Brake Rotor Bolt Question

Jeff Sligh · Joined: 21 Oct 2010 Posts: 57

I'm just wanting to double check myself on this. For a Road Racing Sprint kart, in section 355.3 Brake Mounting, it says "Steel locking nuts or drilled bolts with castellated nuts, properly pinned, are the only methods for fastening discs or drums to hubs." Does this mean that all I will need is just the all-metal locking nuts on the 5/16" rotor bolts? Do I need to have the bolts drilled with the all-metal lock nuts AND have them cotter pinned? Do I need to use the flex top expanding lock nuts or the distorted thread lock nuts? Just wanting to make sure that I will pass tech, and I'm also getting tired of drilling Grade 5 and Grade 8 bolts with these little 1/16" drill bits. Thanks,
Jeff

Bill Martin · Posted: Wed Jan 30, 2013 8:30 pm Post subject: Re: Brake Rotor Bolt Question

John Matthews · Posted: Wed Jan 30, 2013 8:35 pm Post subject:

I would use an all metal lock nut, and drill and safety wire the bolts. But, you should check with your tech person for an answer that will please them.

Drilling for safety wire is easier if you have one of those fixtures made for it but if not just grind a small flat and center punch the spot you want to drill.

Cheers,
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John Matthews
Heartbeat Power, LLC.

joseph hollinger · Posted: Wed Jan 30, 2013 10:39 pm Post subject:

All of the euro-karts (at least all of the ones I've seen) use all-metal lock nuts. Stick with them and you will not have a problem.
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Walt Gifford · Posted: Wed Jan 30, 2013 11:05 pm Post subject:

Jeff, I have experience in road racing sprint. Mine is the MCP American 4 bolt style with 5/16ths bolts.

I use all grade 8 hardware. The socket head cap screws have a grip length or shank that goes through the rotor and into the carrier for maximum shear strength. Make sure the nuts don't shank out when tightening. If they do just run a die on the bolt and cut a couple more threads.

Put the bolt heads on the rotor side and use thick flat washers under head and nut.

I would advise against using castellated nuts, even though they're being used in a shear application I don't like how thin they are. I use grade 8 steel crip nuts but, the serrated crimp nuts are just as good.

Even with crimp nuts they want to see at least one bolt longer that is drilled beyond the nut for a cotter pin, I drill all of mine. Do not drill through the nut.

Hope that helps,
Gif Cool

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