[TR] high engine rpm

[Joe Curry]

Thanks Michael!  I stand corrected.  But I am still gonna try it for myself
because I am sure that I remember the wheels spinning opposite directions
when they are both free.  But maybe that happens when you turn one wheel not
the drive shaft.  I am obviously confused and need to sort this out for
myself.

Thanks Again for clarifying.

Joe
----- Original Message ----- 
From: "Michael Porter" <portermd at zianet.com>
To: "Triumph Sports car discussion" <triumphs at autox.team.net>
Sent: Monday, July 23, 2007 1:13 AM
Subject: Re: [TR] high engine rpm


> Joe Curry wrote:
> > Mark,
> > I am pretty sure that if you do not secure one wheel, one will spin
backward
> > relative to the other with an open diff.  Don't ask me to explain it but
> > that is what I have noticed when I tried it.
> >
> > I am going to have the Red Mk1 off the ground this week to adjust the
rear
> > shocks and when I have it in the air, I am going to give it a try to see
if
> > I remember it correctly or if I am actually going crazy.
> >
> > I will report back to reveal if I am beaming with success or have egg on
my
> > face.
> >
> >
> >
> Okay, I have just done what I should have done when this brouhaha
> began.  I went out into my generally unnavigable, overstuffed garage,
> dragged the GT6 diff out from under the bench (the one with the cracked
> rear mount), which I know to be a 3.27:1, and applied vise grips to the
> right-hand axle flange, rotated the pinion input until the right-hand
> flange was well-fixed and immobile. Took up the lash, made witness marks
> on input, left flange and case.  One rotation of the left flange made a
> little less than 1.7 turns of the input flange.
>
> Now, releasing the right flange and allowing it to turn with the same
> resistance as the left flange, each flange turns at the rate determined
> by ring and pinion ratio, which makes sense given that the spider shaft
> rotates at the same rate as the carrier, so the spider gears are static
> relative to the rate of rotation of the side gears, if the resistance to
> torque on both sides is equal.
>
> Sorry, Joe. A full floating diff makes twice the revs of a locked diff
> with one wheel fixed.  I made the same mistake-brainfart when I advised
> the original poster privately.  The simple fix, of course, is to jack up
> one side and count two revs of the wheel, or, jack up both sides and
> count one rev.
>
> The reason for it becomes obvious when one figures in both rotation of
> the spiders and the rotation of the carrier/spider shaft assembly. With
> one side gear fixed, the free side gear is being turned by the spiders
> rotating around the fixed side gear and the spiders rotating with the
> spider shaft as the spider shaft rotates with the carrier, so the rate
> of rotation of the free side gear has to be double the rate of carrier
> rotation alone. Easy to visualize when one compares both wheels turning
> to one wheel turning. When both side gears are free to move, the spiders
> don't rotate--one tooth set on each side engages the side gear and the
> spiders, side gears, spider shaft and carrier move as one unit.  Lock up
> one side gear and the spider begins to rotate around the fixed side gear
> _and_ is turning with the spider shaft and carrier.
>
>
> Cheers.
>
> -- 
> Michael D. Porter
> Roswell, NM
>
> Never let anyone drive you crazy when you know it's within walking
distance....
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