RE: [DML] Re: Grady's, HRC Angle drive
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RE: [DML] Re: Grady's, HRC Angle drive



David,

I've seen you mention "plastic gears" before but I can assure they are not
and have NEVER been plastic. Take it from someone who has replaced &/or
rebuilt hundreds of angle drives over the years. I still say the only way to
make this inherently weak design last longer is harder gears, better
lubrication, and tight tolerances on the gear-set via better quality
control. Been there done that!

The cause most often is that the shallow cut helical gears jamb up due to
poor lubrication and even the slightest wear. I have examined many failed
units and the gear-sets almost always show wear on the load bearing side of
the smaller gear's teeth. I'll send you a few if you want to see it for
yourself. The smaller gear then jams momentarily on the larger gear and
"poof" goes either the short axle cable or it's interference fit in the
larger gear (Of this I m sure). The answer is how best to control the wear
or come up with a completely different design that won't "break the bank".

I spoke to Stephen this morning about the failures on the new unit's (you
can tell them from the originals because they use a grease fitting instead
of an, shall we say, oil access screw to allow for re-lubrication. He said
the factory blamed the problem on inconsistent fitment of the brass bushings
the gears ride in. We're back to poor Q.C.! He did not know if the gears
were harder but if the bushings aren’t a perfect fit the gears will jamb
anyway. He further explained that all of the units are spun for about 15
minutes forwards and backwards on some sort of drill setup to weed out the
most obvious ones with Q.C. problems. Personally I have seen about a 10%
failure rate on the new units my shop has sold within the last year which is
higher than my HCR units after three years so obviously there is room for
improvement using the methods I've already indicated. The next step is to
have the FACTORY incorporate similar methods so I won't, or you, have to
spend countless hours stuffing tiny little gears into teeny little gearboxes
with handmade pressed in cables! I'm tired of it and can think of better
ways to make a living such as restoring DeLorean's instead of angle drives.
If I have to however I will... but I think we should give the factory ONE
more chance to get it right as I'd hate to see another thousand lot batch of
angle drives with the same problem. I'm going to start by taking the next
failed new angle drive apart and checking the tolerances and send the gears
out for hardness testing. I'll report my findings to Stephan and see if we
can get the longevity of this lousy design into at least the forty to fifty
thousand mile range. I believe in many cases I achieved this with the HCR
units (Stands for "Hard core rebuilt" for those who would pose the question)
using the methods I already suggested. I'll update you when I have more to
offer.

Rob Grady

P.J.Grady Inc.

-----Original Message-----
From: David Teitelbaum
Subject: [DML] Re: Grady's, HRC Angle drive

I wonder just how much "hardness" plays a role in the longevity of the
gearset. In many instances of gearsets one gear is purposly made
softer than another so that you only replace 1 gear instead of 2. In
any case there are many origional angle drives out there still
operating with plastic gears.




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