Anybody running a Gear Vendors OD?

I installed a gear vendors unit behind the TH400 in my 70 Grand Prix last summer. I’m pleased with the drop in rpm but as others have stated they do have their drivability quirks that you will need to get used to.
As Racingsnake said, The engagement of the overdrive can seem a little harsh, but not terrible.
I would question GV on how well it will fit the transmission tunnel of your car, I had to do pretty extensive surgery on my trans tunnel to get it all to fit. Ended up cutting out a section of floor board that was roughly 12” x 14” in size and modifying a factory floorpan strengthening rib. Wasn’t happy about having to do that but to get the correct u-joint angles that’s what needed to happen.
I have a 2004R sitting on my garage floor and considered using it before going with theGV unit. Some models of this trans are better than others but I wouldn’t consider any of the 2004R’s “strong” enough in stock form to stand behind much abuse in a 400+ hp street engine, but that’s my opinion only, Although they did put them in the 89 turbo V6 Trans Am and I think some GN’s got them too. I guess it would depend on how you drive and the weight of your car. There are a couple places that can build them up to withstand a large amount of horsepower but the cost goes up quickly. Check out Gearstar and a few other vendors for pricing.
The 2004R does have a better overdrive ratio than the GV unit or the 700R4. If I remember correctly it’s got a .67 final drive ratio versus .7 for the 700R4 and .7 something for the GV.
The 200 is lighter and smaller, nice added bonuses.
You might also look at the 4L65 but I am clueless as to installing one, overall dimensions and any carb hookup issues.
Good luck. 4:11’s are great fun in town if the cops are nowhere around, but it’s not much fun getting to town if it’s any distance.

 

Actually all of the intercooled grand nationals including the gnx came with 2004rs. Super easy trans to build up

 

I'm not totally opposed to a OD trans, I've just never had to set one up before. Hell, my built TH350 doesn't even have a kickdown lever, I downshift it by hand.
Seems like for the expense of doing the GV, I could get a decent 700R4 or 2004R. I'm also not opposed to the modern GM OD automatics, assuming they will fit the space. Supposedly the 4L60/65 has the same dimensions as the 700R4 it replaced? I know the E models of those transmissions need a trans controller, which I'm not opposed to.

 

With the 4L60E and 4L80E you can add a vacuum modulator kit to handle line pressure, and a full manual kit with a bump shifter, and you effectively have a clutchless manual vibe happening. No trans controller needed.
Let the fun begin.....

 

The 4L60 IS the 700. Same transmission, new naming scheme. The 4L60E is the electronic version.

 

I helped put a 350/700R4 in my buddies 56 Nomad. Just added a transmission crossmember (and side motor mounts). I presume you’ve already done that. No clearance problems. I also put a 2004R in an OT 67 Camaro in place of a powerglide. Slid right in, just dealt with the crossmember for the transmission mount.

Just out of curiosity, what you got for rear gears and tire height?

 

Between the 200 and 700 in my personal experience the 200 is a bit more forgiving on tv cable adjustment if you don't quite get it right as long as long as you aren't doing holeshot digs or hauling a gooseneck camper lol. One thing to note is that if you decide to go 2004r make for sure that it is a 2004r as I've seen people unknowingly (and occasionally knowingly) sell 200c's as 2004r

 

Correct, but line pressure in a 700R4 or 4L60 can't be controlled with a vacuum modulator kit. You will need the keep the TV cable with these earlier transmissions.

 

Yes and No Jim. That is basically true, but from it's original configuretion it evolved each year with improvements.... and then they changed the name to 4L60 its last few years of manufacture. So technically its the same transmission but the later versions are more desirable. They also changed the size/number of input splines somewhere along the line, so if changing to a 700R4/4L60 the swapper has to make sure they have the correct torque converter or they will mess things up.

You mentioned earlier that you had run a switch pitch converter, and I remember that used to be a popular set up. How about maybe a little elaboration on what you did and how it worked?


@Mr. Sinister...........If it were mine, since you are not running EFI on your motor, I'd stick with the versions that don't require a trans controller. The good side of an electronic trans control is that the newer E versions of the 4L60 are very common today and have all the factory upgrades, but trans controls can be expensive. A pre-Electronic 4L60/700R4 built with some aftermarket improvements should work well for you. Also with the OD trans, you get a lower first gear as well as the OD. As always, it comes down to what you want. If you decide to go with one of these transmissions I would suggest getting an aftermarket book about them before plunking any money down.

$27 on Amazon

 

the switch pitch converter has a stator with moving blades, the angle changes when hydraulic pressure is applied to a piston in the center of the stator. The piston is controlled by a solenoid mounted to the pump. So when you apply 12v to the wire on the side of the transmission, the stator angle changes, and stall speed increases. Stock was about 400-500 rpm increase, but aftermarket ones with modified stators can get more than that.

The TH400 used in Buick, Cadillac, and Olds used this setup through 1967. Chevy and Pontiac did not get it.

It was also used in the two speed SuperTurbine 300, same year era.

The ST300 converter was a inch smaller than the ST400, so the trick is to get the smaller converter from a Buick 2 speed, and the pump, drum, input shaft, from a Buick 400, and install it all in a Chevy TH400. I started doing this in 1980 in my old truck, and the truck still has this setup. I used one in my Chevy II that ran as quick as 9.86, and put 33k miles on it street driving. Pretty neat setup. But also it's very old technology.

 

They are like a poor man's overdrive, but actually more like an underdrive. It was designed to get 5000 lb barges up to speed with only 3 speed trans. I ran one in my Studebaker with a Gear Vendors like Squirrel which together provided lots of RPM adaptability. The Buick GS guys got into them a lot. I used a 13" PAE converter, 1300/3500 stall, or stahl if you're inbred! Anyways I built a dual purpose street/landspeed car and needed the ranges. I used 3.23:1 to have good stoplight acceleration but also effective 2.52:1 to get me all the way up to 205 MPH at 6,500 RPM. Parts are pretty scarce, and so is know-how. There's not a lot to the conversion if you have an older 400. A modern tech conventional converter can be almost as good though.

 

Thanks again for all the info guys, I appreciate it!
Leaning more and more toward a 700R4 built to task. My buddy has one sitting in his shop I could probably get for a reasonable price, and there's a local trans shop that does great work (they built the TH350 in my car currently).

 

One additional thing........If you go with a 700R4/4L60 , be sure that the TV (throttle valve) cable is adjusted correctly........"achilles heel" so to speak. There is lots of info on adjusting them, but the carb linkage on a Holley carb used with a 350 Turbo is wrong. You can get the correct geometry linkage from Holley. Use a pressure guage to adjust it, thats the most accurate way.

 

There’s a reason I asked about the rear gears. In the Nomad, the 700 tends to go into o/d a bit early, and the engine tends to lug a bit. Not a big surprise, we knew the transmission had been set up behind a 383LT engine in a light car (62 Vette). So it gets put into Drive (column shifter works for everything but low, never bothered to go beyond that in the linkage). But a good transmission shop will take all that into account when they set it up. The Nomad has only power to the lock up, and except for that works fine. It’s about a 3.5 rear end, and a 3.7 or 3.9 would solve it. 4:11’s would be perfect IMO.