Wheel studs in alloy hubs

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Wheel studs in alloy hubs

Postby Baggers » Tue Jul 09, 2019 8:39 pm

Hi all,

I'm trying to insert wheel studs into some DRD alloy hubs that I have. The holes in the hub are 12mm, but the studs I have are 12mm x 1.5 thread, but are about 12.5mm shank and 13.1mm spline diameter. I don't think these should be pressed in as they are, but I don't really know. Should the hub should be drilled out somewhat (maybe 1/2 inch) ? and then pressed in. Or do I need to get a different sized stud??

Thanks

Alex
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Re: Wheel studs in alloy hubs

Postby geofff » Wed Jul 10, 2019 9:07 am

Hi Baggers,

I cannot answer your question because I didn't measure my studs when I did a similar job on replacement Cortina alloy hubs several years ago (Westfield). They were a pig of a fit though and I had to use the stud nut to 'pull' them on as it were.

However I would like to add another question to the engineers out there: Aluminium upright holes and steel bolt shanks, do they cause lozenging? Do you need to have a steel insert? I'm thinking steering arm to track rod connection or where ball joints connect to uprights.

Ta

Geoff
:)
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Re: Wheel studs in alloy hubs

Postby Martin Kemp » Wed Jul 10, 2019 12:27 pm

The best thing would be to check with DRD. I think that the 12mm diameter is to correctly centralise the stud and the splines will cut and form matching splines in the hub. Increasing the hole size could lead to weaker hub splines which could fail- the wheels won't fall off but if the studs revolve in the hub it will be a hell of a job to get the wheels off.

On Geoff's question if the bolts are tightened to the correct torque and if there is sufficient land on the ally part to support the bolt tension the the holes should not elongate.
This is because a proper bolted joint relies on the friction of the 2 faces clamped together by the bolt tension not on shear in the bolt. Only if the bolt is not tight enough will the bolt apply any load to the sides of the hole.

Problems can occur if the bolt becomes loose, or the weaker material yields and reduces the bolt tension. Also if service loads exceed the limits of the joint stretching the bolt or collapsing the component materials and so reducing the tension in the bolt. Usually the bolt is still strong enough in shear to hold the parts together but this is when the holes start to elongate an things start rattling about.

The are plenty of tables of suitable bolt torque. The idea is to stretch the bolt so it acts as a spring to keep the joint tight. Usually it is less than you think on small bolts and more than you think on big ones.

Suspension joints with tapers work on the same principle but the taper puts an expanding load on the hole which needs to have sufficient surrounding material to support the load induced by the tension in the bolt and the service loads as well

Martin
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