UK Karting - Notice Board (General Karting) : Re: Wheel hub nut torque???

Notice Board (General Karting)

Re: Wheel hub nut torque???
Posted by 'SimonS' on 28 Jul 2014 @ 19:21

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SimonSJoined: December 2004
Total Posts: 4
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Various sources suggest that the proper torque for nuts on an 8mm bolt with 1.25mm pitch is between 18 and 26Nm, so torquing up to 25Nm is around the maximum you should be using.

The Kay nut or Jet nut has been found to have a drag torque value (ie the force needed to overcome the self locking) of about 1.5Nm. (http://www.vansaircraft.com/pdf/revisions/RV-12/05-10.pdf since Kay nuts are designed for aircraft)

So at 25NM you are actually achieving 23.5 NM of locking torque.

However I have looked at the wheels of one of your colleagues who complains quite regularly of shedding a wheel.

The centre of the rim is a precision cut hole. It fits with a sliding fit over the locator ring in the centre of the spider. A common fault is to fail to locate the rim evenly on the locator, with the rim pressed firmly against the spider before putting the nuts on. If the rim is not properly located, tightening the nuts will gouge out metal from the inside of the rim and from the locator as teh rim is pulled towards the spider face. In some case the wheel will jam even though the nuts appear to be tightened. Turning someone who doesn't appreciate the need to get the faces mating before tightening the nuts loose with an impact hammer is a recipe for disaster. Particularly dangerous is one of the new 18v impact hammers because they have a ferocious acceleration and appear to secure the wheel in an instant.

If the wheel is at a slight angle, either because it jammed or because it is supported clear of the face by a sliver of metal gouged off the locator or rim, then as soon as the wheel starts to turn it begins to work free. Once there is free movement it is highly likely that the nuts will dynamically undo, or the sideways loadings will break the studs.e Your colleague's wheels have got elongated holes and wear patterns ground into the alloy, showing where this has happened. In some cases the gouging of rim / locator has become so severe that the wheel cannot be located by hand properly, increasing the probability that the wheel won't be properly seated next time and will depart the kart yet again.

I have fairly forcibly suggested to your colleague that he gets rid of his powerful gun, puts the wheels on properly to start with, but words like "Water" and "Duck's Back" come to mind.

A few years ago (alright, a decade) I had similar problems and anyone whose locator or inside of the rims are chewed up is likely to suffer the problem.

Nor is the answer to widen out the inside of the rims / file off the circumference of the locator ring. Nor, since the locator is often a push fit into a rear spider is the answer to push it out, as a way to get a further 10mm per side reduction of rear track. The locator ring has a job to do in preventing the wheel from moving on its bolts and undoing the nuts / breaking the studs.

Torquing the nuts up is not the whole of the answer!

Message Thread:

Wheel hub nut torque??? by 'goman' (28 Jul 2014 @ 14:29)

Re: Wheel hub nut torque??? by 'buzzinrussell' (28 Jul 2014 @ 14:57)

Re: Wheel hub nut torque??? by 'SimonS' << You are here!

Re: Wheel hub nut torque??? by 'goman' (28 Jul 2014 @ 19:55)

Re: Wheel hub nut torque??? by 'alanrr' (28 Jul 2014 @ 20:13)

Re: Wheel hub nut torque??? by 'goman' (28 Jul 2014 @ 20:21)

Re: Wheel hub nut torque??? by 'SimonS' (28 Jul 2014 @ 21:52)

Re: Wheel hub nut torque??? by 'wavedyellow' (28 Jul 2014 @ 22:50)

Re: Wheel hub nut torque??? by 'wavedyellow' (28 Jul 2014 @ 22:52)

Re: Wheel hub nut torque??? by 'alanrr' (28 Jul 2014 @ 23:12)

Re: Wheel hub nut torque??? by 'Ditch' (29 Jul 2014 @ 6:58)

Re: Wheel hub nut torque??? by 'BanzaiBoy' (29 Jul 2014 @ 7:25)

Re: Wheel hub nut torque??? by 'Hootsman' (29 Jul 2014 @ 10:31)

Re: Wheel hub nut torque??? by 'alanrr' (29 Jul 2014 @ 10:47)

Re: Wheel hub nut torque??? by 'alanrr' (29 Jul 2014 @ 10:32)

Re: Wheel hub nut torque??? by 'wavedyellow' (29 Jul 2014 @ 18:01)

Waved Yellow by 'alanrr' (30 Jul 2014 @ 10:41)

Re: Wheel hub nut torque??? by 'SimonS' (29 Jul 2014 @ 15:38)

Re: Wheel hub nut torque??? by 'goman' (29 Jul 2014 @ 18:10)

Re: Wheel hub nut torque??? by 'bwfcste' (29 Jul 2014 @ 19:49)

Re: Wheel hub nut torque??? by 'RevvedUp' (03 Aug 2014 @ 12:52)

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