have just got that hot that the studs expanded enough release the tension and allow the wheel to fatigue the studs? I've replaced all the springs on the trailer and it's been ok since...

I had a wheel fall off my SJ (offroad only) a few times, I'd done a rear disk conversion and gone from alloys to steel wheels, every so often the back wheels would come loose but not the fronts. I swapped to a different type of wheel nut and it was fine after that. I know steels and alloys can have different leads on the nuts but I don't know why it was only the backs?

The same SJ I had a problem where the brakes would have to be pumped a few times before it would grab but if you braked again straight away it would be fine. I tried all sorts to find out what was wrong with the brakes but in the end it turned out it was a wheel bearing that was on the way out, it was allowing the disk to push the piston back in so you had to pump a few times before it would grab.

This is also why I never ran my offroaders on the road as I don't have the time to check stuff like this everytime I went offroading and the amount of abuse they got there was always bound to be something.

Then there's this which I pinched off someone elses facebook, who says LR shafts are weak :)

Screenshot_20171029-153236_zpshxfjthuf.p

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26 minutes ago, WesBrooks said:

So these bolts hold the hub assembly to the half shaft? If the half shaft snapped would it not have the same effect?

They bridge the hub to the axle, by way of the bearing lock nuts tightening the hub to the stub axle shoulder. The half shafts aren't attached at the diff end, so the whole lot can come out.

IMGP7009.thumb.JPG.3aa8410b9ff0d5695671895e3e86f5c4.JPG

On the front axle there are swivel housing bolts that also have the same hub-axle interface, but if they failed there are also the track rods holding this section. The rear wheel is more likely to totally detach from the axle, but the stub axle bolts failing would allow it all to come away on both axles (given the calipers not retaining the wheels).

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The bigger the wheel, the greater its mass and the greater all forces, especially gyroscopic, and the greater the diameter for a set mass, the greater the gyroscopic forces.  That is a big factor to consider when fitting oversize tyres and wheels.  You'd have to go very large to overstress the hubs, studs and wheels if they're genuine and in good order, but it could be done.  But the main causes are the nuts not being tightened enough or being overtightened and cracking the hub flange or shearing the stud.  Ask yourself how many times you see "professional" tyre fitters just use an air gun to tighten the nuts, banging away to get them as tight as possible without a thought to torque specifications.

There are two more issues pertinent to LRs.  One is spacers, which as mentioned by MickeyW, not only have a nasty habit of slackening, but are hidden by the wheel and awkward to check.  The other is fitting LR alloys to older Defenders with the thick hubs; the alloys don't fit the hubs and a 3mm gap between the back face of the wheel and hub flange is typical, but this is impossible to see.  Tightening the nuts gives the impression the wheel is correctly fitted, but it is in a very dangerous condition.

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Yes, that is the case that triggered me into thinking about it in far more detail. I'd suggest it wise not to delve to much into the specifics of that case as it is active, and there is a good chance it maybe someone from this forum. It's a gut wrenching case with a recently new owner of the truck and the girl passing following the accident. I feel there's a fine line between rubber necking style reactions and genuinely wanting to make sure I've minimised the risk of it happening on other cars.

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4 minutes ago, Snagger said:

Ask yourself how many times you see "professional" tyre fitters just use an air gun to tighten the nuts, banging away to get them as tight as possible without a thought to torque specifications.

I've actually had a stand up row in a Skoda dealership after I damaged the lock nuts trying to remove them after a service. Demanded they replaced them all. It's been high on my priority list to replace the standard wheel bolts too. I didn't see them wizzy gun them on but I couldn't shift them with a length of pipe on my breaker bar!

Got a torque wrench in my boot at the moment as I've just fitted the spare wheel due to a punture. But I am certainly not infallible. Had a wheel work loose earlier this year but caught it just before it went AWOL. The was on a standard road going car whose biggest bump is a pot hole. Perhaps why this case struck such a resonance with myself.

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It happens a lot.  My wife had to take my 109 in for a drive flange gasket after I had emigrated but before she followed.  It was done by a friend at an LR specialist.  He claims he tightened the nuts but clearly didn't - she phoned me to say there was knocking on the way home from Nottingham, but she couldn't find a loose wheel when I said to rock them by hand.  She took it back to the garage and another guy spotted swarf around the wheel nuts (alloys); dead giveaway.  Innocent mistake, but the pros are even more prone to it than us because of rushing and often a level of complacency.

I had the spacers problem myself in the past, using steel spacers and steel wheels.  The nuts would unwind behind the wheels very quickly, even when thread lock was used (and correctly torqued up).

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There was an 'issue' with defective welding on some Defender axles which potentially could result in the front wheel, hub, stub-axle, swivel etc. separating itself from the main axle-tube.

"MY2011/2012 Recall Action P047/048 Front Axle Case" -


http://www.defender2.net/gallery/albums/userpics/11689/P047a3~0.pdf

Rather than properly fixing the problem the recall involves a bracket to keep the stub-axle/swivel in place if the welds do fail!

Edited by Tanuki

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It' common in caravans, whenever I take mine for a service they make you witness them torquing   the nuts and you sign to say you will check them in 50 miles.

The tyre place I use always torque wheels properly, partly why I use them.

On lorry wheels they say look for rusty or dirty lines coming away from the nuts as a sign they're loose. Not sure how well it would work on a car but worth looking for.

I've always found just wobbling the wheel doesn't show loose nuts as the car is too heavy to notice. 

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13 hours ago, Cynic-al said:

It' common in caravans, whenever I take mine for a service they make you witness them torquing   the nuts and you sign to say you will check them in 50 miles.

The tyre place I use always torque wheels properly, partly why I use them.

