[Land-speed] Synthetic Motor oil

[23weldon]

So far the talk about rear gears has centered on hypoid types like the Ford 
9 inch.  How about spiral bevel gears used in the prewar Ford designs that 
morphed into today's common quick change setups?  Correct me if I'm wrong; 
but isn't the spiral bevel type a derivation of the involute spur gear which 
theoretically has no sliding contact, only rolling?  If so then perhaps the 
only sliding that goes on is due to the inevitable manufacturing 
inaccuracies that come with a very complex geometry between mating parts?
Seems to me if you are only one or two mph off a record there may be some 
wisdom in dropping the heavy gear oil and replacing it with a straight 
15W-50 synthetic.  In anticipation of this scenario I think I would engineer 
an inspection port into the QC side cover.  Any thoughts on this?
I do realize that if you lose a ring or pinion in a quick change you are 
pretty much done for the meet unless you brought a whole spare center 
section with you.  But champ ring/pinion sets are not that expensive. Ditto 
the housings bearings.
Sometime this century maybe someone will publish some scholarly research on 
rear axle gear efficiency with modern lubricants.
Rick - With your contacts in the automotive industry can you find out if 
there are any SAE papers old or recent that deal with this subject?  Or put 
me in direct touch with someone who can help?   Right here in town the Santa 
Clara University library has an archive of SAE papers.  My son is got his 
MSME there so we can get access to the stacks.
Ed Weldon
Missed Speedweek this year due to family imperatives.  Hope the weather 
holds for World finals.

----- Original Message ----- 
From: "Rick Byrnes" <Rick at RBMotorsports.com>
> I'm in agreement with Brian that  rears should use only hyphoid lubes.
...... I haven't used anything but  75-90 Mobil 1 Hyphoid lube.  I'm not 
sure I'll go lighter than this for some
> time in the trans or rear.