Joe Curry wrote:
> 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
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.
Michael D. Porter
Never let anyone drive you crazy when you know it's within walking distance....
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