On lorry wheels they say look for rusty or dirty lines coming away from the nuts as a sign they're loose. Not sure how well it would work on a car but worth looking for.

I've always found just wobbling the wheel doesn't show loose nuts as the car is too heavy to notice. 

It seems to be something that's changing, as a kid I never remember seeing any tyre fitter using a torque wrench, but in the 10 years I've been driving myself they've always used a torque wrench for the final torque.

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13 minutes ago, landroversforever said:

It seems to be something that's changing, as a kid I never remember seeing any tyre fitter using a torque wrench, but in the 10 years I've been driving myself they've always used a torque wrench for the final torque.

It has been getting better. There was a big fuss around the time I started driving about people needing to call recovery out to change wheels where both the situation and people involved should have been fine changing the wheels. My daily driver (2009 reg Skoda Superb) only needs 120Nm of torque. This is well within the strength of most able bodied people with a good wheel brace. This is unless of course the wheel hasn't been removed for a long time and has corroded in place, but this only really indicates that the car isn't checked over well enough on a regular basis as disks and pads can't really be checked well until the wheels are off.

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I had 4 new tyres fitted to the classic a few years ago, went straight from the tyre fitters to the airport to collect the other half, coming back from the airport on a dual-carriageway I thought there was a slight vibration but there wasn't anywhere to stop and I put it down to improper wheel balance. Got home and checked, one of the front wheels was loose! The garage appologised and claimed they had torqued them up but that would suggest otherwise.

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Lots of possible causes, a case here (fortunately off road) where not one but both swivels sheared, so both front wheels came off. Aftermarket parts of course. A seized wheel bearing will eventually shear off the stub axle but you'd have to be pretty deaf not to notice the noise!

However losing wheels is 90% due to wheel nuts coming off in my experience, and I guess spacers make that a bigger problem from the previous replies. Never have used them and never will.

If anybody else has had a wheel off any of our vehicles for any reason at all I will always go around it and check the nuts myself.

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I know you weren't particularly interested in loose wheel nuts, just wanted to say that sometimes there is little warning. I lost a wheel before on the 110, the wheel hadn't been removed in 6 months and had gone through an MOT a few months before it happened. The only thing I can put it down to was clipping an embankment at very low speed (passing a van down a very narrow country lane) a few days prior to the journey during which it came off.

The only warning sign was a small vibration which made me decide to pull over, the wheel came off whilst I was changing lanes to pull over. The dash cam footage shows how little warning there was, and the music wasn't that loud. 

 

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Had a front wheel come off a 2a 109 many years ago. Going round a corner quite slowly, thank goodness. All wheel nuts present and correct, but wheel 50 yards up the road. Do you remember the long wheel nuts with a taper on each end? Apparently over the years they had been over-tightened so many times they had gradually cut through the wheel rim to the point where it finally gave up the struggle

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Main thing for any drum brake rear axle is if the wheel bearing is finished; I had this on the front axle of the S3, and the only way I noticed was that the wheel had a lot of camber. The hub stayed with the front driveshat with the circlip. No such luck at the back though, as the diff end is not held captive.

On disc axles, the hub will always stay captive with the brake caliper. 

I had recently a wheel coming loose, which I had done up with a rattle gun. I just did it up until I heard it rattle. But the thread was contaminated , which caused the wheel nut to seize on the thread, rather than on the wheel. Luckily, you get a warning, as you can hear there is a wheel loose. I now always do up by hand to be sure.

Also be carefull if you change a wheel in the mud; if there is dirt in between the mounting face and the wheel, that could work loose.

I had an old wheel once that seem to have worn on the nut contact faces; you could do it up tight, but it would come loose after a few miles; There was no real solution short of binning this wheel.

I don't think wheel size or offset is going to remotely worry the stud pattern, the M16 studs on that diameter are way overkill. People have been using massive 40" tyres with big offsets and not break the studs.

 

large.rangeroverwheeldeath.jpg.eb1d576257e4c772d66e3358ef917a63.jpg

I know it is not very clear from the picture, but It looks to me that the disco has alloy wheels with spacers as they stick out side the body and has wheel arch extensions. The spacers are not preferred in my opinion, especially when they are aluminium; they can relax and the wheel can work loose, with disastrous results. But as said it is early to draw conclusions. It will be worth keeping an eye on what happened on this occasion as i am sure there will be an investigation. It is a tragedy though.

 

Daan

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On 19/03/2018 at 1:30 PM, WesBrooks said:

So these bolts hold the hub assembly to the half shaft? If the half shaft snapped would it not have the same effect?

The half shafts are fully floating and don't take any side-loads, so unlike some other 4x4's and trucks the half-shaft isn't holding the wheel on. Seen a few vehicles (everything from Lada to Land Cruiser) where they have a different design and the wheel gradually gets further and further away from the car until the shaft falls out or someone notices!

Spacers are IMHO evil things, they just add so much opportunity for mistakes, failures, and poor manufacturing / materials never mind the extra load due to offset.

The linked article certainly gives pause for thought for everyone who's modded their vehicle and/or ever bodged something in a hurry - picture yourself standing in court defending your handiwork having killed someone's kid and ask yourself how confident you'd be arguing your side.

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6 hours ago, CwazyWabbit said:

I know you weren't particularly interested in loose wheel nuts, just wanted to say that sometimes there is little warning.

 

No problem. I only intended to make sure the wheel bolts/nuts didn't become the sole fixation of the thread. To be honest I've a better understanding of the issues around alloys and loosening bolts following this thread and am happier with my decision to use steel modulars over alloys.

I've heard of spacers being banned in some territories and didn't fully understand the issues with them, but also weren't considering using them so hadn't needed to understand the issues better. If they are a contributing factor here then I could see them working their way into the list of MOT failure triggers.

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