[AMC-List] To Jim Blair - Chrysler transmissions... and my favorite...

["Jim Blair" <carnuck@xxxxxxxxxxx>]

PS: I'm passing this on to the AMC-list, FSJ-lists and others as well 
because they mostly run Mopar trannies as well. (that's why other info not 
pertaining to stroked AMC 6 cyls) We have been trying to work out a 
reasonably low buck "bolt in" overdrive, especially for FSJs where 1-2 mpg 
equals 10-20% increase in fuel economy!


A: That's a fun read (when I'm feeling better, I'll read it more thoroughly. 
) I'm fighting some kind of bug right now, but I'll mention I used to be a 
Mopar trans tech (mostly stock rebuilds) back in the day when police and 
taxis used Mopars (and many ran much heavier than ATF in these things! In 
AZ, they ran 80W90 because they never cooled down!) It's too bad Der Mopar 
never ran a 518 (45RFE) behind the 4.0L, even in Grand Cherokees.
  The GM 200R4 (I've been hearing how Landrovers ran a version of this 
lately, and still with the nailhead pattern!) can be built much stronger 
than a 42RE (Grand Cherokee 4.0L trans that will also bolt behind an AMC V8, 
but isn't very strong) but unless this tip I got from a Land Rover mechanic 
about their trans is right (and it comes in a 4x4 version) then anything AMC 
would need to be worked up to handle a V8 as well.
  IF the 200R4 was used with a nailhead pattern (why couldn't they have used 
a 4L80 or 4L60 with that pattern?) then the AMC TH400 adapter ring used with 
Nailhead TH400 before AMC got their own case in '74 could be used. It's a 
long shot, but you never know unless you ask.
  Back to Mopar trans, have you ever dealt with the 6 speed version of the 
727 (used in 5 ton trucks) It's essentially the same as the O/D version 518, 
but with the planetary reversed for an underdrive. I had one in a 5 ton dump 
truck I rebuilt back @ 1980 with a 318 wedge motor (that I installed) and 
drove to Mexico and back. With the 2 speed axle, it was kind of fun figuring 
out how the 12 gears forward and 2 reverse worked.
  On to the 700R4, aka 4L60 (non-electronic for carbed rigs, just to keep 
things simple) It's easy to bolt up an FSJ tcase (but other than the NP208, 
why would anyone want to? <G>) You need to have the output shaft of the 
700R4 replaced with the 23 spline adapter for round input D300 (I've written 
a few companies explaining the input depth and spline count is the same and 
only heard back that FSJs were such a "niche" market no-one had asked them 
before) or replace the input gear of the tcase with one that matches the 
stock 700R4 27 spline 4x4 output. (supposedly the 4.3L V6 and 2.8L V6 S 
series with 700R4 came with 23 spline at first, but I don't know about the 
depth. If they are like later Jeep units, they are 7/8" too long to bolt 
right up)
  I'm replacing my original tank and the spare tire spot on my '84 J10 with 
LPG tanks, with another large in box tank for really long trips (I estimate 
over 1,000 miles on 1 fill up)

Enough ravings from this sick guy.


To Jim Blair - Chrysler transmissions... and my favorite...
   Posted by: "Harrel (shop)" harrel@xxxxxxxxxxxxxxx pontiacgto71270
   Date: Thu Oct 12, 2006 8:12 am (PDT)

Jim,
   You are pardoned!  : )

Thanks for the LPG suggestion, but I don't have room for a tank!  Besides, I 
am
a Sunoco racing fuel dealer, so octane isn't a problem!

Well, you asked for it... Now for my spiel on Chrysler transmissions!  Sorry
this is so ridiculously long!

As you already know, the 42RE (A500) is basically an electronic Lock-up
TorqueFlite 904 with an overdrive stuck on the back of it.  The TF 904 and 
727
were decent transmissions, 40 YEARS AGO!  In fact, the 727 TorqueFlite (the
904's big brother, and later a A518 O/D) was first put into production in 
1962!

When it came time for an overdrive, Chrysler decided to go cheap and use the 
old
trans technology.  They simply made an O/D fit in place of the super long
tailshaft.
There were two major flaws in this design:
1.. Because it was placed at the rear of the trans, the OD unit had to be 
very
heavy and beefy to withstand the engine/converter torque PLUS the nearly 2.5 
to
1 torque multiplication of the trans itself when in low gear.  It has a 
DOUBLE
ROLLER sprag in it (big, heavy, expensive) to handle the torque.
2.. The extra bulk of the OD unit made the trans unable to be retrofitted to
early Mopar cars.  It simply wouldn't fit inside the trans tunnel (torsion 
bar
crossmember cannot be removed).  In doing this, Mopar (probably unknowingly)
turned their back on Dodge and Plymouth musclecar owners.  Imagine, not 
being
able to fit a "modern" Chrysler transmission in your Mopar!...  Which is so
terribly ironic, since the Chrysler O/D was built from a trans designed in 
the
early '60's!  That is why I installed a GM O/D trans in this car:
http://www.popularhotrodding.com/features/0507phr_1970_plymouth_road_runner 
This
car has a 520 cubic inch motor and a Six-Pack carb setup. Because of the O/D 
and
lock-up convertor, this brick of a car cruised at 2000 RPM @ 70 and achieved 
17
MPG with the A/C running!

