Gear vendors OD

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Jason Holt

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Has anyone put a gear vendors overdrive kit on a 1967-69 Dodge Dart? If so what rearend gears were you running?
 
If you are just curious about what gears make a decent combination, I have a few observations.
I have a buddy that had a '71 Challenger. He ran a 416 with a 727. 4.56 gears and the Gear Vendors. Even in OD, it was still a gas hog. It was only raced a few times. He is a great guy but makes some bad decisions with cars. He later swapped in a Tremec 5 speed and switched to 3.91 gears.
I bought the GV unit and had it in my Charger with a 440/493 and 4.10 gears. I later switched to 3.91s with it. The 3.91s in OD were just over 3.05 give or take. Not bad at freeway speeds but the unit I had wasn't ideal. It was an early unit that had no mount for the floor shifter. An add on bracket had to be used. This resulted in sloppy shifter feel and the occasional habit of the trans NOT staying in PARK....W T F ?? Yeah, the car would start to roll and I'd be walking away....Huh?? Turn back and get in the car to smack the shifter a few times to get it to lock in. Also, the OD would sometimes NOT disengage as I slowed to a stop. Yeah....I'd end up leaving a stop in 1st OD and 2nd OD. THis was annoying.
 
I run one in my 67 Dart with 27" tire, 4.10 gear. 2800 rpm @75mph highway cruise. If you are not in the flow of traffic in FL you are asking for trouble. Gear reduction in O/D is .78 I only use a shifter mounted switch and a relay to manually control the O/D. A slight throttle bump when disengaging allows O/D to disengage smoothly. I've run 1/8 mile in 2nd over vs normal 3rd and the car picks up 1.5 mph. 1/4 mile I do not use it at all. I bought mine used and glad I did since round trip is 100 miles to run at the nearest track.
 
Thanks for the info I am thinking about putting one on my 67 convertible and running 3.91 gears with it. I've been told 340's work great with those gears.
 
I have run the GV in my 68 Barracuda/ 4-speed, with almost every gear you can think of from 2.76 to 4.88. and 5.38s besides. My favorite ended up being 3.55s. My 367 gots torque.
I actually liked 3.23s better with my 4 speed, but she traps to 60 slightly better with 3.55s and splitting gears, and traps at 93mph in the Eighth, running four tight-split ratios...

Depending on your camshaft, sometimes the engine will not get any better fuel economy, or say not significantly better, in overdrive as it might with say 3.55s ..So if fuel economy is your goal, then you have to gear your car to be in the engine's sweetspot, not just slam the rpm into the basement.
And then there are the costs involved. Depending on your annual mileage, it can take 5 to 10 years to break even, and you'll probably have to get it rebuilt at least once during that time. which will add maybe 5 years to the break-even. So
where will you be in 10 to 15 years?
As to fuel-economy, perhaps just broke even.
So, IMO, if fuel economy is your goal, there are more cost effective ways to deal with that.

Yes, I did install a GVod, but not for fuel economy. I split gears with it, to keep my small-cammed engine on the power peak for more average power to the ground per unit of distance. This makes my combo quicker than it should be given the cam that is in it, I trade away gear for a reduced cruise-rpm.
Between the small cam, and the overdrive, that is where some of the economy comes from. Another place is cylinder pressure; my combo runs ~180psi., Another is cruise timing. With the factory timing controls, it is impossible to give your engine the cruise timing it wants,at 2000 to 2200say; and if you don't, the fuel economy will just not be there.

I can tell you this; with a HFT cam of 230*@.050,and geared for 65=2240rpm, I have long-ago stopped trying for big-number fuel economy, It actually gets better with more speed.... At 80=2760, it's doing all right.... but I can only cruise at that speed when I go stateside.
And you know what's funny? 2760 in direct with 3.55s is 62.6 Mph,which is the speed limit in Manitoba everywhere except on certain parts of the Trans-Canada Hiway,lol. I must admit tho, that cruising at 2240 rpm trumps 2760, for NVH; that is Noise,Vibration, and Harshness.

If I was able to start over, this is not the path I would choose. It's been a lot of fun, but we have IMO, better options today than I had in 2002 or 2003, whatever year it was that I installed the GV.

Whatever you decide;
Happy HotRodding.
 
Last edited:
Jason Holt said:
Has anyone put a gear vendors overdrive kit on a 1967-69 Dodge Dart? If so what rearend gears were you running?
Click to expand...

I drove a car with one for a long weekend. It was just too little of a good thing with that set-up's overdrive ratio. I wish Gear vendors would offer in a deeper overdrive, but they don't.

I ended up using a built up 2004R, which has a .67 overdrive and a lock-up torque converter. Aside from that, it's also the best automatic transmission I've ever driven.
 
jbc426 said:
I drove a car with one for a long weekend. It was just too little of a good thing with that set-up's overdrive ratio. I wish Gear vendors would offer in a deeper overdrive, but they don't.
I ended up using a built up 2004R, which has a .67 overdrive and a lock-up torque converter. Aside from that, it's also the best automatic transmission I've ever driven.
Click to expand...



With an A904 automatic, the ratios are
2.45-1.45-1.00-.78 with splits of .59-.69-.78 It's actually a great set of progressive splits, keeping your engine in the powerband, IF you have a decent rear gear..... Like 4.10/4.30s.

It works even better with a 4 speed; the ratios are;
2.66-1.92-1.40-1.00-.78 with splits of
.72-.73-.71-.78
But if you shift 1-2-3-3od, then 4od, you get a nice short 4th, and a deep overdrive. It looks like this
2.66-1.92-1.40-1.09-.78 and splits of
.72-.73-.78-.71. If you combine that with a Commando box, the ratios are;
3.09-1.92-1.40-1.09-.78 with splits of
.62-.73-.78-.71 This work really well with 3.23s or 3.55s
But it doesn't stop there! I split those gears like so;
3.09-2.41-1.92-1.50, and then into 4th-over for splits of
.78-.80-.78-.52. This works awesome with 3.55s cuz 93=6150 in 1.50 gear, which is what my combo traps at in the Eighth. The starter gear is 3.09x3.55=10.97,, which compares well with 2.66x4.10=10.91.
The result of this is 4 very close-ratios with a deep low, and then that .52 split at the top makes 65=2240rpm
But it doesn't stop there;

Going back to autos, the A904 ratios are
2.45-1.45-1.00, splits of .59-.69.. If you split those, you get
2.45-1.91-1.45-1.13-1.00-.78 with splits of
.78-.76-.78-.88-.78
In this case you would shift; 1-1od-2-2od, them 3od for splits of .78-.76-.78-.69
That 2-od would get me 93@6150 again,now with 4.30s, the starter is 4.30x2.45=10.54, and 65=2710.. That's all very doable. But I will never have an auto.
The A999 ratios are slightly better at the top, and slightly not as good at the bottom. And the split from 2od to 3od is .65, and you can run 4.10s(or even 3.91s) instead of 4.30s
My point is this: if you buy a GVod strictly for the cruise-rpm reduction, yur leaving a lot of performance on the table. Install a bypass on the GV computer, and start splitting gears; the thing shifts like lightning. My combo gets to 93 mph with one pull on the stick, and two electric shifts. After the tach hits 7200 in first, it stays there all the way. Then later, I cruise home at 2240.

But it doesn't stop there. When cruising around I never split gears, so with enough torque, I shift at 2800, and pretend I'm a tractor.

The thing is, with a 230*@.050 cam, if I cruise at any less than 2240, the fuel mileage just gets worse, as the cam don't work right for that down there. My combo actually gets better mileage at a lil higher rpm
 
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