>"when you do the math, the ratios are the same." !!!!
>While this is true ...and here are the tooth count & ratios,
>[Front, 39/8 = 4.88 / Rear, 44/9 = 4.88]
>Then, the wheels would seem to spin at the same rate.
>Yes ?
Well they are not exactly the same
39/8 = 4.875
44/9 = 4.8888888
Close enough but if you want to be picky they are about 0.3 percent off.
>Therefore, one differential is not receiving the full turn and consequently
>may never get to "output the same ratio" as the other ???
Not really, one pinion rotation will turn the ring gear about 0.205
revolutions in either case, again the two are only off by about 0.3%.
>I imagine, that you would possibly see tires, gouging & scrubbing & skipping
>and hopping ?
So close you would never tell. There were trucks delivered from the factory
with ratio differences far greater than this, typically when GM for example
used thier own rear axle but went to Dana for a front axle, they would/could
get close to a match but some combinations were off. They try to pass it
off as a marketing gimmick by saying that the front will pull more than the
rear for whatever reason but it really comes down to basic product availability.
>At any moment ...one diff is trying to be pushed or pulled by the other.
>This may not matter if you are sure that the vehicle is always running on
>wet muddy surfaces allowing the tires to be the final slipping point.
>Then, begs the question what happens when the vehicle hits solid ground
You will/can have a far greater mismatch if for example one tire was under
inflated on one axle or if you replace say the rear tires but use older or
different front tires. Basically this is why you do not want to run a
conventional 4wd vehicle in 4wd on hard surfaces, you will start loading up
the drive shafts as these mismatches, from many sources, start building up
as you suggest. Now if you have a full time transfer case like the hummer
has then this is not an issue as it has a diff unit in the transfer case
also, like the old NP203 transfer case that so many people disliked for some
reason, I happen to think it's a nice way to go, but that's another story.
Hope this helps, that's all I can add.
je
This archive was generated by hypermail 2b29 : Fri Dec 07 2001 - 00:36:24 PST