Old Hot Rod Article about converting a std 4 speed to OD
I have been kicking this idea around in my head to replace the three speed in my Duster. I would love to be able to run through the first three gears and then drop into OD when I reach highway speeds. Seems like the best of both worlds to me?
There are two A230s, one of them has very similar ratios to the first three gears in the A833od; either is a natural to be swapped.
the A230(-1); 2.55-1.48-1.00 / splits of; .58-.68, versus
the A230(-2); 3.08-1.70-1.00 / splits of; .55-.59, versus
the A833od; 3.09-1.67-1.00-.73/splits of; .54-.60-.73 ....for reference,
the Commando is; 3.09-1.92-1.40-1.00, and splits of; .62-.73-.71
A nice street Roadgear for Second, is ~6.50, give or take ~.3
To get there would take;
with the 2.55low/A230, will take at least 4.30s, and 65=3480
with the 3.08Low/A230, will take 3.91s, and .......... 65=3165
with the A833od ............. will take 3.91s, and ........65=2310
with the Commando, will take at least 3.23s, and ....65=2615
All rpms are by the math and, are approximate.
All are with 27" tires.
But now:
Lets say you have the 2.55Low A230, and a 3.73 gear; your Roadgears are;
9.51-5.52-3.73, and 65=3020
Notice;
that 9.51 is a very nice starter gear,
Second is way short of 6.50,
and the cruise rpm is getting right up there into annoying territory.
Let's say you swapped in the A833od
and kept the 3.73s. Your new Roadgears would be
11.52-6.23-3.73-2.72, and 65=2200
Notice;
the super low starter gear of 11.52, and
the 6.23 Second is daymn close to 6.5
the 3.73 Third gear remains the same as the previous combo, and
65=2200 in od is about perfect.
Let's say you installed the Commando, and to get the Second gear up to 6.xx you would need 3.23s. Ok your Roadgears are;
9.98-6.20-4.52-3.23, and 65=2615
Notice;
9.98 is an excellent starter-gear, and
6.20 is a pretty good Second.
4.52 is an excellent third, and
65=2615 is acceptable to most drivers.
Finally
From the ratios list above, and looking at the splits;
the A230(-2) splits are a wide ratio design
the A230(-1) is has a wide 1-2/ short 2-3, nice progression
the A833od is a very wide ratio design, albeit, a nice progression
the Commando is a close ratio design, with a nice dropped starter gear
>> I have driven all of these ratios behind my 367, with numerous rear gears, and if your V8 has a "bit of a cam", then, IMO, the Commando is the hot ticket.
But if a low rpm engine, then any combo will do.
For a stock to slightly hopped up 273/318/340 IMO, the Commando is the natural choice; it's hard to argue with those Commando splits.
The 360 has enough torque to run just about anything, no matter the cam, but I still prefer the Commando, because the starter gear lets me run right down to 2.76s .....if I might be so inclined to. and I once was.....