Sanity Check, D44 Full Floater

My spindles use the 1.625” bearing for both inner and outer.  Interestingly enough, my spindle bore is 1.272”.  My tab groove is 0.055”.  My particular 30 spline axle ends measure 1.290”, not the 1.310” that I thought was the published diameter.  For those that actually have 30 spline axles, what is you actual diameter?

So with my 1.272” spindle bore and my 1.290” 30 spline axle diameter, I would only have to bore the spindle about 0.025” to obtain clearance, which would reduce wall thickness by only about 0.013”.  This reduction would not cut thru my tab groove.  BUT....my question is:  Is a spindle wall thickness of approximately 0.160” sufficient to wheel the Rubicon, Moab, Sand Hollow, et al?  I think probably it would be ok, but I’m afraid to rely on that.  If that spindle breaks, you better have another one just like it to get off the trail.  If a FF axles breaks, you can just keep driving.  Either way I decide, I’m planning on having spares.

Jeff’s idea is very interesting to me.  Having two “large” I.D. bearings would alleviate the spindle thin wall worries, but would they need to be heat treated?  Can you do that or have it done, Jeff?  And how much would they cost?  I would rather have them made like this, than to use a disc brake, large bore, D30 spindle, which is the way to go right now if you want to bore them.

I spoke to Herm this week.  He said he will warranty them, but only once.  He wouldn’t say who makes them, but he did say it was a major U.S. axle manufacturer and they only make a run of them once per year.  He said they are made from 4340 and have a Rockwell hardness of 57.  I bought mine from him in 2015 and I don’t know if they are the same manufacturer or the same material (4340) as they are now. 

Here are the spindles (1.272” bore) that I’m currently running on my D41 with Herm’s FF 30 x 27 D44 axles: