Quote:
Originally Posted by MAStuart
Thanks again David. You know if you give them a little they will want more. So could you tell me and others were the drive hubs forged then heat treated and then machined. Or forged ,machined then heat treated and then ground to final dimensions.
I am scratch building and would like to machine my own hubs. Would 4140 pre hardened be a usable material to machine these parts from a solid chunk of shaft? I might be able to buy these cheaper than machining these myself but sometimes I get a lot of satisfaction out of making things.
Mark
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This is rather subjective on my part, but it is based on a ton of experience. I imagine the parts in the 60's were made very much like we used to make them in Poland.
They probably started with a forging; I have seen forging marks on original hubs. The drive flanges, front uprights, and hubs were all forged orignally.
They started with a forging because hogging it from a billet is very time consuming with manual machines. The forged parts would have probably been machined "as forged," as that is the cheapest way to get it from the forging house.
The parts are then rough machined with a certain tolerance left on the part--say 0.020" and then sent to heat treat. After heat treat the parts are finish machined to take out any warpage. Finally, the bearing surfaces and rotor face was ground.
Pre-hardened 4140 is not all that hard. I wouldn't use it. I have nice broken hubs made from 4140 here in the shop that another guy made.
4340 drive line parts are usually heat treated to the high 40's or low 50's RC. That hardness is very difficult to machine, however. I'd use what we use, 17-4PH. The chromoly alloys are just not that great for long life. They corrode like mad.