"tkoth" <tkoth@cox.net> wrote:
: That's the opposite of what I've read. I was basing my
: comments on reviews in 4 Wheeler magazine where they called
: the Dak's 9.25" rear "stronger than most 1/2 ton pickup rear
: axles".
That I can definitely see. The 9.25 is a beefy unit for sure,
and I wouldn't be surprised to hear that it is stronger than most
1/2 ton rears; its just not quite up to the task of the drag racing
needs of some folks, in stock form.
: If someone has real knowledge of the internals of
: both then I cant argue. Like I said.... the 9" can be made
: much stronger than the 9.25", but then we aren't comparing
: stock axles. But that's where the real benefit of the 9"
: lies, there are so many of them and so many after market
: parts available that they realy are versatile.
True. It would almost seem to me that if an 8.25 or 9.25
isn't going to be sufficient in stock form, then a 9" *probably*
won't be sufficient in stock form either, BUT at least the 9"
can be built very strong for not much money whereas the parts
for the 8.25 and 9.25 to build them to the built 9" level will
either be not available or very expensive. So, in a situation
like Bill's where he has come across a good deal on a 9" for his
drag racing Dak with an 8.25", it would make good sense to seriously
consider the 9", IMHO. (Would also make good sense to make sure
the 9" is built to take the power.)
I couldn't find the original post I had referred to earlier about
the strength of the 9", of, but I did find some info from some posts
on the MML with much of the same info. What I was speaking of before
about the design of the 9" is that is has an extra pinion bearing at
the rear of the pinion shaft, where many rears do not have that. This
helps to hold the pinion in place so that it doesn't start walking
around.
I'm attaching some posts from the MML about the Ford 9", note though
that they are actually comparing the 9" to the Mopar 8.75", not the
8.25" or 9.25". So, I don't know if this helps to resolve anything
regarding comparing the Dak rears to the 9", but it is some additional
info about the makeup of the 9" anyway.
The first post is a response to people who suggest replacing the Mopar
8.75" with a Ford 9". The second post is a post comparing the 8.75"
to the Ford 9", and the third post is a reply to the 2nd post.
------------------------------
From: "Big Al" <sal1@qwest.net>:
>From the factory a 8 3/4" Mopar or a 12 bolt Chevy is stronger than any 9"
Ford. However, with the available aftermarket parts a 9" Ford can become
very strong. Very expensive too:) The stock 9" Fords have weak carriers.
Their LS unit is about the worst of any so called performance rear end. Ford
made a number of versions and they are all weak. The problem is the one
clutch pack design dictated by the rear, or third, pinion bearing. If anyone
wants a clear definition of why, just ask.
The reason the aftermarket guys went for the Ford is easy to see. Ford made
millions of them, and they are easy to set up. Unlike a Dana or 12 bolt
Chevy, you can make and market new gear housings. (Correct name of the
chunk.) So they can sell every part in a 9". About the only stock Ford 9"
parts that are good are the "N" housings and the ring and pinion. All else
needs to be replaced. Like many Mopar parts the stock "N" housing is worth
more used than a new Strange or Moser housing. It's them collectors looking
for the correct parts:)
Al
------
From: "Dave Grove Grove Automotive" <groveautomotive@ka.net>:
Another "note": - Actually, - the Ford 9" diff is quite a bit stronger than
any 8 & 3/4" (assuming you use the "right" case). Just take a look at the
design, and note that the *rear* of the pinion gear has it's own bearing
(making a total of three pinion bearings). The problem with any diff when
subjected to too much HP/torque/load is gear "deflection" (they try to "move
away" from each other) - and both the pinion & ring gears "move". In the
case of the Ford, - half of the "problem" is eliminated by use of the
"extra" pinion bearing. Other factors too I'm sure, - that's just the one
that's "obvious" (to me, anyway).
Now, - if you could figure out how to keep the bearing caps from "moving" in
an 8 3/4", - they would live a hell of a lot longer...........
Ever notice that the bolts are usually "bent" after a gearset failure?
Just my .002 & 3/4 worth.
Regards,
DaveG.
------
From: Tony Underwood <tonyu@roava.net>:
>Another "note": - Actually, - the Ford 9" diff is quite a bit stronger than
>any 8 & 3/4" (assuming you use the "right" case).
Yes, assuming you use the RIGHT case. I've seen 9s fail as well, usually
it's the spiders or bearings or center section.
>Just take a look at the
>design, and note that the *rear* of the pinion gear has it's own bearing
>(making a total of three pinion bearings). The problem with any diff when
>subjected to too much HP/torque/load is gear "deflection" (they try to "move
>away" from each other) - and both the pinion & ring gears "move". In the
>case of the Ford, - half of the "problem" is eliminated by use of the
>"extra" pinion bearing.
But the 9" failures I saw weren't involving the pinion. They involved the
center sections. Of course these were relatively standard stock Ford
items, not "exotics" like lockers etc. However, there's that cadre who
still insist that pound for pound the 9" is better than the 8.75 and that's
simply not been my experience.
------------------------------
---Jon-
.---- Jon Steiger ------ jon@dakota-truck.net or jon@jonsteiger.com ------. | I'm the: AOPA, DoD, EAA, NMA, NRA, SPA, USUA. Rec & UL Pilot - SEL | | 70 Cuda, 90 Dak 'vert, 92 Ram 4x4, 96 Dak, 96 Intruder 1400, 96 FireFly | `------------------------------------------ http://www.jonsteiger.com ----'
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