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Replacing Brake Rotor Bolts

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Dirk_S:
When replacing brake rotor bolts, can any grade steel be used, or does the high torque and the hub’s alloy threads dictate a certain softness/give for bolt threads?

The V7’s rotor bolts are a flange-head type, no recess in the rotor that I recall. The ham-fisted utilitarian wants to replace them with hex head bolts, knowing that rotor bolts can sometimes get stuck and strip their heads. Maybe external hex head style is overkill.

Regardless of head type, would stainless steel bolts be OK to use? Regardless of material, I’ll plan on using blue threadlocker.

John A:
Stainless Allen heads, property class 70 or better is ok . 80 is overkill but don’t use 60

John Croucher:

--- Quote from: John A on January 17, 2022, 12:21:39 PM ---Stainless Allen heads, property class 70 or better is ok . 80 is overkill but don’t use 60

--- End quote ---

McMaster Carr is a good source. 

Old Jock:
The advice AFAIK is not to use stainless for disc rotor bolts due to the lower yield stress, and use either carbon steel (or titanium)

I've used stainless bolts for a long time in brake rotors and not experienced any problems but there are quite a few threads warning of dire consequences

Perhaps others know more than I do, but personally I wouldn't be worried about changing the head type as long as it covered the same area (or greater) on the rotor.

If the flanged heads use an Allen key, I find these bolts a PIA as they usually utilize one key size down from a normal cap screw of the same bolt thread so round off the hex a lot easier.

That said it's usually quite easy to remove them if they round off by cutting a slot into the domed head the use a small chisel (or old screwdriver) and whack the fastener with a small hammer to shock the screw out.

If you want to use a hex I'd just purchase flanged hex bolts instead

That's just my experience, there might be some engineering reason for the head type, but I'd guess it's more likely for cost/aesthetic reasons

Dirk_S:
Just for clarity, the V7 uses flanged external hex head, not a socket cap (Allen). My Ural’s rotors used socket caps, and it freaked me out when trying to remove them and found the mating to be corroded. Went through 3 different Allen wrenches before I found one tough enough to break the corrosive bond. I was thinking that the flanged hex might simply be more aesthetically pleasing over a bulky looking, larger diameter standard hex head bolt.

There could be some type of clearance issue, but that side on both wheels also has the ABS sensor wheel attached and sticking farther out.

Another thought that came to mind is that perhaps a smaller head is correlative to the amount of torque that bolt is specified for. Smaller head = don’t overdo it, dummy.

I have to spend some time learning more about steel / bolt grades.

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