I just wanted to post and say bravo on this post - great, great
technical info on the transmissions.
Everyone may continue now. :)
-Ryan
99 DA RC R/T
Yes, I read but don't get to post too much.
-----Original Message-----
From: owner-dakota-truck@bent.twistedbits.net
[mailto:owner-dakota-truck@bent.twistedbits.net] On Behalf Of WiLieR[SS]
Sent: Tuesday, November 01, 2005 1:40 PM
To: dakota-truck@dakota-truck.net
Subject: Re: DML: Transmissions - I need a little skooling!
On 11/1/05, Terrible Tom <SilverEightynine@aol.com> wrote:
> I'm trying to determine iwhat to do for a transmission for Christine.
I
> want something that has nothing to do with electronics. I'm also
> going to be doing this on somewhat of a budget so I'm going to do the
> bone yard or donor truck, thing. Which makes my logical choice a 46RH
> transmission right?
>
> Now as far as I can tell from Allpar... the 727, 904, A-500, A-518,
and
> the 42/46/RE/RH variants are all based off the same Torqueflite. Does
> this mean the case dimentions and bell housing patterns are going to
be
> the same between an A-500 4x4 tranny and a 46RH tranny? I suppose
what
> I could do it get under the Ram and take some measurments of that
> 46RE... And Compare them to Christine's A-500.
>
> Anyone know if the output shaft splines are different?
I can not verify the output shaft question, but I can tell you there
are minor differences between the 904/A-500/42RH/42RE and the
727/A-518/46RH/46RE. Of course, the RE series is electronic. The RH
series uses standard internal trans pressures, throttle valve position
and engine vacuum to determine shift points. The A-500/42(RH & RE)
trans are based on the 904 transmission (hence the term "baby 904s").
The A-518 and its descendants (46 RH & RE) are based on the TF727
trans (added od unit). Internally there are differences in gear
ratios as well. I don't have the exact specs on hand, but they are at
the house, but the 904 series and its descendants have a lower first
and second gear compared to the 727 and its descendants. Third gear
is the typical 1:1 ratio with the overdrive unit (if equipped) also
has a slightly different ratio between the two. There is also a
difference in the number of clutchs and disc involved in the drums of
the trans, even though all use two drums and two identical bands to
control these drums.
I don't remember the drivetrain of Christine, but if it is a v-6 I
would go for the 904 series of trans to get more grunt out of the
engine while crawling or slinging in first or second gear. There is
also a difference in trans as to which is lock-up and which is not.
Lock-up converters will provide more fuel effieciency and will not
harm low end work as they will still allow the converter to slip when
needed.
The bellhousings of the two trans should be similar in bolt pattern as
the 3.9 series and the la based 5.2/5.9 all used the same bellhousing
bolt patterns and sensor locations. The main differences will be in
how the engine was originally balanced (internal vs external) and the
torque converter/flexplate needed for the engine/trans combo.
If you are going to rebuild the new transplant trans, there are
several tricks to making it stronger and last longer. But first we
need to settle in on which trans will be used as each tranny has
specific tips for its build that will increase fluid flow and extend
the life of the trans internals while making the entire unit stronger.
WiLieR
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