Wheel Bolt Knurl Press Fit Interference

[Billybaru]

We have a 9/16-18 wheel bolt with a straight knurl under the head. What is the typical interference? The low diameter over the knurls is 0.6305. Approximate contact length in the mating part is 0.065 (steel is 1/8" thick and 0.060 max length under head to start of knurl).
Thanks!

 

[desertfox]

Hi Billybaru

You can't reliably come up with a typical interference, interference fits depend on function and in addition there is no need to knurl a diameter to generate a interference fit.

Regards

desertfox

 

[TVP]

A typical interference for wheel studs with knurls/splines/serrations would be as follows (sorry everything is SI units):

hole diameter = minimum spline/knurl diameter - 0.1 mm

So, for an M12 wheel stud, the hole diameter would be 12.73-12.76 mm, and the spline/knurl diameter would be 12.83-12.86 mm.

 

[patdaly]

I have to ask, is this 9/16-18 stud going into a 1/8" thick hub?

I would think you would distort the hub long before you pulled the stud in with any appreciable interference.

What is the application?

 

[TVP]

Billybaru,

I forgot to post a link that shows a variety of knurled/splined/serrated wheel studs:

http://www.forma-tech.com/downloads/Catalogo Colonnette Zigrinate.pdf

patdaly,

The interference fit is so that there is torsional resistance between the fastener and the hub during tightening of the wheel to the hub.

 

[patdaly]

TVP, I figured that was the case, I was just intrigued by the 1/8" hub section and the need for a 9/16" stud. It could well be a scalloped hub though.

 

[Billybaru]

Thanks all! The bolts are used on a hub that is attached to a motor that turns large diameter wheels for irrigation purposes. It is in an enclosed piece of equipment. The hole in the hub is punched twice to reduce the taper. The user was concerned about possible slippage of the bolts and potential warranty costs. There were some bolts with undersize knurl diameter, but I thought the interference might still be sufficient. Unfortunately I do not recall the max hole size in the hub.

 

[LennyTheLizard]

I have a similar question to this topic. I'm trying to design some wheel adapters for a buddy's Jeep. I want to know where to find standards for wheel lugs. I have the Machinery's Handbook, but the fasteners in there do not match the automotive style studs. Basically, I just want to know the proper hole size for press fit of the lug bolts, and counterbore dimensions for the actual lug nut with socket clearance. Does anyone know a good resource for these standards? I'm going to use 1/2" Lug nuts and studs for a Jeep, but they use 2 different sizes from the front and back.

In a previous reply, it was mentioned to use .1 mm interference fit, but I was unclear where you found the min/max tolerance of the stud, or is this the taper on the wheel stud?