In 1980, the 904 got a revised planetary set that had a 2.74 1st, 1.54 2nd, 
and
1:1 third.  These same ratios are in the 42RE along with the .69 O/D ratio.  
The
ratios are almost identical to the 2004R GM trans, but inside a much heavier 
and
larger package.   The 200R4 and 4L80E were also contrived from 3 speed
transmission designs.  However, they have the O/D planetary in the front of 
the
trans.  This means the O/D planetary is only subjected to the torque of the
engine/converter, thus the planetary was able to be much smaller and lighter
than the Chrysler/Fred Flintstone O/D transmission.

Recommended Chrysler transmission mods:
a.. Bypass the original radiator mounted cooler and eliminate the
converter-drainback check valve located in the end of the rubber hose
connection.  Then install the largest trans cooler that you can.  Make sure
there is an unrestricted path for the fluid to flow to and from the trans.  
The
return fluid is the only source of lubrication for the trans. Inadequate 
fluid
flow will starve the trans of lubrication and it will self-destruct, and the 
O/D
unit will go first!
b.. Raise the line-pressure adjustment by simply turning the P/R adjuster 
bolt
CCW (can be done by dropping the pan).  This will result in higher clamping
force for the friction materials and more fluid volume for better cooling 
and
lubrication.

Also, many of my customers who own Chrysler/Jeeps do not realize that the 
trans
fluid MUST BE CHECKED IN NEUTRAL.  If it checks 'full' in park, it is 
actually
about 2 quarts low.  There is no fluid flow to the convertor or cooler in 
park.
I have seen many TorqueFlites burned up simply because of low fluid levels.
Trans-Go offers a 'shift kit' that includes a new pressure regulator valve 
that
causes the trans to circulate fluid through the converter and cooler 
circuits
and provides better pressure control at all times. Sonnax manufactures the 
valve
and is available separately:
http://www.powerglide.com/parts/parts/22771A-10K.htm

Heat is the biggest killer of transmissions, mainly because trans fluid 
breaks
down and gets as thin as water when overheated.   The torque convertor 
generates
most of the heat, so be sure that you are aware of RPM and MPH when the 
torque
converter is locked up.  When towing, vary the load on the trans using your
right foot to keep the converter locked up as much as possible.   Put a
temperature gauge on the (trans) front cooling line, which is the outbound
fluid, which will also be the hottest temp of the trans.  260F is maximum
operating temp!  A trans is not like an engine, which has to be at least 160 
for
proper lubrication.  The trans can safely run as cool as possible.

If your trans will be subjected to spikes in fluid temps, such as towing for
hours and then getting stuck in traffic ('heat soak'), I recommend filling 
the
trans with synthetic fluid.  It has better viscosity stability in extreme
temperatures and protects hard parts better than conventional fluids.

Clutches/bands have to slip/overlap to produce smooth shifts.  2 seconds of
shift slippage (absorbing 150 horsepower or more) combined with a heavy foot 
and
a heavy load, creates a huge spike in clutch temperature.   Normally, that 
isn't
a problem, because the steel plates/iron drum act as a heat sink and absorb 
the
temporary heat spike and prevents the paper friction material from burning.
(Each clutch plate (paper/steel/paper) is less than .100 thick!)  But when 
the
trans is totally saturated with heat from towing a load on the hot freeway 
with
the A/C on, the heat generated by the slippage has no place to go.  Keep 
that in
mind after getting off of the highway and getting in stop and go traffic.  
Until
the trans cools back down, you could even lift off of the throttle at every
shift point to eliminate slippage and toasting of clutch material.

Personally, if I were starting from scratch, I would use a Novak adapter and 
put
a 700-R4 behind the 304.  The 700-R4 began life as an overdrive, not a 
3-speed
automatic.  It is a marvelous design; a genuine 4 speed automatic, 
ingeniously
accomplished with just 2 planetary sets.  It has much less rotating mass 
than '3
plus 1' (3 planetary sets) 4 speed autos.  It has NO heavy cast iron drums 
or
iron front pump like Chrysler & earlier Ford transmissions.  It has an
efficient, variable-volume, vane-type aluminum front pump.  It has a 3.06 
first
gear (which makes 3.55 rear gears feel like 4.33's after switching from a 3
speed auto trans) and a .700 O/D, and is much smaller, lighter and stronger 
than
the 42RE, and doesn't require a computer to operate.  12V is all it needs to
lock up the converter and it will handle 600+ lb/ft of torque (properly 
built).
It is the exact same length as a 904 (2wd versions; here is a morph I made 
of
the first 904 to 700-R4 swap I did back in '03:
http://www.racebay.com/images/movies/transformation.avi). Since it also has 
the
same tailshaft bolt pattern as a TH350, I would think there are several 
suitable
transfer cases to choose from.  (I don't work on 4X4's, so I am not familiar
with transfer cases.)  I have built 700-R4 and 4L60E transmissions for low 
10
second cars.  In stock form, they do have a few inherent problems and
weaknesses, but properly built, they will make you grin.  If you consider 
its
size, weight, strength, adaptability and availability, there is no better
overdrive than a 700-R4.

I warned ya it was a long read!

Harrel Lamkin
Lamkin Automotive
911 East Georgia Ave
Ruston, LA 71270
318-255-8350
Since 1980 - 'The little shop with big ideas.'

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