[DeTomaso] Driveshaft bolts--the final answer

[MikeLDrew at aol.com]

Hi guys,

Got this from a well-known auto engineer and Pantera owner who chooses to 
remain anonymous, but said I could repost this for him:

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Mike,
So I get an e-mail from a P-car owner here in Detroit, that asks me what is 
my take on the half shaft bolt thread on the forum. I tell him I don't read 
the forum but for him I would look at the conversation.

So - which way do the bolts go in at the ZF. Nuts to the inside or nuts to 
the outside. ???

Some people got the answer right, but nobody got the reason. NOBODY.

The bolts should go in with the nuts to the inside. Reason - - the counter 
bore in the companion flange on the ZF is slightly smaller than that of the 
counter bore in the half shaft. Just enough that the tips of the hex dig 
into the radius of that counter bore. When the bolt is installed with the nut 
to the inside, the counter bore in the half shaft flange is just large enough 
to clear. So - you ask "what about the nut? Won't its hex tip dig in the 
same? After all - it is also a 5.8" hex."  Yes  EXCEPT the SPECIAL lock 
washers that go on that side elevate the nut enough to clear the counter bore. 
These are not standard lock washers. They have a much smaller diameter and 
whole lot more thickness.

Your answer sir.  :-))))

Of course, the only sample of this phenomenon that I have to work with is 
MY car. As such, this is what I base my evaluation on. Other peoples (yours) 
may be different. If you look closely, (again at least on mine) the hex tips 
will dig into the radius of the counter bore on the ZF flange and the axle 
companion flange. Not only does it create a stress riser, but it inhibits 
the tensile load from being distributed in a uniform fashion over the flange 
seat. On the other side you really should use the designated lock washer. It 
really does elevate the nut so its hex tips are clear of the counter bore. 
Yes - you should use nylock nuts. Note: A.N. bolts are equivalent to grade 5. 
Ductile - not hard. They take shear loads without breaking. (well - some 
people can break an anvil)  :-)))) At these harnesses they are also very good 
at tensile loads. I suspect NOBODY has actually torqued their nut/bolt. I 
would estimate they could take 80-100 ft/lb no problem. I did it once before a 
long road trip, to 70. Not easy to get to. I probably did not get it exact.

Also - A.N. bolts are (by design) slightly smaller than the designated hole 
size. i.e. 7/16 = .4375"  The bolt shanks are .4330 to .4370. You ~could~ 
sort through a bin of them and probably find the required number of 'high 
end' sized bolt. IMHO - not worth the time.

http://www.zenithair.com/kit-data/ra/an.html  For reference.

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So, there you go!

Mike