alistairolsen
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| posted on 7/7/10 at 12:20 PM |
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Thread pitch conversion….
I want to use some wheel adaptors (mad from steel) somewhat like this:
Now the adaptors have studs facing outwards to take the new wheels so I can torque the new wheels to manufacturers settings.
The fixings holding the old wheels to the hubs were studs and nuts (M12x1.5mm) and will be replaced with bolts which obviously require to be larger
due to the hole left by the splined section of the stud (in this case 13.9mm meaning an M16 bolt is required)
For comparison, Vauxhall hubs use m12x1.5mm bolts to attach the wheels and these are tightened to 110Nm so I feel it is a same assumption that this
would be the situation if my hubs had used bolts rather than studs.
So, if I use some M16x2mm fixings to hold on these adaptors to what torque should I be tightening them? Do I compare the % of yield in the bolts? Or
the stretch? I suspect the usual answer of “as tight as you can get them and apply plenty of threadlock” will probably suffice but I’m curious what
the theory is!
Cheers!
[Edited on 7/7/10 by alistairolsen]
My Build Thread
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alistairolsen
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| posted on 7/7/10 at 12:55 PM |
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found this:
http://www.engineersedge.com/calculators/torque_calc.htm
and
http://www.thetoolhut.com/Torque-Conversion-Newton-Meters-Inch-Pounds.html
and working with a 12mm bolt at 110Nm found axial then worked back to torque and got a fraction under 147Nm but that takes no account of thread
pitch.......
My Build Thread
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indykid
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| posted on 7/7/10 at 02:57 PM |
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i could probably work it out for you but why would you want to do that? you probably need to give us a bit more info about the application
if you have studs, why not just use nuts and cut the studs down if required?
tom
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flak monkey
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| posted on 7/7/10 at 02:59 PM |
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You dont need to use bolts to hold the adaptors on, just use the original studs and nuts its much easier....
As for torques - I never bother on wheel nuts. Do them almost as tight as you can with a proper wheel brace from your cars kit and that will be the
right torque. There is a reason they are about 10" long....
Sera
http://www.motosera.com
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alistairolsen
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| posted on 7/7/10 at 03:08 PM |
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indykid: Im fitting a flat plate to the old ford hub so I can bolt landrover wheels on. Im using OE landrover studs recessed into the plate, and
machine screws into a threaded hub.
I cant use the original studs because I dont have enough thickness to use a nut and have it flush below the new wheel mounting face.
Flak monkey, the reasons for doing them up tight is to get them in the correct elastic range to prevent cyclic fatigue failures and gain the required
clamping pressure. The reason for using a torque wrench is to make sure they are all the same, otherwise they have a horrible tendency to come undone
on certain wheels.
Using a cars wheel brace takes no acount of the strength or weight of the person, or the angle of the wrench and theyre normally utterly horrible to
use so for all the time required I use a torque wrench.
Seeing as these bolts will be fitted once, and wont require to be disturbed to remove and refit wheels id prefer to know what value I need to aim for,
and apply them to that torque 9within the confines of the accuracy of the torque wrench)
Cheers
My Build Thread
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flak monkey
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| posted on 7/7/10 at 03:30 PM |
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I know all about the reasons for torquing nuts and bolts, believe me. I have never, ever had a wheel nut/bolt come undone or come loose or anything
similar and simply never bother to torque them. If torquing them makes you happy then go for it.
The optimum torque for a 12.9 M16 bolt is 288lbft for optimum clamping load which takes it to 70% of its yield strength.
I reckon you would rip the threads from the hub though as they are normally soft. You would be looking at using a toque of around 180-200lbft I would
think. But this significantly reduces your clamping load.
You need 7-9 turns of thread engagement on wheel nuts. How thick are your spacers going to be.
Sera
http://www.motosera.com
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alistairolsen
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| posted on 7/7/10 at 03:46 PM |
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I have had some come undone and have torques them ever since so we'll agree to disagree!
Yeah Id heard that it was meant to be close to 75% of yield to be in the appropriate elastic range.
I doubt this will be an issue, as it will still far exceed the clamping load of the original M12 done up to 110Nm which held the wheels on fine.
This is the big issue, the original hub which will be tapped is only about 12mm thick at a guess and the finest thread I can find is M16x2 which only
gives me 6 threads.....
Im not sure if I can torque the bolt so it will do its job without tearing it out of the hub (assuming that to do its job properly and not come undone
it has to be that tight)
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flak monkey
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| posted on 7/7/10 at 04:07 PM |
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Optimum thread strength on std pitch bolts is 1.5xD so no its not enough.
How thick are your spacers, are you sure you cant get enough threads engagement on nuts?
Sera
http://www.motosera.com
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alistairolsen
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| posted on 7/7/10 at 09:10 PM |
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its 14mm thick, and an M16 nut will be at least 10mm so i doubt it will work.
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indykid
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| posted on 8/7/10 at 09:13 PM |
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quote:
Originally posted by alistairolsen
its 14mm thick, and an M16 nut will be at least 10mm so i doubt it will work.
if it's 14mm thick, you've got planty for an m12x1.5 stud with a turned down nut.
like flak, i'm aware of the yield and the reason behind torque specs but likewise, i've never used a torque wrench on wheelnuts.
i don't quite understand why you want to overcomplicate it. is it because you'd need some nuts turning down? can you buy m16 bolts with a
60degree taper to fit the spacers?
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alistairolsen
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| posted on 9/7/10 at 06:38 AM |
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Im only 'overcomplicating' things because I dont see how I can get a full nut below the surface of the adaptor and still have sufficient
thickness of metal. If I machine down a nut Im back to the same issues as with the hubs (albeit a smaller thread size) because I wont have sufficient
threads.....
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flak monkey
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| posted on 9/7/10 at 06:39 AM |
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Buy new wheels of the correct offset? 
Sera
http://www.motosera.com
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indykid
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| posted on 9/7/10 at 03:02 PM |
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you take some standard m12x1.5, 60degree taper nuts......and you turn them down so they're 14mm long or however long they need to be to fit.
wheel nuts for steel wheels have a full hex after the taper so you'll still have enough to get a socket on. studlock them on and you're
away.
fwiw, sva only required 6 full turns on 60° taper wheel nuts.
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