Boog,
I think the 500 is based on the old 904 series (3spd) trans, while the 518
is based on the 727 series! The 727 series is better for high loads since a
lot of the guts are beefier, but the 904 series does not sap as much power
from your engine to do the same job (up to a point)! I use the 904s on
built smallblocks (most drag racers do too) fo maximum effect. If they have
been modified properly thay can reliably handle over 400HP. You can switch
the first gear set out with an extra low set as well for street/strip
gearing. More Torque capacity for the 518 means it can handle the torque put
out by a BIG motor without toasting itself. Bigger clutch friction area,
better bearings, bigger shafting etc. All the bigger stuff though puts
additional drag on your engine!. I wouldnt put a 904 series trans behind a
big block, its just not designed for the torque. I am putting a 518/46re
behind a stroked 440 though :^) Hope it can handle 500+ponies...
"Damn you,... You cut out his.... transmission"!
BKB
-----Original Message-----
From: Boog318@aol.com [mailto:Boog318@aol.com]
Sent: Friday, February 19, 1999 8:45 AM
To: dakota-truck@buffnet.net
Subject: DML: Transmission gearing and gear ratio
Ok heres something out of the July 98 High Performance Mopar Magazine:
They are gonna throw a 518 into a Road Runner.
These guys compare the A-500 and the A-518 which is the hydraulic version
of
the newer A44RE (A-500) and A46RE (A-518).
Gearing Table:
A-500 A-518
1st 2.74 2.45
2nd 1.54 1.45
3rd 1.00 1.00
OD 0.69 0.69
Torque multiplication table with 3.55 and 3.92:
Effective overall gear ratio
A-500 A-518
3.55 3.92 3.55 3.92
1st 9.73 10.74 8.70 9.60
2nd 5.47 6.04 5.15 5.68
3rd 3.55 3.92 3.55 3.92
OD 2.45 2.71 2.45 2.71
We know that for the gear ratio in the differential, say 3.55, for every
revolution of the drive shaft, the axle turns 3.55 times
So if I am interpreting this right, then in 1st gear (A518) one revolution
of
the planetarys turns the output shaft (hence the driveshaft) 2.45 times
which
turns the rear axle 8.7 times.
Comparing to the A500; One revolution of 1st gear turns the drive shaft 2.74
times which turns the axle 9.73 times.
That would mean the A500 has more torque in 1st then the A518. It seems that
a
318/500/3.92 Posi would be a killer combo, but even this article says the
A518
has more torque capacity.
There has to be something else involved. Like the engine maybe? Torque
Converter?
(Charelton Heston Mode-on)
God...Someone please help me make some sense of this!
I WANT THE KNOWLEDGE!! Dammit! Why cant I FIGURE this OUT!
(Charelton Heston mode-off)
One thing that is easily understood. When you are running in overdrive your
final gear ratio is 2.83 which turns our Daks into guttless wonders at low
speeds. I have always turned my OD off until I hit at least 50mph and can
sustain it. The previous owner didnt know any better and even ran around in
4wd with OD engauged. Thats why I got a new trans at 53k. Thank God for
that
warranty! I'd rather frequent the gas station then the tranny shop. I get
about 13-14 running around town (no OD) and the best on the hiway was 19.3.
I hope someone out there can finish up on this and explain the differences
between trannys.
I must rest now, all this damn thinking is too much for a Friday!
BOOG
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