Tension Tension

Submitted: Tuesday, May 29, 2007 at 09:00

ThreadID: 46016 Views:3511 Replies:8 FollowUps:8

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Member - Kevin J (QLD)

Have been trying to assertain the correct tension - or near enough - for the wheel nuts on the 'cubby-house'.
Our tandem van is fitted with ROH 15" white steel wheels and various posts on a range of forums have indicated that there could be a problem with the nuts on these coming loose in operation. While these anecdotal comments are unconfirmed I wish to be sure rather than sorry so have acquired a torque wrench and now only need a figure to work to.

Anyone?

I too have taken the plunge and acquired membership of Explore Oz after many moons lurking in the wings.. The offer just made it impossible to say no. I will set up profile etc much later. Time is against me just now as we are about to head out to western Queensland for about two months to work as 'Drought Assistance Volunteers" and there are about a million things left to do. Not knowing what we will be doing makes it a little difficult to decide just what gear to take so I'm doing a lot of 'Put it in the truck. Take it out of the truck'. Any odds I will end up without what I need?

Kevin J

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Reply By: Member - Phil G (SA) - Tuesday, May 29, 2007 at 09:31

Tuesday, May 29, 2007 at 09:31

If the studs are 12mm, then about 110Nm should be OK.
A bit of antisieze (or grease) on the threads helps them to torque up correctly, and makes undoing them easier

AnswerID: 243104

Follow Up By: Stevo - Tuesday, May 29, 2007 at 13:53

Tuesday, May 29, 2007 at 13:53

Any form of lubricant is an absolute NO, NO.
Wheel stud torque specifications are for clean and dry threads (no lubricant) that are free of dirt, grit, etc. Applying oil, grease or anti-seize lubricants to the threads will result in inaccurate torque values that over tighten the wheels.

FollowupID: 504142

Follow Up By: Member - Pesty (SA) - Tuesday, May 29, 2007 at 20:58

Tuesday, May 29, 2007 at 20:58

Sorry Stevo,
But im with Phil, have been greasing wheel studs for a very long time, and never been a problem, and i run 10 vehicles and trailers.
My theory is that you can get a better tighten if all is smooth running, and it makes getting undone easier.
Recently bought a s/h 4 ton truck and i had to use 4feet of pipe over wheel spanner to crack them, and they went off like a cannon when they let go. Absolutely rediculous to make them so tight.

Cheers Pesty

FollowupID: 504254

Follow Up By: Member - Phil G (SA) - Wednesday, May 30, 2007 at 08:22

Wednesday, May 30, 2007 at 08:22

Its an interesting argument. My Toyota manual specifically states "do not grease the wheel nuts", and I'm guessing they do because theres a chance they will work loose.

But I've seen a few wheel studs break off in the back of nowhere - often when untightening to replace a flat tyre on an older vehicle - and the rest of the nuts don't undo smoothly - you have to put the waterpipe on it to loosen them.

With the greased studs, you have to regularly check for tightness, which I do anyway - they usually tighten up a little after about 1000k, and then are fine after that.

Also I'm no expert, but I'd expect a smooth thread to torque up more accurately than one that was sticking. Isn't that why we lube clean threads on cylinder head bolts?

FollowupID: 504344

Follow Up By: Robin Miller - Wednesday, May 30, 2007 at 09:10

Wednesday, May 30, 2007 at 09:10

This is an interesting point , that needs exploring , have no definitive answer but
I have always used a light smear of (normal) grease and ensured the wheels nuts run freely.

To extent that have a tap/die that I run over stud threads/nuts if ever one doesn't feel like it did up right.

Also do not torque up wheels to a spec but rather go around them 2 or 3 times
with a brace, ensure that they are not done up hard but rather that they are done up evenly.

Also try and just touch up wheel nuts some km's after my frequent wheel changes.
Once every 4 or 5 changes I do find one nut or so that is a little slacker than others.

There have been articles on how unreliable torque wrenches can be unless everthing is in good order , and I based my approach on policy of a Toyota dealership service chain.

The bottom line being that consistent even and reasonable tension was more important than any given setting.

Anyway , don't carry torque wrench into bush

Robin Miller

Robin Miller

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FollowupID: 504359

Follow Up By: Stevo - Wednesday, May 30, 2007 at 09:44

Wednesday, May 30, 2007 at 09:44

Torque is made up of three components - thread friction, mating surface friction and the resilience or "stretch" and "rebound" of the bolt itself.

In certain applications lubricants are required to be applied to bolts. In these situations the manufacturer will stipulate the type of lubricant required. It is important that the recommended lubricant be used as it will have a known coefficient of friction and this has been taken into consideration when the engineer calculates the required torque value for the particular situation.

Unless a manufacturer states otherwise, the use of any form of lubricant on wheel studs should NOT be used.

There is a very real risk that you will over torque the stud to the point where it becomes stretched too much – you have exceeded the yield strength and it’s ruined. If the wheel stud is longer than manufactured it is in a partially failed condition.

FollowupID: 504364

Follow Up By: Robin Miller - Wednesday, May 30, 2007 at 10:31

Wednesday, May 30, 2007 at 10:31

Hi Stevo

Because of these two different approaches , I am wondering if there is some hidden factor or reason why so many places do it differently, and what is there logic behind the theory.

Perhaps the difficulty of getting a correct torque setting because of thread imperfections overrides other concerns and light grease smear makes that approach more consistent and practical - don't know.

Robin Miller

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FollowupID: 504375

Follow Up By: Member - Phil G (SA) - Wednesday, May 30, 2007 at 12:57

Wednesday, May 30, 2007 at 12:57

Stevo,
Nice explanation. I understand a little better.
So what happens with time? We all know how nice the nuts do up on a new vehicle - no doubt that's the ideal, but with time due to corrosion, dirt or whatever, the silly things seem to get more prone to binding. Perhaps thats why its been popular to slip the anti-sieze or grease on.
I would guess that studs should be maintained with a wire brush, and nuts should be cleaned to prevent binding.

FollowupID: 504407

Follow Up By: Stevo - Wednesday, May 30, 2007 at 13:39

Wednesday, May 30, 2007 at 13:39

Gooday Phil,

as you say the studs and wheel nuts should be maintained, with the threads and mating surfaces kept in a clean condition. But hey we all know this is a totally impractical situation and wheel nuts will always bind to a certain extent over time (unless you grease them up !!).

Your comment about how easy wheel nuts do up on a new vehicle is interesting (and I agree). However, in theory friction is at its highest value when a fastener is first tightened. Each additional time a fastener is torqued and loosened, this value gets smaller. Eventually the friction levels out and becomes constant for all following repetitions.

This is the reasoning beind the recommendation that new fasteners be tightened and loosened through several cycles before applying final torque (I wonder if vehicle manufacturers do this with wheel nuts ??).