Another Nissan loses a wheel

If you were doing 120 in Queerland you would have more to worry about than roadtrains.


Spooks in the bushes with cameras.


LOL

In the past there have been lots of threads on Patrols with factory alloys loosing wheels (i can remember any cases when steel wheels have been fitted) but i dont remember reading if there had been a definite cause found

Regards Don

Michael

I have seen wheel bearing cones cracked in half after impacts with gutters so I suppose a collision with another car could damage a wheel stud. The problem with studs is you usually can't see just by looking at them.

The most common problem with wheels coming off seems to be nut tension and doing then up very tight is not the answer. The importance of this was stressed during a trade course at TAFE many years ago. We were shown how the area around the stud on steel wheels does not touch the hub. It is designed to bend as the nut is brought up to the correct tension. Tapered holes in alloy wheels are said to enlage slightly as the nut is tightened. I have used tension wrenches on all of my cars ever since and never had a problem.

If you had your tyres fitted by a tyre service using a rattle gun then that could have been the start of your problems. The tension on my six stud ute for example is 25 ft lbs less than the five stud 2wd version of the same model. The five stud Landcruiser is double the tension of mine. If you get it wrong you will end up with either loose nuts or stretched studs that are on their way to breaking. The nuts should also be tightened in the correct sequencs.

If your tyre service did not adjust their gun to the correct tension for your car and the gun was accurate then who knows what they set them at.

The following two links give some usefull information on wheel nut tensions and causes of stud failure. The first mentions near side rear wheels coming loose and possible causes of it..

http://www.boltscience.com/pages/failure4.htm

http://www.caravanandmotorhomebooks.com/articles/why_wheels_fall_off.html

The thought of you "doing 120 out the back of Charleville while approaching a roadtrain" with the missus and 2 tin lids on board is enough to give me nightmares. Why such a bloody rush?

It is a well known that this is a frequent occourance on Nissan patrols we had one fall off last year and the driver was told at the road house they have one a week come in and it is always left rear regards Alan.

THis may be a frequent occurrence on Nissan Patrols but I have seen it happen on Toyota Landcruisers and Honda Accords.

I had issues with over tightened wheel nuts years ago and did a bit of investigating. It seems that there are two main causes for wheel nut or stud damage. The first is under-tightening of wheel nuts and the second is over tightening. The primary cause of both is rattle guns at tyre shops.

If you look in a workshop manual for any vehicle it will specify a torque for the wheel nuts. On a Nissan Patrol with steel wheels, that is 80 foot pounds, a lot less than most people would imagine.

Following my research I decided to check and re-tighten my wheel nuts using a torque wrench. Now some people have said that is a bit over the top "just make sure they are good and tight!" is what is constantly thrown at me, even by my brother the mechanical engineer. It actually takes me less than 1 minute to put the torque wrench over the 6 studs on a wheel. I start at 60 ft/lb then 70 and finally 80. I have never had a problem since I started doing this.

Is that a bit obsessive? Ask what the guy with the Landcruiser 200km south of Birdsville or the guy with the Honda at Hattah in Victoria. Having a wheel fall off at 120km/h or even 20km/h or any other speed is not fun.

A lot of people on this forum make a big deal about manufacturers specs, the wheel nut thing is too easy to overlook and very easy to get right.

Duncs

Michael, maybe I've missed something obvious here, but when the wheel came off, were the studs still intact or broken? In other words, what caused the wheel to come off - the nuts working loose and falling off, or the studs breaking (with the nuts still on them)?

Well, from what I've seen, Nissan are using the same 'acorn' nuts on their alloy wheels as they've always used on the steel wheels, and I reckon that this is the root of the problem...

According to folk who are more knowledgeable than I, the correct nuts for (taper seat) alloy wheels are the 'bulge acorn' type, as shown here

Gorilla lug nuts

The bulge nuts are said to have a 60% greater seating surface (when used with alloys) than the standard acorn nut, and are much better matched to the machined recess in the alloy wheel..

Combine under-size studs with incorrect nuts, poor seating/tightening techique, and, well, 'taint no surprise to me that these incidents continue to occur.............

Don't know if this is right, just another theory.

My mechanic showed me there is a little lip on the Patrol rear wheel hub assembly and if the wheel doesn't sit on this properly then there is the potential for the wheel to work loose and eventually come off. It is small so can be missed easily.

Just my bit.

Cheers
Ev

My Nissan GU (Y61) workshop manual specifies 118-147Nm or 87-108 ftlb not the 80 ftlb as quoted above

The other major contributing factor that I see here is stud length/ thread engagement...

The alloy wheels have a substantially thicker mounting pad than the steels, but the studs are the same length, resulting in a correspondingly shorter thread engagement...
All very well nuts are torqued up correctly, and regularly checked, but as we all know, in the 'real world', this does not always happen...

That's when it all goes pear-shaped, as there is absolutely no margin for error...

Anyway, I've 'put my money where my mouth is', and replaced all of my studs w/- custom made ½" ones (cheaper than off-the -shelf Nissan ones), and they are also 6mm longer...

Thanks for the thoughtful replies.

By the time the wheel came off, three studs had broken, but by the rub marks on the inside of the wheel and the fact only five of the holes had been elongated, it seems the first stud broke clean off, then the rest worked loose.

I can't see any other explanation other than the stud had a hairline crack in it after the accident. The combination of torqued-up nuts at the tyre joint and a lot of km has caused it to break off. The rest must have worked loose and when the next two studs broke, the wheel came off. The hub/brake assembly landed inside the wheel thereby saving the bottom of the disc from scraping on the road (although it was damaged beyond repair anyway...)

Needed new wheel, new studs, brake disc, backing plate, and a set of wheelnuts. Thanks to the mechanic who got us back on the road today!



As for the "rush"; with the time I had, we had to get from Wagga to Charters Towers in two days, then 3 weeks to get home...