Some people, not pointing the finger at Kern Dog above;
say that the .78od ratio of the GVod is "not that Great" or something to that effect..
Well, by the numbers, and compared to some other options, that is true.
But
For a street-driven car,
there is a clever way around that, which I have found, works exceptionally well, namely;
If you shift First>Third, then into Overdrive, and lastly into Fourth, you get a short fourth, and a deep Fifth.
Here are the standard A833 ratios, with the GV, and splits
2.66-1.92-1.40-1.00-.78od ---- .72-.73-.71-.78
and the way I used to shift mine
2.66-1.92-1.40-1.09-.78od ---- .72-.73-.78-.71
Notice the short-Fourth, and subsequent deeper Fifth.
My car
is geared with 3.55s to make 65=2240rpm.
This is about the lowest rpm that I can give her the cruise-timing that she wants/needs. and so,
this is the rpm at which , with the current cam, makes the best fuel-economy. If I run her faster or slower, the fuel-economy will be worse. So there I am, "stuck" at 2240. and That means,
if I had a deeper overdrive, it would just cost me fuel economy.
In other words, with 3.55s, the GVod has the perfect split/perfect final drive ratio.
However, the starter gear of 2.66 x 3.09= 8.22, is a little shy of a good-time at take-off, so then, I installed the Commando trans, with ratios of
3.09-1.92-1.40-1.00 and added the GV to that
3.09-1.92-1.40-1.00-78. and in reverse shift pattern this is
3.09-1.92-1.40-1.09-.78 with splits of .62-.73-.78-.71
You see that progression? That's about the perfect Street march.
Shifting at 6000, the rpm drops in each gear are; 2280/1620/1320/1740
The starter gear is now;
3.55 x 3.09= 10.97; which takes off like 10.97/2.66=4.12s
For the money spent, this is a very hard combo to beat, and she is a pleasure to drive.
But it doesn't stop there.
I sometimes use the GVod as a splitter, for Seven useable ratios. Two are very close so I use only one of them. At the track The first four, get me to a trapspeed of 93 in the Eighth@6170 rpm. The ratios and splits are:
3.09-2.41-1.92-1.50 --- .78-.80-.78
You see that progression? This is THE perfect Ratio-march, for the track, with a small engine like mine. The rpm drops are ~1320/1200/1320.
When I stick it into 4od at 93 mph, the rpm drops to 3210, which is to 52%
Back to street;
The above configuration allows me to better run on the fattest part of the camshaft's powerband, and not suffer the usual drivability issues of a having a pipey cam, AND, I still get a nice take-off, AND great fuel-economy for the combo, AND, with 3.55s in the back, versus hi-4s or even 5-series gears, the oil stays cool and the gears last forever, and the driveshaft rpm at cruising speed, doesn't excite the usual A-body pulsation..
Finally,
using the GVod as a splitter, you can engage it in any gear, and at full throttle, which makes it shift like an auto trans except faster and harder, on account of the modest rpm drop. Shifting at about peak power of ~5200, in my combo, after the shift, puts her at about 4000, near peak torque. Sometimes for max fun, I wind her up to 7000 bouncing off the rev-limiter in those first four ratios, and just keep her there to 105mph; then, off the throttle, and into the last gear she goes, pulling the tach down to 3650.
Without the GVod, and with 4.10s@105mph, the rpm would have been ~5360.
Since 2004
when I installed mine, I've never been sorry. IMO, you will not get this kind of versatility in any other 5-speed configuration.
Would I have been happier with a regular 5-speed? IDK, I never tried it. But I doubt it .........
The real point I'm trying to make here, is that the GVod is so much more than just a .78overdrive.
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and BTW
It works pretty good with an automatic too, maybe better. I would have been able to give you a definitive answer, but the GV folks would not sell me just a stand-alone adapter.
Nor would they rent me one, just to try it out.
Nor would they sell me the tools to take one apart to rebuild it. which I was really miffed about when I broke mine.
So there's that...............
Oh and one more thing.
I have a pretty torquey 360 that sounds real sweet as it runs thru 2800>3200. So lots of times, I just run it up normally into that zone in First gear, the split into First-over, then back into Second-direct, then third, then Third-over. This gets me to 65=3140, and finally, into Fourth-over she goes.
Now imagine if you will, that you are in a car behind me, keeping pace, and hearing those five short ~600rpm shifts, then 900 into cruise gear. I do this a lot, So much fun I am having.
BTW-2
The truth is;
had I not been been confident that I would be able to use the GVod as a splitter, I would never have bought it. I would have continued to use the A833od, and kept the 223 size of cam, for it's outstandingly broad powerband, which worked reasonably well with that trans.