gun drilled axles
09-26-2006, 12:16 PM
#5
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i would say no smaller than 35 spline is the limit you would want to be at for gun drilling axles, i would definately say its worth it in terms of reducing rotational mass, i believe it was on a 9 inch in a TA they ended up reducing the total weight between the two axles by something like 6 lbs
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09-27-2006, 10:52 PM
#8
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There is near nill effect in rotational inertia from gun drilling. Mass and inertial have very little effect in terms of rotation when on the centerline, but do when in terms of larger diameters..... like the axle flange. Now as far as sprung/unsprung weight.... there is a big difference.
Gun drilling was started as something to combat strength issues. Nothing more, nothing less. The more surface area, the stronger. That is it.
35 spline's or less doesnt matter. The problem associated with actually performing gun drilling, on an axleshaft, is the actual surface finish of the thru hole. Small diameter thru holes are much tougher to finish than something like that of a 35 or 40 spline.
The strength increase is well worth the meager amount spent on larger diameter shafts.... but goes up exponentially in cost with shafts smaller.
Gun drilling was started as something to combat strength issues. Nothing more, nothing less. The more surface area, the stronger. That is it.
35 spline's or less doesnt matter. The problem associated with actually performing gun drilling, on an axleshaft, is the actual surface finish of the thru hole. Small diameter thru holes are much tougher to finish than something like that of a 35 or 40 spline.
The strength increase is well worth the meager amount spent on larger diameter shafts.... but goes up exponentially in cost with shafts smaller.
09-28-2006, 08:42 AM
#9
I'm not following how drilling a hole thru an axle makes is stronger. The ability to resist twist and strength is going to be a function of the cross-sectional area of the shaft (for a given metallurgy and shaft OD). If you drill a hole through the shaft that cross-sectional area is reduced and the shaft is weakened and less stiff. Certainly most of the stress is carried by the outer diameter of the shaft, but the center helps too. If anything, gun-drilling reduces overall mass (with negligable effect on rotational inertia as previously mentioned) and helps with un-sprung weight (but is 12 lbs worth it?). You may reduce shock to the axle flange studs due to more springiness in the shafts, but again I doubt there is much advantage there.
You mention surface finish on the ID, is there something done to change the metallurgy along the ID of the gun-drilled hole that increases strength that I'm not taking into consideration?
You mention surface finish on the ID, is there something done to change the metallurgy along the ID of the gun-drilled hole that increases strength that I'm not taking into consideration?
09-28-2006, 09:12 AM
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Originally Posted by JohnnyBs98WS6Rag
You mention surface finish on the ID, is there something done to change the metallurgy along the ID of the gun-drilled hole that increases strength that I'm not taking into consideration?
