Drilling out alloy wheel bolt holes?
Discussion
Should be ok. Most wheels are designed for the hub to be machined and drilled to fit a number of differing fittings. Just opening up a hole is ok. Check that the PCD is the same though, and also the central spigot hole dia if it's that type. And finally the bolt lengths, and shoulder style.
doogz said:
Squishey said:
Is it possible/safe/advisable to drill out alloy wheel bolt holes?
I've just bought some winter wheels but the holes are for M12 bolts and mine are M14.
Out of interest, what size are the existing holes?I've just bought some winter wheels but the holes are for M12 bolts and mine are M14.
And what'll you take them out to? I've never actually measured a wheel bolt hole, are they 0.5mm clearance? 1mm? More?
doogz said:
Zulu 10 said:
Sorry, I think this is being considered from the wrong angle:
The wheels were originally fitted to a vehicle which used 12mm bolts to hold the wheels on.
This presumably means that the wheels were designed to withstand the stresses imparted when the wheel is clamped to the hub by 5 x 12mm bolts.
The OP now wants to take those wheels and fit them to a different vehicle, and one which according to the calculations of Mercedes’ design engineers requires 5 x 14mm bolts to retain the wheels.
Assuming that Mercedes don’t routinely over-specify materials, that means that they consider that 36% extra clamping force and/or strength is required – presumably because of the forces which the vehicle can impart.
Obviously there are safety factors applied to all the calculations and fastener sizes, but in the absence of any other information (i.e. that the identical wheel casting has been used in both 12mm and 14mm bolt applications ) surely the bottom line is that by doing what he is proposing the OP will be using the wheel outside its design loading?
Where'd this 36% come from? That seems to be the difference in shear area of the bolt. A M14 bolt tightened to an arbitrary 95lb*ft provides 17% more clamping force than an M12 tightened to the same torque.The wheels were originally fitted to a vehicle which used 12mm bolts to hold the wheels on.
This presumably means that the wheels were designed to withstand the stresses imparted when the wheel is clamped to the hub by 5 x 12mm bolts.
The OP now wants to take those wheels and fit them to a different vehicle, and one which according to the calculations of Mercedes’ design engineers requires 5 x 14mm bolts to retain the wheels.
Assuming that Mercedes don’t routinely over-specify materials, that means that they consider that 36% extra clamping force and/or strength is required – presumably because of the forces which the vehicle can impart.
Obviously there are safety factors applied to all the calculations and fastener sizes, but in the absence of any other information (i.e. that the identical wheel casting has been used in both 12mm and 14mm bolt applications ) surely the bottom line is that by doing what he is proposing the OP will be using the wheel outside its design loading?
This is an ALLOY WHEEL. As I said before, wheels are usually designed for a range of bolt numbers 4/5/6, bolt dia's, PCD's, for economics. As long as these parameters are within a small range, one basic wheel design is used. Look at an aftermarket alloy wheel, and you'll see designs have a range of bolt patterns available. I would however tighten the bolts to Mercedes 14mm bolt torque value. It's the preload induced in the bolts that provide a clamping force between the wheel and hub that transmits the engine torque via friction.
Sure I've read somewhere that the clearance on Merc alloys is half a millimetre bigger than the thread diameter. Might have been on here.. http://www.alloywheelsdirect.net/information/fitti...
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